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Alser

Worcester Green star 37cdi Pressure loss.

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Alser

Hi folks,

            hoping to find an answer to my issue with my Worcester 37cdi combi boiler.    Boiler is now 10 years old and up to the last few months had never failed us.  Now have to admit that boiler has had only 4 services in that time.  Out of sight, out of mind, I suppose.

Around a year ago we realised an issue when we heard gurgling from downstairs radiator and when checked boiler noticed that pressure gauge had fallen well into the red. Re- pressurized, bled the rads, and over the space of 4 to 8 weeks noticed a gradual fall in pressure.     Had someone come out,  checked PRv and all rads for leaks and found none and suggested that likely issue was a leaking pipe somewhere under the floor, likely at the manifold,  (all microbore pipework ).

 

Because our whole downstairs has laminate flooring and also because another engineer had said that unless pipework had been disturbed at some point,  it was unlikely to be an issue with the manifold,  we put up with re-pressurising as required.

3 weeks ago after boiler kept cutting off,  an engineer diagnosed a failed expansion vessel and PRv and replaced with new parts.  Problem we thought was fixed however days later we noticed that pressure gauge was at zero and after re-pressurising again noticed that after around 6 hours would fall back to zero. During this time we would have hot water and heating as normal.

  Having now convinced ourselves that issue must be leaking  pipework under the floor we have been working out the cost of lifting all flooring and having to fix issue and re- laminate.

Situation now is that re-pressurising lasts only 20 min and boiler goes into Ea code. Could this problem be the heat exchanger, either failed or blocked?

Just cannot afford to call out an engineer at this time Jan 2nd and pay huge call out charges, have no option but to wait until holiday period is over.

We did call the engineer who said he would come day after Xmas to have a quick look and tell us for sure if it was the heat exchanger or not but failed to appear.

 

I did re-pressurise the system and left boiler off completely and pressure continued to fall back to zero.

Any ideas, insight welcome before I call engineer out again in a few days,

                                                    Thanks.

 

 

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poni

Can you isolate the boiler from the heating system (my boiler has two isolation valves on the main heading pipes under the boiler)you could charge the system then shutoff the valves and watch the gage too see if it falls, if it does then the leaks inside the boiler of not then it's outside the boiler ,if it takes only 20mins to fall then its big ,heat exchanger inside the boiler or a pipe under the floor

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Alser

Cheers for the reply, there are no isolation valves fitted to try and there is no obvious leak from the boiler when looking up from below. The engineer that was the no show on boxing day did say when I explained the issue over the phone that it was either a leak from rad pipes or the heat exchanger and the water going back down the pipe, didn't get what pipe he was talking about

On two of the boiler services I had not seen the heat exchanger being taken out and cleaned or serviced, don't know if this would be part of a service in any case.

Did note on another post here with same boiler that the heat exchanger was quite costly and boiler was not worth fixing but like the poster I have noted that the cost is around the £200 mark, so how much would I reasonably expect to pay in labour cost to fix?

   Had just spent £220 on the expansion vessel and prv replacement.  -4 degrees tonight as I type, no hot water and no heating, time to cosy in to my other half I think.

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Geoff1946

I think there WILL be isolating valves. They are usually part of the actual pipe connection under the boiler and need a screwdriver or spanner to operate . If you find and close these it will tell you if its the boiler or external system pipework.

The rate you are losing water at it should be clearly visible somewhere if its a simple leak.

Rapid pressure loss when operating, over a few heating /cooling cycles, can mean the pressure vessel hasn't been pressurised with air, but if system pressure still drops when switched off, then its not that.

I have a Worcester Bosch 28SI boiler and I use only their own service tech's who really know their gear, but I have a service contract and I don't know if they do non-contract repairs.

One of the technicians told me that my boiler uses a heat exchanger which directly heats the DHW, rather than having the diverter valve/secondary HE system that many combi's use.  I don't know if there is any possibility of a leak within the HE, between the heating and hot water sections on these, or whether your boiler works like that.

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Andy™

any water coming from the blowoff? if not then there isnt realy any other way that much water could escape from the boiler, so you have a leak on the pipework somewhere. not really much else you can do other than find it

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binky

I had a problem with dirt on the PRV valve many years ago. The expansion  vessel had failed, so we topped up system pressure, but as soon as you put heating on, the water has nowhere to expand to, so blows off through the PRV which gets dirt on the seals. If you pressurise the system, without running the boiler for heating or hot water, does it hold pressure? If it's losing pressure and the vent pipe from PRV isn't dripping water, then it would seem a leak in pipework. Not sure about Heat exchanger leak - I would think that would leak water out of the boiler casing itself? 

