Nightmare time with Worcester Bosch repairs

[Cazza]

Hi

Was wandering if anyone can tell me if a competent boiler repair man should be able to detect a leak on an isolation valve to the boiler fairly easily. Worcester Bosch repair men came out 10 weeks ago to repair what was a leaking left flow unit. They also took boiler apart and replaced a few other things just in case that could leak (prv and expansion vessel). To cut a long story short I've had continuing pressure loss since they came out, one bar every 2 weeks. They kept telling me it couldn't be the boiler but I kept running isolation tests which proved to be the boiler. In all they've come out 7 times and 4 times there has been a leak on the left and right isolation valves. They tried tightening one, then replacing both washers, then replacing the right valve and now hopefully they are coming back to replace the left valve which still looks to be leaking.
Their attitude has been horrible, they are now unwilling to come out again they said if there is a continuing pressure loss after their visit today. I've had this worry for 10 weeks, had to run 4 isolation tests, had to take 8 days off work for their all day appointments getting up very early. I don't think I should have had to go through this. They kept telling me I had practically a new boiler so not to worry about the pressure drop. I think they should have ran some sort of isolation test on the second visit to determine where the leak was and properly diagnose it first (on the second visit they actually put in a new heat exchanger instead of finding the valve leak). Can any competent boiler repair man tell me what they think please?

 

[Aire]

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.

Quoting specific amounts of water lost is a little daft given that the amount of water it takes to drop pressure varies more on system volume than the size of the expansion vessel. I know the 2 go hand in hand but the standard vessel within the boiler is good for up to around 100 litres of water. Has op specified how many rads she has? A 5 rad system running at around 50 litres is going to show a much bigger pressure loss with a cup full of water compared to a 10 rad system running at 100 litres. I've had a system where the combi was in the loft in a bungalow, and bleeding a cup full of water out a radiator was enough to drop the pressure to nearly zero. So in my opinion, depending on the size of OPs system, yes a few drops from the isolation valves at the boiler is enough over a week, to drop 0.2bar of pressure.

 

[Cazza]

Thanks for all your thoughts everyone. I have 10 radiators. 4 of them are only a 1.5 foot wide tho. There is a large 4ft one, two 3ft, and three 2ft.
I did not know it takes 2 weeks for any air to vent out of the boiler. That changes everything. Perhaps this was accounting for the pressure loss I saw shortly after the recent repairs, on top of the isolation leaks. No one from Worcester told me this. After they came out the first time it went from 1.5 bar to 0.5 bar within 2 weeks. I doubt that was just air venting. But maybe after they re-pressurised the deflated expansion vessel that fixed that and then any continuing drops in pressure (0.4 bar a week) was just air venting from the boiler. I think i'm going to have to let it settle. If it is still dropping in 2 weeks time then i will run another isolation test. But now I am wondering how reliable isolation tests are if there is auto air venting. I will have to run the test without filling it back up with water (as that would put air back in the boiler)

 

[Cazza]

I forgot to say I only use 5 out of those 10 radiators tho. Keep the other 5 off.

 

[John.g]

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

I did point that out in my post above and IMHO the Bosch service man should have shut off the air vent, stayed around for a few hours and if the pressure increased slightly then vent again.
I spent many years running and maintaining large industrial boilers and various pressure vessels and carried out many pressure tests for leakages, some of these vessels had auto vents but in all cases once all the air was expelled then the auto vents were shut until the pressure test was completed.

Yes please be careful on what you post!

Double post.(above, mine)

 

[J Davies]

I find all the above interesting as someone trying to decide between a WB Highflow 550 and a Viessmann 222F. One installer who quoted for me (and who installs both makes) told me that WB customer service was really good, which was making my decision difficult as for various reasons I prefer the Viessmann boiler over the WB. The comments by Rob F now make me wonder if there is another reason the installer wants me to choose WB and not Viessmann. Perhaps a better profit margin, or maybe Viessmann customer service is worse than WB. Are WB easier to install than Viessmann? Decisions, decisions!

 

[Cazza]

I don't know anything about Viessmann but I was speaking to a boiler service man a year ago and he said he only now installs Valliant boilers as he has had too many problems going wrong with the WB. In my first house I had a Valliant and it was fine (but I was only there 7 years). I don't think i'd get WB again. Although the new WB ones come with a 10 year guarantee, but even still if you can't trust their service men to get to the bottom of any issues what good is their guarantee, just a load of stress.

