Help - System losing pressure after oil boiler was replaced

[pufferfish91]

Are those fire boards inside combustion chamber? Is that a hole in pictures 2 and 3? It looks damp on refractory base. If the expansion vessel has lost its charge then you will slowly lose pressure out of PRV when heating at a constant drip. Like I said to check vessel charge it needs to be done when system is drained to get an accurate reading and of course a leak wont help. Every sealed boiler needs a low pressure switch installed and if there isn't one I don't know why

Not sure if it's a fire board or some sort of steel bar, but it looks to be part of the unit.
No, I think it must be a particular hot point that is showing a burn mark that looks like a hole. From eyeballing it, I don't believe it's a hole.

Ok, so maybe we're getting somewhere. I let the remaining air out of the expansion vessel with the heating switched off. The pressure gauge directly connected to the vessel read 0. I pumped the vessel up to 1.5 bar this time as per the spec, so both the reading on the pump gauge and the vessel gauge read 1.5 bar. I set a tray under the pressure relief discharge pipe (which goes directly to the floor under the vessel), then turned on the heating system and watched the gauge. I could hear this creaking sound, like a spring. Then low and behold, drips of water on to the tray from the pressure relief discharge pipe. I never noticed any water here before. I was expecting it to gush out for some reason. Does this mean the vessel is faulty? I'm starting to think I might have caused this. About a week after the boiler was installed, I bled all the rads. I made a bit of a balls of it to be honest. Once I bled them, I topped up the system using the filling loop. I never thought anything of it. I bled the rads a second time and made a much better job of it (in terms of heat from the rads). So maybe I did something incorrectly?

One thing I'm struggling to get my head around is the correlation between water and air in the system. When I use the filling loop, I am putting more water in the system I believe, so if there's no leak, where does it all go? When I pump up the vessel with a pump, the gauge moves up as expected, but I didn't add any more water to the system. This is what is confusing me the most. Thanks for all your help so far and I'm sorry for the noob questions!
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Your boiler expansion vessel should have air in it. Could be faulty - air valve leaking air or diaphragm inside it ruptured. Needs vessel air charge redone to test.
There is something blocking your burner inside the boiler and it should not be used without an oil engineer sorting it all. Burner could destroy itself as well as burn badly and sooting boiler.

Thanks @Best I've just posted an update, suspecting there might be an issue with the vessel. Are you saying that the burner is being blocked by looking at the pictures or is this just a possibility? I believe you are local to me so if you want a bit of work if I can't get this fixed I would really appreciate it. Thanks!
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As Best has said and what I was getting at above. They look like fire boards inside the chamber, these will restrict burner operation, resulting in poor performance and more. The only reason I can think of them being there is to mask a problem. If the vessel diaphragm is ruptured it will fill with water, leaving no room for expansion, the pressure will easily rise to 3 bar and the PRV will discharge, if the valve on top is faulty as well then the same will happen

I'm going to call the manufacturer and find out what this bar thing is. I will let you know the outcome.

My pressure gauge did not move upwards at all. It stayed at 1.5 bar, then I heard the spring of the pressure relief discharge pipe and then noticed a few drops of water. I can see the pressure has dropped slightly in the past hour, so the issue is still there. Thanks.

 

[SJB060685]

When you open the filling loop you are adding water from empty yes. When the system is full you are just increasing the pressure inside, yes you're adding a little more water to go from 1 to 1.5 bar for example but its minimal. Even if a system was pressurized to 1000 bar you're only increasing its density slightly. Density and pressure are closely related. The vessel charge should be set to about .2 - .5 bar under system pressure, something has to give in order to accumulate the expansion of water, in this case the diaphragm. If both set to same then the charges fight each other until one gives way by which time the boiler pressure has increased and getting close to PRV setting.
Drain boiler, electrically isolate and recharge vessel to what I said, leave for an hour and check again, from what you've said I expect it to have lost its charge and bingo we have your culprit, or at least one of them. Further more as Best and I both stated, firing that burner up with restrictions is NOT advisable at all, that's another problem that is equally, if not more important than losing pressure.

