Combi loosing pressure

[PinkFloyd]

Hi All,

My Combi is loosing pressure very slightly. I filled it so that the gauge read 1 bar earlier after noticing a dip, and now it has dipped again. There are no obvious leaks, but I do have two radiators removed for decorating. Its a Worcester Greenstar 350i.

My thoughts are that there is some air in the system that is slowly going causing the drop in pressure as the water takes up space, or there is a small leak under the floor dripping into the foundations / under the house - hence why I cannot see it.

When I moved in I found a screwdriver next to the still connected filling loop which makes me wonder if there is an underfloor issue.......

Any help appreciated.

 

[conny]

How much does it drop by and over what period of time?

Have you tried bleeding the remaining rads working from the lowest to the highest and then topping up the pressure. After doing this keep an eye on the pressure and note how far it drops over a period of time, say, 24hrs.
Check around all connections and look at seams of rads to see if they have any signs of corrosion.

 

[ub9533]

I would also check your expansion vessel the big red thing in the boiler will have tyre cap on it open up press slightly if air comes out ok if water could be loosing water from pressure relief valve outside is there a 15mm pipe outside dripping

 

[PinkFloyd]

Thanks guys. It is dropping 1/10th of a bar roughly over 24/48 hours, this is a rough estimate as I'm working off the little gauge on the boiler. There has previously been some corrosion on radiator pipes, but I've now changed the offending valves, and although there was a slight leak from one it's now sorted.

All the other connections look solid enough. I'll double check the radiators later. I can't see a drip outside, but I'll take a look later also. I'm covered for all of this under my central heating cover, but as I have radiators off etc I'm reluctant to call them out as I do not know if this invalidates the cover. In fairness I could have called them out to change the corroded valves etc, but I didn't know I could initially, and didn't think it fair.