Pressure loss

9 Jan 2005
Reaction score
United Kingdom
I have a Barlo Duo combi boiler. The problem is air is getting into the system somewhere and i can\\\'t find it. I have bled all radiators and got the pressure upto 1.5 bar. Within 1-2 days the pressure has dropped to nearly 0 and the rads are full of air again. Any suggestions would be appreciated.
Sponsored Links
You will have to go around every joint with a toothcomb. :(

Check your valves, bleed points, and Prv.

The water is leaking somewhere and will have to be rectified.

Good luck :D
To reinforce the point....
Most likely, pressure is being lost FIRST, then air is being drawn into system somewhere, possibly through auto airvent inside boiler. That's normal in a zero pressure situation. Look first for a leak of water OUT not air IN. At that rate of loss, it should be obvious!
Sponsored Links
kevplumb said:
check the pressure release valve aint passing :)

Should have said i'm not a plumber. I'm an electrician but have a basic knowledge of heating systems from wiring them up for plumbers of the past few years.
Could you explain what you mean by "pressure release valve passing" my guess is you mean the valve is stuck open???

I have checken all radiators for leaks over and over with no signs. I have no sign of a leak anywhere. However when i bought the house a few months back i noticed a small amount of water on the floor directly below the boiler. I took the front off but couldn't see any signs of a leak. Although the stain is still there it hasn't been wet since and i check it regularly.
the pressure relief valve has a red top (dont touch) and should be connected to a pipe leading outside
not always the case the if you look under the boiler you should be able to see it

or look outside :idea:
On looking under the boiler there is a pipe that leads outside (15mm copper) but i would have to romovee the cover again to see where it goes. I also have the loop off the cold feed into the flow which has a black tap on it. The return pipe has a red tap on it. I take it this valve is up inside the boiler? How do i test it or do i just replace it.

Thanks very much for your help
At the moment the pipe is dry but the pressure was at 0 again. I've just opened the loop bled all the rads and got it back up to 1 bar again. Heating is on full and waiting to see if it starts dripping outside.

As an afterthought my GF has been complaining that when doing the dishes (as they do) the boiler makes a terrible screeching noise like its gonna explode if the hot top is not open all the way. I've heard the same when in the shower.(straight off the boiler) are they linked???

Another thing is the hot water seems to come out white and full of air bubbles but if let to settle in a glass goes back clear???????? And it is really hot...too hot to touch.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links