Water heater sizing

House with 4 1/2 baths and 6 bedrooms. Sizing charts call for 50 gallon gas water heater. I know this is right, but 50 gallons sounds a little small to me, for this many bedrooms and baths. What are your thoughts.?

Charles, look here, or here.


50 gallon maybe the minimum but a 75 gal water heater is more appropriate.

I agree, I did advise that 50 gallon heater might be “taxed” if house is full.

Wouldn’t that depend on how many people are actually living in the house?

I have a buddy who lives in a house with 5 bathrooms. By himself.

But of course, if it’s a couple, with 4 kids, plus grandma living with them, then yes, it’s a concern.

I also inform my clients when the heater might be too big.

Some are quick recovery.

You guys make a recommendation on water heater size?

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Not me !

Nope I Just state the size and age

If you want to get involved in that, and I don’t, it seems it would be better to give them the tools to determine for themselves what is adequate and let it go at that.

They will figure that out when the shower goes cold.

The manufacturer’s recommendation is the best resource for this and it would be hard for the builder to dispute. This is going in on the report from a new home inspected Sat. It’s surprising that some inspectors would not advise on this.

The water heater size does not meet the minimum requirements for a family of 4 with a large tub installed at the master bathroom. Please see the water heater manufacturer’s website for proper sizing. http://www.statewaterheaters.com/cust/sizing-res.html
This home should be installed with a minimum peak demand output of 85-100 gallons. The home currently has one 50 gallon unit installed at the garage.

Water heater “size” (gallons) does not matter, it’s the recovery rate (first hour rating) that matters. Otherwise, tankless water heaters could not be acceptable.

Considering the perimeters of the OP, theoretically, you could install a 20 gallon water heater with a first hour rating of 80 gallons (if such a heater exists) and it would be compliant.

Jeffrey is right, recovery is what is important.

I have a 60 gal. electric WH and sometimes run out of hot water.

Below is what Giant recommends:

© 2013 Giant Factories Inc. Printed in Canada GI-PB039En-0913
For more information
on this technology,
please visit the
following websites:
Hydro-Québec Giant Factories Inc.
2 to 3 people
Regular usage High usage
40.5 Imp. gal./184 litres
3,000 Watt Elements
62.5 Imp. gal./284 litres
4,500 Watt Elements
Eco-friendly usage
62.5 Imp. gal./284 litres
3,800 Watt Elements
4 to 5 people
Regular usage High usage
62.5 Imp. gal./284 litres
4,500 Watt Elements
2 X 62.5 Imp.gal./284 litres
4,500 Watt Elements
or or
Eco-friendly usage High usage
62.5 Imp. gal./284 litres
3,800 Watt Elements
80 Imp. gal./364 litres
9,000 Watt Elements
6 or more people
Regular usage High usage
2 X 62.5 Imp. gal./284 litres
4,500 Watt Elements
100 Imp. gal./454 litres
12,000 Watt Elements

These guidelines take into consideration regular usage only. They do not take into consideration teenagers,
whirlpools, spas, extra large bathtubs, and multi shower head systems. Anticipate the future needs
of your family when selecting your water heater.
NOTE: These figures are based on the latest customer satisfaction statistics of your local utility company,
taking into account Canadian winter conditions. These recommendations may be higher than those
of other manufacturers. U.S. figures will be less.

I am not sure what other areas of the country use but around here a 40 gallon tank is the norm. I see them installed in homes with one bath all the way up to three baths and a half bath. No complaints about running out of water.
I would never put in my report that the water heater seemed small for the size of home. That a plumbers job when the home is built.

I have no problem reporting on an improperly sized water heater, but (as I said) it has nothing to do with its holding-capacity.

Some people will replace the 60 gal. with a 40 gal WH.

If I see a 3 bedrooms house with a 40 gal electric WH, I make a comment in the report that it may not meet their hot water needs.

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Yup, what jeff says. Its easy to understand when comparing a commercial water heater and a cheap residential one of the same capacity. The commercial water heater can churn out hot water like crazy.

Residential version

commercial version

Make note of specs / gph recovery

Its very possible to have a decent lower capacity h2o heater perform better then a higher capacity crappy one.

Lots of really good units out there. With tankless you need to buy a quality unit that is rated for your area. Different climate zones need different units based on the average temp of the incoming water. Rinnai makes a good quality unit but they are not inexpensive. You will see a reduction in your gas usage that reduces your bill and helps justify the cost.

Something like the commercial type should work fine for you.