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Column radiators for heat pump

Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls

Last Post by Toodles 1 year ago

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ENC

(@enc)

Active Member Member

Joined: 3 years ago

Posts: 20

Topic starter 19/11/2024 1:26 pm

I have seen a couple of fancy column radiator recommendations kicking about in this forum which work well with a heat pump. Currently our single panel classic convection radiator in the hallway is not large enough to match the heat loss of the hall with the door opening etc.

I really want to go traditional column rather than stelrad K2 or K3... is this a bad idea? Does anyone have a calculator for calculating the BTU at lower temperatures?

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 3 years ago

Posts: 4469

19/11/2024 3:25 pm

Posted by: @enc

↑

I have seen a couple of fancy column radiator recommendations kicking about in this forum which work well with a heat pump. Currently our single panel classic convection radiator in the hallway is not large enough to match the heat loss of the hall with the door opening etc.

I really want to go traditional column rather than stelrad K2 or K3... is this a bad idea? Does anyone have a calculator for calculating the BTU at lower temperatures?

Radiator manufacturers generally provide either outputs at lower temperatures, an equation, or the 'exponent'. For radiators other than fan radiators (and possibly radiators with a very high 'aspect ratio') the equation is invariably "output is proportional to deltaT^n" where deltaT is the average temp difference radiator to room and ^n means raised to the power of n (n is 'the exponent'). Furthermore n is almost invariably 1.3 or very close, so output is proportional to deltaT^1.3.

Thus (for example) a radiator that outputs 1kW at 50C deltaT will output (25/50)^1.3x1kW at 25C deltaT = 406W.

I don't know of any reason why fancy column radiators should perform particularly badly or particularly well with a heat pump, however others might,

This post was modified 1 year ago 6 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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IanMK13

(@ianmk13)

Reputable Member Member

Joined: 3 years ago

Posts: 194

20/11/2024 4:10 pm

I have a couple of tall (1.8m) column radiators im my kitchen diner. I presently have a boiler and have assumed the usual downrating for ASHPs. One problem I have experienced with my boiler setup is that it takes an age for the radiator to heat up. Flow and return are both at the bottom of the radiator and the installer did not fit the baffle - available seperately - to divert the flow up the first column to the top of the radiator. Conequently, the flow much refers to go straight across the bottom of the radiator from inlet to outlet. I don't know what would happen with the lower flow temperatures and higher flow rate with an ASHP in this situation, but I would definitely recommend ensuring flow across diagonal corners one way or another.

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Toodles

(@toodles)

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Joined: 3 years ago

Posts: 2631

20/11/2024 4:31 pm

We have an 1800x500x100 mm. radiator in our dining area (insufficient wall space for conventional shape. This one works with our heat pump and provides a very even radiant heat over the whole panel space and I assume the convection is equally good - but it is well above our heads! Regards, Toodles.