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Alser
On 03/01/2021 at 09:05, Geoff1946 said:

I think there WILL be isolating valves. They are usually part of the actual pipe connection under the boiler and need a screwdriver or spanner to operate . If you find and close these it will tell you if its the boiler or external system pipework.

The rate you are losing water at it should be clearly visible somewhere if its a simple leak.

Rapid pressure loss when operating, over a few heating /cooling cycles, can mean the pressure vessel hasn't been pressurised with air, but if system pressure still drops when switched off, then its not that.

I have a Worcester Bosch 28SI boiler and I use only their own service tech's who really know their gear, but I have a service contract and I don't know if they do non-contract repairs.

One of the technicians told me that my boiler uses a heat exchanger which directly heats the DHW, rather than having the diverter valve/secondary HE system that many combi's use.  I don't know if there is any possibility of a leak within the HE, between the heating and hot water sections on these, or whether your boiler works like that.

   

      Appreciate all replies,  did look under boiler again and there is indeed isolating valves, (4) off, that can be turned off using a screwdriver.

So, would I re-pressurise up to normal pressure and then isolate all 4 valves ?

Worcester will repair out of warranty boilers, cost is as of now starting at £298 inc vat, not sure exactly what is covered though, claim 91% fix first time as they carry most parts with them and if I could discount a leak from pipework would probably use them.

There is definitely no blowoff from prv.

 

My query is that I could understand a rad pipe leaking  if perhaps it had been disturbed or knocked and pressure loss as a result, but  loss now is substantial enough compared to loss previously so what would make a pipe fail so completely?

I did have a suspicion that maybe the shower valve could be an issue as hot/cold feed is hidden behind a partition wall and has been pretty erratic for a while with tempereture fluctuating between too hot, then too cold,  (non thermostatic valve). but put this down to failing valve.

 Is it possible that there is a hot water pipe fail and could this also be the cause of pressure loss in the boiler?

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Geoff1946

If you close the boiler isolators with the system pressurised and the pressure gauge on the boiler stays up then you have proved the loss is not via the boiler.  That's all. As you are confident it's not leaving via the PRV, and presumably it's not dripping out of the boiler, I guess there isn't much doubt anyway.

 

I can't think how a fault on the hot water would cause heating circuit pressure loss. In principle there is no connection between the two. Further, your cold water supply, and consequently the hot will be at a higher pressure than the heating circuit; that's how you pressurise the heating system to start with.  Hence, if they did somehow become connected the heating system pressure would rise, not fall.

 

A common cause of copper pipe failure is corrosion from the outside where the pipe is in contact with masonry, cement, etc., and especially if there is any dampness.  It will only take a pin-hole to de-pressurise your system over a few hours; you're not looking for a torrent!  

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Andy™
22 minutes ago, Geoff1946 said:

 

I can't think how a fault on the hot water would cause heating circuit pressure loss. In principle there is no connection between the two. Further, your cold water supply, and consequently the hot will be at a higher pressure than the heating circuit; that's how you pressurise the heating system to start with.  Hence, if they did somehow become connected the heating system pressure would rise, not fall.

 

 

heat exchanger leaking between 2 sides will allow water to pass between but always from the higher pressure cold water side to the heating side so wont cause a loss, itll cause it to go up and blow off

 

2 hours ago, Alser said:

  

 Is it possible that there is a hot water pipe fail and could this also be the cause of pressure loss in the boiler?

 

no. you have a leak on the heating system somewhere. no point getting manufacturer out either, unless the water is coming from the blowoff or some other way out of the boiler, which id expect you to notice, then its not that

 

if your lucky and have very good hearing and a quiet room, you may be able to hear the water under the floor. maybe take the pressure a little higher, maybe 2 bar, but be aware if a fitting is just hanging on then the higher pressure may force it apart and open it completely so youll never get any pressure back in without fixing it

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Sharpend

Have you any pipes buried in a concrete floor? We had one which the hessian lagging hadn’t been fitted correctly and over time the cement had eaten through pipe, it took a while to find try leaving boiler off, pressure up boiler to 2bar and listen for leaking water? 

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SPECIAL LOCATION

You say the boiler has only been serviced 4 times in 10 years....

 

What about draining and/or flushing of the heating itself?

Have you had the heating water flushed out and refilled including fresh inhibitor fluid put in?

