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Heat pumps are really amazing and can be used both for cooling and heating with the same hardware. If it wasn't for natural gas they would make sense for many A

Heat pumps are really amazing and can be used both for cooling and heating with the same hardware. If it wasn't for natural gas they would make sense for many American homes https://medium.com/hackernoon/the-magic-of-heat-pumps-fd2721a00586 https://medium.com/hackernoon/the-magic-of-heat-pumps-fd2721...

quickthrower2 6y ago
It might solve some of the solar demand problem. Heat water up during the day when the sun is out, and then store that in an insulated tank. Have both bath water and central heating run off that.
- ants_a 6y ago
  Makes sense for hot water, but with central heating less so. The energy is mostly needed during the months when there is not a lot of sun, over-sizing the solar collector is financially untenable, as is large enough insulated storage to cover months of heating.
- JshWright 6y ago
  That's already a thing, they just skip the intermediate steps and run the water through black pipes in a sunny spot.
  - quickthrower2 6y ago
    Black pipes are great, it would make some interesting calculations to compare: Pipes vs. PV taking heat pump characteristics into account, whose efficiency depends on climate. Installation costs, maintenance costs. The Pipes compete for real estate space against the PV, so if pipes are more efficient, does it off set the lost electricity (that would be more expensive, but cheaper than from the grid, but only when it's sunny and you can use the appliances at that time, unless you have a battery which is more capex, so does the interest/repayments on that cost get offset by using electric 24/7). Etc. Etc. It might need some ML to figure out the best solution. And by ML I mean linear regression.
henrikberggren 6y ago
*if it wasn't for cheap natural gas
- jay_kyburz 6y ago
  Gas is super expensive here in Australia and I plan to try and put 10kw solar on the roof next year. Our hot water is currently gas but I would like to move to electricity. The solar will take 10 years to pay off, I expect adding this to the mix would take another 10 years.
  - artpop 6y ago
    10kW on the roof and a Sanden heat pump hot water set to only run 9-5. I get credit from the Energy Australia for all the summer months which I spend on on the AC heat pump in winter. 25 year warranty on the panels and 20 on the micro inverters. The economics stack up.
    - gwicks56 6y ago
      Sanden do seem to be the recommended option for this. The problem is if you have a functional gas, the economics rarely stack up to change. If I knew for sure the Sanden would last 10 years yes, but unlike very simple gas water heaters, heat pumps have a disturbingly high failure rate.* *At least that was the way it seemed from my research, similar situation 6.66kw solar on roof, functional gas hotwater. We do have both Gas and Heat pump house heating/cooling. Heat pump is much cheaper, gas is much faster, even running the largest size possible ducted heat pump split system. I have the gas warm the house from 6am to 8am, then heat pump take over for the rest of the day.
      - artpop 6y ago
        My Daikin is near instant, even when near freezing outside. The compressor is yuge though, so maybe that’s why. Daikin RXYMQ6AV4A 2 x Daikin FXMQ80PAVE
  - artpop 6y ago
deleted 6y ago
[deleted]
torpfactory 6y ago
They even beat natural gas on operating cost for many installs these days: Gas Furnace: 1 Therm = 29.3kWh, Cost $1.5 (at least where I live), Furnace efficiency = 95%. Cost per kWh heat delivered = $0.053. Heat Pump (COP=5, EER=17): 1 kWh = $0.14, COP =5, Cost per kWh heat delivered = $0.028. Heat pumps are quite a bit more expensive to install though.
- frosted-flakes 6y ago
  That depends on the cost of electricity, which varies widely across the continent. I ran the numbers a few years ago for central Ontario (napkin math), and natural gas was 2x or 4x the cost (I can't remember). Anyway, definitely not worth it, especially since it falls back to pure electric heat when it can't keep up. And the house is heated with NG anyway, no point in making that energy transfer even less efficient. (NG fireplace heats the air, air heats the hybrid water heater coils, which heats the water via refrigerant and a noisy compressor. Instead of NG just heating the water directly.)

quickthrower2 6y ago

It might solve some of the solar demand problem. Heat water up during the day when the sun is out, and then store that in an insulated tank. Have both bath water and central heating run off that.

ants_a 6y ago
Makes sense for hot water, but with central heating less so. The energy is mostly needed during the months when there is not a lot of sun, over-sizing the solar collector is financially untenable, as is large enough insulated storage to cover months of heating.
JshWright 6y ago
That's already a thing, they just skip the intermediate steps and run the water through black pipes in a sunny spot.
- quickthrower2 6y ago
  Black pipes are great, it would make some interesting calculations to compare: Pipes vs. PV taking heat pump characteristics into account, whose efficiency depends on climate. Installation costs, maintenance costs. The Pipes compete for real estate space against the PV, so if pipes are more efficient, does it off set the lost electricity (that would be more expensive, but cheaper than from the grid, but only when it's sunny and you can use the appliances at that time, unless you have a battery which is more capex, so does the interest/repayments on that cost get offset by using electric 24/7). Etc. Etc. It might need some ML to figure out the best solution. And by ML I mean linear regression.

henrikberggren 6y ago

*if it wasn't for cheap natural gas

jay_kyburz 6y ago
Gas is super expensive here in Australia and I plan to try and put 10kw solar on the roof next year. Our hot water is currently gas but I would like to move to electricity. The solar will take 10 years to pay off, I expect adding this to the mix would take another 10 years.
- artpop 6y ago
  10kW on the roof and a Sanden heat pump hot water set to only run 9-5. I get credit from the Energy Australia for all the summer months which I spend on on the AC heat pump in winter. 25 year warranty on the panels and 20 on the micro inverters. The economics stack up.
  - gwicks56 6y ago
    Sanden do seem to be the recommended option for this. The problem is if you have a functional gas, the economics rarely stack up to change. If I knew for sure the Sanden would last 10 years yes, but unlike very simple gas water heaters, heat pumps have a disturbingly high failure rate.* *At least that was the way it seemed from my research, similar situation 6.66kw solar on roof, functional gas hotwater. We do have both Gas and Heat pump house heating/cooling. Heat pump is much cheaper, gas is much faster, even running the largest size possible ducted heat pump split system. I have the gas warm the house from 6am to 8am, then heat pump take over for the rest of the day.
    - artpop 6y ago
      My Daikin is near instant, even when near freezing outside. The compressor is yuge though, so maybe that’s why. Daikin RXYMQ6AV4A 2 x Daikin FXMQ80PAVE
- artpop 6y ago

deleted 6y ago

[deleted]

torpfactory 6y ago

They even beat natural gas on operating cost for many installs these days: Gas Furnace: 1 Therm = 29.3kWh, Cost $1.5 (at least where I live), Furnace efficiency = 95%. Cost per kWh heat delivered = $0.053. Heat Pump (COP=5, EER=17): 1 kWh = $0.14, COP =5, Cost per kWh heat delivered = $0.028. Heat pumps are quite a bit more expensive to install though.

frosted-flakes 6y ago
That depends on the cost of electricity, which varies widely across the continent. I ran the numbers a few years ago for central Ontario (napkin math), and natural gas was 2x or 4x the cost (I can't remember). Anyway, definitely not worth it, especially since it falls back to pure electric heat when it can't keep up. And the house is heated with NG anyway, no point in making that energy transfer even less efficient. (NG fireplace heats the air, air heats the hybrid water heater coils, which heats the water via refrigerant and a noisy compressor. Instead of NG just heating the water directly.)