Horrible boiler installer - micro leak - how to find it?

[lizziecupcakes]

Hi all, sorry to rant but just been pretty upset. We had a new combi (Vaillant ecotech plus) installed in our home 3 weeks ago. It’s a 1907 edwardian semi detached.

The boiler before was on its last legs and it was also not heating the rads up properly so we had to get a new one installed.

Anyways the guy we had install the new boiler seemed absolutely fine and experienced (good Which? and google reviews). I asked him a few questions about the pressure and the ideal water temperature because I didn’t understand some of this. He did make a comment that he’d never been asked do many questions before , which I was taken aback by. Anyways, I didn’t tell my partner about that, but after, he finished installing it, sent invoice, we paid him, certificate issued etc to building control. The hot water has been great, pressure excellent, all rads heat up fine.

Anyways, over the past week the pressure to the combi seems to fall quite a bit. It was at about 1.2 since installation (on a cold system), but in the past week it settled to 0.9. If we use the shower or hot water it would rise to 1.6 or about that. Then gradually while we are out and return several hours later, it’s settles at 0.9 . Imo this is big drop.

The paper manual and the Vaillant site says the pressure should be between 1-1.5 when the system is cold. The boiler should start alerting us to top up if it falls below 0.8 (which it hasn’t done… yet ). I know 0.9 isn’t that far off 1.0, but I feel worried.

Just to explain our pattern at home: we don’t really use the hot water for hand washing (we also eat at my mum’s mostly because the kitchen is still a mess and not great for cooking in yet). We shower every other day. We have been putting the radiators on through the house about once a day (mostly the evening only, maybe twice on the weekend). Some might say we aren’t using the boiler and hot water much. Apart from the drop in the boiler’s water pressure reading, we have no issues with the hot water or pressure itself.

I haven’t topped up the system at all, I thought I’d ask the original installer about it and get him to check if it’s a faulty boiler or if there’s another cause (e.g. a leak somewhere). I’ve checked the house, walls, ceilings, skirting boards, any pipes under any loose boards I can lift… I can’t see any signs of a leak. I’ve been upset because he was very rude to me on the phone telling me he has explained this before and has now had to explain several times overall that it’s normal if the pressure drops to 0.9 and that the bouler will alert me if it needs topping up. I told him that’s not what the Vaillant site and manual says. He advised me not to do anything at all and just leave it alone. He kept saying the system is sorting itself out and will take several weeks to “settle down” and it’s probably dropped because it’s colder bow. I told him that i’d like him to come and check it etc since he installed it and he has basically refused to. He was very rude and raising his voice. I hung up on him.

So, I decided to get a Vaillant engineer out and they came out within a couple of hours. My boiler is under warranty so if there’s a fault with it they’ll fix it for free. They advised the pressure should be minimum 1 and not 0.9 . They isolated the boiler and tested it and said it’s working normally. They said the slight drop to 0.9 is down to a micro leak somewhere in the pipe work. He went and looked around where he could and did find a slightly weeping rad valve in one bedroom. He doesn’t think this is the cause of the drop but suggested we get it fixed and see how it goes. He recommended if it’s still happening then get a good plumber to check all the pipes to try and find it. He suggested a temporary solution could be to use “leak sealant” which you add to the boiler system and from the inside of the pipes it can seal up micro leaks but it’s not a permanent fix, might only work for a few months to a couple of years. He topped up the system to 1.5 before he left.

I don’t really know what to do. I am quite exhausted from decision fatigue too with all the work going on in the house and just feeling like my mind is shutting down.

Sorry for this long and probably boring post. If anyone has any suggestions, I’d be super grateful. Thank you

 

[Feltwell]

An old plumber's trick that I heard of, from a good plumber I have to say, is get a bottle of cheap perfume and add it into the system.

Give it a few hours and whichever room smells like a tart's boudoir has the leak!

Sounds comical but it would narrow it down.

 

[lizziecupcakes]

@Feltwell you just made me laugh so so much!!!

Are the chemicals from the perfume okay to put into the system though? That’s my worry with this (although sounds like an amazing idea)

 

[lizziecupcakes]

How do I do this? I will give it a go. My bathroom towel rail is electric, so can’t introduce the perfume there. Can you give me advice on how to add it via a different radiator? I have convenction heaters in my house

 

[fernicarry]

A drop in pressure on a newly filled system could be the last bits of air being purged out of it. The installer should have bled each radiator one by one but maybe he missed one and its only recently kicked in causing the pressure drop.

