5 ms·

I think you’re a factor of 5-10 out on your calculations. 2 outdoor units running 110V x 50amps is 11.0kW which using a base efficiency you can expect from a h

I think you’re a factor of 5-10 out on your calculations. 2 outdoor units running 110V x 50amps is 11.0kW which using a base efficiency you can expect from a heat pump of 4:1 input electricity to heat results in 44kW of heating / cooling. If your 4 bedroom house needs 44kW of heating I would be looking at other winter warmers first, like buying glass for your windows. For comparison a reasonably large heat pump would have a heating cooling rating of 12kW

endisneigh 5y ago
My calculations were not talking about the usage of electricity, but the breakers the panels require. Hyper-heat models require 50 amp breakers and are 230V. Peak load usually only happens when the compressors cycle. The actual non-peak usage isn't that high as you've stated. Regardless the breakers must accommodate peak-load.
- drusenko 5y ago
  Yes, electrifying everything will result in more peak demand which will require upgrading many house’s main panels. It’s not an insurmountable challenge though, especially relative to dealing with the effects of 2+ degrees of warming.
  - endisneigh 5y ago
    You're missing my point - in the context of the article the issue is not upgrading the panels, it would be replacing the entire current electrical infrastructure. I'm not claiming it's insurmountable. The point is that these changes will increase the cost of housing, which will make people sprawl, the very same sprawl that will decrease the efficiency of the very same things we're talking about. There's a political, economic and cultural balance to be struck here, technology changes notwithstanding.
    - drusenko 5y ago
      A fully electrified home actually reduces overall system cost through 1- higher efficiency of electric appliances and heat pumps than their gas counterparts, and 2- a significantly reduced infrastructure cost to no longer having to maintain gas infrastructure, the totality of which (scouting, mining, transportation, last mile) is incredibly expensive. In fact, for new construction, it is often cheaper out the gate to go all electric and the efficiency savings in terms of lower electric+gas bills are significant and pure upside. Moving on to electric retrofits, they are expensive but not crazy expensive. On the order of $2500-7500 per SFH to wire 220/30-50 amp circuits to the right places (HVAC, stove, water heater, clothes dryer, EV charger) and maybe upgrade the main panel - a far cry from redoing the entire wiring. It’s not an insane proposition to think we could retrofit all existing housing stock in a 15 year period if we wanted to take it seriously. We are going to need more electricians though. Do you know what is actually really expensive? Billions or trillions of dollars in climate disaster losses and mitigation which we are seeing ramp up very quickly. If we continue burning fossil fuels even remotely like we are now, in 20 years time the losses we say today will look like peanuts in comparison. Buildings make up a very significant amount of the CO2e emissions (depending on the location, often tied #1 with transportation) so doing nothing here is not really an option.
      - endisneigh 5y ago
        The efficiency increase for all electric appliances except for heat pumps is generally not worth the conversion cost. Gas infrastructure is already in place so the expense is irrelevant. If what you were saying were true then economic forces would already have led to dominance of full electric without the need for government mandates to begin with.
        drusenko 5y ago
        That’s not really true. New high efficiency heat pump water heaters - as one example - often have a 1-2 year ROI, which is pretty dramatic. HVAC is actually often the most expensive from an ROI standpoint because of larger upfront costs. Market forces will lead us down this path eventually but they are not instantaneous, and we don’t have much time to wait. Policy can help 1- accelerate, 2- bootstrap emerging markets (eg creating demand for more induction stoves turns that market from a niche to mainstream, with more competition, more choice, and reduced cost, all of which will serve to boost demand) and 3- finance infrastructure investments that may be beyond reach for many. On gas infrastructure, yes it is in place but it still requires significant ongoing maintenance costs which would be eliminated if it was shut down.
- briHass 5y ago
  The breaker size almost never matters in a circuit, including ac/heat pumps. These units are rated in MOCP (max overcurrent protection, aka, the breaker size) and MCA (minimum circuit ampacity, aka, what gauge wire to run.) You actually want to look up your unit's RLA (running load amps) which is what it's likely to max pull most of the time. I'm assuming you're talking about a 4 ton multi-zone unit (which is pretty large). Those call for a 50A MOCP, but in reality, they only draw like 20A while running, plus a couple for the indoor units' fans.
  - endisneigh 5y ago
    The peak load for the hyper heat units I describe do require a 50 amp breaker. Breakers depend on peak load, not average.
    - ikiris 5y ago
      And again, that doesn't matter because that's for inrush current for starting the motors, and not a steady state draw.
      - endisneigh 5y ago
        It does matter because my comment was talking about breakers in a typical house electrical panel. The breaker needs to be able to handle the peak, not the average. Just go Google Mitsubishi hyper heat - it clearly states 50 amps per condenser. I’m not sure what’s difficult to understand about this.
        lixtra 5y ago
        > Just go Google > I’m not sure what’s difficult to understand about this. Of course you may expect the casual reader to do the googling themselves. But if you want to make your arguments heard, it’s helpful to put a link to an authoritative source. Of course this is also true for anyone making the counter claim.
        5y ago

endisneigh 5y ago

My calculations were not talking about the usage of electricity, but the breakers the panels require. Hyper-heat models require 50 amp breakers and are 230V. Peak load usually only happens when the compressors cycle. The actual non-peak usage isn't that high as you've stated. Regardless the breakers must accommodate peak-load.

