Pipework sizing

[stukayak]

Hi folks, another newbie! Hopefully you can help.

I'm looking at having an air source heat pump installed, which is most efficient at water temp of 35 deg C. Rather than upsizing all the radiators, I'm considering Dimplex Smartrads which are fan assisted and therefore much more compact. They also contain very little water so heat up in less than a minute.

My question is, can I get away with utilising the existing 8mm copper pipework? Ordinarily I would expect the answer to be no, but as we have a 2 bed flat, the pipework runs from the manifold are very short - around 8m round trip per radiator. My only alternative would be dropping new pipework from the loft.

Thanks,

Stuart

 

[Nostrum]

You could although it may limit the effectiveness of the smart rads. The heat pump design will require a high flow rate which the Pipework may have an effect on. Without calculating it is impossible to say.

One way would be to use a header or buffer and two pumps. The flow rate to the heat pump can then be separated from the system circuit.

 

[Roger Welton]

I believe most heat pumps need a 5 degree delta T so unlikely 8mm will be any good (unless you go via a buffer tank)

 

[stukayak]

Many thanks to you both. Looks like new pipework then!