DIY Doctor UK DIY Forums

Help and advice please
Drained my system recently (as i have done previously) to add inhibitor before putting c/h on for the first time this winter and since then the rads are heating up along with the dhw while the programmer is only set for dhw.
Also the pressure guage on our sealed system now runs up to 1.6 bar when hot whereas it used to run at 1.2 max.
The c/h-rads are on a sealed system with expansion vessel. DHW is from a vented tank in the loft. We can normally run dhw and c/h independant of each other or both at the same time.
Worcester Danesmore 12/14 oil boiler, Danfoss programmer and HSA3 3 way motorised valve. Grundfos pump.
I refilled via the filling loop carefully up to 1.0 bar pressure as i have done previously.
Any ideas as to the cause/remedy?
Could it be a faulty 3 way valve and if so could this also cause the increase in pressure?
Apologies if i havent explained it very well but if you can help please let me know what other info might help you to assist me.
Thanks
Mike

rads normally heating while in hw only usually suggests ur divertor valve is passing (new one required), is ur pressure guage showing higher whilst running? (this is expansion and rises naturally), if whilst cold and haven't toped up check ur filling loop isn't passing (however if this the case, would eventually overpresssurise and blow off via pressure relief valve (usually 22mm pipe outside house).

Thanks for the reply.
The pressure gauge is at 0.9 bar when cold and rises gradually to 1.6 when running. By the time it gets to 1.6 the rads etc are warm enough and i switch it of. The guage has a red needle preset at 1.2 which i presumed was the max safety level.
Could it be a coincidence that the prob showed when the c/h was fired up after not being used all summer? The hw has come on daily as programmed.
Is the divertor valve a diy job and if so any advice on checking/changing?
Thanks
Mike

1.2bar is where the pressure needs to be set at. Your pressure relief valve is set to release pressure if it goes above 3bar (the same for most sealed systems). 1.6bar is just the expansion sounds fine to me, some systems go upto about 2bar + when heating up.

yes it is a faulty 3 port valve, remove motorised head, see if the valve spindle moves freely - if it does - just change the motorised head/actuator.

The system pressure is irrelevant, the system will run at 0.5bar quite happily, 1.0-1.5 is the normal standing pressure when cold, it will rise with expansion, and will discharge if it reaches 3.0bar.

htg