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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3757
Experience:  City and Guilds qualified plumber
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Hello; my 10 y old boiler Vailant started to play by not turning

Customer Question

Hello; my 10 y old boiler Vailant started to play by not turning on hot water and heating during cooler weather. Comes up fault Nr 28. When restart works for a couple times to use hot water and after that again goes into F 28. I have realized when is warmer weather it works fins and heating does the same. But if heating is on constantly, the boiler is workiing and hot water and heating. Please advise what is a kind of problem. I think it could be spark?? thanks
Submitted: 3 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 3 years ago.
***** ***** : Do you have the full model details?
JACUSTOMER-h3ez04u4- :

Vailant turbomax plus; thermocompact

JACUSTOMER-h3ez04u4- :


***** ***** : On your boiler, that fault means it is failing to light;
***** ***** : Faults in the gas supply such as:- Gas meter or gas pressure detector defective- Air in gas- Gas flow pressure too low- Fire protection tap has disengagedFaults in the gas valve, wrong gas setting, igniter (ignition trans- former, ignition cable, ignition plug) defective, ionisation current stopped (cable, electrode), faulty earthing in appliance, electronics defective
***** ***** : Are you able to see if it is getting to ignition?
JACUSTOMER-h3ez04u4- :

But what do you think why the boiler is working in warm weather and is struggling when is cold. What relation is to work on warm and NOT during the cold weather??? Pressure in the gas supply??? dont see it as logic solution; Fire protection tap has disengaged Faults in the gas valve, wrong gas setting,???? i came to this site as to get solution by going step by step repair or call plumber idf not possible to sort things out. boiler itself is not a miracle and if you have 20y experiance, i icould get solution advise

***** ***** : Have you observed the boiler when it has failed to light?
***** ***** : Are you able to tell me how far through the ignition sequence it gets before it fails?
JACUSTOMER-h3ez04u4- :

i cant see the reason why its not igniting; doesnt ignite when you turn on tap after several ignitings

***** ***** : ok
JACUSTOMER-h3ez04u4- :

sometimes it is working ok

***** ***** : is the fan starting when you open the tap?
JACUSTOMER-h3ez04u4- :


***** ***** : every time?
JACUSTOMER-h3ez04u4- :


***** ***** : When the fan runs can you hear it starting to tick as if it is trying to light?
JACUSTOMER-h3ez04u4- :

give me two mins to check

***** ***** : ok
JACUSTOMER-h3ez04u4- :

tried so far 11 times and it keep igniting...

JACUSTOMER-h3ez04u4- :

what pressure has to be of the gas in pipe

JACUSTOMER-h3ez04u4- :

i have a pre-paid gas key meter; could it be a problem with supply in low pressure

JACUSTOMER-h3ez04u4- :

still trying to find when it will stop igniting; irregularry. will give you update how boiler will act once stopped ignitings

***** ***** : The pressure will be 20mb all the time - do you have problems with any other gas appliance?
JACUSTOMER-h3ez04u4- :

hello; yesterday all evening boiler was working; today in the afternoon it stopped; so when water is turned on, fan is working but not a single attempt to ignite

***** ***** : It must not know the fan is running - this is pointing at the APS
***** ***** : Are you able to take the cover off and check?
***** ***** : Do you have a multimeter?
JACUSTOMER-h3ez04u4- :

yes, i have a multimeter

***** ***** : Can you check voltage in and out of the APS when not working, but you should hear it click?
JACUSTOMER-h3ez04u4- :

where is this APs

***** ***** : At the top near the fan, follow the flexible tubes from the fan
***** ***** :

I hope you got this sorted

***** ***** :

I have heard nothing back from you so I assume you are working now.

***** ***** :

If you need anything else from me just let me know