Main 24HE combi - No ignition No fan

[hary_j]

I've just replaced a Diverter valve in one of these, as the original problem was Hotwater only worked whilst on CH mode.

Ever since the new diverter valve has gone in the boiler is refusing to fire up, i've checked for all the common symptoms.. Condensate blockages, all electrical connections, flu pipe blockages.

The FLAME FAILURE light came on couple of times then i managed to reset this after like the 20th attempt.

Now the POWER ON light is flashing once every 2 seconds, i've checked the manuals in regards to lights flashing and nothing is available for it specifically, only other lights.

There is no ignition ticking and neither does the fan start to spin, the only thing that i can hear spinning is the pump.

Prior to the Diverter valve change, the boiler fired up first time, every time.

 

[so-solar]

check if you have 240 at the fan terminals, if so then fan is dead! work through it logically, Pump runs, fan does not, therefore the air pressure switch does not make causing the cycle to breakdown here, this is the reason you cannot hear any ignition ticking!

 

[hary_j]

i did check the fan, did not get 240 there what so ever!.. damn! i soo hope its not the PCB

 

[oldplumber]

prehaps its the pressure sensor thats blocked as youve lowered the pressure to change the diverter valve, and if its blocked it cannt sense the increased pressure now you recharged it hence why nothing will initially start the ignition cycle

 

[Billy Bob Bob]

you have got water in the pcb after changing the diverter valve,get the hair drier on it

 

[aggis]

Check that all air is bled out of the boiler as an airlock will not let the pump flow switch won't activate then fan won't work.

 

[hary_j]

prehaps its the pressure sensor thats blocked as youve lowered the pressure to change the diverter valve, and if its blocked it cannt sense the increased pressure now you recharged it hence why nothing will initially start the ignition cycle

Sorry to sound like a noob but where will this be situated?

 

[hary_j]

you have got water in the pcb after changing the diverter valve,get the hair drier on it

I take it you know your Main boilers really well, small triccles did run down but nothing to have endangered it, will have to see on this one

 

[hary_j]

Check that all air is bled out of the boiler as an airlock will not let the pump flow switch won't activate then fan won't work.

The air release is automatic, situated ontop of the pump housing as usual. when the boiler tried to fir i did get air release out from it, but after that nothing..

 

[Billy Bob Bob]

it will be wet,take the pcb out,dry it should be ok,these boilers are prone to this not helped by a ridge in the control box that acts like a gutter

 

[hary_j]

it will be wet,take the pcb out,dry it should be ok,these boilers are prone to this not helped by a ridge in the control box that acts like a gutter

i totally get what u mean, what a horrible design!.. it could possibly be damp but i'll defo get the hair dryer on it

 

[Billy Bob Bob]

hope it sorts it out,have seen this fault many times normally if a heat exchanger o ring fails but changing any water carrying parts can cause this

 

[hary_j]

will keep u updated, cheers fellas!

 

[SafeGasInstall]

Check fusees as well !!!

 

[Billy Bob Bob]

Check fusees as well !!!

there is only one fuse on this boiler,located on the mains in wiring strip pump would not be working if this had failed just for info

 

[hary_j]

*UPDATE*

Tried all the drying techniques and etc, it ended up being the PCB had gone T I T S up!, HIGHLY recommend the PCB is taken out when ever your dealing with Diverter valves in these darn things!

Thanks for the support fellas!

 

[Billy Bob Bob]

if you can get to a wet pcb as soon as its happened you can save it but leave it,corrosion sets in its knackered,but and its a big but they can sometimes be saved by cleaning in distilled water and allow them to dry

 

[metaldust9]

once youve done one or two of these you realise you need a small towel or tea towel underneath them or round were the pcb is for the reason mentioned thats my way anyway then double check before firing the boiler just incase you need the hairdryer

 

[Puddle]

As said you have to be careful with pcb and water penetration however

Why would you replace the diverter valve ?

They just need servicing,take the old one apart,see how it operates and you will see what I mean,will be able to increase your profit

imho

 

[hary_j]

what really amazed me the most was that, it merely was damp.! and no way for one second you'll think you've knackered it..

Dont we all learn after a mistake or two!.. ohh life!!

 

[DerekJB]

Hi Did you get this fixed and what was it? I have just changed diverter and got some water loss when removing the diverter, but i get no ignitition lights what so ever, pump runs fan runs but no lights on, manaul say check terminals at control switch have 230 going in and only 15 coming out? book says check terminals a & b a & 3 and pcb connector A4 4 & 5 I have nothing at 4 and 5 but cant tell which is which with other terminals as I see no reference on their diagram to terminal a, b,&3 any ideas anyone?
cheers

 

[SafeGasInstall]

Pcb change me think

 

[Billy Bob Bob]

Pcb change me think

yep derek i agree you have wet the pcb

 

[DerekJB]

Hi all, yes it was the pcb and i had dried it with the hair dryer, before firing up, but missed the little gully in the facia panel, must have been some residual water there? next time pcb out,

thanks for the replies.

 

[buckley plumb]

I take it you know your Main boilers really well, small triccles did run down but nothing to have endangered it, will have to see on this one

thats all it takes i learnt the hard way covered pull down panel with towel and then 2 plastic bags and selotaped around and it trickled down the sleeving on the loom and blew the pcb.