valiant thermocompact boiler

[ZIGGY786]

hi mate i have a problem with my valiant thermocompact boiler i have screed under floor heating down stairs and floating floor under floor heating up stairs i also have a hot water storage tank up stairs in loft and the boiler is in the kitchen now i use to loose water pressure on my boiler so i called valiant as it's under waranty and they said it's the expantion vessel and changed it .the problem with loosing water pressure is fixed now but the boiler starterd to fire up even when the timer is switched off for water and heating and at night time my underfloor heating up stairs is making funny sounds under floor boards so i called valiant again and they came and changed the pump and the honeywell valves for under floor heating and put in new z6 divator valve and some other parts they took the boiler out side and changed a few other little bits and the boiler still keeps on firing and goes off within 10 secs so i called them again now the say its the external wiring problem so i have had a electrician and he confirms the wiring is ok as the boiler was fitted in 2004 and has been running very good i cant sleep at night because the pump over run wakes me up i will be very glad if you can help me please their are no fault codes on the boiler apart from first it says s2 s3 s4 and then boiler goes off and codes reads s7 when temp goes down it fires up again i have also lower my hot water tank thermostat to half

 

[twgas]

A little punctuation might just make your post intelligible. I had quite a job reading it, let alone understanding it.

 

[ZIGGY786]

A little punctuation might just make your post intelligible. I had quite a job reading it, let alone understanding it.

sorry mate I need to sort the boiler out I am so stressed

 

[ZIGGY786]

A little punctuation might just make your post intelligible. I had quite a job reading it, let alone understanding it.

My boiler keeps Fireing even though the timer is off no fault codes

 

[bertiebooth]

ZIGGY786 has a problem with his Vaillant Thermocompact boiler.

He has screed underfloor heating downstairs and floating floor underfloor heating upstairs.

He also has a hot water storage tank upstairs in the loft and the boiler is in the kitchen.

He used to lose water pressure on his boiler so he called Vaillant and they changed the expansion vessel - the problem with losing water pressure is fixed now.

The boiler started to fire up even when the timer was switched off for water and heating and at night time his underfloor heating upstairs started making noises so he called Vaillant again and they came and changed the pump and the Honeywell valves for underfloor heating and put in a new z6 divertor valve and some other parts.

They took the boiler outside and changed a few other little bits, but the boiler still keeps on firing and goes off within 10 secs, so he called them again and now they say it's the external wiring.

He asked an electrician who confirms the wiring is ok. The boiler was fitted in 2004 and has been running very well.

He can't sleep at night because the pump overrun wakes him, so he will be very glad if someone can help him please.

There are no fault codes on the boiler, except that it says s2 s3 s4, then boiler goes off and codes read s7.

When the temperature goes down it fires up again.

He has also reduced his hot water tank thermostat to half.

 

[twgas]

If it is in an unheated area eg garage, there might be a frost stat, most modern boilers have some sort of frost protection built in.
Another likely cause is a motorised valve (seized open or switch stuck)

 

[bertiebooth]

My boiler had a similar sounding fault. See the following post:

Please help me. I've read everything I can find on this web site and haven't found the answer.

I have a Vaillant VC GB 242 EH, and I think it has several faults.

I called Vaillant today because I discovered that the boiler kept lighting even during the off periods for heating and hot water. Vaillant concluded that the main PCB has a fault, so I'm arranging for a replacement.

 

[bertiebooth]

the boiler is in the kitchen

 

[ZIGGY786]

the boiler is in the kitchen

valiant called today and they have changed the pcb

but problem still not gone .

the engineneer told me that there is a live feed coming in to the pcb from one of the honeywell valve

if you take the wire out from number 3 on the pcb board the pump over run stops .


can a new honywell valve be faulty as it was only changed 3 weeks ago

 

[twgas]

Do you have a 3 port or 2*2 ports?

 

[ZIGGY786]

Hi Mick
I have 1 Drayton z6 valve for hot water. And
2x honeywell valves for under floor hating for upstairs and one downstairs

 

[twgas]

Isolate power, disconnect the grey wires at the wiring centre, connect one grey wire. reinstate power - if all ok recon another grey - then the other until you find which one is sendind the power back to the boiler.

 

[ZIGGY786]

hi
i will try it tonight

do you know how all the wires should be conected as i will check them all
thanks
ziggy

 

[twgas]

do you know how all the wires should be conected as i will check them all
thanks
ziggy

yes, if the system had been wired wrongly I would think you'd have had other problems. Don't worry about the rest of it for now.

 

[ZIGGY786]

ok i will try the grey wires tonight
do you have contact number please