 

If not there is the possibly of all sorts of gunk, cr4p and debris building up around the system introducing potential for corrosion etc..

 

How old is the pipework?

Copper or plastic?

Does the heating pipework pre-date the boiler?

and if so, was it previously supplied from an open vented header tank?

i.e. do you have the potential for some older solder joints to have deteriorated over time with the higher pressure from the current boiler?

(I have seen joints that have been working fine for years burst open when a combi-boiler was added.)

 

I've have seen bog-standard hot/water copper pipes corrode leaving pin-hole leaks..

 

  

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Alser

Thanks so much everyone for your suggestions and just to update a few more days up the line.  Still without a working boiler and been minus 4 here for last week or two.

 

The no show engineer,  and after I contacted him again,  came out, pressured up the boiler to 1/12 bar and waited to see pressure drop, however after 15 min was still the same.

Still and after checking all rads he is convinced it is either a failed heat exchanger or leaking pipework under the floor and deemed a new heat exchanger as not economically viable and would need a new boiler.

He leaves and I check pressure again after 30 min, and pressure has dropped to 1/14. Rads are heating up nicely.  My other half runs the kitchen hot water tap and gets only cold coming through and then we hear noises from boiler upstairs.  By the time I get to boiler it has cut off and flashing EA code.  I reset and boiler kicks in again but only for a minute and cuts off again.

 

Heating pipework which is 10mm microbore is the original pipework from the 70s, boiler is just short of 11 years old so yes, entirely possible that pipework has give up somewhere under floor. Original boiler was from header tank.

I'm not aware that the system has ever been flushed out although had new rads downstairs when boiler was installed and inhibitor added then.

Have quite a bit of ground area to have to lift all laminate and ply flooring but seems the only sure way to discount,  and consider new boiler and pipework cost.

 

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Geoff1946

Surely the "engineer" checked the boiler worked in both heating and hot water before he left?   

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Alser
2 minutes ago, Geoff1946 said:

Surely the "engineer" checked the boiler worked in both heating and hot water before he left?   

Eh!, no he didn't, lives local and dropped in on his way home, yeah!, I know, thought that myself, did say to call him back if it fails again but reluctant to do so, didn't ask for any payment.  He did mention about the old pipework failing after all these years and said that after he had fitted the new expansion vessel and prv that it was possible it has caused heat exchanger  to fail?

So I suppose my question is now,  why did the boiler work when only heating was on,  and fail when we tried to get hot water?

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Sharpend

Fault EA is no flame detected I think. Would suggest a secondary fault? 

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Alser
4 minutes ago, Sharpend said:

Fault EA is no flame detected I think. Would suggest a secondary fault? 

Sure, makes sense as no green light to indicate flame when reset. Got gas at cooker so no issue with supply.

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Geoff1946
11 hours ago, Alser said:

Eh!, no he didn't, lives local and dropped in on his way home, yeah!, I know, thought that myself, did say to call him back if it fails again but reluctant to do so, didn't ask for any payment.  He did mention about the old pipework failing after all these years and said that after he had fitted the new expansion vessel and prv that it was possible it has caused heat exchanger  to fail?

So I suppose my question is now,  why did the boiler work when only heating was on,  and fail when we tried to get hot water?

 

I wonder if he's feeling guilty, or fearing being challenged, for charging you £££ fitting parts which haven't fixed the original problem but have introduced new ones.

Basically, I think you need someone who knows what they are doing.  NB Don't go to that big company which advertises on TV a lot. Personal experience says some of their guys are just as bad as the one you found.

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Alser

Needed an engineer and found this guy who lives a couple of miles away and had good reviews from satisfied customers, had called him out previously to sort a blocked condensate pipe.  Did call some others but they were talking weeks up the line before they could come out.

Now in lockdown again and just had a couple of inches of snow to make things even worse.  Using electric heaters to try and heat the place up a bit but cost in energy is unsustainable. House is open plan and heaters not up to it. Worried now about a burst pipe scenario just to top things off.   Really at a loss as which way to turn.

 

Not quite sure what big company you are talking about but does it have the initials BG?

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Andy™

think you need to find someone else. to take pressure from 0 to 1.2 bar takes a litre or 2. its a fair amount of water to loose without noticing, so in reality if its not coming out of the boiler then it must be coming from a pipe unde the floor were you cant see it leaking. not really any other explanation. cant he heat exchanger. if its primary then itll be water all over the inside of the boiler. if its secondary between heating & outside then water all over. secondary between hot water & heating side then itll be overpressure of the heating since the water feed is higher pressure...

