ASHP at cold temper...
 
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ASHP at cold temperatures

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(@kev-m)
Famed Member Moderator
5561 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @huwsy

Hi

Thank you for this.  I see the flow temp drop and the radiators must get colder but the room temps don’t seem to drop. Does it reduce the flow or anything to compensate?

Thanks

@Huwsy,

I don't think the house can react that quickly.  The drops in flow temp are only for 10 or 15 minutes. Like I said it pulls the average flow temp down, which means my house is about 1 degree cooler than it should be.  I try to aim for 21.

 


   
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cathodeRay
(@cathoderay)
Famed Member Moderator
6918 kWhs
Joined: 2 years ago
Posts: 1391
 

Posted by: @kev-m

On my system, defrosts definitely lower the flow temp, both on the monitoring and the rads getting noticeably cooler. Does it make the house cooler?  Almost certainly because the average flow temp shown in the graph below is about 3 deg lower that the WC target. Interestingly, defrosting neither increases power used nor decreases the COP.  It would have done both had I maintained the WC flow temp by bumping up the curve. 

Defrosts

Kev - your room temp line looks suspiciously straight to me. It is almost a perfect flat line, with a minute wobble at about 0830. My room temp measured hourly even when in steady state conditions varies by a degree or a bit less either side of a mean. Your ambient record on the other hand is sensitive enough to pick up the brief warming caused by the defrosts. Such a plot would have me wondering about that room temp line, or rather the sensor, and what is actually being plotted. It wouldn't need to be much flatter for me to think it was plotting the set temperature rather than the actual temperature. Might be worth checking what another unconnected room thermometer shows.     

Midea 14kW (for now...) ASHP heating both building and DHW


   
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(@kev-m)
Famed Member Moderator
5561 kWhs
Joined: 3 years ago
Posts: 1299
 

Posted by: @huwsy

Hi

Thank you for this.  I see the flow temp drop and the radiators must get colder but the room temps don’t seem to drop. Does it reduce the flow or anything to compensate?

Thanks

@Huwsy,

I don't think the house can react that quickly.  The drops in flow temp are only for 10 or 15 minutes. Like I said it pulls the average flow temp down, which means my house is about 1 degree cooler than it should be.  I try to aim for 21.

 


   
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