Stupid pressurised heating systems

I'm fed up with this junk. Boiler and heating system only four years old but it lost pressure twice today and I had to do the manual top-up on the boiler. The second time the pressure went to down completely to zero on the gauge.

I can't see any leaks. Could be anywhere - under the floor, in the loft, who knows...

It's a stupid bloody idea. When I had a new boiler fitted this last summer in my rental house, I insisted on having a gravity-fed boiler so that I wouldn't be forced to pressurise the system and modify any of the pipework at all beyond the fitting of the boiler.

I really wish I'd done that at home. I'm sick of the stupidity of topping up a system by hand when we discovered the heating hasn't come on, but with absolutely no indication of where the system might be leaking.

Stupid, all of it.

I'm just surrounded by junk that doesn't work. Doesn't matter whether it's made in China, the UK, or elsewhere, and it doesn't matter whether it was worked on by local people, Polish people, people from who-knows-where - *everything* is just bloody shoddy and poorly designed

Ovesn go wrong. Switch on the kettle breaks. Children's roller skates (Christmas present) break on only the third use. Relatively new plumbing just doesn't hold pressure...that's hardly the half of it...the list of useless, dysfunctional crap is just endless.

Michael

Reply to
Michael Kilpatrick
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If your leak is bad enough to lose all pressure twice in one day, you should perhaps be thankful that you *don't* have a gravity fed system as you might have had a significant flood by now!

The beauty of a sealed system is that it greatly limits the scale of the damage from a leak. Doesn't really sound like you've even tried to find the leak yet...

Tim

Reply to
Tim+

Only fair to add though that a common cause of "leaks" is expansion vessel failure leading to the system "leaking" through the pressure relief valve when it heats up. Easy enough to check.

Tim

Reply to
Tim+

Have you checked the expansion vessel - that's the most likely culprit?!

Re-pressurise the system cold, and then turn on the boiler. Watch what happens to the pressure gauge as the system heat up. Does it over over

3.5 bar? If so, the pressure relief will open to allow surplus water to escape. There will be an external discharge pipe where it comes out. Check that. There may also be a tundish inside, where you can see the blow-off water escaping.

If that's where the water *is* going, it means that the expansion vessel has lost its charge. With the water side de-pressurised, you need to pump up the air side to about 0.7 bar. If water comes out of the air top-up valve, the vessel is shot and needs to be replaced.

Reply to
Roger Mills

I open up the taps to the boiler (in the utility room) and the boiler wakes up when the pressure reaches a sensible figure. I stopped it well below 2 bar. The pressure guage didn't rise to any stupid figure such as

3 bar, no. At least, not when I was watching when it came back on for a minute or two and started heating up.

There is a tundish for the pressure vessel above the hot water cylinder (in the airing cupboard about twenty feet from the boiler). I'll have a look now....

Ah, it feels damp inside. It feels as though the tundish must have passed some water fairly recently.

The pressure vessel above the cylinder has a 15mm pipe that leads to what I assume is a pressure relief valve and then descends to the tundish and to 40mm plastic pipe outside.

What do I need to pressurise a typical pressure vessel? Have I got to pay a plumber some ludicrous call-out charge because it will be something I won't be able to do myself?

Michael

Reply to
Michael Kilpatrick

In some cases merely part drain the system and re pressurise as the pressure vessel is simply a trapped air bubble in a sort of 'pressure dome' somewhere in the boiler..

IN other cases it is a replaceable part.

In all cases adding a new pressure vessel won't do any harm.

Reply to
The Natural Philosopher

On one of my old combis it was a major dismantling job just to get at the nipple to check the pressure. Others are better designed. When that one failed I simply added an external vessel with isolating valves, so now checking and repressurising is a relatively simple job without disturbing the boiler at all. They normally pressurise via a car-type schaeder valve, so a bicycle pump with suitable connector is all you need.

Reply to
newshound

That's Bill Wright's old boiler........

Reply to
ARW

He certainly has the boneless gums for it.

Reply to
Graham.

If you have a gravity fed system with a header tank and ball valve you could have lots of damage done with an unseen leak. At least with a pressurised system you're restricted to just the contents.

Reply to
Dave Plowman (News)

Needing to re-pressurise twice in a day sounds like either a significant leak, or more likely, a failed (or de-pressurised) expansion vessel.

Check the pressure blow off pipe from the boiler - it should discharge through the wall outside of the house. If needs be, tie a small plastic bad onto it with a rubber band such that it will collect water should the valve open. If it does, then you know the cause.

IMHO it a better system than a vented arrangement. A real leak can't flood the place, or slowly feed dry rot. No airlocks on refilling, less corrosion, and much simpler to deal with awkward pipe runs. Also no need for header tanks etc.

Stupid is whining about the symptom, rather than fixing the problem. If its a genuine leak, are you seriously suggesting that allowing it to leak for ever more is a better alternative?

This is a DIY group, stop moaning, and go fix it.

Reply to
John Rumm

Are you sure that is for the heating system and not an unvented water cylinder?

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What make and model of boiler is it?

