Ideal Concord WRS 255A

[nick6999]

Hi - I would appreciate some advice - the boiler Ideal Concord WRS 255A has a small leak in the top of the heat exchanger. I have removed the outer case and the flue cover in the top of the exhaust and can see that the leak seems to be coming from the top left corner of the exchanger and in the middle where the seam is - where the two halves come together. Somebody - and it might be the factory - has smeared a now hardened sealant down the outside of this seam from top to bottom on both sides and on the left top, the sealant has a small pinhole from which the water dribbles. I would like to know whether this boiler can be saved from being replaced by resealing it with a similar sealant and if so, where do I get said sealant? My concern is that I don't know whether the exchanger has rusted through and is now terminally ill or whether it is merely the seam leaking water via the now pinholed sealant which perhaps would not leak if the sealant was intact. I appreciate that it probably needs replacing but it works fine (with the leak), I am a tenant in someone else's house, the landlord is facing a HUGE replacement bill because all the rad's will probably have to be replaced too and frankly, I'm just trying to help the couple out till they can get back here and sort it themselves (they are overseas on contract). I just hate spending thousands for the want of a bit of sealant or the tightening of a nut, that's all (even if it isn't my money) plus I don't really want the hassle and upheaval. Thanks in advance!

Addendum - as I posted this, a few Concord orientated posts appeared at the bottom of the page (duh!) and looking at one in particular, there is mention of replacing 'O' rings (if available, I know..) and taking the front part of the heat exchanger off. The front seems to be held on by 4 long bolts passing front to back but there are also 4 BIG nuts which may be casting holes or something else, not sure. No one else is going to do this but I am willing and mechanically/electrically minded (or dangerous, not sure which) but as per the problem described originally, I am not sure whether this is an 'O' ring problem or what.

 

[twgas]

the 2 water sections are sealed by gaskets, dont know if they are available, even if they are this is definately a corgi job, but not onemany engineers would undertake. the sealant you can see is sealing the flueway/air inlet.

 

[nick6999]

Thanks Mick - I take what you say to mean that the two halves (front and back) are bolted together whilst sandwiching one or more gaskets between them. The sealant I describe is all down the seam created by the coming together of the two halves of the exchanger - runs down the edge of where you say the gasket is, if you like - so maybe this external sealant is just a 'belt and braces' job to check any water oozing past the gasket? If my interpretation of what you say is correct, then it is possibly the gasket that is leaking. Are there any 'O' rings in there and if so, where are they and what are they doing? What is the likelihood of the casing being holed by rust - does this occur or is it unlikely? The rest of the exchanger appears sound, fins and all.
When you say this is only a Corgi job..other than removing the 4 long bolts and supporting the inner half when the front half is removed, can it get any more complicated than cleaning up the surfaces, getting a new gasket/s (if available) and bolting it back together again (with correct torque settings if applicable)?

 

[twgas]

firstly, the reason its corgi is the fact that the heat exchanger carries flue gasses so if it isnt right could be very dangerous,
see //www.diynot.com/forums/viewtopic.php?t=118415[url]
[/url]
the gaskets (similar to Orings) seal the water ways
the sealant you can see is to keep fumes inside combustion chamber

 

[nick6999]

Thanks again Mick - the sealant in this case is not sealing against flue gasses as it is down each side of the water jacket (exchanger). The heat exchanger has a hole up the middle around which are the inner fins of the exchanger itself. At the top of the exchanger, one can see the flue attached quite clearly and in the bend is an inspection plate held on with 3 butterfly nuts. I have removed this to inspect and THIS plate is sealed around the edges with a fabric-type seal - I would say that THIS seal is sealing against flue gasses. When I look straight down from the top, I can see the pilot light below the heat exchanger so there isn't anywhere else for the gasses to go except up through this hollow exchanger and then out the flue past the inspection hatch which I have just opened. Therefore, I am satisfied that the sealant is sealing against water and not flue gasses. That said, the entire cabinet is SUPPOSED to seal air tight against its backplate as - presumably - a secondary back-up to keep flue gasses inside the cabinet if potentially, they don't all rise up through the exchanger and exit via the flue. These seals have disappeared so whilst potentially there COULD be a small leak of CO into the kitchen, theoretically the draw on the outside chimney SHOULD cause sufficient enough vacuum to suck all CO outside. If the wind blew in a certain direction one day however...

That's where the CO alarm comes into it.

 

[namsag]

The seal is NOT for water this is done purely by the 4 O rings this seal is to stop heat/flue gases escaping into outer case area thus making the case dangerously hot to touch and allowing the gases to be drawn back into the combustion process

 

[Nige F]

dose the system with some leak sealer ...."draw on Chimney" it`s a balanced flue isn`t it W R S =W model Room Sealed ...I`m not Corgi, and stopped touching boilers as soon as it became illegal

 

[nick6999]

Thanks namsag - you are correct - I misunderstood Micks reply - I was so focussed on the outside I forgot that on the other side of the sealant was..the flue! Placing sealant here in order to prevent flue gasses from occupying the outer case makes sense.