 

[Millsy 82]

I did point that out in my post above and IMHO the Bosch service man should have shut off the air vent, stayed around for a few hours and if the pressure increased slightly then vent again.
I spent many years running and maintaining large industrial boilers and various pressure vessels and carried out many pressure tests for leakages, some of these vessels had auto vents but in all cases once all the air was expelled then the auto vents were shut until the pressure test was completed.




Double post.(above, mine)

How long do you think they get at each job? They are probably limited to say an hour per job then may have to travel inbetween.

 

[Cazza]

I was told they get two hour slots

 

[Riley]

But I think the point is that not all jobs take two hours and anyone would be naive to think otherwise. That’s not a stab at you cazza im just saying. The expectation and demand on these engineers is sometimes unrealistic

 

[Millsy 82]

I was told they get two hour slots

You will get a 2 hour slot they will have to drive from the last job in that 2 hours if they hit traffic that could affect their time on site.

 

[Cazza]

Yes this is true and must affect their ability to be thorough. The crazy thing is because of their system of trying to save time on visits and repeat visits end up actually spending more time and money in the long run. If they had spent more time diagnosing and finding the isolation valve leak they wouldn't have replaced a heat exchanger! Perhaps Bosch should allow their engineers more time on a job (a stitch in time saves nine). I did find though all the Bosch men that arrived in pairs spent a lot of the time chatting between themselves about personal stuff, rather than fully concentrating on the job.

 

[Millsy 82]

When my dad was in hospital the nurses talked about their holidays to each other, when I go to a shop all the staff chat to each other about personal stuff. Everybody speaks about personal stuff.

I charge a fixed price for diagnosis because on average I spend about 20 minutes on breakdowns but sometimes a leak is extremely difficult to find.

 

[John.g]

If you suspected a boiler leak then with the apparent view that isolation valves don't hold, its obviously going to take longer than 20 minutes if you have to start blanking off.

 

[Cazza]

I've been in hospital before and seen patients wanting nurse attention ignored because nurses were too busy chatting. But yes of course colleagues will chat to one another and they should, what I meant was they didn't seem that motivated to fully diagnose the pressure loss. I think the ideas given in this thread says the Bosch men could have done more, things like test the isolation valves for leaking or block the airvent and see if there was a pressure rise. But they just seemed to want to do the bare minimum as quickly as possible, not to come back and move onto the next client. Even shouting at me almost that they can't come out again and saying I could have my money back, rather than get to the bottom of the issue as they promised they would if the gauge showed a drop in pressure, which it did.

 

[sammathias]

If half of your radiators are 'turnt off' then how can you test for a pressure loss successful?

 

[Cazza]

Hi. I'm not an expert, I'm no plumber and don't understand why this would make a difference as there is still water sat in the pipes. All the radiator valves have been checked for leaks (about 5 times) and there aren't any. The pressure loss test carried out by Bosch with the large gauges was on a (so say) isolated boiler and also on the radiator system at the same time. So at least it shouldn't have made any difference to the boiler test?

 

[John.g]

No it shouldn't but with "proper" isolation and two pressure gauges it should differentiate between the two systems, with both gauges falling together it certainly points to isolation valve(s) passing but doesn't tell which system is leaking.

 

[Riley]

This to and fro is kind of going in circles. If the OP gets nowhere with WB following this latest fix and contacting CEO then they will need to enlist an independent. Simplest option would be cut two ISO’s into the F & R temporarily if the ISO’s on the boiler are suspect. By the sound of it they’ve been replaced so I’d be dubious as to their failed functionality so soon . If you already have a primary filter on the return then you could isolate there.

 

[Cazza]

I'm going to leave it now for 2 weeks, to allow air to vent. If it drops down as low as 0.9 bar (from 1.3) then I will run an isolation test. If it still drops, then with it still isolated I will drain 250 ml from a radiator and watch the gauge to test the new isolation valves. If no further drop then I will assume its the boiler.
If the isolation valves are leaking I will assume it is the pipes (as my boiler sits higher than the radiators being on 2nd floor; so where the last isolation test showed both boiler and radiator leak I doubt a boiler leak would have shown up as a radiator leak).
The previous isolation test was done with a new right isolation valve, and an old left isolation valve. Now both are new. So I can't rule out the previous test had an isolation valve leak.
Thanks for all your thoughts everyone, I will put a note on my calendar to update this thread in a couple of weeks as so many have been interested. Feel free to comment further, but apologies if I don't reply as I need a break now from thinking about it ;-)

 

[sammathias]

Open 'all' the radiators...vent all the air out of radiators, when system is cold put pressure upto 2bar then isolate boiler....no drop over a day or 2 then boiler is fine, when isolation is turn back on and there's a drop then it's your rads or pipework.