How Big Water Heater Do I Need

Fairly sizing a water heater is not all that easy. When choosing a water heater capacity for a family of 2, 3, 4, 5, or 6, in that location are two rather common mistakes most people make:

Getting a too small-scale water heater (undersizing). If your water heater capacity is too low, yous are likely to run out of hot water while showering. Example of a too modest water heater: Installing a xxx-gallon water heater for a family of v. That'due south more 50% of the water heater capacity that you really need.
Getting a besides big h2o heater (oversizing). If the water heater capacity surpasses your hot water needs, you accept unnecessarily higher h2o heater costs. Example of a too big water heater: Installing a sixty-gallon water heater for a family of 2. That's at about 20-gallons more than than you need, and you have needlessly spent $150 boosted dollars on the heater, and wasted space.

Both of these mistakes tin be avoided if you know how to properly cull a water heater capacity for your hot h2o needs.

Hither'southward the thing:

You but take one shot at sizing your h2o heater. You don't desire to accident it and buy a unit that's either too big or likewise small.

That's we will look into how to selection the correct h2o heater size for your domicile. That includes factors that increase/subtract the water heater chapters requirements (size of your family, hot water needs, etc.). We include the general rule of pollex for sizing any water heater (it'south fairly easy to use, but you need to approximate your peak hour hot water demand properly).

On pinnacle of that, we simplified water heater sizing with a 'Water Heater Sizing Calculator' . You just input the size of your family unit, hot water needs, and the calculator will give you a crude estimate of how big a water heater you demand, based on average hot water consumption. Here's what the results expect like (screenshot):

hot-water-heater-capacity-calculator — Y'all can find this 'Water Heater Sizing Calculator' farther on. Only input family size and relative hot h2o needs, and you volition get a rough estimate of how large a hot h2o heater you lot need.

Permit's first familiarize ourselves with h2o heater sizing concepts similar 'first 60 minutes rating', 'water heater capacity', and 'meridian hour hot h2o demand'. With this knowledge, y'all volition easily sympathize the prepared table with h2o heater sizes for a family of 1, ii, three, 4, five, and 6:

How To Approximate The Size Of A H2o Heater You Need?

The key spec that helps us adequately size a h2o heater is the water heater chapters rating.

We talk well-nigh 30-gallon, 40-gallon, l-gallon, 60-gallon water heaters. That number of gallons is the 'h2o heater capacity rating'. This is likewise known as 'beginning hour rating'. It is a volumetric amount of hot water a heater can provide inside the first hour, starting with a tank full of hot water.

How to find what the starting time 60 minutes rating is?

Simple. The FTC (Federal Trade Committee) dominion is that every conventional storage water heater producer has to include this rating on the EnergyGuide label. Just check the label, and y'all will find out how big your h2o heater actually is.

Here is the rule of pollex for water heater sizing:

Beginning Hour Rating (Heater Capacity) ≤ Pinnacle Hour Need (Usually 1 hour when we shower)

That means that your h2o heater should be at least big enough to meet the most demanding ane-hour hot water demands your household has.

Case: From 10 PM to 11 PM three people take a shower. In 1 shower we use 20 gallons of hot water (according to The states Energy Saver). That ways that you volition need a threescore-gallon water heater or bigger.

As we volition meet further on, the exact size of a h2o heater depends on your hot water needs. That roughly translates into how big a family you have. Example: A family of 5 will spend less hot water than a family of three.

After that start hour (we started with a tank full of hot water), the hot water output of a water heater depends on 3 main factors. These are:

Water heater tank chapters.
Heat source (gas vs electricity); this can be either burner (gas h2o heater with tank) or chemical element (electric water heater with tank). We talk about electrical water heaters
Size of the said heat source; namely, how large a burner or how big an element you have.

Obviously, any h2o heater will be able to produce less hot h2o in the second, third, etc., hour after the 1st hour.

