Had 5 plumbers out... not solved. Any ideas? Pressure loss.

Could be the PRV or a cracked heat exchanger causing you to lose pressure from the system water going down the condense pipe.
Without seeing it hard to say.Sorry..

 

as PB says, you need someone to look at it, this firm you're getting in does't seem to have much idea, £1k for a pressure vessell is well steep you need to get another opinion, ask for a couple of free quotes from local plumbers, if they say its not worth their while quoting, they're just money grabbers, there are a lot of fast track plumbers out there just wanting to take money for doing jobs you dont need, if you can't find a decent local plumber the last resort is BG, it'll cost but their operatives have supervisors who you can complain to if things go wrong,

 

What is the make and model of boiler?

 

Have you tried leak sealer? A tiny leak somewhere of the Pipe work may be the cause? How long does it take for the pressure to drop below working pressure?

 

Hi Loopy (I'm guessing you were chust called 'Loo' before your boiler started playing up?)

You definitely have a leak. Somewhere. We know this 'cos you keep filling it with water to raise the pressure, and the pressure keeps falling.

So, where's the leak...

When you say they fitted an expansion vessel, I'm guessing what they actually did was fit a second exp vessel, as there is almost certainly already one inside your boiler casing. A second one is sometimes needed when a boiler is fitted to a larger than average rad system (how many rads do you have?) and the built-in vessel ain't big enough to cope with the expanding water when the system heats up.

(Water expands when heated. Your system is sealed, so the pressure in it would soar dangerously if the excess water didn't have somewhere to go when it was heated, and that place is the exp vessel. The exp vessel is a vessel. Inside is a rubber diaphragm with space for the system water on one side and this is counter-acted by compressed air on t'other. When the system heats up, the displaced water goes into that vessel and squishes that rubber dia against the compressed air. When the system cools down again, the comp air pushes the water back into the system. Your pressure should therefore remain fairly steady throughout.)

So, depending on the boiler you have and the number of rads installed, they might well have done a 'reasonable' thing in fitting a second vessel. (But since an extension vessel costs only around £100 and is a piece of pish to install, they sound as tho' they've robbed you. And, if your system worked fine before you bought the house, then you didn't actually need this extra vessel so they definitely screwed you over...)

I hope they haven't charged you any more - ie - for all their failed attempts to sort this... 'Cos, really, it should be a process of elimination.

First, you had a condensate trap full of metal carp? And it dripped because of this? Snap - I had exactly the same thing recently. If your boiler is poorly designed, that water may well have gotten on to your PCB, so 'SNAP' again. Ie - something broke. (Mine's fine, by the way... )

BUT, that was a separate issue, and not the cause of your water loss.

So, where could this water be going? A few places; (1) a simple leak in your system. A faulty pipe fitting. A dodgy radiator valve. Etc. I take it you've gorn round your whole system and checked? (It would be a sizeable puddle...) Of course there's always under the floor - any way you can access this to check?

I've chust read on a different thread how to check for such simple leaks, but it does mean turning your boiler orf for a day so you'll have to use other heaters and kettles... Top up the system pressure to 1.5bar as before, switch orf your boiler (leave a note on the isolating switch so no-one turns it back on...) Look under your boiler at the 22mm CH flow and return pipes - they should each have a quarter-turn isolating valve on them where they join the boiler. Turn them both fully off.

Leave the boiler for a day. Check the pressure. If it has dropped, your leak is inside your boiler. If it's still at 1.5bar, the chances are your boiler is ok and the leak is elsewhere. Now open the flow and return valves - does the pressure suddenly drop? If so, you have a leak on the rest of your rad pipework, so start searchin'.


Ok, if the fault is instead 'inside' your boiler, the first possibility is a faulty PRV, Pressure Release Valve. This valve is set to open at around 3 bar pressure to dump the excess water out a 15mm copper pipe outside your house, hopefully safely at the ground. This valve is usually triggered when the exp vessel has gone faulty, such as having lost air pressure. Easy to check this - find this pipe end outside your house, and wrap a poly bag over it with a bit of tape. Monitor this for water over a couple of days with your system running as normal. If there's water in it, that's your loss chust there, and you need a new PRV - £35 + a half hour fitting, total <£100.

Of course, if your boiler pressure has reached nearly 3 bar due to some other issue, then this valve WILL open and dump the water - as it should. So, what I'm sayin' is, if there is water coming out that pipe with the pressure only reaching about 2 bar, or even if the boiler ain't even running, then you have a faulty PRV.

Surely to gawd that the plumbers have tried all this?

Third - nastiest - possibility is that your boiler's heat exchanger is bust. This is an expensive part - probably £200-£300 - and a major job to swap, so expect a bill of around £400+, I guess... (Ie - possible new boiler time...)

Water from a leaking exchanger would most likely find its way out the condensate discharge pipe. This is a 22mm plastic pipe, again likely to be heading outside into a drain, but could be connected to an inside drain too. When your boiler is running, this pipe should send glugs of water out at regular intervals anyway, so the secret is to work out if it's actually 'leaking' water instead. I guess if water comes out with the boiler turned off - ie: not running and producing condensate - then it's definitely 'leakage'. Possibly if the water trickles out rather than come in 'glugs', then it could be leakage. But the first indication is the clearest.

Not sure if I've missed anything, but I'd have thought that the above should determine the area of water loss.

A useful tool to have is a baseball bat. Buy a good one, and use it when you call back these arrisoles.

 

when my dads car radiator leaked, he put an egg in it, it was a 1955 ford popular, I was only 3 years old at the time but i thought, would't putting water in and feeding me the egg make more sense, years later someone invented fernox and a whole new industry was formed, eggs were no longer used by ford popular owners, they became the staple diet of protien seekers and got stamped with a lion to show its Britishness, meanwhile people bought radseal,fernox ,stp,wynnns and other chemical magical products to cure simple leaks with complcated chemical cocktails and the world opened up to a marketing fernominom run by desk driving pen pushers makeing fortunes by conning folks with simple leaks which can be mended in a mechanical way for less than the price of a tub of chemicals, call me a old skool plumber and you're right,

 

Could be a number of things but sounds like a lot of plumbers don't know what they are talking about. Could be a faulty PRV, a leak somewhere or a cracked heat exchanger. There are chemical leak sealers that would be worth a try, which is something you could do yourself.

Check the blow off outside the house, if its dripping/wet then its the PRV/Expansion. Check all the rad valves with blue roll especially round the gland nuts. Look for stains on the ceilings etc. It coujld be leaking on the actuator on the diverter valve assembly which is very very common.

If the primary heat exchanger has a pin hole then it might be terminal.........very expensive part. £585.00 for my boiler. Modern boilers are not built to last more than a decade.