Unvented sealed system, pressure drop, and no conclusion..!

[Syd98]

Back again.
Recap: Megaflo H/W cylinder , Ideal boiler Minimiser SE 9 yrs old.
Story so far and 3 plumbers.. and about £120 quid down.
Start December system started losibg pressure one day.
Will lose 1 bar in 2hrs when boiler on..
Diagnosis 1 - Autovent - Changed
Diagnosis 2 - Pump - Changed
Diagnosis 3 - Expansion Vesel - Changed.
megaflo checked out and working.
Plastic bag on discharge for 1 month and no water so PRV's good.
All to no avail. still losing pressure...!
This weekend. all floorboards up and no sign of a leak, anywhere, latest plumber says"could be boiler" but wouldn't commit as when i asked him to promise to sort the problem if i had a new worcetser for £1000, he said No...
Experimet this weekend.
System pressured to 2bar = Max pressure and left, the boiler was not switched on. System lost 0.5 bar in 30hrs, water collected from boiler condenser outlet = 10ml (tablespoon.)
Sysetm and CH switched on.. lost all pressure in 2hrs, water collected from condenser - 20ml.

help...

 

[Bryan King]

YOU MUST HAVE A LEAK

 

[oilman]

These slow leaks can be next to impossible to find. I would use a system leak sealer, or Radweld, which I have previously with no ill effects.

 

[heatingman]

As posted, you have a leak, or maybe quite a few weepy/crusty joints. Can be a nightmare to locate. Inspection of every joint on system. Other option is to drain down, isolate boiler and air test system upto 6Bar and crawl around listening for the hiss/whistle Leak sealer works but can also cause more problems, blocking vents HE's if overdosed. Personally would not use leak sealer on an Ideal.

 

[bengasman]

You have a leak, or leaks, end of story.
Take the heads of the valves and check around the spindles, replace everyone that does not look as if it is completely clean.
95% sure that whoever put your boiler in used cheap valves or just left the old ones in place.

 

[Syd98]

Checked all major joints and can find no , leak, no crusty joints or anything.
Only one rad valve showed signs of not being like new, changed and problem still here..!
The house and all the system are only 8yrs old..!
As mentioned all boards up and no sign at all of a leak.
My plumber/s have all said that i would have seen this ammount of water by now...!
1 month of topping up from 0 - 1.5bar twice a day..!

 

[bengasman]

Well, in that case the only thing you can do is change the locks.

 

[Syd98]

Useful mate.. thanks.
Ask a simple a question, get a simple answer..!

 

[gasisexpensive]

removed

 

[Syd98]

What would be involved to do this...? thanks

 

[bengasman]

convert it to an open vented system.

Eureka. That’s it, don’t fix the leak, construct an automatic top up.
Only one downside. You will get loads of corrosion, kill your pump, possibly your heat exchanger and will need a powerflush in a couple of years.
You must be one of those eco-friendly plumbers who use a horse in stead of a van. Big hat and pointy boots by any chance?

 

[Syd98]

Ok bengasman, you seem to have all the smart quips but no answers, one of the over-priced plumbers who talks a good job but does nothing.
I have used only corgi registered plumbers/heating engineers and too no avail have a useful answer, I will solve this myself as people like bengasman are only good for changing washers etc..
These systems should be plumbed in with check valves and shut-off's in the event of a pressre drop, so the fault finding is easy.
If this was to happen in the "real engineering" sector then most of these systems would have been installed to rigorous specifications.
Thanks for nothing.

pay peanuts get monkeys or even worse "bengasman the organ grinder"

Ask bengasman get GAS...

 

[doitall]

You have already been told what/where the problem is, so if you put the brain in gear instead of having a go at the experts you may just get somewhere.

 

[Onetap]

Ok bengasman, you seem to have all the smart quips but no answers, ...............................................................


If this was to happen in the "real engineering" sector then most of these systems would have been installed to rigorous specifications.
Thanks for nothing.

pay peanuts get monkeys or even worse "bengasman the organ grinder"

Ask bengasman get GAS...

But Bengasman is right, if not very helpful.

Some fool will suggest, and has suggested, converting to an open vented system, which will, apparently, solve the problem. Long term, it will kill your boiler and heating system.

There are leaks, they have to be found and sorted out.

I would isolate and pressure test the boiler on it's own; possibly a leak into the combustion chamber so that the water is evaporating or going down the condense drain.

Air testing can be dangerous, I would be very reluctant to go 0.5 bar above the current working pressure.

If it is a leak from the system, then I would see if you can find an ultrasonic leak detector for hire, pressurize with air ( 1 bar is lots) go leak hunting.

PS I work mostly in the commercial 'real engineering' sector.

If you pressure test with water, you need to disconnect the expansion vessel. It will replenish the pressure lost from a leak, so it will take much longer for a pressure loss to make itself apparent. Do a proper water pressure test on the boiler and system separately and you'll find which one is losing your pressure.

 

[Syd98]

At last a helpfull fellow.. thanks...
I wouldn't convert anyway.. But i can not find anyone who wants to pressure test the boiler, everyone local is a worcester man and only wants to change the boiler and will not give me 100% guarantee that it will cure the problem.