How to find a slow leak?

[Jeremy Harris]

9 hours ago, ProDave said:

I would be surprised if just letting 30mL of water out would drop the pressure that much.  I strongly suspect your expansion vessel either does not have enough air charge, or it has failed altogether.  
 

 

 

As I mentioned above, when our pressure vessel lost it's pre-charge the symptoms were just like this, a dribble of water from the PRV because the system had no way of accommodating expansion.  In our case, the boiler was newly installed, but had been very troublesome from the day after it was fitted; we had around a dozen warranty call outs all told.  In trying to fix the problem the installers had either accidentally released the pre-charge, or had deliberately changed it to try and stop the constant cut-outs we were getting.  As soon as the PRV started to leak it never sealed up again, but continued to drip until it was replaced, under warranty.  With no pre-charge it doesn't take much water loss to drop the pressure.

 

The boiler fault we had (on a brand new boiler) turned out to be installation related, and one that Vaillant knew about and produced a kit that when fitted fixed it 100%.  The installers knew nothing about this at all, it was a combination of me asking questions around a few forums, plus the efforts of the really good plumber up the road, that eventually pinned down the cause.  In the few years since the boiler has been 100% reliable.

Edited March 1, 2017 by JSHarris

[Nickfromwales]

What was the fault J? 

[Jeremy Harris]

1 hour ago, Nickfromwales said:

What was the fault J? 

 

It's an odd one, a direct consequence of the position of the pressure sensor in the Vaillant Ecotec plus the layout of our bungalow.  The flow resistance around out heating circuit with all the TRVs open is very low, and there's no head for the pump to work against, either, as the boiler is the highest point in the system.  What was happening was that in cold weather the house would cool down overnight and all the TRVs would fully open.  When the boiler came to fire up in the morning it wouldn't detect the pump kick, because there was sod all flow resistance after the main water block, where the pressure sensor is normally fitted.  It would try to fire three times, then shut down with a pump fault.  The only way to get it to fire up was to go around turning a few of the TRVs off, then resetting the boiler, when there would be enough flow resistance for the sensor to see the pump kick.  Once it had fired the TRVs could all be reset and the boiler would be fine for the rest of the day, as some TRVs would always be partially closed.

 

We adopted a work-around for the year it took to fix the problem, by turning down a few TRVs last thing at night, so that the boiler would reliably fire the next morning.  The fix was a kit Vaillant sell especially for installations like ours, which repositions the pressure sensor from the main water block to the pipe going into the heat exchanger.  This adds a bit of flow resistance behind the sensor (from the PHE) and so the pump kick is reliably detected.  The fault is the one that indicates F75 on the display and the kit to fix it is called the "F75 kit", and when I eventually spoke to someone at Vaillant they knew all about it and apologised that their installer was unaware of the kit.  They also told me they had no record of the installer having contacted them about this, which annoyed me at the time because the installer kept assuring me that they were working with Vaillant to try and find the cause of the problem.  It was there right from the day after the boiler was installed; they left around mid-afternoon with everything working, at 5 am the next morning my other half tried to use the new shower for the first time and found the boiler had shut down.................

 

They really were a shambles, as every time they came they kept checking the pressure vessel, and messing around with both the pressure vessel pre-charge and the system fill pressure.  They must have fitted at least three new pressure sensors, too.  When they were messing around they managed to lose the pre-charge altogether, which then caused the PRV to open, and it never properly sealed again, hence the need to replace it the next time they tried to fix it.

Edited March 1, 2017 by JSHarris
typo

[Nickfromwales]

Sounds like you had fun. 

The muppets should have asked Vaillant to attend as they're quick at sorting problems and would rather have dealt with this swiftly than have a customer lose confidence in the product. 

Why they changed the pressure switches is a mystery TBH. The boiler automatically restarts upon sensing the pressure increase ( when you top up ) so that would have removed that from the process of elimination immediately, for me at least, ( by simply draining and refilling to prove it works ) . 

Thanks for the explanation though, as inside information is never a bad thing. ?

Ill add the fault code as a tag . 

[Jeremy Harris]

41 minutes ago, Nickfromwales said:

Sounds like you had fun. 

The muppets should have asked Vaillant to attend as they're quick at sorting problems and would rather have dealt with this swiftly than have a customer lose confidence in the product. 

Why they changed the pressure switches is a mystery TBH. The boiler automatically restarts upon sensing the pressure increase ( when you top up ) so that would have removed that from the process of elimination immediately, for me at least, ( by simply draining and refilling to prove it works ) . 

