Vaillant Ecotec Plus 831 losing pressure overnight

[Boiler]

Hi all,

I'm having problems with my boiler and am hoping someone can offer me advice. Few days ago our heating and hot water stopped and on inspecting the boiler I was met with the F.75 error. We had a plumber come out and the first thing he asked was if I had the owners manual which didn't fill me with confidence. Anyway, I didn't have one as we recently moved in so the plumber tried refilling the system to bring it up to 1.4/1.5 as he said this what Vaillant's were supposed to be at. It got it working which was great until yesterday morning when we lost heating and hot water again. As I had watched what he had done, I refilled it and again this morning the pressure had dropped.

Now before I call a plumber out again, I want to try and narrow the issue. I have been searching and found that it could be a number of things but I want to try and establish if it's a leak in the system or if it's a problem with the boiler. Is it possible for a DIY'er to do this? I have checked the visible areas around the radiators for a leak but can't see any signs of one (assuming that going from 1.5 to 0.9 in less than 24 hours would mean a reasonable size leak!). Also, there are a few "valves" with screw slots underneath and one was at 45 degrees. Should all the valves be closed? If not, which ones should be open and which should be closed?

Any help/advice appreciated.

Thanks.

 

[TBServices]

Hi all,

I'm having problems with my boiler and am hoping someone can offer me advice. Few days ago our heating and hot water stopped and on inspecting the boiler I was met with the F.75 error. We had a plumber come out and the first thing he asked was if I had the owners manual which didn't fill me with confidence. Anyway, I didn't have one as we recently moved in so the plumber tried refilling the system to bring it up to 1.4/1.5 as he said this what Vaillant's were supposed to be at. It got it working which was great until yesterday morning when we lost heating and hot water again. As I had watched what he had done, I refilled it and again this morning the pressure had dropped.

Now before I call a plumber out again, I want to try and narrow the issue. I have been searching and found that it could be a number of things but I want to try and establish if it's a leak in the system or if it's a problem with the boiler. Is it possible for a DIY'er to do this? I have checked the visible areas around the radiators for a leak but can't see any signs of one (assuming that going from 1.5 to 0.9 in less than 24 hours would mean a reasonable size leak!). Also, there are a few "valves" with screw slots underneath and one was at 45 degrees. Should all the valves be closed? If not, which ones should be open and which should be closed?

Any help/advice appreciated.

Thanks.

Get a different engineer if you don't trust the one you have. I'd be looking at filling loop and expansion vessel with a drop that big.

 

[Boiler]

I will be calling someone else, someone who's knows the Vaillant like the back of his greasy hand! With a drop that big, are you saying it's more likely to be the boiler at fault? If that's the case then it's a slight relief as I don't fancy having to gut the flooring to redo the pipework!

 

[TBServices]

I will be calling someone else, someone who's knows the Vaillant like the back of his greasy hand! With a drop that big, are you saying it's more likely to be the boiler at fault? If that's the case then it's a slight relief as I don't fancy having to gut the flooring to redo the pipework!

How old is the boiler?

To lose pressure that quickly, you either have

a. A big leak that suddenly sprang out of nowhere, or
b. a pressure increase resulting in a PRV operating.

 

[kay-jay]

Tbh asking for the manual isn't necessarily a bad sign as all boilers have different fault codes and no engineer can be expected to know them all off top of his head.

Agree with comments about prv and leaks.

Sent from my GT-I9100 using Tapatalk 2

 

[TBServices]

Tbh asking for the manual isn't necessarily a bad sign as all boilers have different fault codes and no engineer can be expected to know them all off top of his head.

Agree with comments about prv and leaks.

Sent from my GT-I9100 using Tapatalk 2

Agreed. Always ask for a manual unless I have my ipad handy.

 

[Boiler]

How old is the boiler?

To lose pressure that quickly, you either have

a. A big leak that suddenly sprang out of nowhere, or
b. a pressure increase resulting in a PRV operating.

I believe it was installed in 2007/2008. We've been here 6 months and haven't had any problems until few days ago. What does b. mean? Would you mind elaborating?

 

[REDSAW]

Tbh asking for the manual isn't necessarily a bad sign as all boilers have different fault codes and no engineer can be expected to know them all off top of his head.

Agree with comments about prv and leaks.

Sent from my GT-I9100 using Tapatalk 2

best not call me either because first job is 'the installation manual' i dont like guessing too much.
rather, i like guessing then checking first.
bet the prv's passing.

 

[Boiler]

I guess it was a good sign that he asked for the manual. I did offer to bring it up on my iPad but he said he would check the basics first.

