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Electric tank or tankless water heater v. Propane tank or tankless

4 years ago

I've read a few threads on this so far and still have questions unique to our situation so I'm hopeful someone might chime in with experience. I'm looking at 2 different applications so it may be that we use different options at each house. We are in a fairly mild climate year-round in California (coldest temps all season might be in the mid 30s, even if it's normally in the 50s, and hottest temps could hit 100 degrees even though it's usually 70-80s).

I recognize that there will be a higher amp demand for electric, that tankless models are more expensive, and that the efficiency advantage for a tankless unit isn't that dramatic. I think I'm still leaning towards tankless because of space constraints and the reduction (elimination?) of the risks of a leak in the tank heater (especially for our second home that is usually unoccupied). Plus, we have solar PV arrays at both houses and no access to natural gas lines, so I'm also leaning toward electric units instead of propane-powered water heaters.

We are a family of 4, with 2 girls approaching the teen years (so I foresee more water use in the upcoming 10 years). There is a strong likelihood that my mother-in-law and/or my parents will move in with us within the next 10 years. Currently, no one is home during the day and we shower at night (not at the same time) so there should rarely be simultaneous shower use. We can delay dishwasher and washing machine use to off-peak times, too.

First house:

It's a 4 bed/2 bath home and we're planning a major renovation to add a 1.5 bathrooms and another bedroom (for the grandparents' eventual move in) as well as a kitchen expansion. We currently have two electric tank water heaters (one of which is 12 years old and may need to be replaced soon). The water heaters are sitting in a small room behind the family room that we likely will reclaim (along with pushing the walls out further) to make into a bedroom. Thus, we have to move these giant tanks somewhere, which is why I'm leaning toward tankless models (and maybe 2-3 instead of just one whole house tankless). There's a 400 amp panel already as the previous owner upgraded it. We are in a semi-rural area so there's no natural gas delivery (we get propane trucked in for the whole house generator on the hillside out back). The propane isn't connected to the house and it would be a long run (100 feet?), so I think we're only looking at electric water heater options for this house. It has a large solar PV array but it does not generate excess electricity.

So I think the decisions will be 1) electric tank v. electric tankless and 2) if tankless, one whole-house unit or multiple units.

Second house:

It's 4 bed/2.5 bath and it's a second home, so we go up 1-2 times per month for the weekend. We do not rent it out. We might stay 7 days at most during a school break. It's in a rural area, has a rooftop solar PV system that currently generates excess electricity, and there is no natural gas service either. It currently has a 15+ year old propane powered tank water heater. It needs to be replaced ASAP before it fails. Currently, we set it to vacation mode when we're not there (which is most of the time) and it would be great to just get a tankless model and not have to think about turning it to vacation mode when we leave. I also worry about having a large tank that could leak and have water running until we see it 2-4 weeks later.

I don't know what kind of amp panel we have up there--we'll have to check the next time we go up. The other issue will be finding an electrician and plumber who know how to install tankless units and service that very remote rural area.

Yet I know we have space there to keep the tank (it's in a closet on the back of the house with its door opening to the exterior). I just worry about the risk of a leak/tank failure when we aren't there full-time. If a tankless unit fails, water won't keep running, right? I also know putting in a gas tankless unit will require some venting and more propane.

For this house, the decision will be 1) electric v. propane and 2) tank v. tankless. Since we're there so infrequently and again, don't take simultaneous showers, I think one whole house tankless unit should suffice.

Thank you in advance for any insight you can share!

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