Thanks for the explanation though, as inside information is never a bad thing. ?

Ill add the fault code as a tag . 

 

I couldn't agree more.  They were (they've now stopped trading) a pretty large company, approved Vaillant installers etc, which is why we used them (I'd already settled on buying an Ecotec, having read up that they were about the best performing and most reliable combi around at the time).  They started by changing the pressure sensor, as they said there had been a batch of duff sensors, ones with red housings.  However, our boiler was supplied with the newer black sensor, so it should have been obvious this wasn't the problem.  The second call out they changed the sensor yet again, thinking they'd had two duff ones.  After that they started playing around with the pressures, thinking that was the problem.  Of course, every time they left the boiler was working fine, it only failed to fire when the house had cooled down enough for all the TRVs to open fully.  By the same token, it never failed in DHW mode in the summer, with the heating off, as the flow resistance with the diverter valve in the DHW position was always enough to give a decent pump kick.

 

Our Ecotec permanently goes to lock-out after three failed fire attempts, BTW, and has to be powered off and on again, or reset from the panel to reset it and get it to try and fire again (it's easier to turn it off and on!). 

 

The Vaillant people were brilliant, when I eventually managed to talk to them.  At first they told me I had to go through our installer, as they didn't talk to customers directly.  In the end I got the plumber I now use to call them from our place and then hand the phone to me so I could talk to their technical chap.  He immediately had the answer, and said that it should have been fixed by the installer fitting the F75 kit.  I then ran into a problem where Vaillant would only supply a free F75 kit to the original installer, and I refused point blank to let that installer anywhere near the boiler again, so I had to buy the F75 kit, even though the boiler was still under warranty, and get our current plumber to fit it.  From that time on the thing has worked absolutely perfectly, with one fault caused by a lightning surge that damaged the main board; not a Vaillant problem and easy to fix by replacing the board and programming it for the right boiler model.

 

When the plumber fitted the F75 kit he partially drained the system to empty the boiler of water and found there was no inhibitor in it, so the numpty installers had left the system like this.  I gather that one reason they folded was because some boiler manufacturers stopped supplying them, including Vaillant, almost certainly because they were incompetent.  What was clear was that they employed one Corgi fitter, with the rest being relatively unskilled, as all the removal of the old kit, power flush and installation work was done by two guys that didn't impress with their skill level, and then their qualified guy turned up to leak test and commission the boiler.  Even he managed to lose the manometer port screw from our meter; I had to make up a new one on the lathe so he could commission the boiler...............

Edited March 1, 2017 by JSHarris

[drliamski]

So i will  go test the ev in the boiler, think there are two though, one  in the "layered storage tank".  Should I test this one as well?

 

Also in the loft there is a further EV. It is plumbed into the existing CH loop. Np pressure atm.  Should I pump to 1 bar?

 

Update, tested the EV in boiler, was no pressure, topped up to approx 1 bar and when ttrying to check with guage let air and a few droplets of water came out. Is any a bad sign?

 

 

Expansion vessel.pdf

Edited March 2, 2017 by drliamski

[drliamski]

So the water temp in h

 

Update,

 

So I thought I would experiment and turn on the valve to the red EV in the loft, as the pipes looked new and appear to run into the CH loop. 

I was wrong.

Now the cupboard in the office below is a little damp and the rest of the water is in the kitchen and being soaked up by the books and now towels.

Luckily I didnt put my desktop pc  inside a few weeks ago. Could have been a much more expensive mistake.

 

See attached for pictures of non capped off pipes that run from old EV into where old hot water tank used to be.

 

There are also a couple of pictures of the pipework in the loft next to the EV.

 

 

[drliamski]

On 3/1/2017 at 00:02, Nickfromwales said:

Thanks J, no pressure lol. 

+1 to Daves comment. 

I think this may be a bit more than just the PRV passing, as there usually has to be a problem in order for it to open in the first place. My first guess is that the system volume ( when hot ) is greater than the actual capacity of the boiler expansion vessel ( EV ). 

@drliamski, what is the running ( set ) temp of th CH when it's on ? The boiler temp not the room stat temp please. . 

Ill also assume that if the existing radiators are still there, then the flow temp is probably running quite high to compensate for the fact that the rads aren't great at getting the heat out of the water and into the rooms. That will eggagerate the issue enough to push the system over its normal operating capacity, and cause the problems your having. 

