cross-posted from: https://lemmy.world/post/34021020
I recently installed an Emporia Vue with monitoring for the individual circuit my water heater is on. It captured the very significant difference in energy usage from replacing resistive heat with heat pump.
Had no idea this was a thing.
Oh boy. So the heat pump is probably one of the most important inventions without which modern society wouldnt exist. It uses a refrigerant that has a low boiling point. It is liquified through the pressure of a pump on one side, and let to evaporate on the other side.
Because of the evaporation it can draw heat from there and then give it off at the other side. This way it can cool the cold side more and warm up the warm side more, subsequently “pumping” the heat from one to the other side.
Your fridge uses a heat pump. Most AC units use heat pumps. Any industrial room cooling like warehouses, trucks etc. involves heat pumps.
Now comes the neat thing. For heating a heat pump can have an efficiency factor up to around 4. So 1kW of electrical power can give you up to 4kW of heating power. This is because the electricity isn’t transformed to thermic energy, but rather used to move thermic energy from the outside inside.
Heat pumps are amazing, especially as modern ones provide both AC and heating efficiently. Only caveat is that the efficiency is dependent on the temperature difference it needs to surpass. Because of that older radiator installations that were designed for a higher temperature might need replacement with newer larger radiators. Also if it gets really really cold you might need a classical heater to support the system.
Not to be ungrateful for the explanation, but I’ve had heat pump HVAC for years. I’m originally from Oklahoma and everyone has a heat pump. In fact, I find it weird that they’re controversial in any way!
I meant I had never heard of a heat pump water heater. Which sucks because I just had a new unit installed last year. :(
Are they extra expensive? More complex install?
Heat pumps have less immediate heat and less maximum heat. As electricity conservation becomes increasing vital heating appliances utilizing heat pumps are increasingly becoming an option but those limitations remain.
For water heaters you just need to be certain it replenishes quickly enough for your needs. But for other applications like dryers you may find yourself frustrated with the actual downsides regardless of choice.
A lot of hate for heat pumps comes down to people using them like resistive or gas heating rather than like the backwards air conditioner they are.
Are they extra expensive? More complex install?
Like with an AC you need a place for the outside unit and do some piping. They are also more expensive, but the costs usually amortize well before a new unit is needed. They don’t heat as hot, so you might need a bigger tank.
What’s the upfront price difference in the water heaters?
My utility company chipped in $1,600, so it ended up being the cheapest option anyway. The federal tax credit is 30% of the project cost up to $2,000, and it is still good if you install before the end of the year.
This 65gal Rheem heat pump water heater goes for $2,150 plus shipping and install.
This 55gal Rheem resistance water heater goes for $820 plus about equivalent shipping and install as a heat pump water heater
In my area (in the SF Bay Area) there’s barely any upfront cost, as there’s something like $4k in local and state rebates plus the 30% federal tax credit.
2-3x more expensive, but they normally pay off in about 5 years.
Home depot regularly has them on huge sales and it paid for itself within two years just by the electric savings.
Got one last September and works really well. Used about 2000 kwh over the winter for central heating for a big house, central Europe. Thats nothing compared to previous use of wood pellets and/or oil.
We also have solar water heating (via vacuum tubes) so water heating is practically free in the summer. Though you do need a large tank to store it.
Are these things reliable? I’m not in a position to replace currently but I do like to think about these things before the need arises.
I’ve had gas tanked for years. What I appreciate is that they need nothing from me. I flush the tank once a year and that’s it. They just do their job quietly and without need. I don’t think about it, and I love that.
I’ve been burned with crappy modern appliances. Tried front load washers, three and they were all crap. Sometimes wouldn’t spin, they were smelly, expensive and unreliable. Switched back to top loader because it just works. Same experience with a dishwasher. Used very little energy, but did a lousy job, was expensive and had to fuss with it constantly.
I’d like lower energy costs but not if the thing won’t work or have weird conditions. If five people who live in the house can overrun it with two showers, thats not useful or if it takes an hour to heat a tankful.
At the core it is the same thing like an AC unit or the cooler in your fridge. The technology itself is very reliable.
You need to check though if your house installation is suitable for it and that it has the appropiate size and can be placed in the right place outside.
It might make sense to combine systems. Maybe keep the gas-heater for hot water but run your heating on the heat pump.
I have been running a Rheem one for almost 5 years now and I haven’t had a single issue with it. It’s nice that it will keep the garage dehumidified. I also set mine to 140F and it does pretty well with multiple showers. We occasionally run out but that doesn’t happen very often, maybe a handful of times per year. With rebates and installing it myself it was able to pay for itself in about 2.5 years.
Enjoy your savings! These are wonderful!
I bought my first heat pump water heater in 2007 (GE Geospring) and was sold on the technology ever since. When I moved to a new house I put that upgrade on the shortlist and now have one in this house too. There isn’t much savings in winter (as I don’t exhaust it to the outside air), but for the other 9 months of the year the savings are significant!
I’ll have to watch how it changes in the winter.
I have a State, and actually the resistance heating is the 1st unit after the heat pump failed; then I got it replaced under (parts-but-not-labor) warrantee. So I’m a big fan of the technology but not the brand. However, the new State does have duct connections, maybe it’d be worth hooking those up. You like the Geospring?
I did like my Geospring, but GE sold the entire division off to another company some years ago. Since then I can’t speak to the units. My new one is a Rheem. I got it fairly inexpensively from Home Depot and have been happy with the performance of it thus far.
One word of warning for the Rheem units. They make two lines and they DO NOT call out this major difference between them.
- Professional Prestige - This line is sold through professional plumbing supply houses. These use slightly higher quality parts, and more importantly, include warranty on parts and labor and they can be repaired in place. There’s no way around it, but these are more expensive to buy. When I got quoted me it was over $1200 more expensive to go with this line’s model.
- Professional Platinum The other line is sold at retail to big box stores (like Home Depot). These include some cut corners and sometimes cheaper parts. While the warranty length is decent on these, they offer WHOLE UNIT REPLACEMENT ONLY. Meaning to get the warranty honored, you’re required to disconnect the unit in your house, take it back to a retail store, get a replacement unit, and reinstall the replacement unit. I suppose if you’re handy, have a truck and tools, this probably isn’t a big deal. I personally don’t have those things and if I ever need a warranty replacement I’ll have to pay for all this labor and delivery out of pocket.
If you want full service and support options or go cheap for savings will be up to you.
bravo! Double check if your city offers subsidies. Got $200 for mine.
The utility company for me. They chipped in $1,600!
Replaced my electric dryer with a now broken electric dryer. Turns out we didn’t even need one, we’ve been air drying our clothes and it’s fine, big savings there.
It’s much better for your clothes too, especially anything that stretches. I hang dry most of my clothes, then throw shirts in the dryer with a wet rag for 15 minutes to remove wrinkles.
You can get a heat pump washer/dryer which are very efficient and you don’t need to worry about putting clothes in the dryer.
