Sizing rads for ground source

[TFGplumbing]

Hiya guys traditional heating systems work at ∆t50, so what do ground source heat pumps work at? ∆t25/∆t30; I need to size radiators for a customer with a heat pump as some of their existing ones are to small

Thanks

 

[missplumb]

you cant mix and match your DT!! and a DT of 50 degrees seems a bit drastic, 70/20 split?

 

[TFGplumbing]

you cant mix and match your DT!! and a DT of 50 degrees seems a bit drastic, 70/20 split?

Well it's a systems that's replaced an oil heating system, I didn't install it.. Some of there rads are a little small.
How much do I have to over size the new rads?

 

[missplumb]

has the system been designed or is it a case of using the existing system and changing rads? if you have the heat loss calcs for each room then you shouldnt need to oversize the rads, just put in what is the required output for that room.

 

[Nostrum]

It depends what the design flow temperature is of the heat pump installation.

Also check flow rates are suitable as low flow could create poor performance.