5 ms·

> Moreover, why gas instead of electric backup? Hum, I do not know in you country but here in France the maximum you can get from the grid is 36kW, 12kW per ph

by kkfx 4y ago

> Moreover, why gas instead of electric backup? Hum, I do not know in you country but here in France the maximum you can get from the grid is 36kW, 12kW per phase, 3 phases. And while the electricity is still far cheaper than in Germany if you try to heat a classic badly insulated home (who have a typical 34-40kW gas heating) with electricity you final bill will be a bit astronomical....

lazide 4y ago
US new construction is typically 200 amp (though some go up to 400 amp) 240v ‘split phase’ (so most branch circuits will be 120v). It’s technically single phase though. So 48-96kw, technically.
- kkfx 4y ago
  So it's more than here for private homes (you can get much more, but only for business) BUT even with enough amps how much it cost per kWh in mean? Here we are from 9.7 cent/kWh for the cheapest hours, 15 cent/kWh for the mean, 67.12 for the most expensive hours of most expensive days (22 days per year in winter, the coldest essentially) i.e. https://www.fournisseurs-electricite.com/edf/tarifs/tempo https://www.fournisseurs-electricite.com/edf/tarifs/tempo for business in the "cheap" segment (not more than 36kW) it's from 21 to 25 cent per kWh.
  - lazide 4y ago
    CAlifornia is stupid expensive - averaging over $.50/kwh. Other areas are cheaper - Washington and Oregon have a lot of hydro power, and it is usually $.12/kwh or less there.
    - secabeen 4y ago
      This is changing. Peak cost during summer afternoons is definitely $0.50+/kWh, but most other times are in the $0.20-0.30/kWh range, due to the broad deployment of solar and lower nighttime demand.
brnt 4y ago
The first thing you do when looking a heat pumps is discover how overdimensioned gas heaters are. My house has a 20kW unit, and I'm replacing it with a 6-7kW heatpump, based on a calculation of historical use. Note that heat pump are usually placed in houses that are well insulated and thus never cool down; it's designed to run 24/7, not regularly heat up from eg 15C. Installing a pump without installing insulation (if you need it) is silly.
- yetihehe 4y ago
  I have new home and designer specified 8kW of heating, but I thought it's ridiculously low for such a big home, so I've bought 24kW pellet furnace. Guess what, it averages about 6kW.
- kkfx 4y ago
  I know, I've build a new home, electrically heated and well insulated. An water-water heat pump + and air-air in the VMC, for a total of ~1kW suffice for mild climate (like -2/-5℃ at night) it climb to 3kW for -10/12 and to 4kW to -15/18 outside. Never seen more than 6kW for -25. BUT it's a new home. Classic homes here are built with rocks and mortar, laid down on grownd, often stitched together in villages to spare a wall or two. As a result they are essentially impossible to insulate: insulating from the outside means agree with others for a job often as expensive al living the home for a new one. From the inside it's even more costly and not always doable since old homes tend to be irregular and with low ceiling resulting a too much internal space loss, not counting the effect of having loss much thermal mass. Toll buildings from just after WWII to the sixties are in even worse shapes, at that time almost no one care about insulation or thermal design because heating was veeeeeery cheap. The old rule in winter was "if it's too hot just open a window, it's cheaper than a thermostat". These buildings are the MAJORITY of the buildings and their own tend to be not so rich so they'll reach both natural and economical EOL soon and non one have a viable idea of what to do. Rebuilding anything is possible in mere theoretical terms, but in 30+ years, not tomorrow, and only with a public hand keeping costs low and plan with a bit of design instead of building a new real estate rush with similar results of those of the recent past in few decades. In practice though it's next to impossible because vast majority do not want to relocate. In south EU most home owners are middle class or even some low incomes, not just few rich and all other rent from big society. That's the real point. For EVs and p.v. it's essentially the same: those who live in modern homes have both in mean or can have at least. Almost all others can't. Those who lives in cities have already big parking issues since cities was build far before cars, so with not much room for them, and as well no room for reasonable domestic p.v. systems. Classic homes tend to be badly oriented and many still have no garages. As a result most can only recharge cars from public stations who are spread enough not too few but most are 22kW 3-phase as homes, so you need to find one, occupy it for maybe 4+ hours, move the car thereafter to live the place for another and find a parking for yours now charged. Something stressful enough that most who do not have a private garage simply do not buy EVs. Evolving civil infrastructures is not such a quick and easy things, especially in dense areas and during economic/social crisis of various kind.

