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Rads warm when heating not on but ASHPs heating hot water

Air Source Heat Pumps (ASHPs)

Last Post by Derek M 3 years ago

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AlanB

(@alanb)

Eminent Member Member

Joined: 5 years ago

Posts: 21

Topic starter 31/08/2023 9:20 pm [#1061]

Hi All

Some of our rads are warm when the ASHPs are heating our hot water. The 3 port valve which controls where to send flow from the ASHPs is set to the hot water cylinder only. when not set to heat water, the 3 port valve sends water from the ASHPs to the rad and UFH circuits where that is ocntroledd by 2 x 2 port valves according to heat demand. The 2 port valve in the loft which opens and closes the radiator circuit is closed ( controlled by room stat which is not calling for heat ). The UFH circuit 2 port valve is closed. No sign of any warmth in the UFH system on the Ground floor.

Could the 3 port valve be leaking some hot water to the rad circuit?

Or more likely, the 2 port in the loft is allowing hot water from the ASHP primary circuit to leak through into some of the rads?

Any ideas gratefully received. Hope the above makes sense.

Cheers

Alan

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bontwoody

(@bontwoody)

Noble Member Contributor

Joined: 5 years ago

Posts: 1062

01/09/2023 6:05 am

It’s a bit left of field but could your 3 port valve be a mid position three port valve? Does the CH side of it get hot when DHW is on?

House-3 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
10kWh DC coupled battery
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Mars

(@editor)

Illustrious Member Admin

Joined: 6 years ago

Posts: 4961

01/09/2023 8:03 am

Is it the orange Belimo 3-way valve?

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Derek M

(@derek-m)

Illustrious Member Member

Joined: 6 years ago

Posts: 4425

01/09/2023 8:10 am

Posted by: @alanb

↑

Hi All

Some of our rads are warm when the ASHPs are heating our hot water. The 3 port valve which controls where to send flow from the ASHPs is set to the hot water cylinder only. when not set to heat water, the 3 port valve sends water from the ASHPs to the rad and UFH circuits where that is ocntroledd by 2 x 2 port valves according to heat demand. The 2 port valve in the loft which opens and closes the radiator circuit is closed ( controlled by room stat which is not calling for heat ). The UFH circuit 2 port valve is closed. No sign of any warmth in the UFH system on the Ground floor.

Could the 3 port valve be leaking some hot water to the rad circuit?

Or more likely, the 2 port in the loft is allowing hot water from the ASHP primary circuit to leak through into some of the rads?

Any ideas gratefully received. Hope the above makes sense.

Cheers

Alan

How warm are the radiators and do they remain warm? Are the radiators warm before the system changes to DHW heating?

What is the temperature setting of the thermostat for the radiators?

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