Vokera compact combi boiler problem

[jc3131]

Hello I was wondering if someone could give me advice on a problem I am having with my Vokera Compact boiler.

The boiler has been installed for about 8 years and all of a sudden rusty coloured water is continually running from the overflow pipe. The filling loop is ok but the boiler is filling up all the time and overflowing. The pressure gauge is always on max pressure.

I have had the boiler serviced on a yearly basis and have not had any real major problems with it.

The boiler is insured and there has been about 6 engineers out trying to fix the boiler but the same problem happens. The expansion vessel has been replaced a few times as they said the first one was faulty.

The latest diagnosis is that I need an external expansion vessel as the boiler cant cope with the amount of water in the system (system has been the same for 8 years and no problems). The short term fix was to use one of my radiators as a temp vessel and this would stop the overflow from the boiler. This has not happened because as soon as the engineers went the boiler started to overflow.

I'm sorry if this does not make sense but this is the only way I can explain it.

I have 3 x 600 by 1200 rads downstairs along with a small radiator in kitchen. 3 x 600 by 1200 rads upstairs and a very small rad on landing along with a towel radiator in bathroom.

I would be grateful if someone could give me any advice on this problem.

 

[cross thread]

plate heat exchanger passing

 

[nickso]

There is no plate. I would say the twin pass h/e is passing to the ch side.

 

[Dopeydaz]

There is no plate. I would say the twin pass h/e is passing to the ch side.

I would agree that the heat exchanger is breached. I changed one last week for the same problem. Run the hot water and watch the pressure gauge. You'll probably see it drop.

 

[biscuit77]

X3 twin pass heat exchanger passing.

 

[jc3131]

Thanks for the replies.

Am I correct in thinking that the engineers should have found this problem straight away?

Also is there any need for this external expansion vessel? They said by turning the radiator off in one of the bedrooms and using it as a temp vessel it would stop the overflowing but it hasn't and things are exactly the same.

 

[Dopeydaz]

If the internal expansion vessel is still ok there is no need for an external one. If my/our diagnosis is correct there are some obvious tell tale signs that straight away point to breached heat exchanger.

I mis diagnosed one when I first qualified but got them right since then as its a fairly easy spot... That said I am not bad mouthing the engineers and there may be reasons that make them believe it's not the heat exchanger. We've given an Internet diagnosis and haven't seen the boiler. I do however firmly believe your heat exchanger has breached.

 

[jc3131]

Thanks for replies, I have an update on this problem.

The head engineer came out and said straight away that it was a cracked heat exchanger that was the problem. Now I am just waiting for the part, it's only been broke now for 7 weeks.

On top of that we have been told it would be better not to use the hot water supply as the pressure in the system is too much and if a pipe or radiator split the water will just keep flowing as the water is constantly filling from the mains.

 

[nickso]

7 weeks. I suggest you fire your current lot.

The pressure is not going above 2.5-3.5 bar if your PRV is working. If he was concerned by his own nonsense he could have turned the inlet to the boiler off.

 

[jc3131]

It's been a right *#*# on.

The pressure was right to the max and the overflow pipe was always running.

If I was to turn the hot water tap on it drains the pressure on the boiler so I can't use it. Hopefully it will be sorted soon.

A nice complaint is on the way to my insurers.

 

[jc3131]

Hello, I am still having problems with my boiler and when the hot water is running it is making a clicking noise, this is only when the hot water tap is on low (has to be on low so the water is hot enough for a bath). The last engineer advised a power flush as he thinks there is debris in the system. He drained the boiler and the water was quite clean, same goes for water in radiators. The main problem is that my insurance policy does not include a power flush. The insurance company have gave me 67 quid towards the power flush as a goodwill gesture, but I am unsure on how much this will cost and if it will actually work.

I would appreciate it if anyone could give me some more advice on these problems.

The heat exchanger was replaced the last time the engineers were out.

I was also wondering how much it would cost to change my combi boiler to a condensing boiler, and if there was much change to the pipe work.

 

[Dopeydaz]

A power flush wouldn't help this problem. How often does it click? Does the boiler run when it is clicking?

How slow do you run the taps? That boiler should roughly heat 10l per minute. I don't have a manual in front of me so don't know exactly. But that means it should take 6 seconds to fill a 1l jug

 

[Agile]

If the water is clean then a PF is not needed.

Your boiler is not very susceptible to problems from dirty water.

I am not very impressed by your engineers!

Tony

 

[jc3131]

A power flush wouldn't help this problem. How often does it click? Does the boiler run when it is clicking?

How slow do you run the taps? That boiler should roughly heat 10l per minute. I don't have a manual in front of me so don't know exactly. But that means it should take 6 seconds to fill a 1l jug

The boiler constantly clicks when the water is running (with hot tap running slowly). Everything is working ok bar this clicking noise. Ever since the boiler was installed the hot water flow hasn't been great, but we just thought this was normal. It does not take that long to fill a bath, but if you open the hot tap fully then the water is barely warm.

It sounds as if there is air in the system but the engineer said that this was not the case and then he mentioned the debris. He even said that the water was clean when he drained it to have a look at it.