Any Heating Engineers ? - Little bit of advice please

[d95gas]

Before I go an pull the house to pieces on the say so of British Gas AGAIN!!!!.

 

Hoping we have a Heating Engineer amongst the breathern.

 

 

Have a Baxi Combi boiler which is approx 5yrs old. Serviced every year by British Gas (BG) under our Homecare contract.

 

About a 1 week ago, we started losing pressure of around 1/2 - 1Bar overnight, meaning we get up in the morning to no heating until we pressurise again.

 

2Months ago we had a new bathroom put in upstairs, and new setup in the vanity room downstairs, including new double rads. The guy who did it, is a mate and very very cautious about checking his work for leaks over a a period of a few days..... all was good.

 

Back to today, and losing pressure. Called out BG 2 days ago, Engineer 1 looks over the boiler and reports all good, does some checks (We dont know what) and says keep an eye on it.

 

Day 2 wake up, no pressure. So again called out BG and another engineer attends, with me in attendance he gives the boiler a "Visual" and reports OK, during the discussion I mention the new rads, he immediately jumps in and says "Guaranteed thats where your leak is".

 

Now if the leak was upstairs, we would of noticed it with ceiling marks, etc in the kitchen (Bathroom directly above). So I proceed to rip up the carpet and floorboards in front of him, in the Vanity room..... Sticks his head down along with torch, and reports with horror on his face........ NO LEAKS.

 

He then states it must be somewhere else downstairs and BG wont proceed until we cut up Floorboards in hall, enough for them to get into the 4ft crawlspace (Cellar). Which I am reluctant to do at this stage.

 

So the questions are:

1. Why does it only lose pressure overnight (all heating is off), when we can have the heating off all days (longer period) and never lose a bit of pressure?
   
2. We have tried leaving the heating on all night, and still lose pressure by the morning. Yet heating on all day, and again no pressure loss?
   

 

Checks we have done:

1. Made sure there are no leaks around the boiler itself
   
2. Checked and kept an eye on the rads for leaks
   
3. Checked the Condensation pipe from the boiler for excess water coming out.
   

 

It totally weird, and I dont want to start ripping floorboards up unless it "Last chance saloon".

 

Any advice from the experts would be appreciated...... Even better if we had any living local to Darlington.

 

 

Thanks

[350Butcher]

Hi,

 

Sounds to me like it could well be that the expansion vessel on your boiler has lost its air charge, this means the system water has no where to expand to and causes pressure to rise (over 3bar) on heat up and slowly drip away out the pressure relief valve pipework. Easy enough to check if this is going on. Can you see where the 15mm copper pipe/ pressure relief pipework goes? (Usually straight through the wall from boiler) See if its dripping at all as that will be your "leak"

 

All the time its hot its OK and only drops down to 0bar on cool down as its lost an amount of water while hot.

 

Hope that helps (and makes sense), let me know how you get on

 

Martin

[d95gas]

Hi 350Butcher,

 

Thanks for the information. The daft thing it never goes down to 0Bar. we have the green triangle, I always pressurise to the top of the triangle. in the morning its about half way down but flashing E119. Checked the pipe as did BG but nothing coming out of there.

 

When we have the heating on, I am fairly sure it just sits at the top of the triangle and pretty stable.

 

We have not had the heating on all morning and the needle has not budged from where we set it...... thats the bit I cannot understand, why the heck does it only do it overnight....... drives me mad!!!!!

[gsexr]

yep expansion vessel.

The system is highly unlikely to spring a leak that loses pressure overnight unless someones put a nail through a pipe etc.

 

The expansion vessel has a diaphram inside that will be failing. You can re charge them but best to replace in the long term.

 

Over night the system cools down so the pressure goes below the minimum acceptable for the boiler to run hence it flashes up a fault code.

[P15UL T]

Sounds like the only happens over a set pressure so when your heatings on and the pressure rises to 3bar ish then you leak out some water then when it cools it drops to below your normal set pressure.

 

Mine has a simalir problem but still works so I'm not bothering to fix it as it'll be ripped out in 6 weeks when I renovate the house.

 

Good luck finding the problem

 

Paul

[d95gas]

Bloody hate heating systems I just cannot get my head around the fact that we go to bed at 10pm, we get up a 5am and pressure is down to about 0.5 bar.

 

Yet I can pressurise the system to approx 1bar, leave it all day long with no heating on, and it never budges.

