Crazy but true… we heated our hot water this month for only ~$8 according to the eMonitor.
EDIT: What do I mean “only”?
Only in that… solar hot water heating systems are $8000 or so it seems. So if we spend $150 on hot water heating per year (lets say), and let’s say we offset this fossil fuel usage with a generous donation of $150 to the New England Wind Fund, then that’s $300 a year for hot water. Assuming a solar hot water system only is 50% solar fraction, then we are saying that we are saving only $150 per year. So the break-even vs another sustainable method of hot-water heating is 53 years. And that assumes it is working in 53 years?
And… the hot-water heat pump cooled and dehumidifed the basement a bit for free. And the washing machine is on the same circuit too! So add that in as well I guess — free laundry. (We hang dry our clothes on racks… but they are almost dry when they come out of the front-loader spin.)
Two explanations for this low usage:
1) the hot water heat pump works (it’s a little loud and I have it on a timer to run only at certain times. made possible by a 105 gallon marathon tank used for storage) We have a Nyle Geyser.
2) we don’t use a lot of hot water (even with 4 adults and 4 kids in the house). We do about a load of dishwasher a day but don’t go too crazy on showers and tubs for kids. And the showers have 0.6GPM showerheads. According to the water meter I use ~3gallons pretty consistently per shower.
I think I commented once that we seem to average 52 gallons a day with 8 people and we were at around 26 gallons with 4 people. I should do some calculations to see if this jives with the $8/month number (assuming $0.15/KWh at Hudson Light and Power here in MA)
So would I buy a Nyle Geyser again? I guess so. The noise used to bug me but the timer system (a 15amp 120v cheapo timer) we’ve got now seems to work fine. And I wonder about the sense of heating more in the winter (which is what ends up happening a bit to make up for the cooling when the Geyser sucks some heat out of the basement air to put it into the water). But I bet if I mustered the brains to do the calculations it wouldn’t seem too bad. Especially when it’s running when it’s not TOO cold outside and our air-source-heat pumps (our house heat) are operating relatively efficiently.
A hot water heat pump seems to be a no-brainer in climates where it is at least warm most of the time. And if you have a place where the noise won’t bug you (maybe other brands aren’t quite as loud?) I will measure the actual dBAs sometime with my radioshack meter to give you an idea.
I’m glad we didn’t install a traditional solar-DHW (domestic hot water) system. I think it was money better spent on the HW heat pump and more PVs. From the studies I’ve seen… traditionally-sized solar hot water systems in New England average only around 50% solar fraction in a year, so what would have been the other 50%? A hot-water heat pump probably!?!
Perhaps try home heating with wood. Or with solar thermal (still pondering the best low cost approach for this…) Our heating bill is probably in the ballpark of $500 a year. And offset to basically $0 with the PV (solar electric) panels — we are nearly net-zero even with 8 in the house. But still, that’s $500 in fossil fuels as far as I am concerned. I don’t count the PVs. So that’s $500 which would be better spent heating with wood or the sun. And this would in turn mean the hot water in the house will be indirectly heated with wood or solar.