Vailliant EcoTec 637 losing pressure

[kelbriggs]

Vaillant EcoTec 637 losing pressure

Hi there, I really hope someone can help me.

We have a Vaillant EcoTec 637 and for several months we have been losing pressure. Initially, we were able to top up the water and the pressure wouldn't drop for a several days. Now, it's less than 24 hours. The error code is F22. The pressure only seems to drop when the heating is off.

We have had a Vailliant engineer look at out boiler and he replaced the expansion vessel in case that was the problem. We have had another pulumber give the boiler the OK and put through 2 X leak sealants (we live in a large three storey house with over 16 radiators so this may not be as much as it first sounds). This seemed to work for a couple of weeks (or was that due to the rebalancing we had at the same time?) before pressure began to drop again.

The attention has now turned to searching for a leak. The problem is that there is no noticeable leak anywhere. Because this has been going on for so long there would be evidence somewhere - wouldn't there? No wet patches on any ceilings, nothing visible on the walls. The thinking is therefore that the leak is on the ground floor. A plumber has been under the floorboards to search for the leak but there is nothing at all. I even braved the crawlspace yesterday and looked myself! Nothing.

We are now looking at trace and access. The problem is, no one has one clue where to start.

Now, I am no plumber but for some reason I don't think it's a leak, despite all other scenarios being ruled out (apparently). It's probably wishful thinking on my part but I would like to feel satisfied that I have exhausted all possibilities before hacking my house to bits. I have been researching on the internet and I am wondering if it could be any of the following:

1. A leaking coil in the hot water cylinder. No one has checked this.

2. A leak from the outside pipe. Sorry, I'm not sure what it is called. This initially seemed dry when I felt it yesterday but following internet advice, yesterday I loosely tied cling film around the end. Despite our heating only being on for a little while last night and not at all over night or this morning (it's now approx 11am) there is a small amount of water in there. Is this worth pursuing?

3. A faulty digital sensor

I know I'm probably grasping at straws and that the reality is is that there is a HUGE body of water pooling inside my house somewhere!

If someone could help me with some advice, even if it's to tell me that I'm deluded, virtually floating and to get the damn Trace and Access moving, I would appreciate it very, very much.

Thank you for your time,
Kelly

 

[Killy Bing]

Re: Vaillant EcoTec 637 losing pressure

Hello kelly.
Do you have photos of your boiler installation and airing cupboard where the cylinder is located?

also what area are you based?

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

Hello kelly.
Do you have photos of your boiler installation and airing cupboard where the cylinder is located?

also what area are you based?

Thank you so much for getting back to me.

Are the attached photographs any use?

We are based in Newcastle upon Tyne

 

[Killy Bing]

Re: Vaillant EcoTec 637 losing pressure

That is helpful thanks.

Do you have a red circular vessel located anywhere?

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

That is helpful thanks.

Do you have a red circular vessel located anywhere?

Next to water tank or boiler?

 

[Killy Bing]

Re: Vaillant EcoTec 637 losing pressure

Anywhere.
Attached to the central heating system.

Im off now till later but this thread will be quite active this evening when everyone else finishes work and gets to a pc!!

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

Anywhere.
Attached to the central heating system.

Im off now till later but this thread will be quite active this evening when everyone else finishes work and gets to a pc!!

Thank you. I will look for the red circular vessel and keep an eye on my post!

 

[Killy Bing]

Re: Vaillant EcoTec 637 losing pressure

Ive also messaged another engineer on the forum who covers your area, he will likely appear on here aswell later!

Hold fire on pulling the house apart!

 

[mountainman]

Re: Vaillant EcoTec 637 losing pressure

You may just need an additional expansion vessel as sixteen radiators may contain more water than the existing vessel can cope with.

 

[Howsie]

Re: Vaillant EcoTec 637 losing pressure

That is more than likely. Did the plumber check the PRV pipe?

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

That is more than likely. Did the plumber check the PRV pipe?

When you say, 'That is more than likely', are you referring to Mountainman's suggestion of an additional expansion vessel?

