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What size Electric Hot Water Heater for 4 Bedroom house

I would like an answer for both tank and tankless
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Posted 2016-04-04T02:52:45+0000  by Stems Stems
Sizing a hot water heater is more dependent on the number of people in the house and how those people use the water is than just the size of the house.  For example, a young family with a baby and toddler will have different hot water requirements than the same home with two teenagers and two adults who all need to get off to work/school in the morning.

Depending on your hot water needs, an tankless electric water heater can have some pretty serious electrical requirements and may require an upgrade to your electrical service.  Another option to consider is a "hybrid" water heater.  They work like a heat pump, using the energy in the air to heat the water.

Rheem has a worksheet you can download here to help with the calculations. 

Posted 2016-04-04T08:24:03+0000  by Adam444
Hello Stems.  Welcome to the Community!

There is a Buying Guide on which can also offer some help with water heater sizing.

The sizing for tank type heaters is somewhat vague, but does explain why most homes have either a 40 or 50 gallon tank type heater.

Tank Water Heaters
Determine your required gallon capacity based on the number of people who will regularly be using hot water in your home.
Household SizeGallon Capacity
1 - 223 - 36
2 - 436 - 46
3 - 546 - 56
5 or more56 or higher


For tankless heaters, the guidelines are more of an engineering calculation, as you need to estimate the maximum flow rate needed, combined with the worst case temperature rise conditions.  The guide linked above makes that about as simple as you can make it.


Posted 2016-04-05T16:57:34+0000  by Chris_HD_CHI
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