Multi-Effect Heat-Pumps or MEHP

[Welchita]

Hello there!

A very classic question: I would like to know what the Forum has to say about the MEHP, (air cooling/heating + hot water production from the same unit/equipment) in special, those with the cooling effect power between 5 and 15 kW (or between 17,000 ~ 50,000 BTU). Any related comment, data, references, sites, will be very appreciated. Thank You!

Merry Christmas to you All!
Welchita

 

[rmw]

I have an observation. A neighbor of mine on my suggestion put a hot gas to water heat exchanger made by Lennox on his compressor discharge and he made more hot water than he ever could have used. He could have supplied the whole neighborhood.

The thermodymanics were way out of balance.

rmw

 

[Welchita]

Hi RMW!
Thanks for your reply.
I would say that the 1st Law is always corrected! Better if it turns adequated to all our needs, which is quite difficult, sometimes.
Once you need same cooling, you have much more condensing heating, as consequence. This heat can be used for producing hot-water for climatization or/and for consumption sanitary water. If you have these effects supplied, than some ventilator gives the heat away. Or you can purpose some good solutions to your neighbors... Ecologicaly speaking, this unbalanced situation is not good for environment, but we can manage to optimize as much as we can, those balances.
Of course, we talking here of reverse heat-pumps. May we have a 2nd comment?
Merry Christmas to You!
Wel.

 

[DurtyDan]

Welchita-
My experience on this, from a HVAC contractors' perspective, is that it is a good idea, but complicates the whole home heating and cooling too much for most homeowners. A Carrier dealer in my area (Eastern Washington), installed many of these in the early '90s. Most have failed. Leaks with the domestic water side were the most common complaint, and since the compressor was usually in the basement, the homeowners have opted to go to a conventional direct-expansion, air-air system with resistance water heat.
I have a few customers who installed the system like RMW described, but on a Trane XV1500 variable-speed heat pump (now discontinued), with good results.

One success with this idea is the water-source heat pump, with domestic hot water generator. Climate Master manufactures a selection of these, and we have had very good results with them. I have some customers that have had them in use since the late '80s. If a ground loop or open loop geothermal heat pump is a usable solution, this makes a very easy sell using ROI, and it is very ecologicaly sound.

Hope this helps

 

[drkillroy]

Hi Durtydan

I have heard of 2 Carrier attempts at home heating. I never heard of this problem from the system you mentioned. Just what caused the leak? The other system had a natural gas engine to run the compressor for a co-generation heating and deamed too complex. Have you seen them?
Thanks drkillroy

 

[Welchita]

Dear Fellows

In meantime, I just have to say this thread needs more contributions from everybody, namely those who have experienced to build, work with this type of equipments, experts included!
Why the good ideas, as they look at the beginning sometimes don't work? Shall we go deep into the discussion ?

Happy New Year to All!

Welch.

 

[DurtyDan]

@ Drkillroy-

The failures on the few Carrier heat pumps with hot water generators that I saw were water coil leaks. Since the compressor and water coils were in the basements, it really made a mess of the place. The leaks developed inside the coil themselves. I don't think that it was anything necessarily wrong with the design, but in practical application, as the equipment and plumbing aged, problems developed. The idea works, but needs a commitment to maintenance and a willingness to put up with possible leaks.