Edit: have read above comment.
If the vessel is ok after an hour then it sounds from what you just said that the PRV is faulty, they have a spring inside set to a certain force that opens when that pressure is reached. These can fail both ways, not work at all or open prematurely losing pressure

 

[Gasmk1]

does it have a pipe from the boiler going to outside that is dripping if so get the fitter back to rectify the fault

 

[pufferfish91]

When you open the filling loop you are adding water from empty yes. When the system is full you are just increasing the pressure inside, yes you're adding a little more water to go from 1 to 1.5 bar for example but its minimal. Even if a system was pressurized to 1000 bar you're only increasing its density slightly. Density and pressure are closely related. The vessel charge should be set to about .2 - .5 bar under system pressure, something has to give in order to accumulate the expansion of water, in this case the diaphragm. If both set to same then the charges fight each other until one gives way by which time the boiler pressure has increased and getting close to PRV setting.
Drain boiler, electrically isolate and recharge vessel to what I said, leave for an hour and check again, from what you've said I expect it to have lost its charge and bingo we have your culprit, or at least one of them. Further more as Best and I both stated, firing that burner up with restrictions is NOT advisable at all, that's another problem that is equally, if not more important than losing pressure.

Edit: have read above comment.
If the vessel is ok after an hour then it sounds from what you just said that the PRV is faulty, they have a spring inside set to a certain force that opens when that pressure is reached. These can fail both ways, not work at all or open prematurely losing pressure

Thanks @SJB060685 that is an extremely helpful post. You've explained that brilliantly. I'm going to find out what this thing is in the burner combustion chamber and let you know. Thanks again!

 

[SimonG]

Hi,

This is not a DIY job, you must consult 'Registered Professional Gas Engineer' plumber for this issue.

As there so many criteria to check before come to the conclusion.
It must be leaking somewhere in the system as you need to keep topping it up.

1. Pipe fittings and pipes
2. Pressure relief valve
3. Auto air vent
4. Into the combustion chamber as you can't see this leak as it's run's straight into drain
5. Check your CO detector and ensure its working as combustion chamber leaks give so much problem like light headache étc..
6. Leak in expansion vessel or small expansion vessel
And so many other criteria...

In your case, it must be boiler problem and please seek 'Registered Professional Gas Engineer' plumber advice.

All the best and happy Xmas

Registered gas engineer is no good for an oil boiler! Unless they do both.
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Was your old system open vented or sealed?

 

[pufferfish91]

@SJB060685 @Best I've spoken with the manufacturer and you are both correct. They said no, that fire board shouldn't be there. It's supposed to be in the base of the combustion chamber. What's likely happened is that it has become dislodged in transit. I'm awaiting a response from the installer to see if either I can push it back down into place, or he can come look at it.

On another note, I had the heating system in for a while there (before I found out about this fire board) and the pressure actually increased slightly. I've not noticed any increase in pressure at all since I noticed the fault, unless I manually did it via the filling loop. I'll keep an eye on how much it drops over the next hour or two, then I'll try draining the system and checking the expansion vessel properly. Thanks again!
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Registered gas engineer is no good for an oil boiler! Unless they do both.
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Was your old system open vented or sealed?

It was sealed. The only thing in the system that has been replaced is the boiler/burner. Everything else has remained the same. The boiler it replaced was extremely old and very hard on oil. This new(er) boiler is miles more efficient. Probably 3-4 times more I'd say.

 

[SJB060685]

You should have a refractory base in boiler bottom yes but there seems to be fire board on all three sides of chamber, like I said the only reason I can think of is to repair or mask a problem. Do your checks and let us know in an hour.
PS. You've mentioned several times about how much more efficient it is but I'm willing to bet the guy who installed it probably didn't commission it properly either, you might find theres more to be had yet but this requires an engineer.

 

[pufferfish91]

You should have a refractory base in boiler bottom yes but there seems to be fire board on all three sides of chamber, like I said the only reason I can think of is to repair or mask a problem. Do your checks and let us know in an hour.
PS. You've mentioned several times about how much more efficient it is but I'm willing to bet the guy who installed it probably didn't commission it properly either, you might find theres more to be had yet but this requires an engineer.

Thanks @SJB060685 I don't know if I'll get it done in an hour. It's absolutely lashing outside 😁

Yes I'm sure you are correct about the efficiency. There's probably more to be had. For example, there's no insulation on any of the pipework. I'm sure that doesn't help. There's also a giant hole where the old boiler flue was. It has been very much patched up. There's a small run of about 3-4 inches of copper pipe from the back of the boiler house to the garage that is exposed to the elements too. None of this can help the efficiency surely.

Yes, sorry to keep banging on about it, but we didn't realise how rubbish the old system was. It cost a clean fortune to run the heating system. Once we get these issues sorted, I plan to put insulltion round all the pipes at least from the outside, into the garage loft until it gets to the house wall (it's an attached garage). None of the pipes are tied down either, so they rattle around a lot and they are very easy to lift. I'd like to secure them somehow, but all that will come later.
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Ok, so I've inspected the boiler again and it seems that part of the surround has come loose. I've pushed it to the bottom for now, so the top is a bit exposed. Not sure of the short time significance of this, but guessing I'll need to secure or again to the top somehow.

