How Many Amps Does A Hot Water Heater Use

How many amps does an electric hot water heater use?

Asked in the following category: General The most recent update was made on June 30, 2020. A water heater of this sort must be treated as a continuous load, which means that the branch circuit must be estimated at 125 percent of the heater’s rated ampacity in order to be considered safe. 4500/240= 18.75 amps, which can be accommodated by a 20 amp OCPD, but 18.75*125 percent = 23.4 amps, which necessitates a 25 or 30 amp circuit. The use of an electric water heater necessitates the installation of a 240-volt dedicated circuit that serves just the water heater and no other appliances or devices.

What size circuit breaker do I need for a 40 gallon electric water heater, and how many of them do I need?

How many amps does a 50 gallon electric water heater consume in this manner?

I’m wondering how many amps a 6 gallon hot water heater consumes.

How Many Amps Does Water Heater Use?

It is likely that the water heater in your home is one of the most vital but least thought about pieces of equipment in your residence. When shopping for a new water heater, one factor to consider is the amount of electricity the new unit would consume. The amperage is critical in ensuring that you do not overload the electrical system of your present house. The normal amperage for an electric water heater is 18.8 amps at 240 volts and 4500 watts, according to the manufacturer. With 115Volts, the typical use of a gas water heater is less than 12 Amps (US and Canada).

  • Heater type, fuel type, capacity, and energy efficiency are all important considerations.

It is critical for every homeowner to be aware of the quantity of amps required by their water heater. Making a decision on a water heater may be a difficult undertaking, especially with so many options available. In any case, after you have gained an understanding of the numerous possibilities discussed below, you will be able to make an educated selection.

Heater Type: Tank or Tankless

It is possible to use a water heater in one of two ways: with a tank that holds water that is continually heated or with coils that heat water as needed. Tank heaters are often referred to as storage heaters or container heaters. These pieces of equipment are the oldest and most conventional types of equipment available. Tankless heaters are also referred to as on-demand heaters in some circles. These units have a more recent design. Storage water heaters, on average, consume less electricity than tankless water heaters.

Given the tankless heaters only operate when necessary, their overall power consumption may be reduced, depending on the amount of actual use they get.

What Size Breaker for a 40-Gallon Electric Water Heater?

Among home container heaters, a 40-gallon tank is the most often seen size. As a result, if you are installing this size unit in an older home, it is likely that you will be replacing a unit of comparable size. An old unit will have to be removed and replaced with a new one if an installation decides to use an older unit. In most cases, there is no additional charge. This size unit will often require a 30-amp circuit breaker, which is one of the most common sizes of circuit breakers found in residential buildings.

How Many Amps Does a Tankless Water Heater Use?

On average, an on-demand heater consumes 120 amps of electricity to operate, which is significantly greater than the consumption of typical heaters, which consume just 30 amps. Many older homes only have 100 to 200 amps of available power, necessitating the installation of a professional electrician to improve the electrical system. During this upgrade, an electrician may recommend that you have a subpanel of circuit breakers installed in your home in order to improve the overall amount of amperage that is available.

Fuel Type: Electric or Gas

The type of fuel that your water heater burns has an impact on the quantity of electricity it requires to function properly. A water heater will often be powered by electricity or natural gas to operate.

Electric Water Heaters

These sorts of units are less expensive to purchase than gas-powered units, but they are more expensive to operate. This is due to the fact that electricity is generally more expensive than natural gas on a per-unit basis. The energy consumption of an electric water heater is around $42 per month on average. However, because it may be connected to your home’s electrical system rather than requiring the installation of a gas line, this sort of heater is typically less difficult to install.

How Many Amps Does an Electric Water Heater Use?

An electric heater with a tank necessitates the installation of a 240-volt dedicated circuit with a 30-amp fuse. The fact that this type of equipment requires a dedicated circuit means that an electrical update for your home could be required. A 120-amp circuit breaker is required for a tankless electric unit. When installing this sort of gadget in an older home, the electrical system will need to be upgraded. When it comes to on-demand water heaters, this improvement represents still another additional price in terms of up-front fees.

Gas Water Heaters

Heaters that run on gas are typically 25 to 50 percent more expensive than heaters that run on electricity, according to industry standards. However, because they are less expensive to operate, they are more likely to make up for the price difference over the long term. For the ordinary household, a gas water heater will cost around $30 per month on average.

Due to the fact that gas units must be connected to a gas line, there may be an additional cost associated with installing such a device for the first time. This is especially true if you need to install a new natural gas line or improve your existing natural gas system to meet your needs.

How Many Amps Does a Gas Water Heater Use?

It will take 30 amps of electricity to power a gas water heater with a tank, which normally does not necessitate any changes to the home’s electrical system–even in older homes with just a total of 100 or 200 amps of service. A tankless device that works on gas will necessitate the use of a 120-amp circuit breaker. Because of the high amperage of this type of breaker, many older homes will require electrical system upgrades in order to support this sort of device.

Should You Change Your Heater’s Fuel Type?

Depending on who you ask, many people believe that if they currently have an electric water heater, it is difficult to switch to a gas one, or that the opposite is true. This isn’t always the case, of course. If you are interested in altering the sort of equipment you now have, all you need to do is consult with an expert. A large number of electricians and plumbers provide free consultations. Find a company in your neighborhood that performs this and just ask them to conduct an evaluation for you.

