2 ms·

> But fitting one is a big deal - they are quite expensive, they take a lot of work to fit, really require extensive additional insulation I think this somewha

> But fitting one is a big deal - they are quite expensive, they take a lot of work to fit, really require extensive additional insulation I think this somewhat overblows the complexity of a heat pump. They are simply Air conditioners that can be ran in reverse. One valve is the difference between a heat pump and AC. Why they are so expensive is really just price gouging because they aren't as common. If you are in a home with forced air AC then installing a heatpump system couldn't be simpler and should be something you consider when updating your AC system. It's really just a matter of updating the compressor and maybe adding some smarts to avoid condensation. In fact, it's shocking to me that AC -> heatpump conversion kits haven't hit the market. > So i'm slightly mystified that we basically don't hear anything about fitting drainwater heat recovery [1], in which the lukewarm drain water from your shower is used to pre-warm the incoming cold water. It's extremely simple, pretty cheap, simple to fit, and can recover ~50% of the waste heat, of something which is tens of percent of the energy consumption of a household. Really interesting idea, but I assume you have to rip up the shower to accomplish this right? Also, I'm guessing clogged wastewater piping might be an issue right? That said, that'd be easily overcome by just running the lines side by side with maybe a simple copper connector for heat exchange.

bluGill 3y ago
What is mystifying to me is why governments allow air conditioners without that reversing valve to be installed. A simple change, and the more people installing a heat pump the cheaper those valves get.
- ianburrell 3y ago
  I regret getting just an AC a while ago. I could have gotten a heat pump and used it for most of the heating. Even if I didn't get heat pump installed, one that could have been converted to heat pump without complete replacement would been nice.
computerdork 3y ago
Agree with your take. Recently helped install a heat pump at a single-family home (rental property) in the SF Bay Area. Actually, they aren't that much more expensive than AC's (mine cost about $9k for everything, but again, I did 35% of the work myself for a ducted 3 ton heat pump). And yeah, the installation is almost exactly the same as what you'd do for an AC. And, you don't need to add insulation, but we did (to the crawlspace), costing about $2.5k And, it's been running for about 3 months, and saved about ~$175/month in heating. wow. It'll pay for itself in about 7-8 years.
twic 3y ago
My views are coloured by the fact that i live in the UK, where almost no houses have air conditioning.
- cogman10 3y ago
  That makes sense then. How are heat pumps typically installed? Are they integrated into the radiator/hot water system? Or is some sort of forced air system setup installed? I'd assume a mini split setup wouldn't be too uncommon. (Probably the cheapest route for most homes in the UK). In the US the vast majority of homes and apartments are setup with forced air heating and cooling which really simplifies transition. I'd assume the UKs setup where everyone uses heated water to heat homes would make transition more expensive and costly.
  - twic 3y ago
    Heat pumps here heat water. In a new build with a heat pump from the start, or a big refurb, the hot water is used for underfloor heating. In a smaller refurb, or where that's not possible, it's used in radiators, although I think you typically fit special radiators and bigger pipes which can work at a lower temperature. Some new builds have mechanical ventilation heat recovery, which is a ventilation system with a heat exchanger. But I don't hear much about air to air heat pumps. It's very possible I'm wrong in my perceptions here!
    - cogman10 3y ago
      Is the water ever chilled for cooling? I'd assume that would cause a lot of issues if it is as chilled water would generate condensation (and the UK is nice and humid 24/7)
      - darkr 3y ago
        some air-water heat pumps _can_ run in cooling mode, but speaking to a heating engineer the other week he recommended not doing this for exactly this reason.
  - 3y ago

bluGill 3y ago

What is mystifying to me is why governments allow air conditioners without that reversing valve to be installed. A simple change, and the more people installing a heat pump the cheaper those valves get.

ianburrell 3y ago
I regret getting just an AC a while ago. I could have gotten a heat pump and used it for most of the heating. Even if I didn't get heat pump installed, one that could have been converted to heat pump without complete replacement would been nice.

computerdork 3y ago

Agree with your take. Recently helped install a heat pump at a single-family home (rental property) in the SF Bay Area. Actually, they aren't that much more expensive than AC's (mine cost about $9k for everything, but again, I did 35% of the work myself for a ducted 3 ton heat pump). And yeah, the installation is almost exactly the same as what you'd do for an AC. And, you don't need to add insulation, but we did (to the crawlspace), costing about $2.5k And, it's been running for about 3 months, and saved about ~$175/month in heating. wow. It'll pay for itself in about 7-8 years.

twic 3y ago

My views are coloured by the fact that i live in the UK, where almost no houses have air conditioning.

cogman10 3y ago
That makes sense then. How are heat pumps typically installed? Are they integrated into the radiator/hot water system? Or is some sort of forced air system setup installed? I'd assume a mini split setup wouldn't be too uncommon. (Probably the cheapest route for most homes in the UK). In the US the vast majority of homes and apartments are setup with forced air heating and cooling which really simplifies transition. I'd assume the UKs setup where everyone uses heated water to heat homes would make transition more expensive and costly.
- twic 3y ago
  Heat pumps here heat water. In a new build with a heat pump from the start, or a big refurb, the hot water is used for underfloor heating. In a smaller refurb, or where that's not possible, it's used in radiators, although I think you typically fit special radiators and bigger pipes which can work at a lower temperature. Some new builds have mechanical ventilation heat recovery, which is a ventilation system with a heat exchanger. But I don't hear much about air to air heat pumps. It's very possible I'm wrong in my perceptions here!
  - cogman10 3y ago
    Is the water ever chilled for cooling? I'd assume that would cause a lot of issues if it is as chilled water would generate condensation (and the UK is nice and humid 24/7)
    - darkr 3y ago
      some air-water heat pumps _can_ run in cooling mode, but speaking to a heating engineer the other week he recommended not doing this for exactly this reason.
- 3y ago