 

until you accept the fact that the most likely problem is a leaking pipe under a floor and itll need to be found then youre not going to get anywhere

 

and youre right on the initials. you need to find someone else who can find the problem

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Alser

Okay, latest update.   I call another company , say they will send an engineer out today.  Guy comes, pressure is at zero, pressures up to 1/12 bar,  I tell him about having had the expansion vessel and PRV  replaced.  He mentions the heat exchanger as being a possible cause for boiler not  kicking on, removes the casing and inside of boiler is soaking wet but not dripping that could be noticed.  Removes the heat exchanger cover plate and a flow of water spills out, looks in with a torch and seems to think it looks okay.

     He then undone the condensate trap and flushed it out, ( this had been done about 6 months earlier) and was really badly clogged then but apart from some black gritty stuff flushing out, didn't look too bad.

Dried inside as much as he could and managed to get system up and running however after 30 min I went to check on pressure and was still good,  but noise from HE was like a  gurgling boiling kettle and an obvious trickling of water which seemed to be flowing down the condensate pipe.  Boiler also started to make low deep vibrating type sound.

I turned heating down and boiler cut off and would not restart.

 

Back to square one.  Have started uplifting floor at one side of the house to try tracing leak issue although I'm now considering replacing all pipe work altogether. Think we are talking new boiler.  The present microbore pipework, indeed all copper pipework so Ive been told was imported from China apparently when these houses were built in the 70s during the large house building programme.

 

Any roads up! Hope this post and all the suggestion and answers will help someone else with their problems at some time.  Thanks to all.

    Happy Days!

 

 

 

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Geoff1946

Why are you taking up the floor now, when it sound like you've narrowed the leak to the boiler? Unless you are dead unlucky you won't have TWO leaks.

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UNG

Have seen a problem similar to this on a Worcester boiler a few years ago and it took a while to identify the exact location of the leak

 

In the end after a bit of patience and an inspection camera looking at where I thought the fault was I found a very very tiny leak from the top of plastic fitting that connects to the heat exchanger on the right side of the boiler. This leak was so slight I only noticed it because a tiny spec of dust started swirling round in the hollow on the top of plastic fitting where the leak was swapped the plastic fitting and all was good, part cost about £30

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Bruspark

Unless you really like pulling floors up I'd have turned off the boiler, closed isolator valves (or removed and  linked the boiler flow and return pipes) with a gauge in line and pressurised that arrangement to 2 bar.   If it held its not the external piping

Otherwise/then close/cap the boiler return put 2 bar into the flow and again pressurise and check.  remember that a leak inside the combustion chamber can exit invisibly  down the condensate drain 
Don't over think it - just narrow it down !! 

Edited by Bruspark

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Alser

To be honest, just don't know which way to turn now. Is boiler beyond repair?,I don't know for sure.  You rely on gas engineers to give you the answers but it seems that, and especially more with lockdown and the present below zero conditions that it's a quick in and quick out to the next job without any thorough investigation.

I have no wish to tar everyone with the same brush but it just seems to be the way of it and as a layman you can only rely on the information you are given and engineers to 100% find the problem.

  So, what am I to do, phone another company out and pay more call out charges  I did try re-contact company that came out yesterday but phone ringing out.

I did remove the outer case this morning to see if inside was wet again but was dry inside.  Boiler pressure had fallen back to zero. Pressured up to 1 bar.  Reset boiler but would not kick in,  and no green light. 

 

Temps have consistently over the last 10 days been minus 3 to 6, could this be an issue?

I accept there's a likely leaking pipe issue under floor and had started to lift flooring at one end but have stopped and will wait for weather to turn.

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Alser
2 hours ago, Bruspark said:

Unless you really like pulling floors up I'd have turned off the boiler, closed isolator valves (or removed and  linked the boiler flow and return pipes) with a gauge in line and pressurised that arrangement to 2 bar.   If it held its not the external piping

Otherwise/then close/cap the boiler return put 2 bar into the flow and again pressurise and check.  remember that a leak inside the combustion chamber can exit invisibly  down the condensate drain 
Don't over think it - just narrow it down !! 

Just worked out how to quote, dah!  forgot how to.

Isolating valves was mentioned way back at start of topic, just wasn't sure exactly whether I should shut off all 4, have mobility issues and struggled to get under and shut all 4 off but managed okay.

I'm assuming I now wait to see if pressure drops over a period of time? and if stays at same pressure, it is not a boiler leak issue?

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