Heat Pump to replace my 300k BTU Boiler.

GravityHeat

I have searched for decades for an interchangable heat pump for my 300k BTU hot water Boiler. A system where I could use my closed system/radiators for both heating and cooling. Anyone developing one? This is the Holy Grail for many old house owners.

WMno57

WMno57

I borrowed the photo from @Hotrod post in this thread: https://forum.heatinghelp.com/discussion/189670/air-to-water-hp

Jamie Hall

First off, cooling with a radiator is impractical -- if you run the radiator on cold water it's going to condense and drip all over the floor, unless you are in a dry climate somewhere.

Second, 300,000 BTUh is a lot of power. Even at a CoP of 3 (which you may not get on a cold day) that'50 KW or so. Over 200 amps at 240 VAC single phase. Got that much power?

KC_Jones

Are you sure you actually need 300k BTU? I would speculate on a house at minimum 7500 square feet, most likely a fair amount bigger to actually "need" 300k BTU's

Have you actually calculated the heat loss of the structure?

pecmsg

GravityHeat said:

I have searched for decades for an interchangable heat pump for my 300k BTU hot water Boiler. A system where I could use my closed system/radiators for both heating and cooling. Anyone developing one? This is the Holy Grail for many old house owners.

You're not going to find a heat pump that can make 180°F water!
Next is you're going to have to increase the number of emitters by probably 50% to be usable with the lower water temperatures.

Hot water / Chilled water piping required serious piping insulation and vapor barriers, or you'll have serious flooding during the summer.

pecmsg

Keep the existing HW system as a backup and get a Ducted heat pump installed. 2 stories 2 systems!

Hot_water_fan

The answer isn’t one heat pump, but several of you actually need the full 300kbbtu. Or try to 80/20 it and install 150ish of heat pump and keep the boiler for the rest. If you go the ground source route, they make them bigger than 300,000 btu. 

 You’ll have to come up with something else for cooling, like an air handler. 

WMno57

GravityHeat said:

I could use my closed system/radiators for both heating and cooling

No soup for me, because I did not read past your first sentence. I agree with Jamie. Can't use 100 year old cast iron radiators for cooling. @GravityHeat how do you cool your house now?
TCO of the monster A2WHP i posted will be much higher than a boiler. MTBF will be a much shorter than a boiler. But you can save the planet!!!

hot_rod

More questions than answers

You must do a load cals first
Then a count and sizing of radiators
Determine output at 120- 125F
See if the radiators you have at 120F swt could cover the heat load. I doubt it.

Even if you could cool with chiller radiators you may need to deal with sweating pipes, condensation dripping from the radiators. All the piping would need to be insulated and sealed.

A dewpoint control could avoid that, but a cooling load calc would be needed also.

Cover the AC with some sort of air moving device, mini split or high velocity AH.

Here is a radiator derate example.

Certainly you can find commercial HP to cover a load that size. The Mitsubishi folks I met with last week can get 190F from some units the are working on.

What's in your wallet?