Gas Boiler losing pressure

Diego Murphy

I noticed that my gas boiler keeps losing pressure. It'll keep working but the pressure drops to about 0.5 bar (when operating). I think the leak is coming from around the black valve in the attached picture.

Very small patches of water gather under that part of the boiler during the day, after I have let water back into the system to increase the pressure. I don't think there's a leak anywhere else in the system because there doesn't appear to be water anywhere else.

Basically just want to know if anyone else has had this problem and if it cost much to fix?

claiva

Fairly common problem this time of year as far as I can tell, I had the same issue last week. I let some water into the system and also bled the rads at the top of the house over the space of a few days. The bar stays low now when the heating is off but it goes up when the heating is on. I don't think I've a leak though. I'm a bit puzzled why the bar is dropping when the heating is off.

Egass13

claiva wrote: »

Fairly common problem this time of year as far as I can tell, I had the same issue last week. I let some water into the system and also bled the rads at the top of the house over the space of a few days. The bar stays low now when the heating is off but it goes up when the heating is on. I don't think I've a leak though. I'm a bit puzzled why the bar is dropping when the heating is off.

The pressure drops when the heating is off because the water cools and pressure decreases . It increase when on because water expands when heated. What it starts at cold and how high it goes when in operation is what you need to watch .

As for the op problem , looks like the leak is coming from above the valve . Best get an RGI to have a look

irishgatsu

hi,
i recently had a few jobs done to my system: replaced pressure booster pump, fitted a magnaclean before the boiler, serviced the boiler. since then i noticed a 0.1 bar/day drop in the pressure at the boiler (gas). I checked the pipes the rgi worked on and no signs of leaks both when the boiler is off and on. also no dripping off the boiler safety valve to the outside. if there's a water leak at the moment it's not visible anywhere in the apartment. the plumber should be coming back next week to sort it out but if it was something simple i'd rather have done quickly.
all help is deeply appreciated!

irishgatsu

irishgatsu wrote: »

hi,
i recently had a few jobs done to my system: replaced pressure booster pump, fitted a magnaclean before the boiler, serviced the boiler. since then i noticed a 0.1 bar/day drop in the pressure at the boiler (gas). I checked the pipes the rgi worked on and no signs of leaks both when the boiler is off and on. also no dripping off the boiler safety valve to the outside. if there's a water leak at the moment it's not visible anywhere in the apartment. the plumber should be coming back next week to sort it out but if it was something simple i'd rather have done quickly.
all help is deeply appreciated!

Could be air in the system clearing itself after the work was done, if so it will settle after a period of time(which is dependant on the amount of air in the system)

irishgatsu

gary71 wrote: »

Could be air in the system clearing itself after the work was done, if so it will settle after a period of time(which is dependant on the amount of air in the system)

thanks.
i've topped up the system regularly over the last 2 weeks. considering this is a small 2 bed apt (rads are still off) could it still be air trapped in the pipeline?
again thanks a bunch!

irishgatsu

irishgatsu wrote: »

thanks.
i've topped up the system regularly over the last 2 weeks. considering this is a small 2 bed apt (rads are still off) could it still be air trapped in the pipeline?
again thanks a bunch!

Firstly when your topping up a small system you may not be talking a huge volume of water to actually top up or lose.

If your system didn't leak before the work and you can see the fittings and pipework where any work has been done it's less likely to be a leak.

If there is a leak then it's likely the pressure loss will be uniform and continue in the manor it is at the moment.

It might be worth while putting tissue paper on the rad valves or any other fittings you want to check as it makes it easier to spot small leaks.