I'm not sure if this is relevant but we can't get ALL of the radiators hot at the same time and never have since we moved in three years ago (I think the boiler has been in since Jan 2009)

Is the PRV pipe the metal one outside? I'm not sure if a plumber checked it, although I would assume they did...? When I checked this pipe yesterday it felt dry. It wasn't until I wrapped cling film around it yesterday afternoon to collect any moisture was it clear that there was indeed water coming out of it. Only a few drops mind you, although the heating was only on for a short while last night, not at all over night and not at all so far today

 

[Killy Bing]

Re: Vaillant EcoTec 637 losing pressure

My line of thinking was also an undersized expansion vessel, therefore its been strained and has failed earlier than expected again.
letting the prv set off, let crud to build in the seating.

Hang a small bottle under it instead.
If that fills up its a much better indication than if the clingfilm gets a few drips in it.

 

[happyflyer]

Re: Vaillant EcoTec 637 losing pressure

Kelly,

When was it you first needed to top up the system, you have been in the house 3 years, has it always needed topping up since you moved in, is the boiler on the ground floor, are there radiators on the top floor, under normal circumstances what pressure do you need to put on the boiler gauge when you top it up for everything to get hot and I hope you top it up when the system is cold, have you ever seen the boiler gauge go up to 3 bar when the system is hot. Which radiators never get hot???

We need to be clear on these points or it will soon become a guessing game.

Also are you sure there are no heating pipes buried in concrete floors or chased in walls.

As someone as already said you have a lot of radiators on the system, if there are too many I suspect you had this problem from day one and you got sold the house in that state, the answers above might tell us.

Tony

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

Kelly,

When was it you first needed to top up the system, you have been in the house 3 years, has it always needed topping up since you moved in, is the boiler on the ground floor, are there radiators on the top floor, under normal circumstances what pressure do you need to put on the boiler gauge when you top it up for everything to get hot and I hope you top it up when the system is cold, have you ever seen the boiler gauge go up to 3 bar when the system is hot. Which radiators never get hot???

We need to be clear on these points or it will soon become a guessing game.

Also are you sure there are no heating pipes buried in concrete floors or chased in walls.

Tony

Thanks for the reply, Tony.

The boiler has generally worked fine since we moved - we've not had to top it up before this year. But, for whatever reason, we've never had all the radiators on at the same time. Probably around April time we noticed that we didn't have hot water, checked the boiler and saw the F22 error message. We topped up the system and it fired up but, one month later, needed to top it up again. It became more and more frequent before we called up Vaillant and they replaced the expansion vessel. In the meantime, we did have another plumber round who balanced the system and, for the first time, we had all radiators on at the same time. Anyway, the pressure kept boiling, we put some sealant in the system and that worked for a week or two but now it's worse than ever.

Boiler is on the ground floor, hot water tank in the middle floor and radiators on all three floors. We top the system up when cold to about 0.6 bar. It then heats up and stays at around 1.9bar so long as the heating is on. When the heating drops off over night, it won't start the next morning as the pressure has dropped to 0.2bar and we have the F22 message. The pressure has never been beyond about 2.4bar.

There's very few pipes chased into walls.

I'm at my wits end!

 

[happyflyer]

Re: Vaillant EcoTec 637 losing pressure

Kelly,


First of all I think you will find a cold charge of 0.6 bar is very close to the low trip which give the error code F22, I think you will need to set the cold charge at least 1 bar, what did the boiler man say to set it at after all he installed the new vessel and he should have set the pressure in the vessel to your 3 floor house.

I am off out for about 60 mins, come back to you later, do you know where all the pipe is buried and is it copper and you do need to do a proper test on that pressure relief pipe outside, if the systems is only going up to 1.9 bar the prv should bot be letting by or dripping.


Tony

 

[mountainman]

Re: Vaillant EcoTec 637 losing pressure

What caused the pressure to go to 2.4bar?

 

[diamondgas]

Re: Vaillant EcoTec 637 losing pressure

There's some good advice given here kelly... Sound's like you've got a lot of possible causes... leaking prv, topping up to low, undersized expansion vessel... etc. Not necessarily a straightforward fix when it comes to pressure loss alas

It helps to 'see' what's going on, know how much water it takes to drop the system down to fail F22 ... etc.. etc.. If you have anything coming out of the pipe outside you need to rule that out by having it replaced first! Then you can monitor the system pressure hot and cold for a period of time ... see how much it's loosing over what length of time etc From there comes the next step IMHO

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

Ok. Next time I top up, I'll put more water in to the system. I was worried about putting too much in! I assumed that the plumbers would have put the correct amount in.

