Heat Pumps

This is what I am looking at...
https://www.chiltrix.com/air-to-water/
If you can run pex you can do this...

BunkerdCaddis wrote: ↑

Thu. Aug. 11, 2022 8:13 pm

So I always figured these DHW tanks w/ heat pumps on them were a bit of a joke (taking heat out of the air you just heated w/ your resistance heat at worst) and then I read somewhere about retro fit units that you could at least set outside to take advantage of warmer weather. Can you retro fit one to a domestic coil in a boiler to heat your DHW over the summer? Keeping your boiler warm at the same time instead of a light bulb...

They lower the room temp about 1 to 2 degrees ,which recovers quickly when they are off. They also dehumidify,saves a bundle there. Mine is close to my stoker where its 80 deg all winter anyway.

k-2 wrote: ↑

Fri. Aug. 12, 2022 9:12 am

They lower the room temp about 1 to 2 degrees ,which recovers quickly when they are off. They also dehumidify,saves a bundle there. Mine is close to my stoker where its 80 deg all winter anyway.

In the summer it makes sense but winter? I'll just use the domestic coil on the boiler to heat the water directly, why use a motor to suck heat from your boiler and pump it into a tank through the air, it'd be better to run a coil and small circulater, it's a boilermate with extra steps. As I'm reading more it seems they don't reach full temp without using some resistance heat to top the temperature up.

This Geyser Unit looked promising but doesn't seem to be available anymore.

BunkerdCaddis wrote: ↑

Fri. Aug. 12, 2022 9:35 am

In the summer it makes sense but winter?

In winter is makes sense too for me. My boiler is very small and only has a 20 gallons of water in it. In peak heating season i now get house heat 100% of the time to the baseboard . Previously the water heating gave me a cold boiler and no house heat while hot water demand was constant and taking priority. I use my HPWH on heat pump only mode. 540 watts instead of 4500 watts. No resistance heat. Heats to140 deg 50 gallons

k-2 wrote: ↑

Fri. Aug. 12, 2022 9:54 am

In winter is makes sense too for me. My boiler is very small and only has a 20 gallons of water in it.

Yes that situation makes sense, spreading the "heat" call over a longer period for the DHW, boilermate would do the same except in the summer. What's the max water temp on heat pump only mode?

BunkerdCaddis wrote: ↑

Fri. Aug. 12, 2022 10:06 am

Yes that situation makes sense, spreading the "heat" call over a longer period for the DHW, boilermate would do the same except in the summer. What's the max water temp on heat pump only mode?

Same as all the other modes, as stated 140 Deg. I have a boiler mate but never had to hook it up. I reduced my coal use from 7 ton to 4 ton a yr with the solar room and the HPWH. All while reducing my electric bill and heating a 3000 sq ft 100 yr old house to 77deg in winter.

But…Could anybody buy a Geyser DHW heat pump.
No, been discontinued for quite some time now.

Water to water as well as water to air heat pumps are a very well developed technologies. Constant earth temperature regardless of extreme inverse temperature outside. Why do the hard fight when you need not?!?!

Air to air and air to water have to work from outdoor ambient temperatures which are reversed. Cold outside when you want heat and hot outside when you want cooling. Easy is not always better!!

McGiever wrote: ↑

Fri. Aug. 12, 2022 11:26 am

Air to air and air to water have to work from outdoor ambient temperatures which are reversed. Cold outside when you want heat and hot outside when you want cooling. Easy is not always better!!

Which is why to this point I've kept the A/C unit with the house. What I'm questioning is using a heat pump to heat the DHW by heating the boiler over the summer so Hot Air to Hot Water. If they can heat to 140* it might work.

BunkerdCaddis wrote: ↑

Fri. Aug. 12, 2022 12:47 pm

What I'm questioning is using a heat pump to heat the DHW by heating the boiler over the summer so Hot Air to Hot Water. If they can heat to 140* it might work.

The answer is yes, you can do it. In that arrangement the heat pump would use the boiler as a buffer tank, and you would be counting on the btu's stored in the boiler and available from the heat pump for making your DHW. Although I have never seen this done in concept it is the same as using a buffer tank with an internal coil for DHW.

Thanks Rob, a concern I have is what is a minimum boiler temp for a DHW coil to be effective? I know some guys lower the boiler temp over the summer (at least that's what I understood) so for 120* output does 140* boiler temp work? May not have the recovery rate but it's just two of us now.

BunkerdCaddis wrote: ↑

Sat. Aug. 13, 2022 7:31 am

Thanks Rob, a concern I have is what is a minimum boiler temp for a DHW coil to be effective? I know some guys lower the boiler temp over the summer (at least that's what I understood) so for 120* output does 140* boiler temp work? May not have the recovery rate but it's just two of us now.

That is a valid concern, and the answer varies depending on the boiler/coil design and how much DHW you use. EFM recommends 160F, but Keystoker suggest 140F for the summer. I think some of the air2water heat pumps can go over 140F, but not much more. The part I don't like is having a hot basement in the summer due to a boiler being kept at operating temperature, whether it is fired by coal or heated by a heat pump. After insulating my boiler and piping that is less of an issue, but it is still noticeable. Running a heat pump water heater in the summer and fall (for a cool and dry basement) and feeding it hot water from the boiler in the heating season seems like a better arrangement to me.

BunkerdCaddis wrote: ↑

Fri. Aug. 12, 2022 9:35 am

In the summer it makes sense but winter? I'll just use the domestic coil on the boiler to heat the water directly, why use a motor to suck heat from your boiler and pump it into a tank through the air, it'd be better to run a coil and small circulater, it's a boilermate with extra steps. As I'm reading more it seems they don't reach full temp without using some resistance heat to top the temperature up.

The energy to run the motor can only go one of two places. Back into the room or into the water. However the the BTU's in the electric to run the motor are pretty expensive per BTU.

In the summer time or hotter climates this becomes a no brainer especially if it's located in the living space. Not only are you dehumidifying but you are cooling the living space.

There is other considerations here as well. The coil in the tank cost a lot less than a water heater regardless of the type and you may only have to buy one in the same time you need to buy many water heaters. That by itself is pretty substantial chunk of change in savings, many thousands of dollars over decades. .

Not sure if your location, but in Maryland, if you want a heat pump, they have a program through our power companies. You actually pay for it on your bill. Anyways, you get an energy audit done and they recommend improvements. Company pays up to 7500 towards those improvements. If you have baseboard electric you’re pretty much guaranteed to get the maximum benefit of 7500. Can be for a heat pump, insulation, things like that. Contractor takes care of everything. Most states power companies have these programs. Just something to look into.

We heat our home here in Massachusetts with coal (Woodchuck furnace in the basement). The bedrooms are heated with baseboard electric upstairs - thermostat in each room, if I want to use - the house is all electric. I have been looking into heat pumps, because of the CO2 emissions, but I'm not totally sure, since coal doesn't heat the whole house. I am "on the fence". And just a note, all new construction in 5 or 6 towns in the state have a fossil fuel ban from now on, and Boston will be there soon.

Heat pump have made great strides and be effective down to 0 degrees and they always are more efficient than baseboard electric . You get more heat from a heat pump per kilowatt hour of elective spent than resistance heating. A multi zone heat pump system sound like a good solution for you . Other heat pump system would require ductwork Mini splits are minimally intrusive but do take significant labor to install.