Radiator Upgrade for ASHP

[Cpt Sandwich]

Hi,

 

I had an ASHP installed earlier this year, but at the time didn't have the finances to have the recommended oversized radiators installed.

 

I'm now looking at changing some of the radiators in the main rooms for this winter.

I've upgraded radiators before, so to run some additional piping should be quite straight forward.

 

All the radiators' downstairs have their feed pipes (15mm) from upstairs and these run down the wall in the corner of each room and then across the bottom of the wall to the radiator.

However, some of these 15mm feed pipes serve up to 3 radiators - is this OK, or should each radiator have its own feed pipe from the main flow & return (22mm)??

 

 

Thank you

 

David

[Marvin]

Good question. As you know, the ASHP delivers cooler water, so the radiators need to be bigger which will increase the flow rate to the radiators to fill the bigger size to keep the heat output.

 

I personally think your answer depends on the size of the 3 radiators and how resistant the building is to thermal change.

 

Good luck

 

M

[Bonner]

In theory, yes each radiator should be on it’s own branch. In practice radiator valves are used to throttle the flow in balancing the system so you might get away with just having these radiator valves opened more. Depends on the size of radiator, length of piping, pump pressure etc, etc. 

As you can tell there is no easy answer without going through a full system design. Also depends on your appetite for working on the heating system mid winter if it doesn’t work!

[Cpt Sandwich]

Thanks Marvin & Bonner!

 

One of the 15mm feeds supplies the following 3 radiators:

K2 500x1200 Lounge

K1 600x900 Study

K1 600x900 Hall

 

and the recommended sizing for the ASHP is:

K2 600x1600 Lounge

K2 600x1000 Study 

K2 600x900 Hall

 

The radiators have always been OK when we had Gas Central Heating - but I'd be nearly doubling the size of the radiators with the upgrades!

 

It wouldn't be a massive job to run new feeds if needed. If I did this, I would possibly relocate the Study & Hall radiators anyway.

I think the Study one would be better under the window and the Hall one of the opposite wall to where it currently is - but this would then be on the wall at the bottom of the stairs, would this be OK??

 

Thank you

 

David