Best thing to do is top it back up to the recommended pressure and see how it fares. Run all the rads and make sure they all get hot all the way to the top (if not then there is still air in it). If the pressure falls again get the installer back in.

Have to admit not had much luck with Vaillant. I have two of them and they have both been like Trigger's broom.... and Vaillant themselves have been horrible to deal with.

Not sure how you could introduce perfume into a pressurised system. That hack may have been for old school open vented systems. I'd imagine there will be some sort of leak tracer available that you can inject like the UV dye for car aircons.

 

[lizziecupcakes]

A drop in pressure on a newly filled system could be the last bits of air being purged out of it. The installer should have bled each radiator one by one but maybe he missed one and its only recently kicked in causing the pressure drop.

Best thing to do is top it back up to the recommended pressure and see how it fares. Run all the rads and make sure they all get hot all the way to the top (if not then there is still air in it). If the pressure falls again get the installer back in.

Have to admit not had much luck with Vaillant. I have two of them and they have both been like Trigger's broom.... and Vaillant themselves have been horrible to deal with.

Not sure how you could introduce perfume into a pressurised system. That hack may have been for old school open vented systems. I'd imagine there will be some sort of leak tracer available that you can inject like the UV dye for car aircons.

Thanks, i’ll try that tonight.

The thing is, the installer is a horrible person so i won’t be using them again. Since buying this house I’ve actually gotten to the point where i detest most tradespeople.

 

[a twig]

I’d second @fernicarry ’s suggestion - every year when our boiler is serviced, the plumber fills the system up again, does the paper work and tootles off, and every year within a week the pressure has dropped to the the extent the boiler flaps and throws an F22 pressure error, so I do two cycles of filling back up then bleeding all the rads and then we are fine for another year.

We clearly have some interesting pipework somewhere with a tendency to airlock

Regarding Vaillant boilers we have been using Vaillant for almost 2 decades across three properties, each with a new Vaillant put in by us.

The internal pressure sensor should frankly be considered a consumable as it seems to fail every 18-24 months, fortunately we are under a 10 year warranty on this one so does not cost me anything and as I have registered everything with all the paperwork as soon as it was installed the warranty repairs are pretty painless.

Other than that though the latest one seems pretty solid and survived some “agricultural” plumbing alterations by the builders during our recent extension so I think their latest designs are a bit better.

 

[lizziecupcakes]

I’d second @fernicarry ’s suggestion - every year when our boiler is serviced, the plumber fills the system up again, does the paper work and tootles off, and every year within a week the pressure has dropped to the the extent the boiler flaps and throws an F22 pressure error, so I do two cycles of filling back up then bleeding all the rads and then we are fine for another year.

We clearly have some interesting pipework somewhere with a tendency to airlock

Regarding Vaillant boilers we have been using Vaillant for almost 2 decades across three properties, each with a new Vaillant put in by us.

The internal pressure sensor should frankly be considered a consumable as it seems to fail every 18-24 months, fortunately we are under a 10 year warranty on this one so does not cost me anything and as I have registered everything with all the paperwork as soon as it was installed the warranty repairs are pretty painless.

Other than that though the latest one seems pretty solid and survived some “agricultural” plumbing alterations by the builders during our recent extension so I think their latest designs are a bit better.

Thank you for sharing!

Sorry, but I don’t understand the why behind what you wrote: “so I do two cycles of filling back up then bleeding all the rads and then we are fine for another year.”

Why do you need to bleed the radistors after filling them? Why does this fix everything for another year? On the Vaillant website they say topping up 1-2 times per year is ok, but above that then there’s probably an issue.

Do you think our pressure drop three weeks after installation isn’t unusual?

Thanks so much for taking the time to reply

 

[lizziecupcakes]

A drop in pressure on a newly filled system could be the last bits of air being purged out of it. The installer should have bled each radiator one by one but maybe he missed one and its only recently kicked in causing the pressure drop.

@fernicarry thanks again. If the installer missed a rad, and it’s only recently kicked in, why/how would this cause a pressure drop? Sorry, I don’t understand this bit… could you kindly explain?

After he installed the boiler, I forgot to mention that he power-flushed the whole system because the previous old boiler and heating system wasn’t working sufficiently. Most of the radiators were barely warming up. But after he flushed the whole system, all the rads worked fully and we didn’t need to buy news ones, which was a relief.

