Vokera Linea problems

[andyboiler]

We had a Vokera Linea 24 based central heating system installed about eight years ago by a company called GasSave. They stopped trading shortly after we bought the system. We have had countless problems with the Combi boiler, which although covered by a guarentee, were never properly resolved.
1) the hot water goes from hot to cold in ten second cycles, even at low pressure, and it is getting worse.
2) If we have the radiators on in the Winter, the boiler pressure goes up to over 3 BARs and then trips the valve, so then it goes down to zero.
We are still paying for this system (to First National Bank), due to a dodgy bit of selling, and payment clauses of the finance agreement.
I would like to know if this is a common problem with this type of boiler, or is it probably down to bad maintenance/servicing/repairs?
Help me please, because I don't fancy cold showers at 6 in the morning in the Winter.
Cheers, Andy

 

[gas4you]

Check the pressure in the expansion vessel with a tyre pressure tester. It may need recharging, see FAQ's on here or search for it on here.

If water comes out when you test it has had it and needs a new expansion vessel.

 

[Agile]

And th cycling hot water is probably a blocked plate heat exchanger.

Tony

 

[andyboiler]

Thanks for the advice folks, is ait a straightforward job to service the heat exchanger, or should I leave well alone? The pressure testing was done by the last engineer (Iwatched him doing it), but didn't seem to do any good.
My radiators are off at the moment, but I did notice during the summer that heat was coming from them occasionally.
The pressure at the moment is about 1.5 BAR, but if i turn the heating on tonight, I think it will go up over 3 BAR and trip the valve. This constant fluctuation in pressure surely can't be good for the boiler can it?

Andy

 

[Agile]

It indicates the expansion vessel needs CORRECTLY repressurising!

Merely measuring the pressure is NOT correct.

Many muppet engineers dont even know how to do it properly.

See the FAQ for details.

Tony

 

[andyboiler]

Thanks Agile/Gas4You, I have been looking through some of the other posts, and have noticed that this seems to be a common problem on Lineas. I forgot to mention that I live in a hard water area, resulting in a lot of lime build up.
Is it worth me using the three way switch to isolate the water/ch system, then switch it back to normal, and see if the valve has opened?
As the boiler is nearing ten years old, is this as much as I can expect from it, and if I were to replace it with a similar (more efficient) model, would I be able to keep the existing flu/pipework etc., without having to shell out for extra expensive work?

Cheers,

Andy

 

[DP]

On this boiler the expansion vessel can have correct pressure AND still blow off from the PRV.

I would suggest get a competent heating engineer who is able to repair boiler instead of someone who fixes by changing parts. You boiler is in need of proper service as detailed in the manual.

Your troubles are caused by fitting the boiler to a system that was not cleaned. All boiler would would eventually fail in the similar manner (hot and cold water at the tap). Get the competent heating engineer to carry out system water analyses (or you can do it yourself- you can send the sample to Fernox or Sentinel for tests- for a fee)

Just because the man (or woman) has a CORGI card (you must check the card before allowing anyone to look at your gas appliance) does not automatically mean they can fix your boiler. If you indicated where you are one of the regulars may offer a fix or you could talk to friends and relatives to find someone they are happy with.