Radiator sizing for Heat Pump

[MarkW1979]

Hi all, and a happy to New Year when it comes.

 

My plumber needs to know the sizes of radiators I am using and as usual I have left planning it to the last minute and thought interpreting the information I have from the heat pump installer would be straightforward (it may be that I am just overcomplicating things as usual!).  The heat pump installer has provided the heat loss calcs for the rooms. I am only having rads in the bedrooms: 1,2 & 3. The radiators I am finding online seem to only need to be fairly small to match the wattage calcs as recorded below (at Delta 50) - I had expected them to be required to be much larger (i.e. oversized for a HP). Am I missing something? Should I be looking at achieving the stipulated wattages at Delta 30?

 

Thanks in advance!

 

 

 

[JohnMo]

All the info you need

 

https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-for-a-heat-pump/#google_vignette

[Marvin]

Hi @MarkW1979

 

Delta 30. That's the difference between the room temperature and the water temperature entering the radiator (so 20C room 50C ASHP water)

[MarkW1979]

Thanks guys, lightning fast response as usual!

 

All the best

[SimonD]

On those bedroom losses, you'll be looking at T22 (double panel) at somewhere around 600mm high x 500mm wide mark Delta 30 so if you went 600 x 600 or even bigger, you could reduce your flow temps by a bit

[HughF]

Multiply the radiator output by 0.41 to go from delta-t 50 to delta-t 30 (70 degree flow, down to 50 degree flow).

[SteamyTea]

As a rule of thumb, if you halve the ∆T, then double the surface area, then round up to the next available size.