Some carriers may even be able to offer you with an estimate of the expenses over the phone, if you ask nicely.

  • Is the gasoline type you’re looking for available in your area? What will be the cost of the installation
  • Will the installation necessitate the acquisition of a permit
  • Will you be required to improve the overall amperage of your home? When you switch to this new gasoline type, how much will your monthly payment be?

Once you have answered the questions above, you will be able to determine whether or not changing the fuel type of your heater is worth the time, effort, and money required. Changing the fuel type of your heater may necessitate more effort and expense during the installation process, but it may be more cost effective in the long run.


It is only when you have hot water when you need it that a water heater is truly beneficial. Regardless of whether the unit has a tank or not, or whether it is powered by gas or electricity, if it is not the proper size for your household’s water needs, it will not function properly. It is also dependent on the capacity of your heater as to how much power it will demand from it. Storage water heaters, for example, come in a variety of tank sizes ranging from 20 to 80 gallons. The larger the tank, the greater the amount of energy required to heat the water.

  1. You should increase the size of your water tank by 10 gallons for each new person that lives in your house.
  2. Your electricity or natural gas utility bill will rise in direct proportion to the amount of power the device consumes at any one moment.
  3. To put it another way, if you want to be able to take a shower while also doing laundry and running the dishwasher, you must add the flow rates of each of these machines together.
  4. Using the Tankless Water Heater Sizing Diagram, you may determine which size heater will be most suitable for your needs.

When it comes to heater capacity, it is critical that you strike a balance between the demands of your home and the electrical capacity of your heater. It may seem enticing to get a unit with the highest capacity available, but doing so may demand more amps than your home is capable of providing.

Energy Efficiency

According to studies, heating a home’s water accounts for around 18 percent of the overall energy consumed by the residence. The efficiency with which your heater utilizes energy will also have an impact on the number of amps the device consumes. Generally speaking, the more energy-efficient a heater is, the more amps it will require to operate. However, even though a more energy efficient heater may require more amperage to turn on, the unit will be in use for a shorter period of time, resulting in a reduction in overall energy costs.

In the event that your unit is more than 10 years old, it may be time for you to consider upgrading to a more energy-efficient model.

However, because natural gas is often less expensive than electricity, the two units are typically equal in terms of cost.

This mark indicates that the device complies with the Energy Star requirements.


Having access to hot water when you need it is no more a luxury, but rather a need in today’s day and age. As a result, you must locate a unit that is within your budget, both in terms of up-front fees and ongoing operating expenses. It is also critical to evaluate the total quantity of energy that your water heater will use from your home in order to verify that your electrical system is capable of handling the demand.

What Size Breaker for a Hot Water Heater: A Breaker Size Solution

Is your electrical water heater tripping the breaker on a regular basis? Is it possible that your heater overheated without you noticing? You have clearly indicated that you are experiencing difficulties in matching your appliance with its safety device based on just a few questions. What size breaker do you recommend for a hot water heater, I hear you ask? For the most part, 30-amps is the common size for heaters. It is important to note that this breaker ampacity does not necessarily work for every water heater available.

Understanding Your Water Heater

When purchasing an electric water heater, one of the most common mistakes made by homeowners is failing to verify the amperage rating of the unit. Some heater tanks are just labeled with the voltage and wattage requirements, but not with the ampacity requirements. It is preferable if you obtain your tank specs from the shop or the brand manufacturer directly themselves. The size of your heater must serve as the foundation for establishing the appropriate breaker size. The following are the three criteria you should examine in order to assure your safety: Voltage-The volts provided by your boiler are critical to the operation of a properly functioning circuit.

Make a note of how much power your heater requires and include it in your list.

It will assist you in your quest for a proper breaker to manage the situation.

Last but not least, it is necessary to understand which cable type is suitable with the breaker size of your hot water heater. An mismatched size or broken cables that have been reused might put your heater and breaker at greater risk than they are worth.

A Breaker Size Solution: What’s the Formula?

If you’re unsure of the amp size you’ll need, doing a simple calculation will provide the answers you need. Knowing the wattage and voltage of your water heater already, all you have to do is follow the Ampere formula, which is I (amps) = P (watts)/V (voltage) (volts). As an example, I have a 3,000-watt heater tank that requires 120-volt power to operate. You must divide your watts by the number of volts in order to obtain its amperage. Solution: I = P/VI = 3000 watts / 120 volts is the formula.

  1. You could be thinking that a gadget with a current of 25 amps necessitates the use of a breaker with the same capacity.
  2. The National Electric Code (NEC) stipulates that you must maintain a continuous load of 125 percent of the maximum continuous load at all times.
  3. Applying the continuous load rule to the previous example, we get 31.25 amps: 125 percent x 25 amps = 31.25 amps.
  4. The Square D by Schneider Electric HOM235CP is a highly recommended device for a 35-amp circuit breaker.
  5. Allowing enough room for your breaker will allow a power surge to occur without triggering the breaker.
  6. to get a better understanding of how to properly size your water heater wires and breakers!
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What Size Breaker for 40 and 80-Gallon Water Heater?