 

[Flyfisher]

I have a Valliant ecoTech mains gas boiler, though it's the system version not a combi. It was installed in 2013/14 so about 10 years old and has worked well with only irregular servicing in all that time - except for a failed logic board a few years ago.

However, it does occasionally lose pressure. I've not really bothered noting how often because it's only a few times each year. Each time it happens I just open the filling loop to add a bit more water pressure and everything is fine again for many months. The heating system here is a little out of the ordinary because we have a 'heat store' as a hot water tank to enable both the gas boiler and a wood burner stove to contribute to the heating system. That's not particularly relevant to the loss of pressure but I mention it because the gas boiler plumbing simply consists of the flow and return pipes connecting only to a coil within the heat store, ie the boiler water doesn't actually flow throughout the heating circuits to the radiators.

Also, the gas boiler and heat store are in the same small 'plant room' and I'd guess the entire length of the boiler circuit is no more than 4 metres (not taking into account the coil inside the heat store. Because the relevant pipework is so short and so localised I'd expect to notice any signs of leakage, but there are none as far as I can tell. But even if there was a micro leak somewhere, I'd expect the pressure to drop evenly and for the boiler to therefore stop working regularly, but as far as I can tell it's pretty random (perhaps I really should record every event?).

Because it's only an occasional problem and very easily fixed by opening a lever valve for a few seconds, I've never bothered to really investigate what's going on, though I've long been curious about what's really happening.

All of which is probably not much help but I mention it in case others have experienced irregular pressure drops in their heating systems for no apparent reason.

 

[a twig]

So we have some very old and interestingly routed pipework in our system, which I suspect creates airlocks when the system is partially drained during the annual boiler service. I’m slowly eliminating them as I find them when doing other works.

Thus when the service is complete, the plumber uses the cold fill to top up the central heating until the pressure reading is back within its normal range (ours usually sits at 1.2)

However that reading of 1.2 that the boiler pressure sensor “sees” is actually false as the airlock has prevented the water fully filling the system, so in reality that 1.2 pressure reading is only applying to the bit before the airlock.

Now when the heating gets going, the hot water plus the oomph from the pump pushes that air along the system, forcing into the rads (usually the upstairs ones in our case, downstairs circuit seems pretty reliable and airlock free).

Without going too far into the weeds of the relationships between temperature, pressure and flow, when the heating clicks off, everything cools down, the air in the system contracts and thus the pressure in the system drops. The boiler now “sees” the real pressure (which is invariably 0.6 - 0.8 bar lower in our case) and throws its toys out of the pram, and displays a pressure error next time there is heating demand.

So I fill it back up to 1.2 then go round and bleed the rads, which lets out all the air that has been pushed into the rads.

Obviously letting that air out then drops the pressure again, so I fill it up again and then go round again with the bleed key. Usually on my second trip round no more air comes out, but I like to be sure

In short, no I don’t think your pressure drop is unusual or anything to worry about.

 

[a twig]

If we didn’t have the boiler serviced every year, then I wouldn’t have to do this exercise every year but then the boiler lifetime would be reduced and my 10 year warranty would be invalidated so we are where we are

I’ve got pretty quick at it now, all done in around 20 minutes or so

 

[a twig]

Not sure how you could introduce perfume into a pressurised system. That hack may have been for old school open vented systems. I'd imagine there will be some sort of leak tracer available that you can inject like the UV dye for car aircons.

I’d imagine you could isolate a rad via the lockshields / TRVs and then undo one of the top plugs in the rad, suck some water out and then whack in the perfume / dye etc there before refitting the plug and opening the valves.

With open vent you could dump it in the header tank but then you’d have to hope your loft was airtight otherwise the whole upstairs would rapidly become very fragrant

 

[paulc]

A drop in pressure on a newly filled system could be the last bits of air being purged out of it.

After I had a new system installed last year, I had to bleed the radiators for several weeks afterwards. Put it down to being a sealed system, and air contained within the water was slowly being released as to got repeatedly heated. Then added a bottle of Fernox F4 just in case there was a pinhole leak somewhere. Not had a problem with the pressure dropping since.
Over the last few weeks, I've been messing around with pump speeds and radiator balancing to get a bit more efficiency out of the system. The guy who did the original installation had just left the pump running at full speed and had made no attempt to balance the radiators. In the process of collecting data, but early indication is that I'm using less gas and still managing to heat the place up just as quick.

 

[fernicarry]

why/how would this cause a pressure drop

The circulating pump also contains an auto-bleed thingy so any air being pushed around the system will be expelled when it reaches the pump. The remaining water expands to fill the volume previously occupied by the air so the overall pressure drops.