I think this needs a secondary EV added to the heating return pipework, say 8-12 litres capacity, but first things first, the existing EV pre-charge pressure needs to be checked, along with the state of the diaphragm. 

 

With the boiler cold and the pressure at 1.5 bar, depress the shraeder valve centre pin on the EV ( the valve that looks like a car tyre inflation valve ) and allow all / any of the air to escape. Keep the pin depressed for a full minute afterwards. This will prove that the rubber diaphragm inside the EV hasn't become perforated. If it has, water will eventually come out of the shraeder valve during the 1 minute 'test period'. If it does, the EV will need replacing. If it doesn't, it'll simply need to be re-pressurised accordingly. Instructions for that upon request. 

 

The big bummer here, if it turns out to be as I suspect, ie insufficient EV volume, is that it's actually an installer error. So if that's the case, maybe ask them to fit the unit FOC? Needs a bit of investigation and surmising before pressing any buttons though. 

 

 

Hi nick, you assume correctly, temp set to 75 deg C atm

 

@Fallingditch  Do you have details of the installer?

[Nickfromwales]

Ah. Just tapped out and deleted a response as I missed the previous from you. 

It looks like an additional EV has been fitted, so the plot thickens. 

The leak you've uncovered seems the obvious culprit. Do you know exactly which pipe it's coming out of? The 15 and 22mm pipes which are sheared off should be dead, as if they weren't there would be a lot coming out. 

[Nickfromwales]

Also, not a very neat install . 

Is the red EV supported by a clamp / bracket ?

[Fallingditch]

4 hours ago, drliamski said:

 

@Fallingditch  Do you have details of the installer?

 

Afraid he retired and moved to Devon.

[Nickfromwales]

Which valve did you turn in the attic? The silver hose black tap ( secondary ( unnecessary) top up link ) or the red capped valve ( prv ) ?

Do you know where the water came out from?

[drliamski]

There was a lot, I turned the silver hose tap. it filled a cupboard and pissed out onto the floor below through the ceiling!

 

Pretty sure the water came from the   sheared off  pipes. 

I did not touch the red valve under the pressure guage of the EV.

 

Loads of water. LOADS 

[Nickfromwales]

Ok, I think I've got it. 

Sounds like they've put the additional EV in accordingly, but have inadvertently connected it to one of the severed pipes, rather than connect it to a live central heating pipe. 

Result 1) water pisses out where it shouldn't. 

Result 2) you aren't benefitting from the secondary EV volume, so your boiler is giving the pressure issues that started this thread. 

A non-retired plumber needs to attend and make said connection accordingly, at which point your books and towels will be dry and your CH will be reliable and function as it normally should . 

 

[Nickfromwales]

 

And on further inspection, the gauge shows zero, which reinforces my last. 

Therefore :- 

Result 3) previous plumber is a penis.  

[drliamski]

On 3/2/2017 at 19:54, Nickfromwales said:

Thanks nick, this confirms my fears. One last question!

I will monitor the CH pressure for a few more days but at present no further discharge from prv at boiler. EV in boiler seems to be working, but I think I need to get the EV in the attic plumbed in due to size of system. Can I just T the old pipe into the return in the office cupboard? There are all water pipes running into the cupdoard (hw cw mains, ch flow and return)

[Nickfromwales]

You can tee the EV in just about anywhere tbh. Ideally it should be local to the boiler, and if it were me, I'd do that just to have a plumbing-free attic. 

At the moment you have a cold feed for the secondary filling loop. Not needed. 

You have a secondary PRV. Not needed. 

You have a secondary D1 discharge pipe from the PRV. Not needed. 

Youd have central heating water up there heating the EV and wasting gas. Not ideal. 

 

Strip the the ev back to its input connection, bin the rest of it, cap any unwanted / redundant pipework accordingly, and mount the secondary EV at the boiler. Match the two pre-charge pressures at 1 bar and end of problem. The EV in the attic looks a terrible install to me, so is just a liability waiting to go wrong. Far better to have all the boiler related equipment in one location IMO. 

Do the cold and heating pipework that go up to the attic and terminate there, or do they traverse the attic and come back down to service another rad / etc after picking up the EV ?

 

[Nickfromwales]

Oh, if your feeling fancy, you could mount the unwanted filing loop and pressure gauge in the office / other as a remote means of checking the system pressure and topping the boiler up. Maybe preferential to going into the dungeon to do it? 

