EV or PRV problem?

[shamilt1]

I have had a problem losing pressure from my combi boiler system - I have to top it up on a daily basis. I have a Worcester 24i RSF. When the pressure rises There has been water coming out of the PRV pipe outside of the house ( this doesn't happen when the system is cold) I have checked my Expansion Vessel - with the water pressure at 0 Bar I pressed in the valve and no water came out- hardly any air came out either. I got my bike pump and pumped it up to around .8 Bar. When I did this the gauge on the boiler went up too, to around 1 Bar. I then tried the heating and the pressure still went up to around 2 1/2 Bar, before creeping back down - the pipe outside of the house from the PRV was still dripping. When it had all cooled down I checked the air pressure in the EV and there was hardly any air in it again!? Does it sound like the PRV or the EV or something else? Please help guys.......

 

[David937]

When you pump up the EV, you have to have a drain cock open and the system de-pressurised. I find it easiest to use the drain valves under the boiler to drain the boiler, leave them open whilst re-pressurising the EV before closing them and re-pressurising.

 

[twgas]

when you pumped the vessel up did you have the drain valve open and did any water come out while you were pumping?
I don't see how pumping the vessel up would increase the system pressure unless you've done something totally unusual.

 

[MANDATE]

//www.diynot.com/forums/viewtopic.php?p=1932207#1932207

 

[David937]

when you pumped the vessel up did you have the drain valve open and did any water come out while you were pumping?
I don't see how pumping the vessel up would increase the system pressure unless you've done something totally unusual.

It happened to me once when I had left drain valves closed

 

[shamilt1]

Oops, no I didn't open any drain valve What should be my next step? ( apart from calling a plumber!)

 

[shamilt1]

What I forgot to put was that after testing the EV for the second time and finding hardly any air in it, I operated the PRV to remove the water pressure before pumping up for a second time. I know that you shouldn't operate the PRV, but as its been opening all the time to releave the pressure I guessed it wouldn't do any more harm. Does this mean that I have now pressurised the EV correctly?

 

[David937]

Unfortunately not, the EV needs to be open to the atmosphere on the water side so you must have a drain valve open while you are actually pumping it up with no pressure in the system.

 

[shamilt1]

Unfortunately not, the EV needs to be open to the atmosphere on the water side so you must have a drain valve open while you are actually pumping it up with no pressure in the system.

Any idea where a drain valve is on this system? The only thing I can see with a tap on is on a flexible pipe that loops between two copper pipes- that fills it up though

 

[David937]

Sorry I am not familiar with your boiler, hopefully one of the RGI's can inform you.

 

[shamilt1]

Sorry I am not familiar with your boiler, hopefully one of the RGI's can inform you.

Do you know if a drain cock is usually fitted inside a boiler, or on the pipework somewhere?

 

[David937]

Usually on the flow and return pipes directly under the boiler.

 

[shamilt1]

Okay thanks. There is a flexible hose that links two of the pipes beneath my boiler. One of the pipes fills it up, so Im guessing the other is the return which I could use to drain the boiler.....

 

[David937]

I am sure that will be a check valve on the return. I am not familiar with the your boiler TBH so don't really know if there are any drain valves on the underside of the boiler to drain it properly. You could hold the PRV open whilst pumping up the EV but it's not good practice and chances are the PRV will leak afterwards even when the system pressure is normal.

 

[shamilt1]

I have identified the pipes that are beneath my system. They are, from left to right -CH flow, DHW out, Gas inlet, mains cold water in and CH return. The CH flow and the Mains cold water in are linked together by a flexy pipe. Is the one I need to drain the CH Flow?