Anyone used a UV dye to trace a central heating leak

[Gattopardo]

Looking at using some monument drain dye and a uv light to see if there is a visible leak.

Good idea?  Or will I blow the boiler up.

[Aunt Maud]

Try it.

If you blow the boiler up, let us all know and we'll remember to avoid doing it.

Seriously though, you might want to run it in a cold system off the pump, if you can, and flush it out afterwards.

[Gattopardo]

After having a chat his comment was doesn't hurt a car engine, so boiler will be fine.

Then the fun of trying to buy a uv torch that isn't a cheap chinese torch (from China) or a chinese copy of a torch from a comapny claiming to be in the UK and, meh.

[Aunt Maud]

All a boiler really does is pump water over a hot plate, so the only moving parts are in the pump.

Pretty basic really.

[fuaran]

Why does it need to be UV? Wouldn't any sort of brightly coloured dye work, and be visible without a special torch.

[PaulF]

Why does it need to be UV? Wouldn't any sort of brightly coloured dye work, and be visible without a special torch.

Possibly to avoid staining carpets, floors etc.?

[Quisling]

If you don't already know where the central heating leak is then it's probably under a floor board or buried in a service void so no amount of dye or UV torches is going to help, although some areas may be accessible without a boroscope, e.g. by dropping out a few spot lights and poking your phone camera up through the hole into the ceiling (like I had to do recently....)

We recently had an apparent leak, but after topping up the system for several days in a row and still no ominous stains appearing anywhere it turned out to be a failed expansion vessel so the leak was contained in a defective component.

With respect to chemical issues I'm not sure whether this would be a problem.  Boiler heat exchangers can be made of cast iron, stainless steel, copper or all sorts of aluminium alloys these days.  Modern boilers are seem to be heading towards the latter to improve heat transfer, save weight and improve corrosion resistance when in condensing mode.

[chrisbainbridge]

I did once work with a very senior colleague who had access to low level radio-isotopes.  he had a leak in his rolls-royce's cooling system so added radio-isotope and then went over the engine bay with a small geiger counter.

[Gattopardo]

I did once work with a very senior colleague who had access to low level radio-isotopes.  he had a leak in his rolls-royce's cooling system so added radio-isotope and then went over the engine bay with a small geiger counter.

Good idea 

[Brucey]

when you have tiny leaks there are some much simpler, easier and more effective methods that you can use.

My preferred method is to drain the system and to pressurise it with air to about 1 or 2 bar.  [When building a new system, it is tested this way before being filled with water; much easier to fix leaks on a dry system.]

If it holds pressure for a day, there is no appreciable leak.

If it does not hold pressure then there is a leak of some kind.

This test is very sensitive; a leak that wees out many litres of air may only leak water at a miniscule rate, because water is so much more viscous than air, and surface tension reduces the (low pressure) leak rate out of tiny holes too.

To find the air leak, just go over suspect joints with a brush (or trigger spray) and soapy water. Any joint that you can easily repair will be accessible in this way.

 Obviously you can  find leaks in engine cooling systems this way too, but in a dry system the water pump gland may leak all the time, and you may need to hook the system up to a regulator so that it holds a constant pressure whilst you are looking for leaks.

BTW to pressurise a domestic heating system, I typically use a blanking cap with a bicycle valve (Presta of course... ) set into it.

cheers

[Gattopardo]

The air pressure test is an idea.  But I am lazy, and can't have the heating off for a day as there will be much moaning.  So introducing a dye means that I can see if there are any faults in visible joints.  I replaced all the radiators, added thermostatic valves and added a filter in november 15 so want to check the valves, the rads or any of the soldered joints I did.

This is in a second floor flat, the concrete the pipes are buried in are the ceiling of the flat below so no complaints of any leaks.

[Kim]

I've had some luck detecting leaks by knotting a bit of kitchen roll round a suspect joint.  It wicks the water away and becomes soggy tissue, rather than it dribbling down the pipe and evaporating.

[Gattopardo]

I've had some luck detecting leaks by knotting a bit of kitchen roll round a suspect joint.  It wicks the water away and becomes soggy tissue, rather than it dribbling down the pipe and evaporating.

