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Harnessing America's heat pump moment

heatpumped.org

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Re: Harnessing America's heat pump moment

#151

Post by kragen »

ssuds wrote: post #149
kragen wrote: post #134

Earlier quoted context omitted.

Yes, it's just a mini split. Two guys (skilled, but AFAIK not licensed) installed it in about 6 hours. I'm in Argentina, but I don't think US$1000 an hour is a common labor rate even in the US? Maybe for a famous lawyer or surgeon?

Ha. It's not straight labor. So much other overhead to consider - workman's comp insurance, back office staff, technician utilization, vehicle repair and maintenance, etc... There are lots of other costs that get baked in when you're looking at a licensed company compared to a guy in a truck

Okay but US$5k for half a day of work? It would have been faster if the guy had had his own ladder instead of us moving my desk so he could stand on it to work. (He's bought one since then.)

Re: Harnessing America's heat pump moment

#152

Post by throw0101a »

Loughla wrote: post #101
doctorhandshake wrote: post #98

Earlier quoted context omitted.

The notion that heat pumps don’t work at low temperatures hasn’t been true for years. I think you may be surprised to find that just about any heat pump you look at has good efficiency down to very low temperatures.

Define low temperatures. Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.

> Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.

What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen:

* https://basc.pnnl.gov/images/iecc-climate-zone-map

ASHRAE—an HVAC organization—has data on the coldest and hottest days for areas so that you can design things for the coldest or hottest 1% of the year (4 hottest/coldest days):

* https://ashrae-meteo.info/v2.0/

I think that if you have an older, leaky/ier, less-insulated house you may need to 'brute force' heating your (probably older) domicile. But if you have a Mitsubishi publishes data were they have 100% heating capacity at -15C, which some models being 100% at -20C and -23C:

* https://www.mitsubishielectric.ca/en/hvac/home-owners/zuba

At -25C they have 80% capacity:

* https://www.mitsair.com/wp-content/uploads/2024/10/MEM-20240...

Re: Harnessing America's heat pump moment

#153

Post by doctorhandshake »

sokoloff wrote: post #150
doctorhandshake wrote: post #108

Earlier quoted context omitted.

I’m not sure what yours is but it doesn’t sound appropriate to your application. Mitsubishi hyper heat is indicative of a contemporary inverter design - 100% efficiency to -5f: https://www.mitsubishicomfort.com/articles/mythbusters-heat-...

100% efficiency is terrible for a heat pump. Electric resistance heat is 100% efficient.

I should have said 100% performance. COP is typically 3-4:1 with mitsu

Re: Harnessing America's heat pump moment

#155

Post by rootusrootus »

sitharus wrote: post #146
darth_avocado wrote: post #57

Earlier quoted context omitted.

I’m in California, I have two heat pumps installed. I can sum up the problems as follows: 1. They are EXPENSIVE. The equipment itself isn’t that expensive tbh but installation is pretty expensive. The government subsidies have made sure that the contractors jack up their own prices by as much. 2. I end up paying more in utilities because electricity is very expensive and heat pumps aren’t nearly as good at heating in…

I was shocked when I saw the price of heat pump installation in the US, even with an existing ducted system. There’s no reason a reversible heat pump system should be significantly more expensive than a cooling only one.

It's going to vary by installer, of course, but when I looked into getting a heat pump it was about $1500 more than just replacing the A/C condenser and evaporator with a like-for-like unit. Keeping the existing natural gas furnace as backup. This was in the PNW, about three years ago. $4500 for A/C, $6000 to replace it with a heat pump instead.

Re: Harnessing America's heat pump moment

#156

Post by smileysteve »

darth_avocado wrote: post #57
galoisscobi wrote: post #3

> we’re waiting on people Right on. I have a heat pump water heater and a heat pump heating system in my HVAC. Getting those installed felt like swimming upstream. Most contractors would try to dissuade me from them. Luckily, I found a contractor who was skilled and knowledgeable about heat pumps and rebates (back when govt thought climate change was real). Very happy with my heat pump tech.

