DHW is heating some radiatosrs

[graham1]

Just had my ASHP system power flushed. The radiators on the system were all new when ASHP was installed 2 years ago but most of the copper piping is about 20 years old being used for oil fired central heating

 Today (1 daY AFTER FLUSH)with heating turned off as it has been since about May) several radiators (4)  are heating up to +- 30.

Any ideas - installer at a loss

Thanks

Graham

[JohnMo]

You will either have a single 3 port diverter or 2x 2 port valves. Were any of these put in to a manual position and not reset?

[Beelbeebub]

Or the power flush has damaged the little ball in the valve (if you have that system) and it's letting a bit by.

 

But the culprit is likely in the valve(s) as JohnMo says

[graham1]

If it is a problem with 3 way valve would not all the radiators heat up not just 4 or 5

[dpmiller]

nope, a tiny bit of flow can move heat to odd places...

[Beelbeebub]

  On 10/07/2024 at 01:50, graham1 said:

If it is a problem with 3 way valve would not all the radiators heat up not just 4 or 5

Expand  

Need more facts, but if the valve, either diverter or 2 port, is letting by just a tiny bit, then the first few rads in the loop would get a bit warm.

 

The OP states they are getting to maybe 30C during DHW cycle, but the flow temp would typically be higher, which points to a little flow sleeping past. Possibly because the valve is damaged of maybe a little bit of crud from the power flush is stuck on the seat.

[sharpener]

Honeywell diverters in particular have had all sorts of QA problems in recent years. Installers seem to recommend ESBE valves for anything over about 5 kW.

[JohnMo]

  On 10/07/2024 at 23:29, sharpener said:

Installers seem to recommend ESBE valves for anything over about 5 kW.

Expand  

That could be more to do with pressure drop than anything else. Normal diverter valves have quite large pressure drops, so when you start pumping more than about 1.5m3/h the drop is quite big, even with 28mm valves.

[sharpener]

No, reliability. This is just one of several recent posts on the Arotherm Plus forum about duff Honeywell valves falling apart https://www.facebook.com/share/p/nqxrMWsS4CE7Uio4/.

 

 

Edited July 11, 2024 by sharpener

[graham1]

  On 09/07/2024 at 16:09, graham1 said:

Just had my ASHP system power flushed. The radiators on the system were all new when ASHP was installed 2 years ago but most of the copper piping is about 20 years old being used for oil fired central heating

 Today (1 daY AFTER FLUSH)with heating turned off as it has been since about May) several radiators (4)  are heating up to +- 30.

Any ideas - installer at a loss

Thanks

Graham

Expand  

 

  On 10/07/2024 at 01:50, graham1 said:

If it is a problem with 3 way valve would not all the radiators heat up not just 4 or 5

Not sure how to respond to answers

  The  valve was in the manual position. Waiting to see result as set now

Expand