Closed Heating system

patrickyy

Hi,i have a closed heating system.the pressure in the system keeps going just over 3 bar and lets water out of a safety valve at the boiler which is outside.i have to let out water out of the system every couple of days to bring the pressure down to 1 bar.
In the hot press i have a red tank and the mains feed which tops up the system.on the 1/2 inch pipe which tops up the system there is a red wheel valve and an automatic fill valve.i have both of these turned off.But still the system goes to 3 bar every couple of days,Any idea why this is happening

Robbie.G

patrickyy wrote: »

Hi,i have a closed heating system.the pressure in the system keeps going just over 3 bar and lets water out of a safety valve at the boiler which is outside.i have to let out water out of the system every couple of days to bring the pressure down to 1 bar.
In the hot press i have a red tank and the mains feed which tops up the system.on the 1/2 inch pipe which tops up the system there is a red wheel valve and an automatic fill valve.i have both of these turned off.But still the system goes to 3 bar every couple of days,Any idea why this is happening

There are two possibilities
The fill valve is passing and letting full pressure of water mains into heating
Second is expansion vessel been either busted or in need of recharging
Does this happen when the heatings on or is it happening without the heating been used

Pete67

Most likely your expansion vessel has either lost it's air charge or the bladder has failed. To test it properly the system needs to be drained down and the air pressure in the vessel checked. It should be somewhere between 1 and 1.5 bar. I would also suggest getting rid of the auto fill valve and installing a filling loop so that you can keep an eye on system pressure over time and top up manually as needed. This should only need to be done every few months unless there is a leak somewhere.