Incidentally, the pressure has dropped rather fast from 1.5 bar to about 0.75 bar in the last 1-2 hours. Not sure if me messing about with the oil burner has made this worse than normal.

I'm going to drain the system later today if I can and do as @SJB060685 said about checking the vessel. Thanks!

Roof of combustion chamber:

 

[SJB060685]

For now let's just find the cause of the pressure dropping without the boiler running. The boiler is something you need to get an engineer out for, I appreciate this close to Christmas you don't like that idea but from what I can make out from what little I can see in photos it shouldn't be fired up.

 

[pufferfish91]

For now let's just find the cause of the pressure dropping without the boiler running. The boiler is something you need to get an engineer out for, I appreciate this close to Christmas you don't like that idea but from what I can make out from what little I can see in photos it shouldn't be fired up.

Thanks. I don't think I'll be able to do without the boiler over Christmas with the sub-zero temperatures we're getting, but if it does fail then I'd be expecting some help from the installer. I have emergency home heating cover with my home insurance in case it does fail completely. I'll let you know how I get on with draining the system. The pressure has almost dropped to zero now. It has dropped very rapidly in the past few hours.

 

[SimonG]

I would be really surprised if your home cover, covers an oil boiler. Seen many a customer in the past with 'cover' to find out they're not!

 

[Stigster]

Hi,

This is not a DIY job, you must consult 'Registered Professional Gas Engineer' plumber for this issue.

It's an oil boiler matey.

 

[pufferfish91]

I would be really surprised if your home cover, covers an oil boiler. Seen many a customer in the past with 'cover' to find out they're not!

I don't see what choice I have really. There's just no way I can leave the heating off until after Christmas. I'll try and get it checked before Christmas, but it seems unlikely.

 

[SimonG]

The more you put on here the more Mickey mouse the install sounds.
Second hand boiler, un insulated pipes outside, installer not getting back to you.

Any pics of the outside of boiler and new pipework?

Might be worth trying to get hold of a decent oil guy and go from there. Bin off your installer.

Its either the ev or leaking underground pipes. But theres also something not right in the combustion chamber.

 

[Brambles]

The quickest way to test this is to drain the system and fit isolation valves to the boiler flow and return. Thereafter pressure test the boiler. From the photos you have posted, to me, it all points to boiler feed water leaking into the combustion chamber. The surfaces you have photographed should look like a slightly singed digestive biscuit - not like a barnacle encrusted hull of a boat.

Whilst I can understand that you want to continue to try to use the boiler - if the exchanger is leaking, unless the boiler is on load 24/7 (evaporating the leak at source), it will quickly fail to a point where it is unusable. The damp refractory linings / protection boards will disintegrate allowing the flame / heat to attack the inner then outer casing.

 

[SJB060685]

Exactly what I was getting at earlier Brambles, just not worded as such

 

[pufferfish91]

The more you put on here the more Mickey mouse the install sounds.
Second hand boiler, un insulated pipes outside, installer not getting back to you.

Any pics of the outside of boiler and new pipework?

Might be worth trying to get hold of a decent oil guy and go from there. Bin off your installer.

Its either the ev or leaking underground pipes. But theres also something not right in the combustion chamber.

I'll get some pics up tomorrow. I just gave it a break for this evening. The whole thing is stressing me out. I don't want to jump the gun here, but since i moved the fire board out of the way, checked all the release valves and topped up the system, the pressure hasn't dropped at all. That's about 7 hours now. It would normally be well down at this point. I'll know for sure in the morning.
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The quickest way to test this is to drain the system and fit isolation valves to the boiler flow and return. Thereafter pressure test the boiler. From the photos you have posted, to me, it all points to boiler feed water leaking into the combustion chamber. The surfaces you have photographed should look like a slightly singed digestive biscuit - not like a barnacle encrusted hull of a boat.

Whilst I can understand that you want to continue to try to use the boiler - if the exchanger is leaking, unless the boiler is on load 24/7 (evaporating the leak at source), it will quickly fail to a point where it is unusable. The damp refractory linings / protection boards will disintegrate allowing the flame / heat to attack the inner then outer casing.

What you say here makes perfect sense. The pressure doesn't appear to drop when the heat is on, likely because any water in the chamber is evaporating with the heat. It seems overnight, it drops like a stone. I never have the heating on overnight until 7am the next morning, so this is the most likely time it will happen.

