Our water heater needs to be replaced and we are considering getting a heat-pump water heater
Our water heater needs to be replaced and we are considering getting a heat-pump water heater. We could really use some advice as to whether or not this makes sense for us.
Our current water heater is still under warranty, allowing us to replace it with a 5 year unit (current unit is a GE 40 gallon natural gas-powered tank). We are a family of two adults and one 3 year old. We could get $1,050 rebate if we bought one before the end of the year.
Other details:
Therm cost: current month 88.1¢, last month $1.36
Klw cost: current month 10.3¢, last month 10.5¢
We have 1000 square feet in our unheated basement.
The water heater would be near the gas furnace and could take some of the waste heat if it was a heat pump.
Our basement temperature over the last month was 56°-62°, with 50% humidity
We use a dehumidifier in the basement in the summer.
We live in Massachusetts in a 3 bedroom, 1,300 square foot house.
Our electricity from our utility is 50% from natural gas, 12% from coal, 15% from nuclear, etc. It would seem to be more efficient to continue to use natural gas to heat our water rather than have it be converted to electricity at the power plant first. However, we also know that natural gas prices are expected to rise substantially in 10 or 20 years. At this time we do not have solar panels but may get some (not many -don’t have the space) in the future. We like the idea of reducing our reliance on natural gas and may some day insulate our house enough that we could use minisplits instead of our gas furnace. None of these are guaranteed, however. -We may be unable to install solar panels, further insulate our house and install minisplits. What would you do? Buy some time with a five year gas water heater paid for with our warranty or spring for the heat pump water heater with a 1,050 rebate? Is maintenance a factor?
Thank you in advance!
Leah
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Replies
Leah,
There is no simple answer to your question. Heat-pump water heaters are relatively new, and may have more maintenance issues than gas water heaters.
I'm not sure what your warranty provides. But if your warranty provides you with a new gas water heater for free, that's probably what I would choose if I were you.
Free gas unit though the summer basement drying potential might be worthy.
It will make your basement significantly cooler. If your ducts are in the basement, it will "steal" some of the gas furnace's output through duct heat loss. It will also steal some heat through your floor, if it's uninsulated. But since your basement is unheated, I think it will also be taking a significant portion of its heat from the ground that your basement is buried in. It'll certainly be more economical than a regular electric water heater. Compared to a gas unit, I'm not sure. But I also think it's a good idea to wean ourselves off of directly using fossil fuels.
It'll be much more beneficial in the warm months. It'll take some load off of your dehumidifier, and will be able to use some "free" heat the sun sends into your house.
If you ever directly heat the basement, the efficiency of the HPWH becomes more dicey. It will be constantly stealing heat from the basement heating system. If that's gas or electric resistance, then it'll be pretty wasteful and inefficient, and it would make sense to switch it to resistance-only mode. If you heat the basement with a mini split, then the HPWH will have an effective COP of something like 1.5 (efficiency of 150%), which is still significantly better than a regular electric water heater.
As for reliability, I think it's safe to say that HPWHs are new and somewhat complex, and probably will be somewhat less reliable than electric/gas models. But on the other hand, they're the same technology as a refrigerator, and those are very reliable. And if the heat pump does break down, you'll have the built-in resistance heat to serve as a backup, so you probably won't be out of hot water.
Another thing. Check out drain water heat recovery units. If you can install one on the drain stack below your shower, it'll cut your hot water energy use roughly in half. If you have a HPWH, then that means it'll also reduce the cooling of your basement by about half. A HPWH + DWHR would yield a ridiculously efficient water heating system. It should use about a quarter the energy of a regular resistance water heater. EFI has awesome prices on Power Pipe DWHRs. Hat tip to Dana Dorsett. Link: http://test.efi.org/sites/default/files/power_pipe.pdf
Thanks everyone for all of your help. It is great to explore this with people with so much experience and expertise to help us make an informed decision.
Nick, that is an interesting idea about a DWHR combined with a HPWH but our house is one floor and does not have the vertical drain pipe length for it to work.
We are still not sure what to do. We were reading some online discussion about GE water heaters failing (parts not as reliable as they used to be) and people having to pay to a plumber to replace faulty parts repeatedly. The parts are not expensive but are covered under the warranty; the labor is not. So, we will have to weigh that against the potential for HPWH potential for failure.
Thanks again,
Leah
Leah,
Make sure you're reading about the right GeoSpring. There have been two different models (the old blue robot-looking one, and the new red/white one), and a lot of the bad feedback seems to be for the old model. Then again, I can't vouch for the new one... I've had mine for a couple months and it has worked fine, but only time will tell how reliable it is. Considering it was free (after tax credits) and my house is electric-only, it was an easier choice for me.