DIY heat pump 12kW

Hello to all,

I am new to the forum and already found and read a lot of good information.

I want to build water to water heat pump about 10-12kW. I have knowledge in assembling, automation etc, but not in selecting components. I plan to use Copeland ZH compressor and Swep plate heat exchangers. I have downloaded Copeland's selection software and have some questions about selecting operating points. My water source has about 5-10 deg. C and I will use heat pump for underfloor heating. I will also use inverter to control heat pump power (control compressor's rpm).

My questions (for start :)) are:

1. what should be evaporating temp. and superheat?
(My guess is 5 deg. C and 5 deg. C. superheat)


2. what should be condensing temp. and subcooling?
(My guess is 35 degC so I go with 30C to underfloor heating)


3. I want to use heat pump also for domestic water heating (55deg. C)

Does it mean I just divert heated water to the domestic water tank and leave it circulating until it reaches 55 deg. C?


Regards and thank you for your help!

Quote:

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Originally Posted by kimusabi

Hello to all,

I am new to the forum and already found and read a lot of good information.


My questions (for start :)) are:

1. what should be evaporating temp. and superheat?
(My guess is 5 deg. C and 5 deg. C. superheat)

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The lower the evap temp the more chance of freezing the water.
Use brine / glycol to alow you to run the suction as low as you want.
Just leave the superheat set to the factory setting. If you do adjust set to about 6 to 8K

Quote:

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Originally Posted by kimusabi

2. what should be condensing temp. and subcooling?
(My guess is 35 degC so I go with 30C to underfloor heating)

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Condense about 8 to10deg higher than your intended water temp. For floor water needs to be about 27 to 30degC
For hot water, well then thats up to you. You could run a coil through your hot water tank before you then go to the heat exchanger. This will then desuperheat the refrigerant and heat up the water to between about 50 and 60degC. then the cooler refrigerant could heat water in your floor loop. You do need to be aware of legonella so you need to be able to take the water to about 60C on a regular basis.
Hot water does not need to be too hot if you intend to just cool it down to use in sinks or baths.

Quote:

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Originally Posted by kimusabi

3. I want to use heat pump also for domestic water heating (55deg. C)

Does it mean I just divert heated water to the domestic water tank and leave it circulating until it reaches 55 deg. C?

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Yes see above.

Quote:

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Originally Posted by kimusabi

Regards and thank you for your help!

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Cheers taz.

Taz, thank you for clarification. I think I will buy ZH21 compressor from Copeland.

Quote:

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Originally Posted by kimusabi

Taz, thank you for clarification. I think I will buy ZH21 compressor from Copeland.

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Your welcome.
Where is your ground water coming from?

Cheers taz.

Well, I don't have ground water yet. I am planning to make deep well - about 25 meters of 4inch pipe. My neighbour has plenty of water which was found on 21 meters, then it rised to 15 meter.

Plans are for end of june. I'll keep my fingers crossed ;)

Quote:

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Originally Posted by kimusabi

Well, I don't have ground water yet. I am planning to make deep well - about 25 meters of 4inch pipe. My neighbour has plenty of water which was found on 21 meters, then it rised to 15 meter.

Plans are for end of june. I'll keep my fingers crossed ;)

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Pumping ground water can be expensive in the long tearm.
Have you considered a closed loop and recirculate the water. A central heating water pump will do that and only 30 watts of energy.

Cheers taz.

Ground source heat pumps seem to be the way forward using a secondary circuit. Don't forget to consider the use of antifreeze in the system

Or making two wells of the same depth, one for pumping out the water and one to reject the water again in the ground.
It's forbidden in Belgium to use ground water in an open circuit for cooling or heating purposes.
If everybody should do it this way(only one well), then the lower subsoil water layers aren't disturbed any longer.

We tried to bore 33m and no water. And 100m away from me all the neigbours have plenty of water 4m below ground.
Now I am considering about air-to-water heat pump.

Hi don,t worry, go ahead with the air to water unit, you will only need a very good defrosting system. I don,t know what your plans are, but you have to think of an air to water system with a termal storage system that can help to defrost if the need comes. Till then it,s good luck.

that or over size your out door coil considerably and use an inverter controled fan to keep the SH constant.

IE program a control with a pressure transducer & thermister to slow the fan if SH gets too high or speed the fan should sh get too low

Quote:

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Originally Posted by kimusabi

Hello to all,

I am new to the forum and already found and read a lot of good information.

I want to build water to water heat pump about 10-12kW. I have knowledge in assembling, automation etc, but not in selecting components. I plan to use Copeland ZH compressor and Swep plate heat exchangers. I have downloaded Copeland's selection software and have some questions about selecting operating points. My water source has about 5-10 deg. C and I will use heat pump for underfloor heating. I will also use inverter to control heat pump power (control compressor's rpm).

My questions (for start :)) are:

1. what should be evaporating temp. and superheat?
(My guess is 5 deg. C and 5 deg. C. superheat)


2. what should be condensing temp. and subcooling?
(My guess is 35 degC so I go with 30C to underfloor heating)


3. I want to use heat pump also for domestic water heating (55deg. C)

Does it mean I just divert heated water to the domestic water tank and leave it circulating until it reaches 55 deg. C?


Regards and thank you for your help!

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HI ! im new member,

Im interesteed how dit this projekt went..

-Toni