Glow-worm exchange plate

[Agile]

"""The radiators are working fine. It is not a flushing problem. Even though some of you don't want to believe that for some reason! """

Sylvian, its a very common problem that users cannot understand that heating will work fine in a very dirty system. The hot water delivery in a combi boiler depends totally on the operation of the plate heat exchanger.

Its very difficult for us to understand where the dirt on the secondary of the HE could keep coming from. Its fed ( we assume ) from the mains water which is usually clean!

You have not given us a clear answer to the question about the flow rate of hot water. If the secondary is blocked then the water will be very hot but the flow rate will be seriously reduced. Is this what you have.

Didn't the Glow-Worm engineer leave a job sheet saying what he thinks the problem is?

Tony

 

[sylvian]

the water starts off red hot but then goes cold with fault flashing. The pressure is the same as it always has been.

No the engineer has never left a job sheet nor filled in our log sheet we just received a phone call this morning to say he has ordered a new pump!

 

[Agile]

I asked you about the flow rate. You have not answered.

I will assume its about 10 litres per minute. The pressure is irrelevant.

The symptom you have described is typical of a blocked PRIMARY on the plate heat exchanger.

However, the same symptom will apply if the pump impeller is blocked or in the very rare case of the pump running slow.

Its normal for manufacturers service agents or staff engineers to leave a job sheet detailing what they have found and done.

Tony

 

[sylvian]

sorry I dont know the flow rate I have passed your comments on to my husband who has posted previous questions, who knows more than myself. Apparently glow worm have now telephoned again and have been in touch with the engineer who came yesterday and he thinks it is definitely a pump problem, although the deposits must still be coming from somewhere - no doubt time will tell all I want is some hot water and a nice hot bath!!

diane

 

[ollski]

Just to clarify a point. The bottom of the hx is the ch flow and nothing to do with the mains water so it is dirt in the rads that is causing the problem as tony pointed out. cxi's are paricularly prone to it.

 

[gasgeezer]

I cant see how its the pump if the c/h is okay, it will do the same on both circuits unless the dhw h/exch is blocked system side. if the syst pressure is not rising that rules out a perforated h/exch. The water comes in through a flow sensor then into the h/exch and out to a tap if you have gritty sand coming in blocking it i dont understand how it gets past the filters and does not block any mains fed taps. what fault code is showing is it f14 or f5. Has it got a descaler plumbed in below the boiler perhaps that is the problem if it has try by-passing it .

 

[gasgeezer]

Spot on oilski the system is bottom not top and i will wager f14 comes up as i said before that is a code for blocked h/exch.Sorry for misleading when i said the sytem was top side.What area are you in because the glow=worm engineer sounds like a complete waste of space, ask for a second opinion coz a pump aint gonna cure your problem

 

[sylvian]

the fault is F14 and there is a descaler below the boiler - no doubt my husband will respond more fully later

Thanks

DI

 

[sylvian]

We live in Hessle, East Yorkshire

 

[Agile]

Diane, Ollski has pointed out something which all of us had missed.

I will try to explain! All the symptoms are typical of a blocked HE and we have kept on saying that.

Your husband said it was the bottom connections which were blocked. On virtually every other boiler model the bottom ones are the cold water feed ! Just on yours its not!

So this is now all cleared up! The fault is exactly what we had expected all along. The system was not properly cleaned before the boiler was fitted and rusty debris from the radiators is blocking the plate heat exchanger.

The full solution is to power flush it. Lesser solutions might be to chemically clean it. Fitting an in line strainer might help and fitting a magnetic filter would be even better. The installer should have properly cleaned the system before fitting the boiler.

Tony Glazier

 

[sylvian]

The system has already been power flushed twice and chemically flushed at least 3 times

di

 

[Gasguru]

Yes but not all power flushing is done properly - a few roques round my way just connect up their mickey mouse flushing pump and don't touch the rad valves.

 

[ollski]

The system has already been power flushed twice and chemically flushed at least 3 times

di

But it is still fitted with the original dhw hx which has sat through all those cleanings getting blocked with scale. Personally I never clean them, I always replace, there is no way to may sure you have totally cleaned it out.

 

[Agile]

Power flushing is only as effective as the person who does it.

I once went to a faulty boiler only installed five days before. Already it had failed due to dirt in the system.

The owner agreed that the installer had spent a whole day power flushing the system. I spoke to him and asked what chemicals he had used. The reply was some "pink crystals" sold locally cheaply.

Professional power flushing uses the correct chemicals for the actual problem. There is not just one chemical.

A professional will also clean the HE and give a guarantee on his work.

Tony Glazier

 

[sylvian]

Thanks for your replies, but we are going round in circles. The installer is known to me and has flushed the brand new system three times. He is a corgi registed installer for 20 years. If he says he has flushed the system properly then he has.
We have a collection of heat exchangers now 7 to be precise. They have been replaced not cleaned and still the dirt clogs them up!
Beginning to get annoyed now!