SLHX and solar thermal

[MikeHolm]

I've been thinking of the best way to improve the COP of an ASHP using solar. One way would be use make a SLHX and run the solar through the jacket at times when it is too cool to directly heat a storage tank. Thumbs up (and why) or full of s**t (and why), haha.

[hyperion]

You would have to modify the controls to enable the solar pump system to run whilst not in the "full" solar conditions. You would have to limit the input to prevent too high a suction temperature back to the compressor.
It might also be worth considering using the solar through a HX to pre-heat the make up water.

[MikeHolm]

You would have to modify the controls to enable the solar pump system to run whilst not in the "full" solar conditions. You would have to limit the input to prevent too high a suction temperature back to the compressor.
It might also be worth considering using the solar through a HX to pre-heat the make up water.

The controls are already figured out to work with the "less than useful" temps coming from the panels and to keep the suction temp to manageable levels, so that is OK.

The real question is how the input form a secondary source will affect the energy balance of the system. I would not want to have the liquid line temp to climb too high and start giving off heat to the evap. A bit counter-productive.

[Rob White]

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They sort of already do it with a storage cylinder.
The cylinder of water has upto 3 circuits on it.

1 X lowest circuit is for a solar collector.
2 X middle circuit is for the heat pump.
3 X top circuit is auxiliary boiler.

Is that what you mean? Or are you talking about direct into
the fridge circuit?

Regards

Rob

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[Rob White]

The controls are already figured out to work with the "less than useful" temps coming from the panels and to keep the suction temp to manageable levels, so that is OK.

The real question is how the input form a secondary source will affect the energy balance of the system. I would not want to have the liquid line temp to climb too high and start giving off heat to the evap. A bit counter-productive.

In Europe they are called Bivalent systems.
2 or more heat sources and a control point that
controls both head pump and auxiliary. The point
where one cuts in and one cuts out is the Bivalent point.

Rob

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[padraic]

http://www.youtube.com/watch?v=WGeUKJYx2bs&autoplay=1

something I'm looking at doing in my new house.. Rotex diakin

[MikeHolm]

Yup, I know about the Rotex. Nice kit. All the solar stuff has tanks with 1 or more HX in them but they are all on the load side. Nothing that helps the HPs COP. This is why I am interested in finding a way to use the solar (even if the panels are only at 10C above ambient).