Hi there,

Yes it's an old boiler, but there's not money to change it or even call anyone out. I'm on the verge of bankruptcy, d/c notices etc... :(

I was up all last night, and noticed it was very cold, turned out the radiators were cold etc although the CH showed on. I wound the thermostat down then back up, it clicked and all worked again, and I saw the flame through the little window (this is the pilot) and the radiators started heating.

A few hours later, it seemed cold again, and it had all gone off. The thermostat trick didn't work this time though...

I have gas to the premises, all working fine (eg: cooker).

I found this answer to a similar query online:

"If that doesn't solve it you are really down to checking the gas valve, and this is legally the domain of the CORGI registered gas fitter. There are two solenoid coils on it (there are also two makes of gas valve!), one of them switches on the pilot supply just before the sparking starts. Switch the boiler off, then wait 20 secs. Switch it back on and LISTEN. The fan will start whirring, and after about 10 seconds the pressure switch will operate with a quiet click. Immediately you should hear a more metallic clunk as the pilot solenoid energises, but I suspect you won't if it's broken!
If it is the gas valve you WILL need a CORGI reg'd fitter to fit it, look in yellow pages for a full page CORGI ad in the central htg section."

Now I *do get the whirring (fan?), I get the 10 second delay (12 by my count) and I get the 1st click and 2nd.

So this means it's not the gas valve? What could it be?

I've jiggled all the cables, and also moved around the two clear plastic tubes (pressure sensing tubes?)

Another poster said he had cleaned his out - they don't seem obstructed, but is it safe to pull them off and clean?

Any ideas anyone? I'm flat broke (actually much worse than that) unemployed, and it's two weeks before my next giro and even then there's never money left.

Any advice as to anything I can do myself (I'm handy, but don't know plumbing/CH) would be really gratefully received!

Anyway - thanks a lot in advance.

Jonathan

Jonathan, March 2009

*shameless bump* Sorry!

Jonathan, March 2009

Thank you both for all for the info!

If these were obsolete in 1983, then it looks like it was put in as an obsolete device - that's the year the house was built. It was the show home for the estate, and there are a few things that have been commented on as poor, or older than the rest of the estate (small bore pipes entering the radiators, asbestos ceilings etc).

That said, it's a bit noisy, but has otherwise served well considering it's 25+ years old.

To clarify, yes, I am the home owner (barely atm! lol), it's not a business, nor am I a landlord. My father was an electronics engineeer, and I'm reasonably happy with basic electrical stuff, and have done housewiring etc.

Well it does appear to be intermittent, rather than having failed completely. I was going to refute that, and say it had flat failed but then I got it on again. It ran for a few hours and died sometime whilst I was out this evening.

No rhyme or reason why that I can fathom, but the problem definitely appears to be lighting that pilot light.

I've blown and sucked on both pressure tubes, banged everything with a wooden spoon, wriggled wires etc. I've also pulled of the spade connectors and reattached etc, it's a bit grimy, but nothing is corroded, and good metal to metal contacts. All to no avail. It doesn't seem to be the mercury switch (as I understand it) since the pilot isn't coming on at all, not failing to heat it sufficiently.

There is some kind of relay (that I think was a replacement from work done 3 years ago ish) with a circular set of pins that plugs into a distinctive socket - a Schrack MT326230. This produces one of the clicks, and also seems to spark on activation sometimes unless my eyes are playing tricks. It gets very hot, even if the gas is not lighting - I'm guessing this is normal though. I've taken it off, cleaned the contacts, rattled etc .. just in case.

There is a labelled 'ignition' unit there - I've checked the wires, but it's otherwise a sealed black box. Is the pilot failing to light, as simple as a dodgy ignition switch, or are there other possibilities?

Incidentally I keep hearing of the 16/22's 'widowmaker' reputation. anyone know why? Is it on the electrical or gas side? Or just prone to explode? lol

At the moment everything I have done is in the basic electrics when you remove the access panel at the bottom. I haven't touched the big white casing over the main area - is that safe to remove?

