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Plumberpro
Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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have f28 fault code.changed the pcb but still not firing

Customer Question

have f28 fault code.changed the pcb but still not firing
Submitted: 2 years ago.
Category: Appliance
Expert:  Plumberpro replied 2 years ago.
Plumberpro :

Hi . can you tell me what model of valiant boiler it is? Please

Plumberpro :

Hi . if you changed the PCB then it is most like the ionisation probe . change this ,also called flame rectification probe. When this is at fault it triggers the f28 code. Luckily its not as expensive as the pcb . depending on the model it may come as a group with the ignition probe . p!ease don't forget to rate your answer, thanks .

Plumberpro :

Hi . will be unavailable until 2pm ,thans ,Toby

Customer:

its vailant ecotec pro 24.the boiler goes through the firing sequence.pump ok, fan ok and I can see the spark but no flame.after few atemps it shows fault f28 and subsequently f29.

Customer:

could it be the gas valve as it appears no gas goes beyong the gas valve.

Plumberpro :

No . it will be the flame rectification probe . everyone assumes gas valve but I guarantee it will be the probe

Customer:

how much does the rectification probe cost.is it easy to change

Plumberpro :

Very easy to change . cost from around 30_40 pounds

Customer:

I could see the sparks.after 3 atempts it goes tp fault mode. could it be the gas flow is low due to the boiler location being moved furthe away from the meter in the newly built extention. I am only trying to get to the bottom of this problem as I wasted money on changing a perfectly working pcb.

Plumberpro :

Do you know what size gas pipe is from the Meyer to boiler?

Plumberpro :

Has the boiler been working at all since the moving of it?

Customer:

the pipe is 22 mm but the boiler is almost new.i would say less than 3 yrs old.

Plumberpro :

How many metres from the Meter to the boiler? Also has the boiler been working in the position it is in ?

Customer:

about 20 metres.no it has just been moved to the new position.

Plumberpro :

OK. That's quite a distance give me a few mins to check pipe flow rates

Customer:

bare in mind there is few bends about 10 in total

Plumberpro :

Think you definitely undersized , but was the air removed from the gas pipework before try to light the boiler? The pipe work could still be full of air.

Plumberpro :

Got to pop out for hour .back at 8 pm

Customer:

yes the gas was purged.so I increase to 28mm pipe until at least half way or try changing the flame ptobe?

Plumberpro :

Hi . yes if you do that you'll know for sure you'll be ok

Plumberpro :

I think you should do the gas pipe upgrade , because you will future proof the gas if you ever change to a higher output boiler .if that doesn't solve it then change the probe .

Plumberpro :

Hi . if you are satisfied with your answer would you mind rating me , thanks .

Customer:

if I increase to 28mm half way would be ok.

Plumberpro :

Yes that will give enough for a 31 kW boiler .

Customer:

last question then i will rate u.

Customer:

how do I clear air from the gas pipe.

Plumberpro :

Hi .well that's called purging. The amount to be purged is worked out at Meter size. If u6 Meter then 5 times the capacity , is .35 ftsquared plus the volume of gas in the pipework . however in practice the gas inlet nut on the boiler is cracked open and get someone to open the Meter gas valve . when you smell gas or hear the sound change then turn off gas , tighten gas inlet on boiler.test for leaks with u gauge and leak detector spray on the nut then relight. (This should only be done by someone deemed competent to do so ).

Customer:

thanks u ve been good help

Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience: Heating and hot water heating appliances experienced
Plumberpro and 2 other Appliance Specialists are ready to help you
Expert:  Plumberpro replied 2 years ago.
Thanks for the positive rating

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