Glow worm combi boiler hasn't worked since new

[klemsoft]

Hi. We're desperate for help. We had a Glow worm 38cxi combi boiler fitted from new three years ago. It has broken down at least 30 times since. Glow worm says it's because of our system introducing magnatite into the boiler and clogging the heat exchanger. However, water tests are showing clear. Despite a regular filter on the water supply and a Magnaclean filter, the boiler continues to break down, leaving us without hot water and without heating.

Each time a new heat exchanger is fitted, it lasts about 1 month before F9 errors show. These errors continue for a week or so with intermittent heating and hot water, before the boiler then breaks down completely. We've gone through six heat exchangers, two powerflushes, 1 inhibitor test, 1 water supply test by the waterboard, countless visits by plumbers, etc. All the tests show that the system is fine, that the inhibitor is present and that there's no magnatite. On the other hand, the heat exchangers that are taken out do contain debris. The problem has cost us an absolute fortune so far and we face another winter without heating/hot water.

Glow worm is adamant that the problem isn't with the boiler. Plumbers are adamant that they have done all they can to stop any system debris coming into the boiler.

Occasionally we're forewarned that the boiler is about to break down as the heating comes on with the hot water even though the heating option is switched off (e.g. during the summer).

Despite my great desire to throw the Glow worm boiler out and to tell the world just how awful the product is, I've been advised not to install a new/different boiler because if it truly is a system fault, then the same might well happen with a new boiler.

You can't imagine how grateful I would be if anyone can give me some guidance on this. Glow worm, itself, is not exactly bending over backwards to help.

If anybody has had similar experiences and/or has found a fix, please share the information with me.

Many thanks

 

[fitz1]

do you have a towel warmer.

 

[Gasguru]

An F9 error is low pressure. Does the pressure drop and are you having to top the system up on a regular basis?

Are the radiators old. If the plate exchanger is clogging up there must be debris in the radiators and corrosion happening. It appears the diverter valve is now starting to stick - again an indication of debris or chemical activity.

Has the system been powerflushed correctly ie each raditor in turn and with the correct chemicals? Unfortunately there are installers who turn the pump on and do nothing else.

I am surprised you are going through so many heat exchangers - they can normally be cleaned out.

 

[Agile]

I have no reason to believe that the problem is anything other than dirt in the system as Glow Worm have told you.

If I really wanted to I could bring my power flushing pump and spend five hours and charge you ****and be sure that I did not clean anything from your system.

In spite of what those you pay will tell you power flushing is quite a specialist operation and has to be done properly using chemicals appropriate to the problem.

As you have said you have had NEW secondary heat exchangers fitted. They can be cleaned but anyone fitting a new one was not trying to keep the cost down but rather maximising the cost.

You are obviously the victim of varying degrees of cowboys riping you off or just incompetence.

You mention having "plumbers" whereas I would say that you rather need a boiler engineer.

I am very sorry that you have had such a problem. I am sure that it stems from the original installer. I would love to know who it was. *********** Do you think that he was CORGi registered or was it a builder? Why did you not hold the installer responsible?

Tony Glazier

 

[chrishutt]

As others have indicated, flushing and cleaning a CH system is more art than science. It's not just a question of bunging in some chemicals and connecting a noisy machine. Above all it requires a methodical, painstaking and time consuming approach, which would be unusual in most so-called plumbers.

Even if done properly it does not leave your system 100% clean. If done less thoroughly it may simply serve to loosen a lot of crud that was previously firmly attached to the walls of pipes, rads, etc., which then ends up clogging your heat exchanger. This can go on for years!

 

[gasgeezer]

F9 on some boilers is a global fault i.e you need to have a external diagnostic machine plugged in to see what is going on.It sounds like a blocked secondary heat exchanger(dhw}.It is normal in this situation for the central heating to appear to be working, as the boiler dumps heat into the system side via the built in by-pass to protect the boiler from over heating.I would go with chris, agile, and glow-worms diagnosis.You can send a sample to fernox for anaylis the kit cost about 30 quid.Warning if you power flush with the boiler in situ a good chance the debris will be pushed into the h/exch. blocking it as it has small water ways.

 

[Alfredo]

Sorry to be pedantic, but when you say heat exchanger i assume you mean the hot water plate to plate, and not the main boiler heat exchanger.

If the plate to plate is continously clogging it is system debris, but I am surprised your various filters are not picking it up first.

we do find the diverters on these can stick, but its not a difficult job to remove and clean the piston in the hydroblock

If it runs for a month after each overhaul, then it is something external to the boiler killing it. An internal boiler fault would not be so patient.