I’m in California, I have two heat pumps installed. I can sum up the problems as follows: 1. They are EXPENSIVE. The equipment itself isn’t that expensive tbh but installation is pretty expensive. The government subsidies have made sure that the contractors jack up their own prices by as much. 2. I end up paying more in utilities because electricity is very expensive and heat pumps aren’t nearly as good at heating in…

Re #2.

Tuning a heat pump vs resistive heat is a much tougher game than it should be. In a moderate climate, I use my ecobee to ensure aux heat doesn't come on until it's below freezing, and it should only come on if something has gone wrong at that point too. Unfortunately, many thermostats by default will use resistive heat in relatively normal scenarios, of worse, when you've programmed home and away times intended for efficiency but disparate enough to activate resistive heat.

Re: Harnessing America's heat pump moment

#157

Post by rootusrootus »

notyourwork wrote: post #117
brendoelfrendo wrote: post #80

Earlier quoted context omitted.

No, no ductless magic without mini splits. I feel like a lot of people refer to heat pump systems interchangeably with ductless mini splits, so I wanted to clarify that. Maybe that's just an issue with the people I speak with, though.

You are right. Most do heat pumps with mini splits for each zone. However, ducted houses can certainly use heat pumps with an air handler. Typically this translates to heat pump replaced outdoor condenser (ac unit)and the air handler replaces the indoor furnace.

> the air handler replaces the indoor furnace

If the furnace is a serviceable natural gas unit, keep it. It makes a better backup than strip heat.

Re: Harnessing America's heat pump moment

#158

Post by srjek »

kragen wrote: post #135
notyourwork wrote: post #119

Earlier quoted context omitted.

Some heat pumps are rated for much lower temps.

They can work at lower temperatures, but they do need the auxiliary heat to deice the outside coils.

It's my understanding that nowadays most heat pumps have a defrost cycle where they automatically run in reverse for a bit with some or all fans off

Re: Harnessing America's heat pump moment

#159

Post by sokoloff »

bethekidyouwant wrote: post #114
LgWoodenBadger wrote: post #90

Earlier quoted context omitted.

What do you mean when you say “heat pump hybrid?”

Well, they have electric boilers, gas boilers, and gas/heat pump hybrid boilers. but not restive/heat pump hybrids. (for houses heated with hot water) I suppose this is because the return temperature to the boiler is already 50 Celsius so the heat pump can’t help you at all Edit: Oh actually, I was wrong.(and I guess it makes sense. It would suffer the same problems as an electric hybrid) There is no hybrid gas heat…

There are air-to-water heat pumps that can run hydronic heating (even radiators, though underfloor is a better match due to the lower return temps).

You can then make your own hybrid with a resistive electric boiler or a gas boiler wired to second-stage or emergency heat.

My 1920s house with radiators and terrible insulation outside of Boston runs with return water temps in the low 90s in shoulder season and 120°F when it’s 12°F outside, using outdoor-reset/weather-compensation.

Those return temps are entirely compatible with air-to-water heat pumps. (And result in 22-24 hour run times per day, which makes for extremely comfortable heat, despite the generally lacking insulation.)

I don’t have one because HVAC contractors are living in the 1990s and want to do a 3-hour, 2-person combi boiler install for $10K in profit rather than think through how to do anything unusual.

Re: Harnessing America's heat pump moment

#160

Post by [deleted] »

danielsju6 wrote: post #148

Maybe I have scar tissue from COVID prices but $20k to install a ductless heat pump vs. a $200 to throw a window A/C in or $700 for a portable heat pump. While I get that these heat pumps are better for the environment and much more efficient it's a last mile issue. The installers charge an arm and a leg and I'm not hurting enough to self install. I'm hoping the window heat pumps that just run off mains will be avail…

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