Jonathan, March 2009

Some of the older netaheat range had a mercury vapour type valve fitted.It could be that part which is faulty.Check the pilot is big enough to warm the phial.Getting a spare part for that is virtually impossible now and even if you could you are looking at biggish money.Unfortunately Jonathan you are looking at a boiler which is nigh on obsolete unfortunately.

Tony S, March 2009

Potterton International Neataheat Electronic 16/22e

Last made 1983 - spares will be difficult to find I suspect.

Peccavi, March 2009

Another addendum... (sorry, I'm just working through possibilities as I think of things I can check).

Possibly related to the whiff of gas in the flue - according to the meter, gas *is* being used when the boiler is on. When I turn the boiler off, gas usage is zero.

Now to the best of my knowledge the hob uses gas (and is obviously off) but everything else (ie: heating and water) should go through that boiler, so it can be the only thing consuming gas, right?

I would have assumed with no flame lit that some cut-off would (should!) stop any gas entering the system right?

Jonathan, March 2009

And if you suspect a poor electrical connection tap around a bit with a wooden spoon - it's unlikely you'll break anything.

Hope the finances improve.

Peccavi, March 2009

Jonathan, lovely as it is to read the personal annecdotes they do not help - reading between your many lines the trouble statement is...

Potterton 16/22 - intermittently fails to light main burner - fan runs ok.

The sequence of events following a call for heat is:

Fan runs
Pressure switch detects fan running and signals control PCB
PCB opens pilot valve and makes spark to light flame
(you should be able to see the pilot flame through the little window)
Heat sensor detects pilot flame alight and signals PCB
Control PCB opens main gas valve - pilot ignites gas
(you can see and hear the main burner flame when it starts)

If the pilot is not lighting sometimes it suggests the fault lies in the Pressure Switch area - Fan not running fast enough - Poor air seals - Blocked or split tubes - Poor electrical connection - Poor air pipe connection - Defective switch - Switch working OK but PCB not recognising signal from switch.

On the subject of DIY repairs - unless it's rented property and you are the landlord - you may attempt to repair the boiler yourself it is not illegal. It is illegal to accept payment for working on Gas if you're not properly Qualified/Certified. Your house insurance may not pay out, however, if you blow the street up and you could kill yourself - but it's not illegal. Your bigest risk of course is if you interrupt the gas lines. Corgi engineers wil crow on about "breaking the room seal on the boiler" but if the seal is bad the pressure switch will not make.

People often suspect the control boards of having bad joints and this does happen but not as often as supposed - a digital photo' before dismantling any wires will help your confidence on reassembly. Heres a link to a similar problem with a different Potterton boiler...

http://kaijaks.co.uk/blog/nick/2008/02/10/dodgy-old-boiler

Good luck...take care...

Peccavi, March 2009

Another addendum... (sorry, I'm just working through possibilities as I think of things I can check).

Possibly related to the whiff of gas in the flue - according to the meter, gas *is* being used when the boiler is on. When I turn the boiler off, gas usage is zero.

Now to the best of my knowledge the hob uses gas (and is obviously off) but everything else (ie: heating and water) should go through that boiler, so it can be the only thing consuming gas, right?

I would have assumed with no flame lit that some cut-off would (should!) stop any gas entering the system right?

Jonathan, March 2009

I just realised that mind going faster than fingers I omitted something key from the original description!

the first time I 'rebooted' the system last night, the flame came straight on (I assume this is the pilot?), whereas now it never comes on.

This is obviously the problem, but what is causing it is what I'm looking for. If anyone does have any idea, then any ideas on component cost or whether it's a big fix/little fix etc would be appreciated... (I need to know whether to rob a big bank or just a small one! lol)

Jonathan, March 2009

Some additional info...

Some posts have talked about obstructed flues. The flue is nowhere near any vegetation or anything, but I just got up a ladder to peer in, and it looks clean and fine. Air is blowing out of it (presumably from the fan?) but there is a slight gassy smell to the air blown out - is that normal or a clue?

Jonathan, March 2009