Pipe lagging with ASHP

[Walshie]

Hi,

Id like some advice on pipe lagging for the rad circuit with a heat pump.

 

Just had all new pipe work including a 28mm rad circuit. House is very well insulated. My question is what is the best / most sensible lagging approach for the rad circuit to minimise heat loss and protect against issues?

 

I was thinking of using 13mm self sealing lagging and then wrapping with rock wool?

 

Grateful for any ideas / thoughts please? 
 

Thanks! 

[JohnMo]

Two schools of thought, one lag everything, the other lag nothing.

 

But your best to lag everything that goes to DHW, so you are not adding heat to house during summer.

 

The lag nothing, comes from, with an ASHP, the ideal for good CoP is to run WC and a single zone fully open system. So what is the pipe insulation doing, everywhere in the house, the voids etc are also at a similar temp to rooms. Obviously if you don't run the heat pump like just described, insulation needs added to all pipes. Anything outside the heated envelope insulated to death in both cases.

[marshian]

50% of my CH circuit is under the suspended ground floor - it's lagged to within an inch of it's life as it is outside the heated envelope

 

45% of my CH circuit is between the floors - ie it's within the heated envelope and is not lagged at all 

 

5% of the CH/HW circuit  is from the Boiler to the HW tank and CH zone valve and back - this is lagged to within an inch of it's life to keep the heat in the pipes because in summer as @JohnMo says that contributed to an increase in room temps whenever water was heated

 

Use something like Tubolit and the largest wall thickness that you can - the glue if you buy it in 250ml cans has a dispenser brush which makes it really easy to run along a split and seal it up - I'm not sure with a decent wall thickness pipe insulation you'd get much improvement from wrapping in rockwool