 

 

The other thing that has now made me think BG guy just wasnt interested...... Friday afternoon ..... Wanted to be down the boozer. Bear in mind I am not a heating engineer, so dont really know how a Combi works. But I said to him that we both got up Friday at 5am, house was freezing, error code flashing. Wife got in the shower, had hot water of course, but no heat in the rads. when I checked the boiler lights, the water light was on, the rad light was off.

 

His response was still insistent on a leak, he never bothered to say "Thats how Combi's work", they can pump both rads and water at the same time!!!!!!!

 

Convinces me he dont want to do the job.

 

I think I need to kill the BG contract off, and get an independent in, someone who take pride in their work and getting to the bottom of the problem. Apologies to any BG guys out there, I know its like all trades, you always get a few bad one's amongst the bunch.

[gsexr]

System do develop leaks mate but they are usually slow and lose pressure over time.

 

If the pressure loss is over night mate its most likely the expansion vessel.

Initially the pressure loss is because the diaphram develops a pin hole and the system water passes through it to the air side. You then top it up and it happens again. Eventually the air side of the expansion vessel gets full up and the PRV ( pressure relief valve) will let go to allow the pressure out.

 

Its just expansion as the system heats up and that has to go somewhere, hence the expansion vessel. Its pretty standard heating stuff mate and no biggy. Dont get stressed with it.

Replace the expansion vessel in the boiler or add another to the system.

 

One consideration as you have had new double rads fitted is that the system volume is now too much for the size of expansion vessel in the boiler but you could google your boiler model and see how much volume it can take.

Then you have to look at total number of rads and the size of them and see what that volume adds up to. Then if its close consider the pipework.

But lets not get ahead of ourselves, just a point to consider.

 

Where are you located ?

Edited April 24, 2016 by gsexr

[d95gas]

Thanks gsexr, good information there, all starting to make sense. As far as I am aware the pressure vessel was not tested, but I need to speak to the first BG engineer tomorrow as he seemed to have more about him than the second guy, who was a waste of space really.

 

I am located in Darlington. Had a look on "yellow pages" and there is a local guy who has had a boat load of excellent reviews from locals, so will probably give him a call tomorrow as well, just hit at the wrong time as I am working away in Inverness this week.

[gsexr]

Just make sure they check the vessel pressure isolated from the system pressure otherwise it will just read what eve`rs in the system. ( unless the system pressure is zero then it wont matter)

Vessel should have 1.5 bar in it if its in the boiler or located on the system at boiler level.

Edited April 24, 2016 by gsexr

[350Butcher]

Leaving it all day at a 1 bar with no drop is proof enough that the system is free from leaks. Using the boiler on hot water only doesn't heat enough volume to water to raise the pressure so all is well, it will only be a problem with heating.

 

If you can get to the pressure relief pipework I've zip tied a bag over the end of it in the past just to 100% test to see if its dumping water through it. Most boilers are an 8ltr expansion tank some 10ltr which is good for 80-100ltr of system volume, which using no science at all is usually ok upto 16ish rads

 

Just as a note also, if sometimes does come and pump up the vessel (which is fine as some do just go flat after a few years) make sure they blow the pressure out of the system and leave an open end like a drain hose or manually open the pressure relief valve so it pumps out the water in the vessel as you pump it up and you get the correct reading otherwise its a pointless exercise and you'll be led down the road again.

 

Good luck mate

[gsexr]

I see you mention you have a contract with BG so when they come out tell them to check the vessel and if its lost pressure tell them you want a new one.

 

If they say it just needs pumping up it will be fine

 

Ask him where the pressure has gone.

 

When he says its lost pressure and just needs pumping up

 

Tell him it will lose it again then so you would appreciate it if he would organise a new one..... Simples

[Jonny B]

It certainly sounds like the expansion vessel could be the culprit.

I would be amazed however if the expansion vessel hasn't been checked when looking for a problem with pressure loss. It's pretty basic and the first point to start once any visible leaks have been ruled out.

If they check it and it does just need pumping back up, that is to be expected and does need doing from time to time. They will know straight away if the diaphragm has split (then it will require a new vessel)

It could just be the schrader core needs replacing, but saying the full vessel must be replaced every time it needs pumping up is like saying you must buy a full new wheel and tyre every time your tyres need any air putting back in them. You wouldn't buy a full new wheel and tyre just because the valve was leaking would you?

[d95gas]

Really appreciate the quality replies guys, some fantastic information and ammunition I shall be speaking to BG today and get them to come back. I want them to test the expansion vessel whilst I am there, the wife wont understand and therefore wont challenge what the guys says.

 

I will post back once I have spoken to them

 

 

thanks again