The fact that the only way for water to enter into the front part of the exchanger is via the 4 'O' ringed areas clarifies things too.

I have ascertained that these 'O' rings are still available and have obtained the part number from Ideal in Hull - part number 002921. Ideal won't sell to the general public but they can tell you of a stockist in your area. Their telephone number is 01482 492251 (for the benefit of anyone reading this post in the same predicament).

My boiler is on the ground floor and all of the downstairs radiators are inverted loops so I don't know how to drain the system down yet - any suggestions would be appreciated. The boiler is on a false wall and below it is a kitchen unit with a back to the inside cupboard so I can't see through. I presume that I would drain from the lowest point and that must be the boiler. We ARE going to try and get a professional to come in and drain it and flush it but we still need to figure out where the drain is.

Thanks to everyone who has replied so far.

 

[nick6999]

I have now found the drain point in the pipework underneath the boiler, accessible via the smallest hole in the world. Ideal advised me that the boiler was drained from the system and not direct from the boiler, hence I knew where it had to be logically located.

 

[Soggy_weetabix]

4 'o' rings. A easy job. Drain it, pull apart the heat ex and put the new rings in. Refill and you have a good boiler for at least another 10 years.

David

 

[nick6999]

Thanks soggy_weetabix, my thoughts exactly. OK, well I have removed the front of the heat exchanger and can confirm that the O rings were what was leaking as the exchanger is otherwise sound. It is a simple setup - four holes, one on each corner, which obviously mate up when the two halves are together and through which the water flows. Behind the sealant down the middle is simply..a gap straight into the flue. I have fitted the new O rings, put it back together carefully and have now resealed every possible nook and cranny by which flue gasses could escape - both down each side of the exchanger itself but also all around the chimney part at the top - both inside and outside.

My heating supply company sold me heat resistant silicone flue sealer which apparently withstands prolonged temperatures of 250 deg C. I hope so.

Anyway - whilst waiting for the silicone to cure (12 hours so far but its thick down the sides so a few more hours yet methinks), I have noticed that a temperature sensor is now loose - it wasn't loose before. One end terminates underneath the pilot light and then a small copper tube runs around the outside of the unit and terminates into the top left casting hole - which has in it, a nut of some sort within which is mounted a temperature sensor. I can now move this sensor backwards and forwards a few millimeters. I didn't put pressure on this when it was all apart and didn't dissassemble it for fear of damaging it. However, in lying the front half of the sensor down on top of an upturned washing-up bowl on the kitchen worktop, theoretically I may have introduced a slight torque on the copper tube which may have transferred to the actual sensor. This is all I can think of unless it is fixed into place by something which relies on moisture for a tight fit - if so, it may have now dried out as the system has been empty for two days now.

Anyone know how this works?

The system is still empty and the outer cabinet off at the moment as I am giving the silicone more cure time but I don't want to refill the system if I already know it's going to leak. I know the automatic bleed valve on the upstairs immersion heater relies on a fibrous washer being either wet or dry in order to switch off or on, hence my idea above but I actually don't know.

I have also bought a couple of new cabinet seals - the originals are obsolete so I have bought two from another boiler with which I am going to make up a new seal so that the cabinet is sealed from the surrounding room as the original seal had simply disintegrated and wasn't there.

A warning to any DIY-ers reading this and thinking of attempting this - if you don't have an understanding of why this whole unit needs to be sealed up properly and what the consequences are if you don't - then don't attempt this job because you can only seal the exchanger and flue up effectively if you know WHY you are doing so.

 

[nick6999]

I just answered my own concern above by telephoning Ideal, the manufacturers - but the above may still enlighten someone else so can be left.

I have been told that the sensor on the exchanger is not straight into water but is actually encapsulated in a pocket of air and so therefore cannot leak. This makes sense as when the exchanger was off, I looked inside all of the holes and noticed a small tube at this location - so I now realise that this is the tube within which the sensor lies.

So I shouldn't have any leaks.

 

[Soggy_weetabix]

Would appreciate a conclusion on this boiler fix. Any leaks (good work if you got the 'o' rings to sit properly the first time.)

David

 

[nick6999]

OK - I telephoned the silcone manufacturers as the container did not specify a curing time. A thickness of quarter inch in a very hot spot meant 48 hours advisedly but they said that this sealant was not meant for direct flame contact. Wonderful advice from the heating supply store in selling it to me then. I then rang a different branch of the same heating suppliers and told them this and asked whether they had anything else. He pulled up an old diagram of my boiler and said that he didn't see any seal at this location (each side of the exchanger). A light bulb switched on and so I rang the manufacturers (Ideal) and sure enough, this gap is not supposed to be filled at all. They didn't know why specifically but no sealant required. This made me breathe easier as if the silicone burnt through it now didn't matter so much. I figured that in my 'monkey see, monkey do' approach, I had simply copied someone else's idea without having the data necessary to question whether I was repeating an error. Hmmm.