Auto bleed valves may be fitted at other strategic points in the system where air might collect. I have one on the towel radiator upstairs, that being the highest point, and a couple on the manifold that serves the downstairs rads. Even so it still benefits from a manual bleed at each upstairs radiator maybe once a year.

Air in the system is bad for various reasons so you want to get it out. As to why there is air in the system? Well it started off full of air because it was a new system and fully bleeding it might take a few goes as others have said. Leaks can also allow air to be drawn in as well as letting water out but a "micro" leak would take months to have much of an effect I would think. A sudden step change in pressure is usually air being expelled, a gradual drop in pressure is usually a leak.

Did the installer just change the boiler, or did he do other work? Vaillant obviously only care about the boiler warranty but the installer should take ownership of all of his work, like for example a weeping radiator valve.

If the system has needed a lot of filling you would be advised to give it a can of inhibitor as well to prevent internal corrosion.

Which reminds me, mine has dumped all its water under the floor twice in the last few days so I need to do that...

Since buying this house I’ve actually gotten to the point where i detest most tradespeople

Welcome to the club...

 

[Stevers]

As I understand it tap water has a lot of dissolved air in it that does the opposite to 'settle out' fairly quickly.
Subsequently 'air' in the system can be a by-product of corrosion not least from the interaction of the different metals in the system, so inhibitor is a must.

 

[paulc]

As I understand it tap water has a lot of dissolved air in it that does the opposite to 'settle out' fairly quickly.
Subsequently 'air' in the system can be a by-product of corrosion not least from the interaction of the different metals in the system, so inhibitor is a must.

And on the subject of corrosion, a rough rule says that for every 10°C increase in water temperature doubles the rate of corrosion. So running the heating system at a low temperature is desirable - There are also other benefits such as higher efficiency and lower rates of scale build up. But low operating temperatures are only practical if your radiators have been suitably oversized or you have underfloor heating.

 

[noj]

If the cold pressure is now a pretty constant .9 then you haven't got a leak.

Pressure rises when the system is hot and obviously if the pump is running, just monitor the pressure at cold for a couple of weeks.

As others have mentioned, a freshly filled system has gases in the water that will be lost as it heats and cools. These will either be expelled by automatic valves (causing a pressure drop) or require the radiators bleeding (which will cause a pressure drop!). That's normal.

All sealed combi systems do need a top up periodically but nothing to be concerned about if it's more than a couple of months after the initial settling down.

 

[Cubist]

I'm a little late to this discussion and others have already offered a lot of good advice but I thought I'd chuck in some thoughts of my own, some of which will endorse or echo those of others but will, I hope, add something new. But before that though.

In a few of my asides to the First Lady regarding some of the recent discussions here I've been greeted by a raised eyebrow or two that can sometimes suggest stormy waters to come. Realising fairly quickly that my references to a 'LizzieCupCakes' may be raising her territorial hackles I have now determined for the sake of my personal well-being - and to reduce wear and tear on my keyboard - to abbreviate your 'handle' to LCC.

As I see it you have raised two distinct problems both of which represent conundrums we all often face and may need a little help with. The first of these, your central heating system, is the easiest to deal with insofar that a little hard science and engineering may be all that's required. The other though is tougher and needs some understanding of the 'soft' sciences to address successfully - this being those Tradespeople whose Customer Service skills were honed in the Muammar Gaddafi Charm School - oh, just realised, some here may be too young to remember Gaddafi, they need to think of a nicer version of Trump.

Regarding the Central Heating system, a few observations and things to bear in mind.

