New Water Heater - Cold Weather Triplex

[Chase Farley]

Hello BP,

We recently purchased a Triplex (1BR, 2BR, 3BR) in Vermont. The house has 3 showers, and 6 sinks. The house was definitely owned by people taking shortcuts, and one major issue is a 35gal propane water heater for the entire house.

I'm looking for help on the following questions:

What size water heater should work?

Am I correct that a tank heater is the easiest/efficient route?

Is it better to go through my gas company, or to hire a plumber?

Should we get a water filtration system to help with buildup?

I am struggling to figure out what size water heater we will need. We had a quote come by from our gas company and he suggested a 50gal propane heater with a vent put in that goes out the side of the house at ground level. From what I'm seeing online, 50 gallon heaters are typically for a family of 5 or smaller. This will be a $4300 job from the company.

Due to my climate, and the fact that the heater is in the garage with gas lines directly to the area, tankless or heat pump are probably not the most cost efficient. With tankless, my concern would be that the house would probably need to be split between two or three. We only have one electrical meter, and one propane tank line for the entire house, so the bill couldn't be split you the tenants.

Please let me know of any further details I can provide.

Thank you!

[John Warren]

@Chase Farley hot water heater issues can be so frustrating, and even plumbers often times don't really do much of the math behind sizing these things as they often times just get paid to swap what is existing. I ran into this recently for a property I own in Berwyn, and I had to dig deep to learn more about this. 

I like to look at the refresh rates on the heaters. I deal with natural gas here in Chicago (not propane), but I focus on simple solutions so I never go high tech. I would also rather err on the side of a little too much capacity versus not enough capacity. With that being said, the refresh rate or recovery rate are what you really need to figure out. 

You can calculate the amount of gallons per minute from each faucet, and then back into maybe 1/2 of all faucets being used at the same time for 15-20 minutes (peak shower time in the morning or evening). Then you check that versus your tank to see where you are at.