drusenko 5y ago
Yes, electrifying everything will result in more peak demand which will require upgrading many house’s main panels. It’s not an insurmountable challenge though, especially relative to dealing with the effects of 2+ degrees of warming.
- endisneigh 5y ago
  You're missing my point - in the context of the article the issue is not upgrading the panels, it would be replacing the entire current electrical infrastructure. I'm not claiming it's insurmountable. The point is that these changes will increase the cost of housing, which will make people sprawl, the very same sprawl that will decrease the efficiency of the very same things we're talking about. There's a political, economic and cultural balance to be struck here, technology changes notwithstanding.
  - drusenko 5y ago
    A fully electrified home actually reduces overall system cost through 1- higher efficiency of electric appliances and heat pumps than their gas counterparts, and 2- a significantly reduced infrastructure cost to no longer having to maintain gas infrastructure, the totality of which (scouting, mining, transportation, last mile) is incredibly expensive. In fact, for new construction, it is often cheaper out the gate to go all electric and the efficiency savings in terms of lower electric+gas bills are significant and pure upside. Moving on to electric retrofits, they are expensive but not crazy expensive. On the order of $2500-7500 per SFH to wire 220/30-50 amp circuits to the right places (HVAC, stove, water heater, clothes dryer, EV charger) and maybe upgrade the main panel - a far cry from redoing the entire wiring. It’s not an insane proposition to think we could retrofit all existing housing stock in a 15 year period if we wanted to take it seriously. We are going to need more electricians though. Do you know what is actually really expensive? Billions or trillions of dollars in climate disaster losses and mitigation which we are seeing ramp up very quickly. If we continue burning fossil fuels even remotely like we are now, in 20 years time the losses we say today will look like peanuts in comparison. Buildings make up a very significant amount of the CO2e emissions (depending on the location, often tied #1 with transportation) so doing nothing here is not really an option.
    - endisneigh 5y ago
      The efficiency increase for all electric appliances except for heat pumps is generally not worth the conversion cost. Gas infrastructure is already in place so the expense is irrelevant. If what you were saying were true then economic forces would already have led to dominance of full electric without the need for government mandates to begin with.
      - drusenko 5y ago
        That’s not really true. New high efficiency heat pump water heaters - as one example - often have a 1-2 year ROI, which is pretty dramatic. HVAC is actually often the most expensive from an ROI standpoint because of larger upfront costs. Market forces will lead us down this path eventually but they are not instantaneous, and we don’t have much time to wait. Policy can help 1- accelerate, 2- bootstrap emerging markets (eg creating demand for more induction stoves turns that market from a niche to mainstream, with more competition, more choice, and reduced cost, all of which will serve to boost demand) and 3- finance infrastructure investments that may be beyond reach for many. On gas infrastructure, yes it is in place but it still requires significant ongoing maintenance costs which would be eliminated if it was shut down.
briHass 5y ago
The breaker size almost never matters in a circuit, including ac/heat pumps. These units are rated in MOCP (max overcurrent protection, aka, the breaker size) and MCA (minimum circuit ampacity, aka, what gauge wire to run.) You actually want to look up your unit's RLA (running load amps) which is what it's likely to max pull most of the time. I'm assuming you're talking about a 4 ton multi-zone unit (which is pretty large). Those call for a 50A MOCP, but in reality, they only draw like 20A while running, plus a couple for the indoor units' fans.
- endisneigh 5y ago
  The peak load for the hyper heat units I describe do require a 50 amp breaker. Breakers depend on peak load, not average.
  - ikiris 5y ago
    And again, that doesn't matter because that's for inrush current for starting the motors, and not a steady state draw.
    - endisneigh 5y ago
      It does matter because my comment was talking about breakers in a typical house electrical panel. The breaker needs to be able to handle the peak, not the average. Just go Google Mitsubishi hyper heat - it clearly states 50 amps per condenser. I’m not sure what’s difficult to understand about this.
      - lixtra 5y ago
        > Just go Google > I’m not sure what’s difficult to understand about this. Of course you may expect the casual reader to do the googling themselves. But if you want to make your arguments heard, it’s helpful to put a link to an authoritative source. Of course this is also true for anyone making the counter claim.
        5y ago