Nightmare time with Worcester Bosch repairs

[Riley]

Keep in mind that a 0.2 bar pressure drop is not a lot and hence why such a small leak is often undetectable.

 

[John.g]

Thanks for the information. I've got a mixture of plastic and copper pipes. Upstairs where the boiler is mostly plastic. The boiler/ heating had been cold over night before running the isolation test so not cooling down. I thought it strange the boiler and radiator gauges have both dropped at almost the same rate, they are being tested separated with the boiler isolated from the radiators (valves turned to horizontal). Unless the valves leak inside which would explain the same pressure drop.
There is definitely moisture on the boiler valves though, could these account for a 0.15 bar pressure drop?

A 0.15 bar pressure drop isn't IMO just a drop of water from a boiler that's isolated.
If one assumes a 8 litre expansion vessel with a pre pressure of 0.5 bar and a filling (test) pressure of 2.0 bar, then the boiler will lose 0.21 litres of water. If the pre pressure above is 1.0 bar then the boiler will lose 0.28 litres of water for the same 0.15 bar pressure drop.

 

[Cazza]

Yes this is what i've been worried about since as when I asked the last Worcester guy if those tiny valve leaks could have accounted for a 0.15 bar drop in the test he said in his opinion he thinks it could. Which mean't he knew a lot of other people would disagree. Those two valves only had a tiny drop of water on them. The expansion vessel was pressured to 1 bar. The water pressure was put to 2 bar for the test. The weird thing was both the boiler and the radiator gauge fell by 0.15 bar, even though the boiler was isolated. Because I was told 1 bar is like a coffee cup I was thinking 0.15 of a coffee cup is a lot more than a tiny drop with the boiler off (i.e. not evaporating). But everything has been replaced on the boiler that could leak, including the expansion vessel. But like an earlier member said 0.15 bar could be accounted for by a settling down pressure release within the expansion vessel (or within the plastic pipes for the radiators). The only other thing I can possibly think of if they have put in a faulty new heat exchanger or expansion vessel, but that is unlikely. Or is there a leak on my pipes? The Worcester Bosch man did say the isolation tests that i'd been doing weren't reliable because the isolation valves can leak inside so i'm really seeing a drop on my radiator system (but I don't know if he was fobbing me off and I thought his testing with large gauges was supposed to rule that out, hence the whole idea of it)

 

[John.g]

If the Bosch man suspected the boiler isolation valves then surely he could have bled a drop of water off the rads with isolation valves closed, if both pressure gauges then fell together then the isolation valve(s) are passing.
I think that you will have to get someone to rule the boiler in/out, but I can tell you that with a 1 bar pre pressure, and test pressure falling from 2 bar to 1.85 bar that a 6 Litre E.vessel will release 0.21 litres, a 8 litre; 0.28 litres & a 12 litre; 0.42 litres.
In one of your posts you said the pressure was falling 1 bar every 2 weeks, this relates to a leakage (somewhere) of 2.0, 2.67 or 4 litres respectively, boiler or system??.

 

[Cazza]

Thanks John. Yes that is true! He could have tested the isolation valves that way.
After the initial works they did it was dropping a bar every 2 weeks. Several visits later and isolation valves tightened / auto airvent changed/ expansion vessel pressured from 0.4 bar to 1 bar it was more like 0.4 bar drop every 2 weeks or say a bar a month. So something dropped the rate of pressure loss by half. Since he was here 2 days ago the pressure gauge has gone from 1.5 to nearly 1.3. But he did warn me that there would be some air in the boiler so expect an initial loss. Because they say its got to be my pipes just before he left he said I should let it find its only pressure level, and let it go all the way down to 0.5 bar if necessary as that might stop the pipe leak (if there is one). But I don't really want to do that because that will take another 4 weeks and what happens if it drops lower than 0.5 bar then I have a problem. It will be too late to complain to Martyn Bridges by then.
I've turned my boiler off this morning and thinking of running another isolation test for 36 hours on the boiler. As any air should have autovented by now. Also with the two new islation valves I'm guessing they won't leak inside to the radiator pipes.
I will let you know what happens in 36 hours and if the boiler drops. My guess is that it will as I agree around 200ml of water is what must have leaked. But there is no pooling of water under the boiler. So what does that leave that could leak away from the boiler without me seeing? .... prv, expansion vessel or heat exchanger? All of which are new apparently.

 

[Millsy 82]

Every time you do work on a boiler you allow air into the system. If you fully drain a boiler it can take a few weeks for it to settle back down again and get rid of all the air. So a 1.5-1.3 drop the day after they have carried out.

Just leave the boiler alone don't do any isolation tests tissue tests anything for a couple of weeks and let the air settle then look again.

The chances are with everything you say they have done to your boiler it WONT be on your boiler.

 

[Cazza]

Thanks for the information. I'll leave it then for a couple of weeks.

 

[John.g]

If you could shut off the air vent like in this interesting thread it might tell something but you probably can't if the auto vent is inside the boiler casing (not GSR).
Pressure drops when AAV open

 

[Millsy 82]

If you could shut off the air vent like in this interesting thread it might tell something but you probably can't if the auto vent is inside the boiler casing (not GSR).
Pressure drops when AAV open

I wouldn't advise that as it's inside the boiler.

 

[Riley]

If you could shut off the air vent like in this interesting thread it might tell something but you probably can't if the auto vent is inside the boiler casing (not GSR).
Pressure drops when AAV open

Yes please be careful on what you post!