Having said that we have had the very occasional 30cxi that has been unmendable either by us or Glow Worm, and has been replaced, but its only about 2 a year in quite a few hundred boilers.

Alfredo

 

[chrishutt]

Good point about the Magnaclean. Like Alfredo I'm surprised that it doesn't seem to be doing a good job. How much crud does it collect? How long has it been fitted and where exactly in the system is it fitted?

 

[DP]

Introduse some DS40 (heat exchangers permitting) and see if the boiler runs better.

 

[klemsoft]

Hi and thanks for all your comments. Some comments in return:

- the pressure does drop by anything between 0.1 and 0.4 bars and we find that we're topping up about once a week. A boiler installer has suggested that, because of this, there's probably a big leak somewhere and that this is the reason for the clogged heat exchanger - that is, water out means air in and that it is the air which is causing corrosion within the heat exchanger itself. However, I've been told by my regular plumber that the debris doesn't look like the kind that would come from within the exchanger - i.e. that if it were heat exchanger corrosion, it wouldn't look like magnatite. The boiler installer's suggestion was to isolate any pipework that is under the ground floor (any upper floor leaking would show through the ceilings) and put new piping above the floor, and then see what happens.

- the radiators are 3 years old, put in at the same time as the boiler. They are column radiators but are reproduction steel ones from B&Q as opposed to the original cast iron type.

- the heat exchangers have been replaced as they're beyond cleaning out. Not all the debris can be removed (which is strange because you'd think that if it was small enough to get in there in the first place, it should be small enough to get back out)

- I've had one plumber trying to fix the problem for about 2 years. He's been recommened by several installers in the area and is Corgi registered. The original installer was not an experienced plumber and was not Corgi registered, hence the reason for not calling him back in - in case he does any damage.

- the filters: we have one standard filter (mesh-type) on the water supply into the boiler which is about 2 years old. The Magnaclean is 7 months old and also sits at the supply into the boiler. I clean the Magnaclean every three weeks and I get a good layer of black soot each time. The soot is fine, consisting of small particles. What's coming out of the exchanger are bigger, chunkier particles.

From what all you good people are saying, it sounds like the solution lies in getting another powerflush done and making sure it's done properly. And then seeing what happens from there. Our existing plumber comes with such good references from customers, installers, boiler engineers, etc., it's hard to believe that he wouldn't have done a good job of it in the first place. Assuming you're unable to recommend good powerflush people who are local to me, can any of you recommend a national firm that you would trust to do a good job?

I do appreciate your help, by the way.

 

[fitz1]

is the debris like little iron filings.

 

[chrishutt]

the filters: we have one standard filter (mesh-type) on the water supply into the boiler which is about 2 years old. The Magnaclean is 7 months old and also sits at the supply into the boiler.

Assuming you mean these are fitted to the return pipe, I can't see how any debris can be getting through to the boiler. I therefore think what you are getting is scaly deposits that are already in the boiler, perhaps mostly in the main heat exchanger, and which come loose (helped to do so by chemical cleaning!) and end up trapped in the secondary (DHW) heat exchanger.

 

[Agile]

Its all very well singing the praises of this local fellow who has been "trying to fix it for two years" but at the end of the day he has not succeeded and I dont think that he knows what he is doing.

For a start he does not know how to clean plate HEs !

I think that Chris Hutt has identified the problem and it will be quite easy to clean out the boiler.

Isolating the boiler from the heating system will tell if the leak is n the system or boiler. That can be done now during the summer.

Chris is not very far from you and if you can afford him then I expect that he will know how to fix it and he could always telephone for advice.

Tony

PS Any heating engs here in Weymouth?

 

[Gasguru]

If you are topping it up on a weekly basis then thats where the problem lies. Fix the leak and then sort out the sludge etc.

There will be a leak on either the pipework, radiators, boiler safety valve or main heat exchanger.

 

[chrishutt]

You should have mentioned the leak (weekly pressure drop) in your first post. It's very significant.

Fresh water adds fresh limescale so I suspect that the deposits in your DW heat exchangers are an orange/brown colour rather than black. If so this is mainly limescale which is best removed with Fernox DS3 or similar.

The old plate-to-plate heat exchangers could also have been cleaned with DS3 - I've just done one. It seems that the boiler installer was right in his diagnosis of the problem.