by kkfx 4y ago

lazide 4y ago

US new construction is typically 200 amp (though some go up to 400 amp) 240v ‘split phase’ (so most branch circuits will be 120v). It’s technically single phase though. So 48-96kw, technically.

kkfx 4y ago
So it's more than here for private homes (you can get much more, but only for business) BUT even with enough amps how much it cost per kWh in mean? Here we are from 9.7 cent/kWh for the cheapest hours, 15 cent/kWh for the mean, 67.12 for the most expensive hours of most expensive days (22 days per year in winter, the coldest essentially) i.e. https://www.fournisseurs-electricite.com/edf/tarifs/tempo https://www.fournisseurs-electricite.com/edf/tarifs/tempo for business in the "cheap" segment (not more than 36kW) it's from 21 to 25 cent per kWh.
- lazide 4y ago
  CAlifornia is stupid expensive - averaging over $.50/kwh. Other areas are cheaper - Washington and Oregon have a lot of hydro power, and it is usually $.12/kwh or less there.
  - secabeen 4y ago
    This is changing. Peak cost during summer afternoons is definitely $0.50+/kWh, but most other times are in the $0.20-0.30/kWh range, due to the broad deployment of solar and lower nighttime demand.

brnt 4y ago

The first thing you do when looking a heat pumps is discover how overdimensioned gas heaters are. My house has a 20kW unit, and I'm replacing it with a 6-7kW heatpump, based on a calculation of historical use. Note that heat pump are usually placed in houses that are well insulated and thus never cool down; it's designed to run 24/7, not regularly heat up from eg 15C. Installing a pump without installing insulation (if you need it) is silly.

yetihehe 4y ago
I have new home and designer specified 8kW of heating, but I thought it's ridiculously low for such a big home, so I've bought 24kW pellet furnace. Guess what, it averages about 6kW.
kkfx 4y ago
I know, I've build a new home, electrically heated and well insulated. An water-water heat pump + and air-air in the VMC, for a total of ~1kW suffice for mild climate (like -2/-5℃ at night) it climb to 3kW for -10/12 and to 4kW to -15/18 outside. Never seen more than 6kW for -25. BUT it's a new home. Classic homes here are built with rocks and mortar, laid down on grownd, often stitched together in villages to spare a wall or two. As a result they are essentially impossible to insulate: insulating from the outside means agree with others for a job often as expensive al living the home for a new one. From the inside it's even more costly and not always doable since old homes tend to be irregular and with low ceiling resulting a too much internal space loss, not counting the effect of having loss much thermal mass. Toll buildings from just after WWII to the sixties are in even worse shapes, at that time almost no one care about insulation or thermal design because heating was veeeeeery cheap. The old rule in winter was "if it's too hot just open a window, it's cheaper than a thermostat". These buildings are the MAJORITY of the buildings and their own tend to be not so rich so they'll reach both natural and economical EOL soon and non one have a viable idea of what to do. Rebuilding anything is possible in mere theoretical terms, but in 30+ years, not tomorrow, and only with a public hand keeping costs low and plan with a bit of design instead of building a new real estate rush with similar results of those of the recent past in few decades. In practice though it's next to impossible because vast majority do not want to relocate. In south EU most home owners are middle class or even some low incomes, not just few rich and all other rent from big society. That's the real point. For EVs and p.v. it's essentially the same: those who live in modern homes have both in mean or can have at least. Almost all others can't. Those who lives in cities have already big parking issues since cities was build far before cars, so with not much room for them, and as well no room for reasonable domestic p.v. systems. Classic homes tend to be badly oriented and many still have no garages. As a result most can only recharge cars from public stations who are spread enough not too few but most are 22kW 3-phase as homes, so you need to find one, occupy it for maybe 4+ hours, move the car thereafter to live the place for another and find a parking for yours now charged. Something stressful enough that most who do not have a private garage simply do not buy EVs. Evolving civil infrastructures is not such a quick and easy things, especially in dense areas and during economic/social crisis of various kind.