Gas Fired Absorption Heat Pumps - Take 2

[280plus]

For those of you who have followed the story on the new technology heat pumps I brought in from Italy there turns out to be some snags. Wouldn't you know it. So here is the latest...

A number one: Although these things DO use gas at a VERY efficient rate (up to 157% of input) they do in fact burn gas at all times throughout the operation. I was led to believe they did NOT use gas down to a very low outdoor temp and have related that here, so we all now know that this is not the case.

Secondly and equally important. Yes these things will STILL use gas at 100% of input down to -4*F outdoor temp, there's not another fossil fuel fired heating appliance on the planet that will do so. Unfortunately the manufacturer fails to note in anywhere in the literature in clear language that as soon as it goes BELOW -4* outdoor temp the process ceases to work and therefore THEY SHUT DOWN!! AAAAGGGGHHHH!!!



At this point, given the above average tightness of the house and the nice heated 6"+ concrete slab in the basement we THINK they will be able to do this and let us get away with not adding additional means of heating. Only because it gets that cold only a few days during winter in this area and only overnight. Once the sun comes up the temp comes right back up.

If it turns out that we DO need additional heat I'm going to yank one of them and replace it with a conventional. Then you know who is going to have a nice new heat pump for his own little house. I've been contemplating replacing the boiler and adding central A/C so it's not THAT bad of a thing should it turn out that way.

I'll keep you all posted.

[Ron]

Where do you live?

I am surprised heat pumps are even an option with ambients as low as below zero!

[280plus]

Hartford CT area...

I'd redefine them as more of a heat pump assisted gas fired boiler at this point. But even that doesn't quite define the way they function. At no time does the gas fire directly heat the water. It only aids in the boil off of the ammonia refrigerant. Still pretty darn good technology but not quite what I thought they were.

In a convetional model the gas fire DOES heat the water directly but at a much less efficient rate. 81% last I heard. The ammonia side only chills water.

[cfabe]

Question that just occured to me, 280... how did you get the system charged with ammonia? Did you have to call in an industrial refrigeration guy, or did the units come pre-charged or some other work around? Did the fact that they operate on ammonia cause any other issues?

[280plus]

They come precharged from the factory. At this point there have been no other issues regarding the use of ammonia as a refrigerant. I'm still working on a way to ramp these things too btw. It's on the back burner at the moment. Should there be internal issues with the refrigeration side I WOULD have to call in an ammonia qualified tech which the distributor assures me he can provide. I have plans to take the necessary courses to become ammonia qualified as they become available in my area so eventually that should not be an issue.

[mfree]

If I'm not mistaken all that's required to the ammonia absorption cycle is a heat source and maybe a pump.

It makes me wonder why someone hasn't hooked one of those suckers up to a solar collector, the fresnel lens type, yet

[280plus]

Not a bad idea at all.

I was under the impression that the air provided ALL the heat needed down to a certain temp to boil off the ammonia, turns out it needs to use gas too, just not as much as it would without the air source.