Most households utilize a water heater with a tank capacity ranging from 40 to 80 gallons, depending on how much they rely on warm water on a daily basis. You’ll need their wattage and voltage to figure out how many amps breaker for water heater of these tank sizes you’ll require, and then you’ll use the answer from earlier. The typical capacity of a 40-gallon heater is 4500 Watts at 240 Volts, according to the manufacturer. Using the formula I = P/V once more, 4500W/240V Equals 18.75 amps. Then, taking into account the continuous load (125 percent x 18.75A), we’ll arrive at a total of 23.4 amps.

However, I strongly advise utilizing 30-amp breakers because they are a more secure breaker size.

This means that a 30-amp dedicated circuit breaker is sufficient.

Pro-tip: Although a 30A breaker appears to be insufficient for an 80G tank, putting a 40A breaker will not safeguard the device in the event of an overloaded circuit. A breaker amperage that is far higher than necessary will not trip when it is required.

What’s the Correct Wire Size for a Water Heater?

If the wiring between a water heater and its breaker is mismatched, the connection will not function properly. Check that the amperage of your heater corresponds to the size of the wires on it. You can use the following list as a guide:

  • 20-amp heaters require 12-gauge cable
  • 25-amp heaters require 10-gauge wire
  • 30/40-amp heaters require 8-gauge wire
  • And other big heaters up to 50-amps require 6-gauge wire.

Also, evaluate the size of your water heater’s circuit breaker. Circuit breakers rated at 30 amps, which are often used for big boiler tanks, require a 10-2 nonmetallic or MC cable. It is appropriate for starting loads up to 40 amps and a steady load up to 35 amps with this type of wire.

Preventive Measures Before Buying a Circuit Breaker

When selecting the appropriate water heater circuit breaker size, it is important to be mindful of the amp differential between the breaker and the water heater. It’s critical that you obtain the correct size. A breaker that is either too large or too little might result in an electrical hazard. If your circuit breaker is too tiny for the amperage needs of your water heater, you should anticipate your CB to trip on a regular basis. Not only that, but too much switching on and off of the heater might result in internal damage to the device.

A breaker that is capable of handling a larger amperage than designed does not always imply that it is safer for the heater.


Choosing the appropriate size circuit breaker for a hot water heater is not that difficult if you obtain the necessary information. You can determine the right breaker size simply by studying the three wire heater factors — voltage, wattage, and wire size — and how they interact. A basic calculation would also suffice, but keep the breaker size as close as possible to the quantity of your response (the actual amp size of the heater). A 30-amp circuit breaker is commonly used for an electrical water heater, thus a circuit breaker such as the Q230 30-Amp Double Pole Type QP Circuit Breaker will be suitable for the job.

How Many Amps Does A Tankless Water Heater Use? (42-167 Amps)

Electric tankless heaters heat water solely with electricity and do not need any other fuel. As we all know, boiling water is a time-consuming and difficult operation. As a result, electric tankless water heaters demand a large amount of electricity current, measured in amps. Tankless water heaters consume a certain amount of electricity. Tankless heaters may draw anywhere from 42 amps to 167 amps, depending on their size. We can compute exactly how many amps a tankless water heater consumes since we understand two important factors:

  1. The total amount of power, measured in watts. Voltage and power input for electric tankless water heaters can range from 10,000W (10 kW) to 40,000W (40 kW)
  2. And temperature. All electric tankless water heaters run on a 240-volt circuit in order to limit the amount of electricity consumed.

In order to compute the using the electric power equation (P = IV), we must first express the I (or electric current) in the following way: (amps) = P(watts)/ (volts) (volts) Example: Consider the following scenario: a 30 kW tankless water heater is connected to a 240-volt circuit. In what range of amps does a 30 kW tankless water heater operate at? The electrical power equation is used in the following manner: It is calculated as follows: I(amps)=30,000W/240V = 125 amps A heater of this nature consumes 125 amps (you need several 20-amp or 30-amp breakers for installation).

We evaluated the amp draws for tankless water heaters ranging in power from 10 kW to 40 kW and summarized them in the following table:

How Many Amps Do 10-40 kW Electric Tankless Water Heaters Draw?

All of these estimates are based on the assumption that the heater is powered by a 240-volt circuit.

Tankless Heater Size (in kW) Electrical Current (in Amps)
10 kW 42 amps
11 kW 46 amps
12 kW 50 amps
13 kW 54 amps
14 kW 58 amps
15 kW 63 amps
16 kW 67 amps
17 kW 71 amps
18 kW 75 amps
19 kW 79 amps
20 kW 83 amps
21 kW 88 amps
22 kW 92 amps
23 kW 96 amps
24 kW 100 amps
25 kW 104 amps
26 kW 108 amps
27 kW 113 amps
28 kW 117 amps
29 kW 121 amps
30 kW 125 amps
31 kW 129 amps
32 kW 133 amps
33 kW 138 amps
34 kW 142 amps
35 kW 146 amps
36 kW 150 amps
37 kW 154 amps
38 kW 158 amps
39 kW 163 amps
40 kW 167 amps

You can correctly determine how many amps your tankless hot water heater consumes by using this amp draw table. After that, you can figure up how many amp breakers you’ll need for the installation process. For those looking for a tankless water heater, you can see our list of the best tankless water heaters right here.

How many amps does a tankless water heater draw?

