Air Pressure fault on Vokera copact 25 he

[mattyp]

Upon servicing this applaince today i noticed that one of the air pressure switch tubes was hanging off the venturi [ tube still attached to the switch] The boiler was working ok , i reconnected the tube and guess what ? the switch wouldnt operate !! The boiler would only work with one hose connected . I was of the understanding that if one of the tubes were not in place the switch would not work [ ive attended many faults with rotten hoses or splits etc ]?! It done the same with the case on or off . I tried to phone vokera but couldnt get through for 20 mins so gave up[ it was 4pm !] . The customer had a spare switch [dont ask why !] that i also tried, this also done the same thing ! Just wondered if any of you gas boys had come across this before ? The venturi is clean and the positive side of the switch is connected to the positive side of the fan , its the negative thats hanging off, ive tried swapping the hoses around etc but still no joy and it is deffo supposed to be on as i looked at the parts diagram that showed both hoses connected ! the heat exchanger is clean and the performance test was low as can be !

 

[mattyp]

Vokera COMPACT !! typo !

 

[rm1]

the light at the front of the boiler can help identify a fault what colour is the light and how fast does it blink check to see if you are getting 24vdc at the grey wires to terminal cn8 5-6 at pcb

 

[mattyp]

Not getting any fault lights ! boiler was working, was just a service !! it only didnt work when i connected the hose back on !!

 

[rm1]

if the hose was not required it would not be there

 

[aggis]

One of the connections of the aps tube to the flue could be partly blocked or the aps is under performing.

 

[mattyp]

The hoses are not blocked , what im trying to say is how comes the boiler is working with the hose being left off !? if its supposed to be on, which im 100 percent sure it is

 

[tamz]

Take the venturi out and wash it.
For future ref don't phone the call centre, phone the glasgow number (you will find it if you look, clue shauna street)

 

[mattyp]

I removed the venturi and washed it in hot water ! Made no difference

 

[Vintyd]

Hi new here, I am having the same problem do you have a fix for this? The boiler would not fire so I took the cover off and checked over using help from this forum. I took the two hoses off the Air Pressure switch and blew into, the long hose worked fine but the small one would not. It is clean and no blockages, I then tried the boiler with the small hose disconnected and the boiler is now working fine...

 

[diamondgas]

You need to check the differential pressure created across the tubes ... Should be greater than 1.1mbar ... If it is then the APS is dodgy... The DP between boiler chamber and positive AP tube must be producing enough diff to open the APS when the tube is not connected!

If it is less than 1.1mbar then you have a restriction in air flow or a dodgy venturi!

 

[Vintyd]

Cheers for the reply, will have to get my mate to have a look he works for Heat in Belfast. Just to add some more info when I have both hoses connected and the cover off the boiler works no problem. When I put the cover back on with the two hoses connected it does not fire up. Does this make any sense?

 

[diamondgas]

Cheers for the reply, will have to get my mate to have a look he works for Heat in Belfast. Just to add some more info when I have both hoses connected and the cover off the boiler works no problem. When I put the cover back on with the two hoses connected it does not fire up. Does this make any sense?

I had one a while back doing the same, changed the APS and it worked ok.... Must admit I didn't check the DP across the tubes! If you're not getting the requires pressure difference then you got to be looking at why and what will effect that? With case off your dramatically increasing the "Air intake" option and ballance of the appliance. If there's any obstruction withing the flue air intake it'll not be registered by the APS until the case front is replaced. IMO

 

[desrob]

a micro speck off dust in venturi will give you same fault.