[Nickfromwales]

On 28 February 2017 at 21:25, drliamski said:

Water on floor

 

 

 

 

That water on the floor was probably the PRV connection onto the boiler having not been tightened up properly so basically the pipework leaks when the boiler discharges, from the actual union on the boiler where the copper PRV tail connects via a brass nut. If you have a basin wrench / similar, see if you can check it for tightness. It's got a rubber washer in it so it doesn't need to be super tight, but most put it on hand tight and just forget about it as it never gets tested when filling and commissioning. 

[drliamski]

OK good advice, thanks.

 

The attic has been converted to bedroom with ensuite. They traverse the attic but I think they just end in the office cupboard on the 1st floor. when the filling loop was opened all the water ended up in aforementioned cupboard. Its probably left over from the previous CH system as there was also an old  tank up there which I moved.

 

Probably wont move guage to office as going to basement is not a prob (workshop not a dungeon) and keen to box in pipework in the office properly. 

 

Moving the ev sounds like a job for a warmer time of year.

Should I use leak sealant if the pressure is still dropping or move ev first?

 

 

 

 

[drliamski]

3 minutes ago, Nickfromwales said:

 

That water on the floor was probably the PRV connection onto the boiler having not been tightened up properly so basically the pipework leaks when the boiler discharges, from the actual union on the boiler where the copper PRV tail connects via a brass nut. If you have a basin wrench / similar, see if you can check it for tightness. It's got a rubber washer in it so it doesn't need to be super tight, but most put it on hand tight and just forget about it as it never gets tested when filling and commissioning. 

 

 I think it was from the bag over the prv as definitely had hole in and the junction into boiler is on the left of the boiler, damp was on the right underneath where the test bag was.

 

I will check the PRV connection though. 

 

[Nickfromwales]

4 minutes ago, drliamski said:

OK good advice, thanks.

 

The attic has been converted to bedroom with ensuite. They traverse the attic but I think they just end in the office cupboard on the 1st floor. when the filling loop was opened all the water ended up in aforementioned cupboard. Its probably left over from the previous CH system as there was also an old  tank up there which I moved.

 

Probably wont move guage to office as going to basement is not a prob (workshop not a dungeon) and keen to box in pipework in the office properly. 

 

Moving the ev sounds like a job for a warmer time of year.

Should I use leak sealant if the pressure is still dropping or move ev first?

 

 

 

 

Leak sealer should be the absolute last option IMO. Relocating the EV is quite straightforward, I'll add details in a bit ?

[Nickfromwales]

Ok, for a 'spanner only' ( no soldering needed ) modification.........

 

You'll want one of these ( compression 22mm x 3/4" centre tee )

One of these ( 22mm x 3/4" bent flexi )

and

One of these ( EV mounting bracket and wrap around clamp ) if you don't already have one. 

 

Cut a short piece of garden hose and connect it to the heating pipework via the drain off cock ( DOC ) next to the PRV pump. Put the hose into the pump and open the DOC to a rate that the pump can handle and use that to evacuate the water from the heating circuit. Open all of the rad air bleed nipples to allow the remainder to drain, starting at the top of the house and work down. When dry, go back around and close all the bleed nipples, ( making sure not to miss one  ). 

 

Strip the EV etc out of the attic, and cut / remove / cap the pipework and redundant equipment accordingly. 

 

Cut into the 22mm return pipework under / to the side / or above the boiler where most convenient. Fit the compression tee linked above. 

Fit the flexi to the EV, hand tight, and work out where the EV will fit and mount it so the flexi reaches the tee without being stressed. When happy with the dry fit, strip the flexi back off and apply 20 turns of PTFE tape the male thread and tighten it into the tee. The other end of the flexi should have a rubber seal so only needs to go a bit over hand tight. Do not over tighten. 

Check the secondary EV for .75 - 1 bar pre charge BEFORE refilling the system. 

Fill to 1.5 bar and test for leaks. When satisfied that all is A1 and holding tight, run the heating for an hour to get everything nice and warm and recheck. If happy, re-treat with 2x inhibitor and go open a beer ??.

 

edited to add : with a house and system this size, it may be a good idea to cut a pair of 22mm gate valves into the flow and return to isolate the heating system from the boiler room. That way, any further maintence can be done without draining the whole system and without losing the inhibitor. 

[drliamski]

Revieved all the parts so will attempt this tomo.

Thought you would like to see the results of checking the magnaclean filter

 

Not been done in a while!

[Nickfromwales]

Shows they work 

Better stuck to the magnet than inside the boiler