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> Palmer has a heat pump in her U.S. home, along with a furnace as backup. “If it gets really cold, we can rely on the furnace,” she says And boom, there’s the

> Palmer has a heat pump in her U.S. home, along with a furnace as backup. “If it gets really cold, we can rely on the furnace,” she says And boom, there’s the problem. I have a heat pump for some bedrooms on the second floor but only because I have furnaces heating the other side. I am impressed how the tech has improved though.

ilyt 4y ago
I wonder if it would be economical to make ground-fed heat pump that had piping built in together with house (dig out foundation, put piping for water-to-water heat pump, build house), for the colder places.
- __MatrixMan__ 4y ago
  I'm told that (at least for the soil near my house) you want the ground source piping to make it down to the ground water because without that moisture the soil's capacity to transmit heat degrades over time.
- cyberax 4y ago
  You really need to tap into a watertable for the ground-loop to work. Otherwise it'll be nothing but a huge PITA. And at this point in time, the best air-source heat pumps are good enough until -25C. Meaning that you get CoP more than 1 at this temperature. So this would work for most of the US just fine.
  - wood_spirit 4y ago
    I have a “ground source heat pump” (a long pipe zig zagging under my lawn at about 2-3 foot depth) and kinda sandy soil and nobody mentioned no water table and it works great. Sand is not ideal but it’s not a blocker. The most common heap pumps use bore holes straight down into the rock here in Sweden, but lateral installs are marginally better performance (sun reheats soil every summer) if you have a big garden. Heap pumps dominate in Sweden so the installers have a lot of confidence and give good practical advise.
- c22 4y ago
  The ground is only warm because it's heated all day by the sun. The ground under your house, less so.
montjoy 4y ago
I’m not sure if you’re being literal or figurative, but most heat pump installations using forced air share everything with the furnace so there is no “side”. My thermostat just has a setting to use the NG furnace when it’s colder than X. BTW my heat pump is about 20 years old and works great in the range I have it set to operate in.
- nemo44x 4y ago
  Literal. Did a 2-story home addition where the second floor had a heat pump installed since the existing venting system wound have been underpowered to support it and it would have been difficult to run vents there.
SamBam 4y ago
I think that's less and less of a problem. We just installed a Mitsubishi Hyper Heat, that's supposed to work down to -20⁰F without any auxillary heating. Many other units have auxillary resistive heating when the temperature are that low, which is obviously less efficient than the heat pump, but is still better than needing to maintain a fossil-fuel furnace.
- eljimmy 4y ago
  Are you Canadian? I had previously looked into heat pumps for cold climates and thought that it was economically not a great investment and required a gas back-up.
  - adgjlsfhk1 4y ago
    Canada's really big. Vancouver and Toronto are both definitely warm enough for a heat pump to make a ton of sense.
  - SamBam 4y ago
    No, Massachusetts, so probably warmer than you, depending on where you are. Even in Canada, though, I'd look into whether heat pumps with resistive auxillary heat are economical. If it only ever goes below -20⁰F for, say, a week a year, you'd probably still come out on top. And you'd definitely come out on top environmentally if your electricity is mostly green.
    - bradknowles 4y ago
      And with heat strips, a heat pump unit can continue to provide heating even below -20. Heat strips do make the heat pump more expensive, but I would wager they're less expensive than having a separate furnace.
  - nirolo 4y ago
    Have a look what's being used in the Nordics in Europe. Sweden has 90% share of heat pumps for residential heating systems for example. I've got a Panasonic that heats to -35°C as advertised by the manufacturer and-40°C as tested in the lab.

ilyt 4y ago

I wonder if it would be economical to make ground-fed heat pump that had piping built in together with house (dig out foundation, put piping for water-to-water heat pump, build house), for the colder places.

__MatrixMan__ 4y ago
I'm told that (at least for the soil near my house) you want the ground source piping to make it down to the ground water because without that moisture the soil's capacity to transmit heat degrades over time.
cyberax 4y ago
You really need to tap into a watertable for the ground-loop to work. Otherwise it'll be nothing but a huge PITA. And at this point in time, the best air-source heat pumps are good enough until -25C. Meaning that you get CoP more than 1 at this temperature. So this would work for most of the US just fine.
- wood_spirit 4y ago
  I have a “ground source heat pump” (a long pipe zig zagging under my lawn at about 2-3 foot depth) and kinda sandy soil and nobody mentioned no water table and it works great. Sand is not ideal but it’s not a blocker. The most common heap pumps use bore holes straight down into the rock here in Sweden, but lateral installs are marginally better performance (sun reheats soil every summer) if you have a big garden. Heap pumps dominate in Sweden so the installers have a lot of confidence and give good practical advise.
c22 4y ago
The ground is only warm because it's heated all day by the sun. The ground under your house, less so.

montjoy 4y ago

I’m not sure if you’re being literal or figurative, but most heat pump installations using forced air share everything with the furnace so there is no “side”. My thermostat just has a setting to use the NG furnace when it’s colder than X. BTW my heat pump is about 20 years old and works great in the range I have it set to operate in.

nemo44x 4y ago
Literal. Did a 2-story home addition where the second floor had a heat pump installed since the existing venting system wound have been underpowered to support it and it would have been difficult to run vents there.

SamBam 4y ago

I think that's less and less of a problem. We just installed a Mitsubishi Hyper Heat, that's supposed to work down to -20⁰F without any auxillary heating. Many other units have auxillary resistive heating when the temperature are that low, which is obviously less efficient than the heat pump, but is still better than needing to maintain a fossil-fuel furnace.

eljimmy 4y ago
Are you Canadian? I had previously looked into heat pumps for cold climates and thought that it was economically not a great investment and required a gas back-up.
- adgjlsfhk1 4y ago
  Canada's really big. Vancouver and Toronto are both definitely warm enough for a heat pump to make a ton of sense.
- SamBam 4y ago
  No, Massachusetts, so probably warmer than you, depending on where you are. Even in Canada, though, I'd look into whether heat pumps with resistive auxillary heat are economical. If it only ever goes below -20⁰F for, say, a week a year, you'd probably still come out on top. And you'd definitely come out on top environmentally if your electricity is mostly green.
  - bradknowles 4y ago
    And with heat strips, a heat pump unit can continue to provide heating even below -20. Heat strips do make the heat pump more expensive, but I would wager they're less expensive than having a separate furnace.
- nirolo 4y ago
  Have a look what's being used in the Nordics in Europe. Sweden has 90% share of heat pumps for residential heating systems for example. I've got a Panasonic that heats to -35°C as advertised by the manufacturer and-40°C as tested in the lab.