As an Amazon Associate, I may get a commission on eligible purchases made by you at no additional cost to you. will direct you to Amazon for all of the goods that are recommended on the site. Tankless water heaters have received a great deal of attention in recent years, mostly due to its capacity to offer you with an almost limitless supply of hot water at all times. But, at the same time, you must be fully informed of the qualifications, which include how many amps does an agas tankless water heater use.

  • When a tank water heater with 4,500-watt elements is operated on 10 wires and a 30-amp circuit breaker, the overall electrical load is 28,000 watts
  • When a whole-house tankless water heater is operated on four, 7,000-watt elements, the total electrical load is 28,000. This load necessitates the installation of cable and a circuit breaker capable of handling at least 120 amps, at a cost that is several times more than that of providing electrical service to a traditional tank water heater.

So, how much electricity does a tankless water heater consume? In order to function properly, the average electric tankless water heater requires at least 120 amps. Unfortunately, the overall capacity of the ordinary home is just 200 amps. You’ll have to improve your electrical system to match the increased load demand, which is what it really implies. Not only that, but the increased load would need the installation of a larger, more expensive meter loop and main panel for the residence. Nonetheless, you as the end customer may be responsible for the cost of the wire that connects the neighborhood distribution transformer and the electric meter.

  1. You can figure out how many amps your tankless water heater consumes by doing some math on your own.
  2. A typical electric tankless water heater may produce power of between 10,000 watts (10 kW) to 40, 000 watts (40, 000 kW) (40 kW).
  3. In order to compute the using the electric power equation (P = IV), we must first express the I (or electric current) in the following way: (amps) = P(watts)/ (volts) (volts) Example: Consider the following scenario: a 30 kW tankless water heater is connected to a 240-volt circuit.
  4. The electrical power equation is used in the following manner: It is calculated as follows: I(amps)=30,000W/240V = 125 amps A heater of this nature consumes 125 amps (you need several 20-amp or 30-amp breakers for installation).
Tankless Heater Size (in kW) Electrical Current (in Amps)
10 kW 42 amps
11 kW 46 amps
12 kW 50 amps
13 kW 54 amps
14 kW 58 amps
15 kW 63 amps
16 kW 67 amps
17 kW 71 amps
18 kW 75 amps
19 kW 79 amps
20 kW 83 amps
21 kW 88 amps
22 kW 92 amps
23 kW 96 amps
24 kW 100 amps
25 kW 104 amps
26 kW 108 amps
27 kW 113 amps
28 kW 117 amps
29 kW 121 amps
30 kW 125 amps
31 kW 129 amps
32 kW 133 amps
33 kW 138 amps
34 kW 142 amps
35 kW 146 amps
36 kW 150 amps
37 kW 154 amps
38 kW 158 amps
39 kW 163 amps
40 kW 167 amps

HVAC Metrix (Heating, Ventilation, and Air Conditioning) The SEER equation is (1 EER100 percent + 42 EER75 percent + 45 EER50 percent + 12 EER250 percent)/100EER = BTUcooling/WHSPF = BTUheating/WCOP = Q (useful heat)/WCOP = Q (useful heat)/WCOP = Q (useful heat)/WCOP = Q (useful heat) (input work) Air conditioning capacity (ACH) = CFM x 60/Area x Heightceiling CFM x h = 4.5 times the total heat (BTU/hr) (std.

  1. air) Temperature Sensitive Heat (BTU/hr) = 1.1 times the CFM times the time (std.
  2. air) 1 horsepower is equal to 746 watts.
  3. o, you might be thinking, how can I determine whether or not my home’s electrical system need an upgrade, right?
  4. Just so you’re aware, if you’re intending to replace your conventional water heater with a tankless equivalent in your existing house, the installation costs will be significantly more than they would have been if you’d chosen to build the tankless heater from scratch.
  5. What would be the result of this?
  6. Low voltage or rapid voltage reductions, on the other hand, are likely to result in dimming or flickering lights, as well as a variety of other issues.

Trust me, I’ve encountered issues such as flashing lights in the past, and after conducting a root cause study, I discovered that connecting 28-kW tankless units in houses with 150-amp services to 10-kW transformers was a clerical error on my part.

Gas Tankless vs. Electric Tankless: Which model requires up-gradation of a home electric system?

To put it another way, it ALL DEPENDS. But, I’m confident that you aren’t here to accept this response, are you? Let’s conduct some further study and delve a little deeper into the subject. Simply said, based on my knowledge and experience, I can state that a gas tankless system does not often necessitate the upgrade of a home’s electric system, as an electric tankless system does. I believe this is true. Also important to note is that the majority of the gas tankless water heaters that we’ve examined on this blog have earned the Energy Star certification, and many of them are even eligible for federal tax incentives.

How many amps does a Rinnai tankless water heater use?

To be quite honest, Rinnai tankless water heaters are among the finest in their respective categories. The firm has proven its mettle time and time again by supplying cost-effective, high-efficiency goods, such as tankless water heaters, to its customers. Rinnai Tankless Water Heaters require 120 volts alternating current at 60 hertz and less than three amps to operate.

Are tankless water heaters 110 or 220?

Tankless water heaters are available in both 110V and 220V types, so you’ll be able to pick one that suits your needs. As a result, you may select the one that is most compatible with your household electrical requirements. Most of the power consumed by the tiny tankless heaters, such as those used at the point of use or beneath the sink, is 110V. The powerful tankless heaters designed for commercial use, on the other hand, require significantly higher voltages to operate.