• Guages - are just that, they are guides rather than precise measures. Unless the readings you're seeing on the boiler can be verified with a certified comparable device then those readings cannot be regarded as absolute. However, until proven to be faulty the boilers on-board gauge should be trusted in any decision making.
• Installation of a new boiler can produce some slightly different effects depending on whether it is a replacement for an old one or as part of a new complete system that included the pipework and radiators.
  • In a new system waste materials left in the radiators and pipework during manufacture and installation can damage some delicate components or foul valves.
  • In an old system sediment and particles of corrosion and wear from moving components such as the water pump can accumulate in the radiators and other elements of the system. These can also be disturbed from among the extant sediments by the potentially higher performance of a new pump to cause damage and blockages that affect performance.
  • Whenever any intrusive work is work is done it's wise to flush the entire system at least twice over and perhaps using a recommended additive for this purpose.
• All wet CH systems are initially filled, and would be later topped up, directly from the cold water service to the property regardless of whether its a Mains Pressure water service from an external provider or a Gravity Fed system from a domestic water tank.
  • On filling a new system, or re-filling an old one, Air Bubbles, and some sediments, will be transported from the supply into the CH system but a Mains Pressure system is likely to inject far more such bubbles due to the pressure induced turbulence. Its wise to let the system settle after filling if opportunity allows.
  • This pressure can also stir up old sediments lodged in the various elements of the system to cause problems elsewhere.
• Air Locks
  • As a general rule any air trapped in the CH systems pipework and radiators, introduced when filling or refilling the system, would be bled off by the installer before firing up the boiler. However, some pockets of air may not have had time to percolate up to the bleed valves or be too stubborn to move by themselves.
  • Starting the boiler is intended to help dislodge such stubborn pockets of trapped air to allow it to rise to and be bled off through the usual valves.
  • However, water expands when its heated and, as this could cause things to go BANG. In modern systems this expansion is handled using an Expansion Vessel and Release Valve which captures the excess water from the heating circuit and dumps it outdoors.
  • This though introduces an issue insofar that when the boiler is switched off and the water in the heating system cools, its physical volume reduces/contracts to occupy a smaller space.
    • Relax. This doesn't produce a vacuum and theres no likelihood of any pipes or radiators collapsing under external air-pressure. This problem too is handled by the expansion vessel which allows some of the water previously captured in it to be drawn back in to the main heating system.
  • Nevertheless small amounts of air, regardless of source, will continue to percolate up to the upper reaches of the radiators and will occasionally need to be bled off.
  • Bleeding Radiators is easy but should only be done when the Boiler and its Pump is notrunning. You'll need a suitable key, an absorbent cloth and a little patience.
    • Every Wet System radiator is equipped with its own Bleed Valve and is located somewhere along its top edge. Usually made of either stainless or chromed steel and the key is used to turn its Square head nut at its centre - usual rules apply re Lefty loosey Righty tighty BUT never completely loosen/remove or over tighten the nut. A half turn is usually enough.
    • Wrap the cloth around and under the valve, loosen the nut, and listen to the hiss/bubbling while any trapped air escapes and watch for a thin consistent stream of water before re-tightening the nut.
    • Repeat this process for all radiators in the system starting at the highest in the house, usually a bathroom or attic if equipped with a radiator, and work back to the lowest and nearest to the boiler.
    • If you have a gravity fed water system like mine there may be further bleed valves that are mounted on vertically mounted pipes that are topped with a brass fitting that includes a knurled head to operate the valve.
    • The need to bleed a radiator is determined when the heating system is On but the top of the radiators body remains cool to the touch while the lower gets hot.
  • The need to Re-Balance radiators arises when one or more of them stubbornly refuse to get warm/hot. The procedure to follow is well documented and easy to perform but its always worth remembering that some modern CH systems allow Zoning that in effect switches some radiators off in accordance with user instructions and controls.
• Low Pressure
  • It's important to remember that modern Combi Boilers are also subject to the vagaries of pressure variations in the mains water supply and this can affect the hot water services around the house. However, such variations should not have any direct effect on the heating circuit as this is discrete from the mains water service.
• Water leaks
  • Any water leak from the system can induce pressure loss but these are usually easy to find - for obvious reasons. Pinhole leaks from the radiator bodies, valves and pipework can be more difficult to trace but a simple means to identify any such uses a sheet of cardboard/paper about the same height as a typical radiator and some kitchen cloths.
  • With the CH system switched on and operating.
    • Checks each radiator by gently swiping the cardboard sheet behind the radiator body to see if a jet of water strikes it at any point.
    • Also, drape a sheet of kitchen towel over and around the bodies of the valves to seep if they are weeping.
    • Do the same with the pipework to and from the radiator but be mindful.
    • Be mindful that there is a possibility that condensation may have formed in some areas. If the first towel comes away wet or damp dry the area thoroughly and try the test again.

Enough of perishing boilers for the moment, hopefully this on top of all the input of others will be enough for you to hold your own with any halfway decent plumber.

Now for the Obnoxious Tradespeople.

This too is easy. Ignore the pillocks they're not worth worrying about, Karma will get em soon enough.

 

[lizziecupcakes]

Thanks @Cubist

Thank you EVERYONE.

I’ve been renting since I left for uni (many many years ago) and have lots to learn.

Appreciate you all very much.