air source heat pump

[erj]

I,am first fixing a bathroom, and the customer is thinking a getting a air source heat pump with over size rads, but has been told by the installer that he can not use the old pipe work as it is 8mm to the rads and the ASHP can not cope and needs 28/22 flow and return.
Is this right? I have only read about them so any feed back would be nice.
Thank you in advance.

 

[FD Powerflow]

Understandable considering most ASHP's will kick out around 45 degree flow so you need a bigger volume of water passing through the rad for it to take the heat from the water and put it out into the room.

Check with the manufacturers instructions though, in most cases the best recommendation is to fit overlay underfloor, which can turn large job into a £10k+ one

 

[unguided1]

I,am first fixing a bathroom, and the customer is thinking a getting a air source heat pump with over size rads, but has been told by the installer that he can not use the old pipe work as it is 8mm to the rads and the ASHP can not cope and needs 28/22 flow and return.
Is this right? I have only read about them so any feed back would be nice.
Thank you in advance.

Depends on the type of heat pump being quoted for and the manufacturers recommendations, but I would say that your installer is absolulty correct, also the fact that heat pumps use lower temperature heat compared to traditional boilers they are not that good at producing domestic hot water either unless you are using an exhaust air heat pump for DHW or a high temp heat pump