How many amps is a 50-gallon water heater?

A common electric tankless water heater operates at a maximum power of 4500 watts. Many of you may not be aware that 4500 watts is equal to 18.75 amps in a 240-volt electric circuit, which is something that many of us take for granted.

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Are most hot water heaters 220?

The majority of electric hot water heaters operate on alternating current (AC) voltages ranging from 220 to 250 volts. When purchasing a tankless water heater for your house that operates on 220 volts, you should be aware that this voltage in a home necessitates the installation of a double circuit breaker rated for the amperage demand of the hot water heater.

How many BTUsdo I need for atankless water heater?

Due to the significant amount of gas required to heat the water to an appropriate temperature (usually between 150,000 and 200,000BTUs), an average home would require an upgrade in the size of the gas line to accommodate this requirement.

How many amps does an electric hot water heater use?

The majority of the electric tankless hot water heaters that we’ve tested on our site so far have required a dedicated 30-amp, 240-volt circuit breaker to function properly. The use of an electric water heater necessitates the installation of a 240-volt dedicated circuit that serves just the water heater and no other appliances or devices. In most cases, the circuit wiring will consist of a 30-amp double-polebreaker and 10-2 non-metallic (NM) or multi-conductor (MC) cable.

What size breaker do I need for a 40-gallon electric water heater?

To be honest, the normal household 30- or 40-gallon water heater consumes around 4500 watts, and if my memory serves me correctly, they are often powered by a 30 A circuit breaker.

What size breaker do I need for a 4500-watt water heater?

The breaker is designed for 30 amps because this is an entirely resistive load (5500 watts at 240 voltage equals 23 amps), and the wire is 10 AWG because this is a completely resistive load. Using your example, the elements are strapped for 4500 watts, which results in 18.75 amps of permanent draw. Permanent draw loads should be designed at 80 percent of breaker capacity, therefore a 20 amp breaker is only capable of delivering 16 amps of permanent draw.

What size breaker do I need for a 3000-watt water heater?

240 volts may be supplied via a 14/2 cable and a 15 amp double pole breaker, which can power a 3000-watt induction motor.

What size breaker do I need for a 7500-watt heater?

7500 watts divided by 240 volts equals 31 amps, requiring a 40 amp circuit breaker.

What size breaker do I need for a 5500-watt water heater?

According to the calculations, a 5500-watt water heater is well within the safe maximum for a 30 amp breaker and a 10-gauge electrical cable. When the temperature of a circuit breaker exceeds its rating, the circuit breaker trips. A 30 amp breaker with a 10 gauge wire has an 80 percent safe maximum of 24 amps, which is equivalent to 24 amps. 24 amps multiplied by 240 volts equals a safe maximum of 5760 watts.

Does an electric water heater require a disconnect?

An electric water heater does not require any type of disconnect other than a circuit breaker at the main panel or sub panel, nor does it require to be visible, according to the National Electrical Code (NEC).

Wrapping Up

First and foremost, I’d want to express my gratitude for remaining with us to the very end. Second, I would like to bring your attention to the fact that I, along with my core team, have attempted to answer some of the frequently asked questions, such as how many amps does a tankless water heater draw, in the most accurate and thorough manner that we were able. I hope you find this information useful. And, if you were pleased with our efforts and would like to express your gratitude to us, all you need to do is forward this information to those who could benefit from it.

  • Will Vinegar cause harm to a hot water heater if used? This article will cover all of the basics of tankless water heaters. Is it possible to run out of hot water while using a tankless water heater? I’m not sure what size tankless water heater I need. Is it worthwhile to invest in a tankless water heater? Will a single tankless water heater be sufficient for my home? The advantages and disadvantages of tankless water heaters
  • How long does it take for a tankless water heater to pay for itself to become profitable?

How Many Amps Does a Water Heater Use?

As an Amazon Associate, this website receives a commission on eligible sales made via it. For further information, please see this link. Knowing how many amps a water heater consumes is critical if you want to save money on your energy bills. This article concentrates on electric water heaters since they are the most popular type of water heater used in households; however, the formulae may be applied to a variety of other types and designs as well. A 4000 watt water heater operating at 120V consumes around 33.3 amps.

Water Heater Amp Size Guide

Here is a table showing the most common water heater watt capabilities and how many amps they consume, in case you don’t want to perform any calculations. The same water heater will draw varying amps depending on the voltage, as you can see in the diagram. According on the heater wattage, voltage, and running time, the amps drawn will vary. These power consumption figures are provided just as a point of reference.

Because of variations in manufacturing design, the amount of water used by your water heater may vary. In order to find out how much electricity your water heater consumes, go to the owner’s handbook that was included with your purchase.

Watts Amps 240V Amps 120V Amps 24V Amps 12V
1000 4.1 8.3 41.6 83.3
1500 6.2 12.5 62.5 125
2000 8.3 16.6 83.3 166.6
3000 12.5 25 125 250
4000 16.6 33.3 166.6 333.3
4500 18.75 37.5 187.5 375
5000 20.8 41.6 208.3 416.6

The capacity of water heaters is also measured in gallons. The sizes recommended in the following table are based on the number of people who will be using it. The majority of these water heaters have at least 4000 watts of power, with some of the bigger models reaching 5000 watts or higher. As you can see, a 4000 watt water heater will require 416 amps per hour in order to run off of a 12V battery, which is quite a bit. A few ofMighty Max 250ah batteries will be sufficient for the purpose at hand.