Hahaha I can't help but laugh at your barnacle analogy. It makes perfect sense though. I was going to get the boiler properly serviced, but I'm thinking now I should go back to the installer (who also sold me the boiler) and ask him to sort it out. I've known him for a good few years now and I don't think he would intentionally sell me a dud boiler. If he did know, he'd be mad to fit it too.

Maybe there is some water dripping down where the fire board once was and as a result there's been a minor piercing of some kind in the combustion chamber ceiling.

Do you think it would be wise to check the chamber in the morning and turn off the heat so it doesn't come on in the morning, then see if it's wet? That way, we'll know for sure that there is water leaking into it. Like you all say, the barnacles shouldn't be there.

Thanks again to everyone for your input. I'd never find this in a million years without your help!

 

[Brambles]

GM

The pressure within the primary flow system is rather like a balloon - it either leaks or it does not. But it will leak if the skin is penetrated. Heat protection is outside the primary flow skin. Moving / removing any form of refractory lining, plates or other protection should have no immediate impact on the pressure within the primary circuit.

The boiler needs to be set up in accordance with the manufacturer’s instructions. They (oil fired boilers) should not be configured on a trial and error basis. If the refractory protection on an oil fired boiler fails, in conjunction with the fire valve not responding quickly, the effects can be catastrophic. If you want photo's I’ll post them.

Be aware that most (if not all) UK Insurers subscribe to Athena Intelligence which quickly and effectively picks up forum and web chat (open and dark) et al conducted ahead of subsequent major insurance claims.

 

[SJB060685]

You're misunderstanding what Brambles is saying. There should be no water in the combustion chamber. The water jacket surrounding the combustion chamber should not have pierced, fractured etc. If there was water in there then yes it will evaporate and boil away but you would also have lost pressure, it will not stop boiler pressure dropping, I suspect the reason why you're not noticing the pressure drop when heating is because as I said above the pressure will rise slightly when heating, even on a perfectly sound system. As we've all said, in the morning fill up, isolate boiler power so it doesn't come on and wait an hour, if pressure has dropped check inside the chamber for obvious signs, check around boiler base, check all accessable pipework and check the PRV hasn't discharged by putting a bowl under it.

 

[pufferfish91]

You're misunderstanding what Brambles is saying. There should be no water in the combustion chamber. The water jacket surrounding the combustion chamber should not have pierced, fractured etc. If there was water in there then yes it will evaporate and boil away but you would also have lost pressure, it will not stop boiler pressure dropping, I suspect the reason why you're not noticing the pressure drop when heating is because as I said above the pressure will rise slightly when heating, even on a perfectly sound system. As we've all said, in the morning fill up, isolate boiler power so it doesn't come on and wait an hour, if pressure has dropped check inside the chamber for obvious signs, check around boiler base, check all accessable pipework and check the PRV hasn't discharged by putting a bowl under it.

Sorry but what have I misunderstood? I'm agreeing that there should be no water in the combustion chamber.

So from about 5pm this evening there has been no pressure loss whatsoever. The heating has been off most of this time and normally it would have dropped considerably by now. I'll check it again in the morning to see if there's been any further loss. Thanks!
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I've just checked the gauge and it hasn't budged! It's rock solid now. I'm really not sure what caused this, but my guess would be that maybe the pressure relief valve in the vessel was the culprit. There was a couple of things I did:

• Pushed the fire board out of the way in the combustion chamber.
• Fiddled with the pressure release valve on the expansion vessel.
• Released all the pressure in the expansion vessel with the system off and re-pressurised. I accidentally overdid it a bit to 2 bar.

One of my next projects was to try and get the rad in the utility room working. It was always cold. This morning for the first time in like forever, it was piping hot. This is, to my knowledge the only rad in the house that has the flow and return pipes up the wall. All others are under floor. I would guess that the extra pressure is helping.

Is it safe to leave the system at 2 bar? The orange dial in the gauge says 1.5 so maybe the needle is not accurate and the pressure is too low to drive all the rads? I don't have the kahunas to touch it right now given the constant loss of pressure these last few weeks.

I fully plan to get the oil boiler serviced and I'm in the process of arranging someone to check it. Thanks to everyone for the great help so far!

 

[Stigster]

One thing to take into account is the small amount of water that needs to be lost to drop pressure significantly, or even to zero. I'm running an admittedly small system used for training in my workshop, 5 rads, electric boiler and unvented indirect cylinder but I was just showing an apprentice yesterday, it only takes just under 2 litres of water loss to drop from 1.4 bar running hot, to 0 pressure on the gauge.