They normally have a shrader valve (like a car tyre) on them. They can be pumped back up with a foot or hand pump.

You can also test the pressure on them, If you push the pin on the valve briefly you should get a puff of air. If you get water, then the diaphragm in the vessel has failed.

Reply to
John Rumm

Oh dear, yes I have a radio where the stand broke off and now I just can't be bothered to get a new one again, even if its free. Set top boxes fro Freeview that crash for no good reason or lose the data in their program guide due to no testing and no updates of course if the model is discontinued. I won't go on but tools for cleaners are another source of aggro, being made of crappy plastic. Brian

Reply to
Brian Gaff

That sounds more like an expansion vessel for a mains pressure hot water cylinder than on for the CH system.

I think you need to work out what you've got in the first place before we can advise you on what to do. You seem a bit confused about your system. Make and model of boiler and ditto of your HW cylinder would be a help.

If you have a pressurised HW cylinder you *won't* have a large header tank in the loft and you'll probably have a mess of pipework next to the cylinder with a pressure reduction valve and a pressure gauge. Is this the case?

Anyhow, what's going on with your HW cylinder is irrelevant to what's stopping your boiler firing up which is low system pressure in the CH circuit. It may have a built in pressure vessel for expansion rather than an external one. It's usually much cheaper to add an external expansion vessel than to replace an integral one.

If there's no obvious expansion vessel near the boiler look for a pipe exiting the boiler and going through a wall to the outside. This will be the over pressure relief outlet.

Tim

Reply to
Tim+

Now you see the advantage of DIY. There are no tradesmen being trained these days ,just useless NVQs.

The expansion vessel is probably US. (Diaphragm ruptured) Hence no expansion capacity and system over pressures.

Tape a plastic bag temporarily over the outlet on the safety valve. You will likely find the water is dribbling from there as the system heats up.

If so, new expansion vessel needed.

Reply to
harryagain

Err, sorry, I was misinterpreting the original question.

Yes, the boiler has an internal pressure vessel and an overflow. I can't see the damned pipework behind the cupboards now, but what I think is the boiler overflow appears to be dripping very slowly outside is leaving a copper-coloured smudge - which I assume is caused by whatever sludge might be in the water (yes, the system was pressure-flushed etc when the new boiler was fitted after the extension built.

Obviously what I was talking about previously was the pressure vessel for the unvented hot water cylider. Derrrrr!

The boiler is a Baxi. It's a combi-boiler - we use the combi bit for kitchen hot water and washing machine but the rest of the house is on the unvented hot water cylinder (twin coil, as we have solar thermal too).

The boiler is currently covered (I think) on a plan which is costing an arm and leg every month. That is because it went wrong about a year ago and the pressure vessel was replaced! Along with one of the sensors.

Oh, and there appears to be a tiny damp patch under one of the two system-filling taps under the boiler.

Really, I am not impressed with any of this at all. It's a pain, and an expensive one.

Michael

Reply to
Michael Kilpatrick

ok that makes more sense. Yup the pressure blow off pipe should pass through the wall and discharge outside. It should not drip obviously. It may be that it has operated as a result of a pressure increase (usually due to lack of expansion space). Sometimes when they operate they don't reseat properly. There is normally a manual test knob in the boiler on the valve. Sometimes operating it manually will clear any crud and get it to reseat.

The tundish on that ought not be wet either - but that is a separate issue.

If it is the pressure vessel then obviously it can be replaced or recharged as necessary - although depending on the boiler design, some are right pigs to get to. The alternative is to add another elsewhere in the system. You can also as a temporary work around drain a few litres of water from a rad (both taps turned off - open the union nut), so that it has an air pocket at the top to provide expansion volume.

If they are connected via a braided hose, then you can take that off and see what happens. It may be just a leak form the hose or the connector - but that is only pressurised when topping up.

Reply to
John Rumm

Well, I phoned Domestic and General, as I checked that my direct debit was still active in lieu of finding any paperwork. I'll have to say I was impressed by the telephonist who answered, and the lack of waiting on the phone.

The boiler is covered although all the invisible pipework in the house is not. It seems the repair was just over a year ago and the policy had only just entered its renewal period after 12 months. So, I need to phone again to arrange a call-out as that wasn't possible on a Saturday after 2pm.

Michael

Reply to
Michael Kilpatrick

And Domestic and General?

I booked a freezer repair, they sent an incompetent who tried to gain access to the PCB by levering plastic parts off the back of the freezer.

Access to the PCB is through a removable panel on the front of the freezer.

They are not technicians, they shouldn't be offering repair services that they are not competent to deliver.

Reply to
Onetap

I converted my CH to unvented and pressurised 10 years ago. It's fantastic. I top it up about twice a year, and then only half a bar or so. I get no corrosion, no sludge buildup, a tiny amount of air in the bathroom radiator that's on the return from the HW tank, never any air at all in the main radiators. An open system with a header tank is such a bad idea, admitting corrosion-causing oxygen every time the header tank comes into play. Get it sorted out and you'll soon see the benefits.

Reply to
pcb1962

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