These are just for the sake of reference.

For further information, please refer to the owner’s handbook that comes with your device.

Number of Individuals Size (in Gallons)
1-2 30-40
2-3 40-50
3-4 50-66
5 or more 66-80

Please keep in mind that these size suggestions are just intended to serve as broad guides. Water use varies widely not just from family to household but also from individual to individual, thus take into consideration your particular water consumption when determining what gallon is reasonable. The most accurate approach to determine this is to keep track of how much water each member of your household consumes. Your electricity statement will give you an estimate of the entire amount of energy you have consumed.

Water Heater Amp Calculation Guide

Water heaters are available in a variety of forms, sizes, and designs. As well, use ranges from 10 minutes per day to more than 5 hours per day, therefore you must take into consideration your unique requirements when using these estimates. The formula for calculating this is as follows: Watts of the water heater divided by voltage equals amps drawn If you have a 4500 watt water heater that is connected to a 240V alternating current outlet, it will use 18.75 amps per hour. This means that a 4500-watt water heater takes 18.75 amps from its electrical supply, which is divided by 240.

If the gadget is used for three hours, multiply the amps by three to get the total power consumed.

The equivalent of 18.75 amps per hour is 9.3 amps for 30 minutes, thus 10 minutes would be around 5 amps in total.

Can a 240V Water Heater Run on 120V?

Yes, most 240V water heaters may be operated on a 120V power source. The owner’s handbook will provide information on whether or not your vehicle may be towed. Even if it is possible, the amps that are pulled will be different. Let us use the same example as before, a heater with a 4500-watt capacity. The heater consumes 18.75 amps per hour when operating on a 240V system. However, if you were to plug it into a 120V AC outlet, the power consumption would be as follows: 4500 / 120 = 37.5A A 4500 watt water heater consumes 37.5 amps per hour when connected to a 120V system.

The greater the voltage power, the lesser the amount of current drawn is likewise. Some of these heaters can also be operated at 110 volts, although the amp draw will be larger, despite the fact that the difference between a 110V and a 120V system will be far smaller.

What Inverter Size Do I Need For a Water Heater?

You may use an inverter to power a water heater as well as a variety of other appliances, such as a television, refrigerator, kettle, and other items. In order for this to operate, you will need a substantial amount of battery capacity. In addition, a 4000 watt water heater need the availability of 5000 watts of inverter electricity. Assuming you have a 5000 watt inverter ready to go for the water heater, the next issue is: how many batteries will you need to power the water heater? If a 4500 watt water heater consumes 18.75 amps at 240V and 37.5 amps at 120V, the same figure on a 24V inverter system would be:4500 / 24 = 187.5 amps.

  1. To summarize, a 200ah battery will operate a water heater for an hour and a 600ah battery will run a water heater for three hours.
  2. This is not recommended since deep cycle batteries need to be recharged at a rate of 50 percent or higher.
  3. It is possible to lower the duration of the water heater to 30 minutes or increase the capacity of the battery bank from 200ah to 400ah.
  4. If you use 12V batteries, the requirements are much greater, since they are twice as high as those for 24V batteries.
  5. The idea is that a huge inverter and battery bank are required for a water heater to function properly.
  6. If you have a solar system that is connected to the power grid, the heater can be powered by electricity.

How Many Solar Panels Do I Need to Run a Water Heater?

It is feasible to utilize solar panels in conjunction with a water heater, yes. In order to do so, you will need a huge solar array, in addition to either a battery bank or some type of backup power source. A 4000 watt water heater will require at least 4500 watts of solar electricity, which is equivalent to 12 x 350 watt solar panels. These will occupy a total area of around 210 square feet of floor space. Because there are 5 hours of sunlight each day, there should be enough electricity to keep the heater running throughout the day.

  • The greater the number of daylight hours, the longer you can keep the heater running.
  • If the heater is not in use for as long as possible, the amount of solar power required will be significantly reduced.
  • A refrigerator, air conditioner, and other appliances may be powered by a solar array with a capacity of 4000 watts.
  • The second disadvantage is that you will be unable to use the heater if it rains or if the sky becomes overcast.
  • As previously demonstrated in the calculations, a number of huge batteries are required to power the whole system.

As a result of these considerations, a smaller water heater or a solar water heater is preferable for an off-grid setup.

Are Solar Water Heaters Worth It?

It is preferable to utilize a solar water heater rather than operating water heaters off of solar panels as an option. This should not be mistaken with ordinary electric water heaters that are powered by solar panels or batteries, since they are designed only for the purpose of water heating. Solar water heaters are similar in appearance to solar panels and are mounted on roofs. Built-built collectors attract sunlight into the heater, where it is transformed into energy, which is then utilized to heat the water in the system.

  • There are two types of solar water heaters: electric and solar thermal.
  • An active direct system transfers hot water to showers and faucets by a direct connection.
  • It is necessary to use convection to heat water in passive solar water heaters because they do not have any built-in pumps to do so.
  • In a thermosyphon system, water is heated by metallic plates, which are then conveyed from the valves to the faucets through the system.
  • In either case, they are more convenient to operate than a traditional water heater and consume less energy.
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The wonderful thing about water heaters is that they are long-lasting, and you should only need to purchase one, which should last for several years. You will not have any problems running your water heater from alternating current, batteries, or a solar panel once you get the calculations figured out. Alternatively, as demonstrated, you may use a solar water heater to heat your water.

