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Comment by reaperman | Hacker News Reader

I am so happy that heat pumps are getting more and more attention. They have the opportunity to reduce the energy used to heat a home by 75%.

They're not "perfect" (e.g. they don't work at <0F temperatures without truly absurdly large heat-exchange components that aren't worth the capital expense). I also know a lot of people would like the option to use natural gas, but I'd like to think that with this type of additional investment and focus, some future heat pumps could use natural gas as their "backup resistive heating" instead of electric.

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Heat pumps are pretty incredible and I am always surprised we don’t see more of them. We recently installed a heat pump water heater and it made a noticeable dent in our electric bill. Next up is a heat pump dryer!

Also surprised by the lack of solar water heating in the US. My childhood home had a system but when it broke we could not find anyone that could fix the system and had to remove it.

> a heat pump water heater and it made a noticeable dent in our electric bill.

I think, in most of the USA, a natural gas water heater would have made a similar dent in your overall utility bill. But I still am very glad we're working harder towards good heat pumps.

I'm very against burning gas in my home to heat things when we have options like heat pumps.

Combo Heat pump washer+dryers also just made a huge technical advancement as well, not requiring any ventilation to run, meaning you can put them anywhere in your home with a water line - eg in an unventilated hallway closet with far less risk of fire (dryers cause 92% of house fires). And they use less water and energy per load than a typical washer/dryer.

There’s only one of these that I know of (the GE unit), are there any others that you’re aware of?

There's also the LG one. Reviews are so-so about the LG one, with lots of complaints about reliability and clothes smelling cooked after drying with the heat pump.

They apparently just fixed the reliability issues in their new model with a specialized lint trap

Does water extracted during drying just go down the drain?

Yep same drain as a regular washer

I thought that was a really interesting stat (I believed you, I don't mean I went to fact-check you but that's what ended up happening!) and wanted to read more about it -- it sounds like dryer fires aren't _overall_ that destructive, but in the "washer & dryer" category (~16k fires out of ~350k per year) they are 92% of that category.

Figured you'd want to know, since I found it interesting!

That being said, the dryer fires are certainly preventable and if any technology aids in reducing that, it's well worth it!

I have a heat pump dryer. It's a small LG one. Takes ages to dry but that's the trade off I was willing to make. Super gentle on my clothes, uses hardly any power, no vent to catch on fire.

> reduce the energy used to heat a home by 75%

Compared to resistive heat, sure, but a heat pump powered by fossil fuels isn't much better than a gas furnace. My point is that we need to stop burning fossil fuels for electricity so that heat pumps make sense.

> Compared to resistive heat, sure, but a heat pump powered by fossil fuels isn't much better than a gas furnace. My point is that we need to stop burning fossil fuels for electricity so that heat pumps make sense.

https://en.wikipedia.org/wiki/Coefficient_of_performance

Technically, heat pumps can absolutely achieve greater than 100% efficiency (considering their input electricity as a starting point).

It's also true though that there are also lot of caveats about their effectiveness based on temperature differential, maximum output compared to a furnace, efficiency with which the upstream electricity is generated, etc.

> considering their input electricity as a starting point

I was considering fossil fuels as a starting point, as that's where most of our electricity comes from.

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