That amount of water can be lost into a combustion chamber and evaporated in next to no time at all. Same with a PRV, only a few cups of water lost can significantly drop pressure as you can now imagine. The suggestions you've had to isolate the boiler with service valves and check there is a good one. Even doing as also suggested, topping up the system, don't run it at all and check for water in the combustion chamber will really narrow the problem down.

 

[pufferfish91]

One thing to take into account is the small amount of water that needs to be lost to drop pressure significantly, or even to zero. I'm running an admittedly small system used for training in my workshop, 5 rads, electric boiler and unvented indirect cylinder but I was just showing an apprentice yesterday, it only takes just under 2 litres of water loss to drop from 1.4 bar running hot, to 0 pressure on the gauge.

That amount of water can be lost into a combustion chamber and evaporated in next to no time at all. Same with a PRV, only a few cups of water lost can significantly drop pressure as you can now imagine. The suggestions you've had to isolate the boiler with service valves and check there is a good one. Even doing as also suggested, topping up the system, don't run it at all and check for water in the combustion chamber will really narrow the problem down.

Thanks @Stigster I was expecting to find water gushing out of somewhere. I did not realise how little water you actually have to lose to reduce the pressure to zero. If the pressure holds like it is at the moment, I'm just going to wait until the oil boiler is properly serviced. Whatever was causing the pressure loss is gone for now and I don't want to jinx it by going poking around in the combustion chamber. I'll leave it to an expert. My only concern at the moment is, what impact will it have on my system running slightly above the recommended pressure. Thanks!

 

[Stigster]

The system will be fine running at that pressure. Everything there will be rated to take that and more. If it gets up to 3 bar your PRV will protect the system anyway.

 

[SJB060685]

@Brambles. We've never had any of our systems go up but then we installed correctly and know what we're doing. Do you mind showing us these pictures you mention? I curious to see how bad things got before fire valve kicked in.

 

[pufferfish91]

GM

The pressure within the primary flow system is rather like a balloon - it either leaks or it does not. But it will leak if the skin is penetrated. Heat protection is outside the primary flow skin. Moving / removing any form of refractory lining, plates or other protection should have no immediate impact on the pressure within the primary circuit.

The boiler needs to be set up in accordance with the manufacturer’s instructions. They (oil fired boilers) should not be configured on a trial and error basis. If the refractory protection on an oil fired boiler fails, in conjunction with the fire valve not responding quickly, the effects can be catastrophic. If you want photo's I’ll post them.

Be aware that most (if not all) UK Insurers subscribe to Athena Intelligence which quickly and effectively picks up forum and web chat (open and dark) et al conducted ahead of subsequent major insurance claims.

Thanks @Brambles I'm not sure what you mean by trial and error. It was installed by an experienced installer. Not by me.

I'm not sure why you're mentioning this. If my system suffered a catastrophic failure and water started leaking everywhere then surely it's reasonable to expect some assistance given that I'm paying them for it. I appreciate it is also reasonable to expect your system to be in working order, which is why I'm getting the boiler serviced as soon as possible.
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Finally I think I've found the problem! I was going into my garage this morning to get a few things and when I opened the door, the floor was wet. I heard a hissing noise coming from behind a cupboard and lo and behold; This:

As you can probably tell, this is an extremely old rad that I didn't even know existed. It was behind a whole load of stuff in the garage. I really have no idea how/why it's even still connected. We had a whole new heating system installed when we moved in just over 2 years ago. Would it be reasonable to expect these old rads to be disconnected?

I think putting the the extra pressure in the system has helped me to find this. There's quite a few things ruined in the garage with all the water damage but thankfully nothing too valuable. I've now ripped out this piece of junk and put stop ends on it. The first time I've ever done it, but seems straightforward enough. There's no more leaks at least.

I've topped up the system to 2 bar and sure enough, when I switched the heating back on, the pressure increased to almost 3 bar. It never increased at all during this whole debacle, so surely that's a good sign. I've brought the pressure down to around 2 bar whilst the heat is on, so expecting it to drop a little when the heat is off. So long as it drives the radiator in the utility room, I think the job is done.

I'm going to put some inhibitor back in the system via the towel rail provided it remains stable, then I'm going to get the boiler properly serviced. Not sure if I'll get it done in time for Christmas, but I am trying to find someone to do it.

Thanks again to everyone for your great help. I've learned a hell of a lot from you all. Fingers crossed this is a fix!

The culprit:

Removed (back):

Front

A taped pipe? WTF???

Stop ends on flow an return. Yes, I know you all could do a better job