Pipes are copper and I think it's just the odd wall where it is chased in to the plaster.

The pressure was at 2.4 bar last year after we had put probably a bit too much water in having bled the radiators.

 

[diamondgas]

Re: Vaillant EcoTec 637 losing pressure

Ok. Next time I top up, I'll put more water in to the system. I was worried about putting too much in! I assumed that the plumbers would have put the correct amount in.

Pipes are copper and I think it's just the odd wall where it is chased in to the plaster.

The pressure was at 2.4 bar last year after we had put probably a bit too much water in having bled the radiators.

The manufacturers instructions suggest between 1 & 2 Bar filling and states that it will indicate 'low' pressure at 0.8 Bar and Fail F.22 at 0.5... I'd go with the suggestion of raising your fill pressure first and then see what's going on
I generally charge vessels to 0.7 so if initial charge bellow that then the tiniest of leaks will have the thing dropping to F22 IMO

 

[happyflyer]

Re: Vaillant EcoTec 637 losing pressure

Kelly,

If your house has 3 floors 0.6 bar will only just get you water to the upper floors radiators and as I said earlier when the system cools down you are getting close to the low pressure trip F22 , I think you will need to do a cold charge at least 1.2 bar, the problem you may have is the higher you set the cold charge the closer you will get to 3 bar when the system gets warm and you will loose water out of the safety valve, its catch 22, if the internal expansion vessel is border line in size then you might need to go to an external vessel, but this is all still 100% guesswork, we need to be sure there are no leaks, can you take a photo of the SV vent pipe outside and post it please and then we will explain how to make sure there is no discharges.

Tony

 

[kelbriggs]

Re: Vaillant EcoTec 637 losing pressure

Kelly,

If your house has 3 floors 0.6 bar will only just get you water to the upper floors radiators and as I said earlier when the system cools down you are getting close to the low pressure trip F22 , I think you will need to do a cold charge at least 1.2 bar, the problem you may have is the higher you set the cold charge the closer you will get to 3 bar when the system gets warm and you will loose water out of the safety valve, its catch 22, if the internal expansion vessel is border line in size then you might need to go to an external vessel, but this is all still 100% guesswork, we need to be sure there are no leaks, can you take a photo of the SV vent pipe outside and post it please and then we will explain how to make sure there is no discharges.

Tony

Hi all,

Sorry for the silence. The kids took over my life/time/thoughts yesterday then before I knew it it was bedtime.

Right, an update. I topped up yesterday to the usual 0.6 before reading the advice from you lot to top it higher than that. Predictably, the pressure has dropped again this morning. I will not be topping up again until later this afternoon (as we're going out soon so we'll just shiver until then 'brrrrr') but when I do I will ensure that it is topped up to the levels suggested. I guess until this has been done and we see the result then there is nothing else we can do at the moment.

I have posted a pic of the vent pipe outside. I tried collecting any discharge in a bowl (also pictured) after I topped up yesterday and overnight but it is dry this morning. I'm guessing this is probably not the reason for the pressure drop, despite some discharge yesterday...

I can't tell you how much I appreciate the help you are giving me. Thank you all so much

 

[happyflyer]

Kelly,

That's a brilliant catcher, if there is no water in the bowl you have a leak on the system, we are not talking about a few drips in there, if its the expansion vessel that gone or under size the red bowl will fall on the floor with the weight of water.

Tony

 

[diamondgas]

There is one other possibility Kelly ... It'd be a rare one but if the main heatexchanger is leaking you'd never know as the leak will go straight down the 'drain'

 

[happyflyer]

There is one other possibility Kelly ... It'd be a rare one but if the main heatexchanger is leaking you'd never know as the leak will go straight down the 'drain'

Diamond, I was just going to ask her if the condensation is visible outside for the same reason.

 

[happyflyer]

Bet its been put into the pigging waste