Example: If you lot have a fifty-gallon water heater (get-go hour rating is l gallons), you will become 50-gallons of water heater for the 1st hour. However, in the 2nd hr, y'all will likely get much less than 50 gallons of hot water (well-nigh sixteen gallons on average in this example).

If we desire to follow the above rule of thumb for sizing a water heater, we need to assess how much hot water we demand during our showering peak hour. Here'south a trivial help to do merely that:

Estimating Peak Hour Demand: This Is The Key Step

It's fairly simple to size a water heater in theory (using the rule of thumb). Just add together upward all the hot h2o you require in the most intense hot h2o hour. That's usually the hr when a big part of the whole household showers.

The size of a water heater should lucifer that capacity, and you tin add together some gallons on top of that.

Now, the key stride is to adequately gauge the peak-60 minutes hot h2o demand. That means that you have to add upwards all the hot water you lot use in that 60 minutes, including showering, washing teeth, hand washing, shaving, dishwashers, and and then on.

To assist you lot out, we specify some of the well-nigh common activities that require hot h2o with the hot h2o needs here:

Showering: 20-gallons per shower.
Washing teeth: 0.5 gallons.
Paw washing: 3 gallons.
Shaving: 2 gallons.
Top-loader clothes washer: 25 gallons.
H-Axis wearing apparel washer: 15 gallons.

Here is an example of how you can estimate the elevation hot hour needs in practise. Allow's say that you take a 4 family household with two bathrooms. From 10 PM to 11 PM 3 people have a shower, ane person is shaving, and all 4 family unit members wash their teeth.

The accumulated hot h2o needs are:

3×20 gallons (3 showers) + 1×2 gallons (shaving) + 4×0.5 gallons (washing teeth) = 64 gallons

This ways that y'all need a water heater with at to the lowest degree a 64-gallon chapters. You tin can easily get a 70-gallon water heater in this case simply a 60-gallon water heater will likely exist likewise small (undersized). An fourscore-gallon water heater for a family of 4 is by and large too big.

If yous decide your hot h2o needs using this 'tiptop 60 minutes demand' rule of thumb, you have a bit of wiggle space in the upper direction. You can add about ten% to fifteen% to the calculated water heater chapters. That means that you lot tin can get a seventy-gallon water heater if you lot calculate the elevation hour hot water demand to be 64 gallons.

However, you should non choose a smaller water heater capacity. In practice, if you lot calculated you have 64 gallons height hour hot water needs, you should choose a 64-gallon water heater or bigger. Never smaller.

Notation: Undersizing a h2o heater will be more problematic than oversizing a water heater.

If all this seems a bit complex, don't worry.

In that location is an easier way to size a water heater. It's based on 3 principles:

Size of the family.
Average use of hot h2o per person per 60 minutes. According to Applied science Toolbox, an average person consumes 10 gallons of hot h2o per hour. Nosotros talk nigh the top hr demand, of course.
Baseline of fifteen-to-xx gallons of h2o per household. Every household has some bones hot water needs, independent of how many people live in the house.

Based on these three principles, we can roughly estimate what size water heater you need given how big a family you accept:

H2o Heater Sizing Calculator (Based On Family Size)

This is a 'What Size Water Heater Do I Need' reckoner that will give you lot a rough estimate of how big a water heater you lot need. You simply input your family size and hot h2o requirements (beneath-average, average, or to a higher place average), and the water heater size computer will dynamically determine the water heater capacity in gallons:

Based on this water heater sizing method, you can roughly encounter what size water heater you need for your family:

Family Size	Water Heater Size (Gallons)
Family of 1	25 Gallons
Family unit of ii	35 Gallons
Family unit of 3	45 Gallons
Family of iv	55 Gallons
Family of 5	65 Gallons
Family unit of half dozen	75 Gallons

Annotation of ownership a water heater: Check for the Energy Star characterization besides. Energy-efficient water heaters in most cases pay off. You can read more than near the requirements for an Energy Star characterization here.

We hope all of this was helpful.