However, Ideal advised me that because of this approach, this meant that flue gasses were designed to circulate freely within the cabinet. The thought has occurred to me that this may have been an attempt to use the heat contained in the exhaust gasses to further heat the exchanger unit from all around it but then I also thought that a lot of this residual heat would potentially be lost to the kitchen via making the cabinet super hot. Don't know. Anyway, all this meant that the cabinet seal against the back plate was the only thing between me and death. That was the seal the last remnants of which fell off in pieces when I had removed the cabinet...

I figure that maybe an 'old time' heating engineer - perhaps at installation - didn't trust this idea and so decided to seal the gap up as a precaution. Ultimately I don't know but I think its a handy 'belt and braces' to have, providing the sealant holds together. I have cobbled together a new seal for the back plate using two new seals from a different boiler and am satisfied that there is more of an air tight seal there now than there was before.

I lit the pilot light before putting the cabinet on just in case it didn't light - but it did. I didn't want to fire up the whole burner until I put the cabinet on just in case it all became too hot to work around so I fitted the cabinet, sealing it as mentioned above and commanded it to work. It did!

The house has 5 radiators upstairs and 4 inverted pipe loop radiators downstairs, with the indirect immersion and pump upstairs.

I initially got all the upstairs radiators hot but no hot water and all rads downstairs cold. Then I remembered the Honeywell valve assembly next to the pump that had AB, A and B on it, so I read the bumf in the tenants pack again and then switched it over to manual as I figured there must be an air lock there somewhere. Presto - hot water after a while from all hot taps and shower. (I have now returned it to 'auto').

Thats where I am now - all rads downstairs still cold and I'm flummoxed at the moment - they all have thermostatic valves on them but I removed two and ascertained that the pins were free and when I bleed them, they spurt water immediately. So I presume that they must be all fed off a common pipe somewhere which must have an air lock in it but how to shift it? Do I bleed one rad into a bucket perhaps until the vacuum dislodges the air lock?

On the leak front - I don't know whether the boiler is leaking because I fired it up with the cabinet back on. I'm beginning to think that this wasn't a good idea because now I am in a mystery as to what is happening inside. However, what I DO know is that there is no water leaking out the bottom like there was before I started, I've got hot water and hot rads upstairs - and I had lost those three days ago due to boiler shutting down due to insufficient water - so I'm not doing so bad.

There is a lip inside the cabinet so if it IS leaking, it will have to go a bit before it breaches the lip so that I would be able to see water around the control unit as before.

When I put it together, I made sure that the circular edges of the corners were as aligned as possible with their opposite number, reckoning that if I had each corner equi-distant then that was about as good as it was ever going to get. I did flush the system through twice before filling it a third time finally and saw no leaks when cold. I did flush it until the water ran clean and I have put Sentinel inhibitor in now aswell. (It had had a bit of a flush on the initial draining as a lot of sediment came out plus I swilled the free half of the exchanger out when it was apart).

I've worked on cars quite a bit - my dad tried to make a mechanic of me and failed - but using all of that knowledge, I would guess that there is no reason why those O rings should leak. I guaged the torque on the nuts before I disassembled it and tightened them back up as tight as they were - which was as tight as they could go and I reckon I managed to tighten the two halves together without skewing the O rings as I did so.

So I am going to run it for a week and see what happens. I have learned a lot and am satisfied that despite three engineers all attending and making inward hissing noises and shaking their heads whilst quoting for a new system including radiators, I have managed to resurrect the apparent dead.

I have spent around £100 on parts which I will get back and if there are no leaks after a week and I get the downstairs rads working then I intend to suggest to the landlord that he makes a donation to my pension fund of a few hundred pounds as I suspect that I have just saved him several thousand pounds and added quite a few years of service life to his boiler. Whilst the boiler may be old and not as efficient as a new one, the increased cost to me in terms of consumption, spread over a year - is negligible and it gives the landlord - who is on contract overseas at the moment - time to think about it and save for the future instead of being put on the spot in a hurry and shelling out thousands for a job that he has no control over. I like choice and I think that everyone should have one.

I'm just a nice chap really. I'll keep you posted as to what happens but any advice on the mystery of the downstairs radiators would be appreciated. Ta.

 

[namsag]

You have spoken to a young pup at ideal who doesn`t know what he is talking about ,I have worked on hundreds of these boilers and they all have this seal where the gap is between the 2 sections of heat exchanger ,some of the realy early ones also had a fibre glass blanket coated in foil strapped around the heat exchanger also to stop too much heat getting top outer case