That is no fun  also the pipes have been tweaked as there was an issue when replacing the radiators as the old ones were imperial and the new ones are metric.  I tried the loo paper but could not be sure that the loo paper hadn't dried.

Also found that the one radiator, in the bathroom,that was left without a trv closed.  Yet no one touched it.

[Gattopardo]

So looks like no leak...one more room to go....

I added the powder in to the filter, which I added when replacing the radiators, seems that there are big metallic flakes appearing.  Wonder where they are from.

[Gattopardo]

As an update, I finally decided that the easiest way to see if I could find the leak was drill a few holes.  So marked the area with the rough idea where the pipes were, then drilled.  Nothing, but some of the drilled screed came out damp.  So I SDS drill excavated the area.  That is when I noticed the damaged pipe. 

Draining the system is a pain in the arse.  There is no drain at the lowest point.  So the only way was to use a wet vac and suck the system dry.  Took three goes before I could get the system fully drained so I could solder the pipes.  The bonus of this was that I removed quite a bit of metallic black debris.  There is a filter fitted to the system,when the radiators were replaced, so where was the detritus coming from?  Think I shall add the some system cleaner and leave it for a week or two.  Then drain and refresh with some inhibitor.

The bit that I found that was interesting was that the pressure vessel took quite a bit of inflation from my track pump to get the pressure vessel upto 1 bar.  So far pressure is holding so problem solved...I hope.

Just need to fill the dig with sand and cement, or postcrete.  Which ever is cheaper.

[the snail]

If you've got copper pipe buried in concrete, it will fail - concrete corrodes copper. Best thing to do is bypass the pipes altogether, next best is to replace the copper with plastic. If you use copper pipe then you need to wrap it with denso tape. The black stuff in the system is iron sulphide I think - corrosion of radiators. A magnetic filter is a good idea. If the system loses pressure it's worth checking that water isn't dripping from the pressure relief valve/pipe, also if you let air out of the expansion vessel and water comes out then the expansion vessel is stuffed, and the system will dump water out of the prv when it heats up and you'll lose pressure.

[Aunt Maud]

Burying pipes in anything is a no-no.

I've been using Wavin pex-one, which is a plastic pipe in a duct, which is also insulated. I've routed it through the void between the outer brick wall and the lath and plaster inner wall which I will eventually fill with Leca. This gives me mouse proofing and 300mm of insulation in the walls with a natural product containing no chemicals .

The Wavin pex-one has no joints in it and comes in 50m rolls. it's good and easy to work with, but possibly a pain if you're replacing pipe in an existing system, plus you can't get it in The UK either, as it's far too left field for UK plumbers to get their heads around, the poor dears.

An added bonus was that I managed to get 350m of it for free under a state sponsored energy saving initiative.

[chrisbainbridge]

Is the PEX-one significantly better than standard push fit plastic?  Our whole house is done with plastic pipe and push fit connectors.

[LittleWheelsandBig]

Concrete does not corrode copper. There can be differential expansion and other problems though.
https://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

[Aunt Maud]

Is the PEX-one significantly better than standard push fit plastic?  Our whole house is done with plastic pipe and push fit connectors.

Apart from it being in insulated ducting I don't think there's much difference in the pipe. The fittings I'm using are brass compression fittings with an integral sleeve which supports the end of the pipe in the fitting.

All the pipe is run through the loft in a service duct on one side of the house and is fed to the radiators by manifolds. The pipe drops vertically through the wall and is attached to a box type thing, then to a couple of short lengths of copper to the radiators.

I can't imagine I would have found a plumber who would be prepared to do it, so I did it all myself. If there's a problem with the pipe I can unhook it and pull it out of the duct and feed a new one in.

[Kim]

Draining the system is a pain in the arse.  There is no drain at the lowest point.  So the only way was to use a wet vac and suck the system dry.  Took three goes before I could get the system fully drained so I could solder the pipes.

Sounds like an excellent opportunity to install a drain valve.

[loadsabikes]

Burying pipes in anything is a no-no.