 

[rawr]

I would say exp vessel. from here at my computer. guessing

 

[TBServices]

I believe it was installed in 2007/2008. We've been here 6 months and haven't had any problems until few days ago. What does b. mean? Would you mind elaborating?

Can't elaborate too much in case you try to do a DIY fix and blow yourself up.

 

[Boiler]

Can't elaborate too much in case you try to do a DIY fix and blow yourself up.

I must admit, I'm a keen DIY'er and will try my hand at most things but anything gas related is where I draw the line.

 

[Boiler]

Is there a way of "isolating" the boiler from the rest of the system to see if it still drops in pressure? I mean without fiddling with the internals or disconnecting pipes etc

 

[rawr]

there is

 

[Boiler]

there is

But are you also worried I may blow myself up?

 

[rawr]

haha I know you won't, but you might

 

[Ian400]

Try this site to download vaillant manuals, [DLMURL="http://www.vaillantdownloadservice.co.uk/Pages/Default.aspx"]Vaillant Technical Download Service[/DLMURL]
Find the Isolating Valves on the Flow and Return pipes under the boiler, turn them Off, and leave overnight to see if it makes any difference to pressure loss. ( don't use the central heating during this time ).
You can check the PRV ( Pressure Relief Valve ) is letting by, by looking for the pipe which goes from the boiler through to the outside.

 

[novicegas]

Use the right size Allen key to turn the flow and return isolation valves off or you'll find you rip and damage them using a slotty. Prv can be easily checked. A vaillant savvy engineer will be able to cycle back through the faults on a three year old v combi, might be able to detect some other previous fault that might shed some light on this one. Any pipes on ground floor that might be letting by, under screed or floor boards, fernox leak sealer will only deal with small weeps not drops of your like.

 

[lame plumber]

if you say that the boiler runs ok when pressurised but loses pressure overnight, probably what's happening is the expn vessel has failed and this means when the boiler runs, there's nowhere for the hw to expand and the prv operates until 3 bar is established, then everything is tickety until the heating goes off, water cools, pressure drops and next morning boiler wont work due to low system pressure. So ask engineer to check expn vessel first before looking at prv and other leak possibilities.

from memory doesn't gsr state you shouldn't work on a gas appliance without access to the mfis

 

[stevetheplumber]

we are not actually supposed to work on any appliance with out the manufacturers instructions present a lot of engineers will have a laptop with them onyears ago we had a plate on the boiler which told us everything we needed to know now the plate would need to be as big as the boiler

 

[Centralheatking]

I advise u get a vaillant listed engineer in - mucking about with pressurised systems when you
have little knowledge is v. dangerous. Combi systems and other pressurised set ups have highly
pressurised v. hot water all around the circuit. Get it wrong and if you unlucky someone dear to you
can get scalded - last one i read about was a baby in bed - pipe above over pressurised - 2-3 degree burns.

centralheatking

 

[Boiler]

Well... the boiler is screwed. Had a leak which wet pretty much the whole of the inside. It's water tight now but still getting errors and I think due to water getting everywhere it may be beyond economical repair.

So my question is, what is a reasonable price for a new Ecotec Plus 831 and like for like replacement fitting? I'm also thinking about getting a Magnaclean and some sort of limescale filter fitted at the same time. Probably need a power flush too.

Im in NW London and for the boiler plus fitting have been quoted £1600 (excluding the extras). Is this reasonable?

 

[tom609]

cheap price, check your house insurance some policys cover this, worth a phone call

 

[Centralheatking]

£1600 in London seems pretty good to me - but just what is the quote for ? - post it on here and we can all go over it - have you tried an independant Vaillant specialist - they can work wonders -
magnaclean is only one ferric sludge capture device there are others - which are better in my opinion and can do more - pm me if you want more totally independant info cause the centralheatkings do not do N London - we stick to West Lancashire

Well... the boiler is screwed. Had a leak which wet pretty much the whole of the inside. It's water tight now but still getting errors and I think due to water getting everywhere it may be beyond economical repair.

So my question is, what is a reasonable price for a new Ecotec Plus 831 and like for like replacement fitting? I'm also thinking about getting a Magnaclean and some sort of limescale filter fitted at the same time. Probably need a power flush too.

Im in NW London and for the boiler plus fitting have been quoted £1600 (excluding the extras). Is this reasonable?

 

[tom609]

this is an old post sure its sorted by now

 

[Roger Welton]

Op posted again today.

May be worth a go at getting Vaillant out on a fixed price repair?

