Potterton Combi 24/28/33 not firing for central heating

[MrShed]

Hi all,

My boiler, 2 years old, seems to be playing up slightly (only bought the house with it in 2 weeks ago!).

Basically, when I turn the thermostat right up, the therm clicks, and the boiler lights up beside the central heating symbol.

However, the flame light doesnt light (at all, not even for a few seconds initially). Needless to say, no rads get hot.

Strangely though, hot water works fine. Also, I can "force" the heating on by turning the heating on, then running a hot tap - this fires the burner, and then water begins to circulate to the rads.

Any ideas?

Cheers!

 

[powell30]

which is it....24,28,or 33???!!

And it's a diverter issue. You need to get is changed.

 

[MrShed]

I dont know - will check!

Until I can get it changed, is it OK/safe/non damaging causing just to force the CH on by turning on the tap?

 

[powell30]

Yes.....but what a waste of water.......i assume your not on a meter!

It's not that cold yet. Order it tomorrow, with you wednesday. 1 hour to fit. Assuming you have the knowledge and MI's

 

[MrShed]

Well no thats the funny thing.

I only need to put the tap on until the boiler fires.

then, when I turn it off, the boiler stays on until temperature reached for the heating!

Still a diverter issue you think?

PS - its a 28

PPS - I havent got the knowledge, will need to get someone to do it!!!

 

[MrShed]

Bump?

 

[MrShed]

Follow up.

Bloke came today, and apparently was nothing but an air lock / air bubble in the boiler....

He looked at it for 5 minutes and fixed it.

However, what a surprise - got home tonight, and erroring with E119 - which is to do with the water pressure valve!

Apparently means that system is below 0.5 bar, even though the gauge says 1 bar - ho hum....

Blokey coming back tomorrow!

 

[Agile]

Follow up.

He looked at it for 5 minutes and fixed it.

Blokey coming back tomorrow!

Thats what can happen if you jump to conclusions and dont stay a few minutes to check its working properly.

Tony

 

[MrShed]

Follow up.

He looked at it for 5 minutes and fixed it.

Blokey coming back tomorrow!

Thats what can happen if you jump to conclusions and dont stay a few minutes to check its working properly.

Tony

To be fair to him, he was there for an hour servicing it afterwards, and it kept working - was only when I got home that it didnt!

 

[Agile]

Boilers have a habit of working normally when we are in front of them and stopping after we leave.

A Ferolli service engineer used to say that after a warrantee repair he had to tip toe out in case the vibrations from his footsteps stopped the boiler working!

I have that problem at a minicab office, twice its working when i go there but stops an hour or two afterwards.

Trouble is they all have a fiddle too! Last time the red light was on and the gas turned off! The red light would not have come on unless the boiler was lit or trying to light!

Tony

 

[rojaca]

1. e119 error code.pressure switches do tend to be a little temperamental and will sometimes need around 1.2bar (yes I know what m.i says) - though do have tendency to block up inside casting of hydraulic block.
2. Htg does often take a lot longer to fire up than dhw as goes through a pre purge phase prior to firing which can be bypassed by sticking into dhw to get to fire and will then go into htg straightway once dhw demand off.
If you have had it firing up htg this way then would be very surprised if airlock in blr. Was wondering if blr had been firing on htg but no circulation to rads hence cutting off on blr stat. Had rads been getting warm when you'd been firing htg using your dhw trickery?
Anyway hope its working okay now

 

[MrShed]

1. e119 error code.pressure switches do tend to be a little temperamental and will sometimes need around 1.2bar (yes I know what m.i says) - though do have tendency to block up inside casting of hydraulic block.
2. Htg does often take a lot longer to fire up than dhw as goes through a pre purge phase prior to firing which can be bypassed by sticking into dhw to get to fire and will then go into htg straightway once dhw demand off.
If you have had it firing up htg this way then would be very surprised if airlock in blr. Was wondering if blr had been firing on htg but no circulation to rads hence cutting off on blr stat. Had rads been getting warm when you'd been firing htg using your dhw trickery?
Anyway hope its working okay now

Hi mate - thanks for your post.

Yes it was exactly as you said. Gas fella came back and said that it was due to temperamental pressure valve - he pressurised it up to 2 and it worked straight away!

The rads did get hot when doing it that way - thats what confused me as well, couldnt quite understand it!

Pleased you said that about the purge - I came back tonight and thought it wasnt working - AGAIN! But, left it a while, and it came on

Next question - pressure fluctuates anywhere between jusdt under 2.5 and about 1.5 during usage, I guess this is normal?

Cheers

 

[rojaca]

pressurising it up to 2 bar when cold is a bit excessive, its certainly reducing the amount of play that your expansion vessels got during htg.
1.Was this the pressure when it (the system) was cold?
2. If it was, was it necessary to fill it to 2 bar to activate the pressure switch.
3. Is the pressure moving slowly between 1.5-2.5 during htg or is it vacillating wildly

 

[MrShed]

1) I think he pressurised it to about 1.8 ish...I was out of the room.
2) Dont think so - dont know for definite though.
3) No - its gradual, the pressure drops or rises suddenly but very slightly when the dhw or htg is first turned on.

 

[rojaca]

1.8's really too high- grey area really as to where you draw line once you say 'sometimes they need a little more than what's stated. Myself I would have been investigating this if it was necessary to pressurize to this extent.
Pressure drops/ moves a little initially owing to positon of pressure gauge ref pump.
Pressure climbing is down to expansion of the water during heating.