I've been using Wavin pex-one, which is a plastic pipe in a duct, which is also insulated. I've routed it through the void between the outer brick wall and the lath and plaster inner wall which I will eventually fill with Leca. This gives me mouse proofing and 300mm of insulation in the walls with a natural product containing no chemicals .

The Wavin pex-one has no joints in it and comes in 50m rolls. it's good and easy to work with, but possibly a pain if you're replacing pipe in an existing system, plus you can't get it in The UK either, as it's far too left field for UK plumbers to get their heads around, the poor dears.

An added bonus was that I managed to get 350m of it for free under a state sponsored energy saving initiative.

An interesting work of utter fiction!

[Aunt Maud]

An interesting work of utter fiction!

Really, why ?

[Gattopardo]

Burying pipes in anything is a no-no.

I've been using Wavin pex-one, which is a plastic pipe in a duct, which is also insulated. I've routed it through the void between the outer brick wall and the lath and plaster inner wall which I will eventually fill with Leca. This gives me mouse proofing and 300mm of insulation in the walls with a natural product containing no chemicals .

The Wavin pex-one has no joints in it and comes in 50m rolls. it's good and easy to work with, but possibly a pain if you're replacing pipe in an existing system, plus you can't get it in The UK either, as it's far too left field for UK plumbers to get their heads around, the poor dears.

An added bonus was that I managed to get 350m of it for free under a state sponsored energy saving initiative.

That is interesting, but completely irrelevant to this situation.  Yes in an ideal world the pipe work would be in ducting,  but this is not an ideal world this is the situation I find myself in. 

Concrete does not corrode copper. There can be differential expansion and other problems though.
https://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

Think that expansion contraction was the issue here.

If you've got copper pipe buried in concrete, it will fail - concrete corrodes copper. Best thing to do is bypass the pipes altogether, next best is to replace the copper with plastic. If you use copper pipe then you need to wrap it with denso tape. The black stuff in the system is iron sulphide I think - corrosion of radiators. A magnetic filter is a good idea. If the system loses pressure it's worth checking that water isn't dripping from the pressure relief valve/pipe, also if you let air out of the expansion vessel and water comes out then the expansion vessel is stuffed, and the system will dump water out of the prv when it heats up and you'll lose pressure.

The pipes have been rewraped.  The bit I don't get is that the system has new rads and where is this coming from?  Left over in the system as Icould not drain it fully?  PRV is fine, checked with a bag taped on to it.  The expansion vessel doesn't leak, it just had some of the air escape.  I inflated it to one bar and it held with just the track pump attached for over an hour.  The only way to test the pressure vessel is with the system empty.

Draining the system is a pain in the arse.  There is no drain at the lowest point.  So the only way was to use a wet vac and suck the system dry.  Took three goes before I could get the system fully drained so I could solder the pipes.

Sounds like an excellent opportunity to install a drain valve.

How?  I added a drain valve, at a radiator, when I replaced the rads.  How can I install one lower?

Suspect part of the issue is that the system was open and with a hot water tank.  How it was altered I don't know.  Have found a 15mm pipe that is redundant so far.

Burying pipes in anything is a no-no.

I've been using Wavin pex-one, which is a plastic pipe in a duct, which is also insulated. I've routed it through the void between the outer brick wall and the lath and plaster inner wall which I will eventually fill with Leca. This gives me mouse proofing and 300mm of insulation in the walls with a natural product containing no chemicals .

The Wavin pex-one has no joints in it and comes in 50m rolls. it's good and easy to work with, but possibly a pain if you're replacing pipe in an existing system, plus you can't get it in The UK either, as it's far too left field for UK plumbers to get their heads around, the poor dears.

An added bonus was that I managed to get 350m of it for free under a state sponsored energy saving initiative.

An interesting work of utter fiction!

Can I have one post without people bickering?

[Kim]

Sounds like an excellent opportunity to install a drain valve.

How?  I added a drain valve, at a radiator, when I replaced the rads.  How can I install one lower?

Ah, the lowest point's under the solid floor?  That's annoying.

Otherwise, valve under the floorboards somewhere, or even sticking out through an external wall.