 

[Destroyer2813]

Sure be worth a try i had Baxi heateam out on a 7 year old solo pretty much rebiult the whole thing after the hex leaked , will be much cheaper than a new one if they will do it

 

[tom609]

4weeks old is the thread merry christmas to all

 

[Destroyer2813]

Yeah the thread may be 4 weeks old but READ what Roger wrote the op posted again about it Today

 

[dancinplumba]

toms on the pop lolol

 

[tom609]

ok so maybe iam but new to this give a guy a break ha ha vaillant good shout though, needs to be sure its on the boiler though

 

[Rob Sale]

I will be calling someone else, someone who's knows the Vaillant like the back of his greasy hand! With a drop that big, are you saying it's more likely to be the boiler at fault? If that's the case then it's a slight relief as I don't fancy having to gut the flooring to redo the pipework!

Sorry I disagree with the comment that asking for MI's that tells me he is professional. And is going to follow manufacturers fault finding guide.

Check for big leaks around rads, look outside on the blow off pipe that boiler is not blowing off, if it is then get a GSR engineer to check PRV and expansion vessels and the pipe to the vessel.

 

[tom609]

expansion vessel definate common fault i agree but to call vaillant to represurise is over the top unless the vessel is faulty and even then

 

[Roger Welton]

I think an internal leak has been repaired (I'd hazard a guess at one of the rubber hoses) but electrics have taken a soaking so poss pcb, fan, gas valve, pump, etc. deff a job for Vaillant IMHO.

 

[tom609]

i agree though have dried them out before when the hoses have gone usually due to expansion vessel loss of pressure

 

[psk]

But are you also worried I may blow myself up?

that is the first step by you to trying your diy skills on your boiler now.
next you will be asking where is the expansion vessel and what to do about it.
just get a gsr back in and get it sorted

 

[herp_lee]

You need a gas safe registered engineer to come in, identify and repair the fault.

 

[Keefy]

Just been to a customers house to recommend a suitable shower for their new 'combi' which turned out to be an EcoTec Plus 624 (24KW). They've had the same problem as mentioned here with loss of pressure and leaks everywhere which has seen the engineer come out on numerous occasions without finding the fault. On the last visit the engineer gave them a brand new filling loop and told them to just top it up if it happens again. Unbelievable!

Going to go back in a minute to check for leaks but I've a feeling it may be the expansion vessel which I'm not getting involved with, they can get the gas engineer back AGAIN.

 

[Roger Welton]

Expansion vessels are basic stuff, always annoys me when I find them flat, as pound to a penny will need a prv also. It doesn;t take much to check them on a service, you're draining some water off to check inhibitor levels anyway why not drop a little more out to take pressure off and check vesel whilst you're there.

 

[bewsh]

You want to be checking the 15mm copper pipe which goes from the boiler through the wall to outside. If that is dripping/running then your PRV is passing. If it's passing, you want to be looking in to why the PRV has gone off in the first place.

Either the expansion vessel has lost it's air charge or the rubber diaphragm has perished and the air side is now full of water. If this is the case, when you're heating the water it has nowhere to expand to so the pressure on your boiler will keep going up until it hits 3 bar and then goes out the PRV. Easy way to check if there's an expansion issue - Top the boiler back up to 1.5 bar pressure, run the heating, if the pressure keeps rising to 3 bar, that's your problem. You could even have a blockage in the pipe which connects to the expansion vessel, I've seen this multiple times, specially on the ones with the flexi pipe connecting from the back of the pump housing to the expansion vessel.

Or, if the filling loop is passing, the pressure will keep going up even with the central heating turned off.

Or, another possible cause, but most unlikely is that the plate to plate dhw heat exchanger has pin holed, causing cold water to enter the central heating side.

If the PRV is passing, you can normally clean them up and they'll be fine, but sometimes you will need to replace them.

But whatever the cause, really you need to be getting a Gas Safe registered engineer back to check it all out.

 

[Keefy]

Checked the PRV outside and it doesn't look like it's ever discharged. I did however find a leaking conex on the heating flow going into the cylinder and evidence of a recent leak through the ceiling which was just another conex which needed nipping up. All fine now anyway and I told them to hit the Conex Kid with that filling loop if they ever see him again.

Seeing as I only went out to speak to them about a shower it's ended up being a good evening. They want a new kitchen fitting too! *Dances*

 

[dancinplumba]

Checked the PRV outside and it doesn't look like it's ever discharged. I did however find a leaking conex on the heating flow going into the cylinder and evidence of a recent leak through the ceiling which was just another conex which needed nipping up. All fine now anyway and I told them to hit the Conex Kid with that filling loop if they ever see him again.

Seeing as I only went out to speak to them about a shower it's ended up being a good evening. They want a new kitchen fitting too! *Dances*

you rang ?