Size of water heater for just a bathroom

[bjscheel]

We added on to the house and are going to put in another water heater just for the new bathroom. Basically only needs to handle one shower in the morning and one in the evening.

We are looking at on-demand, and at smaller tank heaters. If we go the tank route, does anybody know what size of tank we would use? We would want the short style Menards has a 20 gallon in stock, but a 30 gallon would be special order.

I've tried looking online, but similar topics seem to be addressing the size for a whole house, not a single bathroom.

 

[Anthony1971]

uhless you like a part cold shower 40gal is likley the best option.
On demand you will still need a larger unit.
You may be able to use a 30 gal but make suer you buy a higher end one with higher BTU's as they heat the water a lot slower then a 40 or 50.
A shower uses a lot of water... Look at the rate of your shower head and how long you take a shower and do the math...
A 40 gal does not give you 40 gal of hot water it will be hot for the first x amount of gallons and be cooler as you go down and in warmer months the heater does not run as much making it run mostly when you start using hot water. As you use the hotwater it is replaced with cold water which at some point will turn the water heater on and slowly reheat the water. On demand units have a rate of use and temp rating, you need to watch the input temp ratings or difference between the temp. of the water you want and the temp. of tap water.... only the bigger $$$ units will produce hot water for a shower.
note all water heaters have a rating... deliver x amount of gallons per hour at a x degree increase in water temp. this is average not exact so the water could be colder or warmer depending on the temp of the tap water and if the heater ran shortly before the shower.