Electric Water Heaters

The address is PE-208 Fairways Dr., Vicksburg, MS 39183. Dr. Ray Franco, PhD The majority of electric hot water heaters are built to work with 240 VAC power. Heating elements of 4,500 watts are the de facto standard size, which equates to 18.8 amps and 12.8 ohms when measured in amperes. Despite the fact that most electric hot water heaters include both an upper and a lower heating element, they are often configured for non-simultaneous operation rather than simultaneous operation. In other words, only one of the two heating components is “on” at any given moment (see link below).

  1. According to the National Electrical Code, the smallest size wire necessary for this load is AWG10 (American Wire Gage), with a circuit breaker of either 25 or 30 amps.
  2. The heating components are encircled by a body of water.
  3. Each heating element has a thermostat that may be adjusted (the typical temperature range is 120 °F to 160 °F).
  4. In addition, all electric water heaters must be equipped with a temperature/pressure relief valve that activates when the water temperature reaches 210 degrees Fahrenheit and/or the pressure reaches 150 pounds per square inch.

For Temperature and Pressure Relief Valves, the ANSI Z21.22 Standard is applicable. To get the highest possible resolution, click on the picture’s body.

What Size Breaker Does a Water Heater Need?

Circuit breakers are required for the operation of your electric water heater and gas tankless water heater. Choosing the incorrect size circuit breaker, on the other hand, might result in poor safety and even damage to the water heater. Because of the increased electrical flow via the breaker, the wires are at risk of overheating, resulting in a fire and inflicting damage to your water heater. Circuit breakers and wiring for electrical safety are specified in the National Electrical Code, which defines rules for their sizing and installation.

  1. For safety reasons, it is suggested that you purchase a circuit breaker with more capacity than the electrical load of your electric devices – in this example, your water heater – to ensure that you are not electrocuted.
  2. This indicates that the breaker only provides power to the water heater and does not provide power to other appliances.
  3. On occasion, I’ll come upon a 4500-watt water heater that has a 20-amp circuitbreaker.
  4. The size of the breaker is decided by the wattage of the heating components, not the size of the storage tank.
  5. 240-volt circuit breakers are required for a water heater that has a 4500-watt heating element.
  6. With a smaller 12/2 cable and a 20 amp circuit breaker, the 3800-watt heating element may be connected to the rest of the system.

Sizing Water Heater Breakers

Understanding how a water heater works is essential to determining the appropriate size for the heater to be installed. Electric water heaters operate on alternating current, which ranges from 220 to 250 volts in voltage. You’ll need a double circuit breaker that’s rated appropriately for the amount of electricity the water heater is drawing. For most electric water heaters, we’re looking at a current of between 20 and 30 amps. When determining the appropriate size based on the power needs, it is also necessary to consider the wire gauge size.

Element Watts Breaker Size 120v Breaker Size 220v Wire Gauge
1500 15 amp 15 amp 14
2000 20 amp 15 amp 14
2500 30 amp 15 amp 14
3000 30 amp 15 amp 12
3500 NA 20 amp 12
4000 NA 25 amp 10
4500 NA 30 amp 10
5000 NA 30 amp 10
5500 NA 40 amp 8

How Do You Calculate Breaker Sizing?

The power and voltage ratings of your water heater should be checked. The wattage and voltage rating of a water heater are labeled on a sticker that is attached to the thermostat panel. This information may be found around the base of certain heaters. While the majority of household water heaters have a capacity of 4500 watts or less, commercial water heaters can exceed 5500 watts or more. Let’s get down to the nitty gritty of determining the breaker sizes. 4500 divided by 240 equals 18.75 amps.

  1. If you have a 4500-watt water heater that runs on 240 volts, you should be able to get 18.75 amperes out of it using the conventional division formula.
  2. As a result, multiply 18.75 by 125 percent to account for the fact that a water heater operates on a continuous load.
  3. When we round that value down to the next tenth, we obtain 25 amp.
  4. It is commonly utilized because the minimum rating of 220 volts is greater than the 25 amp rating of the 25 amp breaker.
  5. 20.45 amps multiplied by 125 percent equals 25.568 amps, which is rounded to 30 amps.
  6. After all, it’s closer to 18.75 than 18.75.
  7. However, according to the National Electrical Code’s 125 percent guideline, a 20 amp circuit poses a danger of frequent tripping and might cause damage to the water heater.

An electrical breaker of 25 amps is sufficient; however, most electricians will construct a 30 amp circuit to allow for electrical fluctuations such as those described above.

What Size Circuit Breaker for Gas Tankless Water Heaters?

Compared to electric tank water heaters, gas tankless water heaters consume less electricity and produce less voltage. Typically, it’s around 12 amps and less than 120 volts in voltage. In order to power the electronic ignition system on gas tankless water heaters, a little quantity of electricity is required. A gas tankless water heater only requires a dedicated single-pole breaker with a 15-amp, 120-volt rating for this reason.

Should I Have Electric Water Heater or Gas Water Heater?

This decision is based on your geographic location as well as the utility costs in your region. Gas water heaters, on the other hand, are often more expensive to purchase up front but less expensive to operate than electric water heaters. In contrast to gas water heaters, electric water heaters are more energy efficient than their gas counterparts. The cost of gas is 40 percent more than the cost of electricity. As a result, it would be more cost effective to utilize gas. Electric water heaters, on the other hand, are more cost-effective when considering the time saved over time.

If you want to make changes to your home in order to accommodate electric, gas, or tankless water heating systems, you should consult with a specialist.

Before beginning any job, you should contact with a competent expert and verify that all necessary permits have been obtained.

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How Many Amps Does a Tankless Water Heater Use

In the event that your heating or air conditioning system requires repair or replacement, we can link you with a dependable and cost-effective specialist in your region. Tankless water heaters are fantastic since they don’t take up much storage space (just a third of a 10-gallon tank), but they’re also great because they save you money on electricity and fuel. Tankless water heaters use less fuel and water than traditional water heaters since they provide hot water on demand. Tankless water heaters, regardless of the type of device you pick (gas or electric), can save you 30 percent to 50 percent on your energy cost by reducing your water usage.

How many amps do tankless water heaters need?

Before you can decide between a gas tankless water heater and an electric tankless water heater, you must first gather all of your information. In certain cases, a gas type may be more suitable for your household, whilst an electric tankless unit may be the best option for your home in other cases.

Due to the fact that gas-fired devices run on gas (propane or natural gas), it goes without saying that their amperage requirements differ from those of electric-powered equipment. Continue reading for more information.

How many amps does a gas tankless water heater use?

If you decide to go with a gas model, you’ll need to think about the venting needs as well as the condition of the existing gas line. Some manufacturers provide gas venting “kits,” which you must purchase in order to complete a correct installation. When it comes to amperage requirements, gas-fired tankless water heaters require just a bare minimum of an electrical connection. When purchasing a model, it is important to review the installation requirements for that model.

How many amps do electric tankless water heaters require?

Given that tankless water heaters only use fuel while you are actively utilizing the hot water, it stands to reason that you will use less fuel and energy overall. A conventional electric tankless water heater requires at least 120amps to operate, with a total capacity of 200amps for a typical family of four people. If you decide to go with electric tankless water heaters, you should consider the following considerations:

  • Voltage- a large number of manufacturers provide devices that accept 110V, 120V, 208V, 220V, 240V, or 277V. When it comes to amp draw, different electric tankless units have varying demands on their power supply. It doesn’t matter which route you go, you should always make sure that your home can handle the electrical needs of your water heater. Circuit breaker- It is very necessary to have a circuit or circuits that are specifically designed to handle the electric water heater. It may even be necessary to connect the water heater to a separate circuit or circuits in some cases.

The fact that you’ll need to modify your electrical system to accommodate a higher load demand makes reasonable, and you’ll likely find yourself out $1,500 in your pocket rather shortly. Not to mention that special equipment for electric tankless water heaters needs to be placed at the meter base in order for them to work. Increase the budget by $2,000, which makes the electric tankless water heaters appear to be more costly than the standard electric water heaters on the market. For electric tankless water heaters, the breaker size and wire gauge must conform with the municipal, state, provincial, and national electrical codes that apply in your jurisdiction.

  1. It is important to remember that the wiring must be sturdy enough to ensure a voltage drop of less than 3% while the system is under load.
  2. Recently released types of classic tank-style water heaters have excelled with their efficiency, achieving an impressive 0.94 energy factor on average.
  3. If you already have a large number of electrical equipment in your house, it is likely that you will want a more extensive electrical service than you already have.
  4. All that is required is an update to the electrical service, which should not be done before consulting with a competent electrician for a price.

Can we get an example for a better understanding?

Because there are several varieties of tankless water heaters to pick from, both gas and electric, it is beneficial to have a general concept of what is available.

  • A 24kW electric device with a 3.3GPM power output and a temperature increase of 50 degrees Celsius. The temperature of the groundwater is 55 degrees, but the maximum temperature at 3.3GPM will be 105 degrees.

According to the manufacturer, the machine requires a minimum of a 300-amp power supply.

It is essential to provide 240V power at 100amps and to install two 60-amp circuit breakers as well as two lines of no.6 copper wire in order to complete the project. We should point you that the device will not be a light load, even when connected to a 300-amp service panel.

  • With the same specifications as the previous unit: 50-degree increase and an exit water temperature of 105 degrees, a 36kW unit rated at 4.9GPM may be used.

4.9gallon capacity may be achieved by using 150 amps of 240-voltage power, three lines of no.6 copper wire, and three 60-amp breakers. Before installing a tankless water heater in an older home, it is necessary to improve the electrical supply to the home. Not all improvements are pricey, but many of them are time-consuming and take a toll on your wallet’s resources.

One last thought

When it comes to amperage needs, different kinds of electric tankless water heaters will have varying requirements. Before making an order for an electrical device, be sure that the amperage specifications are correct. In the case of gas models, the amperage needs aren’t as critical as they are in the case of electric ones, but you should still look into the venting possibilities. It is, without a doubt, a lot of labor in both circumstances! We are confident in our ability to link you with a reputable service in your region that can repair, replace, or maintain your heating and air conditioning systems.

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