Potterton Profile Problem

The message from geoff contains these words:

Just an afterthought.

About 4 inches from the end of the flue there is a chevron shaped hole between the inlet and the exhaust about one square inch in area, presumably where the condensate had managed to pool. Is this likely to have any effect?

In message , Roger writes

Huh! The map overlay puts an access roadway cutting diagonally across one of my fields.

If they got this stuff from O.S. you have to wonder what was being mooted at the time.

regards

In message , Roger writes

A question for Monday ...

The message from Tim Lamb contains these words:

Just to make another point about Marley there are several square miles of it and I am right on the boundary so Google Earth haven't got it entirely right.

A nonexistent road rather than just a misplaced road?

In my experience the OS is almost always expensive and out of date. They do however incorporate deliberate errors to catch copyright thieves so it is possible. It should have been cheaper for Google to source their road maps from one of the road map specialists but they don't always get it right. My in-car sat-nav has several times tried to take me down tracks I would not consider unless driving a tractor.

In message , Roger writes

Yes.

It is likely that alternative routes to reach a prospective tip site would have been under discussion around 1990. The Google photo is perhaps later as it shows the route that was agreed and begun.

We purchased the land as sitting tenants so were not party to any discussions with highway road planners.

Yes again.

Byways, strictly BOATS are included in sat nav info. Legally there is a right to pass with a vehicle.

regards

The problem has not been resolved.

The basic problem is that at certain times the boiler refuses to fire continuously for any length of time. Typically it is at start-up. After the pilot flame lights the main burner will fire for a period of maybe

The pressure switch, ignition lead and ignition module have all been replaced without significant changes.

During the extended course of the investigation I noticed that although I could hear the ignition sparking I couldn't at times see it so the whole pilot and electrode assembly has now been changed. There is now a possible explanation for the hidden spark. With the new assembly I can actually see that at times the spark prefers the larger gap between the pilot flame shroud to the side of the electrode to the proper spark gap at the end of the electrode.

The other difference is that with the boiler casing on and viewing through the little porthole I can now actually see at least part of the pilot flame when the main burner is firing. Previously the pilot flame was masked by the main burner in the background.

Last night I found a major difference between the way in which the boiler operated with or without the casing on. With the casing off the pilot fame started with something of a roar and with the flame foot nowhere near the jet. Up to more than a second could elapse before the pilot flame became normal and during this time the ignition continued to spark. Once the main burner fired the boiler functioned normally. With the casing back on the pilot flame lit normally but the main burner went into misbehave mode. Again might just be coincidence but if so a consistent coincidence IYSWIM.

I have at long last bought an el cheapo U tube manometer. According to that the burner pressure is a fraction over 15 mb (perhaps 15.2 or 15.3) while according to the book it should be 14.9. The meter reading was about 24 mb without usage and about 20.5 when the boiler was on but with the boiler kicking in and out it was difficult to get a steady reading.

The reason I have been quiet on this for so long is that I have been picking Geoff's brains by e-mail (for which many thanks Geoff) but I think it is about time I gave him a rest.

Being at long last able to see the pilot flame while the boiler is misbehaving I can see that that flame is not consistent. The flame foot keeps moving away from the jet and at times even seems to extend past the the end of the pilot shroud. This may well be the trigger for boiler malfunction.

About the only think of note I haven't replaced is the gas valve and that as much because of a reluctance to mess with gas soundness as for any other reason but before I do take that step please has anyone any further views on this seemingly intractable problem.

There a pilot flame adjustment screw on the gas valve see the book to find the exact location. Although the book says that the pilot needs no adjustment it looks like it might just need it in this case. Especially try to make sure the setting lights reliably, reliably lights the main burner and never lifts off.

Never lifts off ??

Ha

ROger - it might be worth forwarding some of our email correspondence to Ed

Ed - there are several problems - spark tracking along the ceramic, flame lift off, possible recirculation of POC

The message from geoff contains these words:

OK with you Ed?

The tracking may have been on the ceramic before I changed the pilot assembly but currently the misplaced spark is from the metal shroud of the pilot flame to the metal stem of the electrode rather than across the smaller gap from the tip of the electrode to the earthing strip. Given that these two elements are part of the same metal assembly I can't understand why that should be. I will have the assembly out again later today and see if using the new jet and electrode in the old frame makes any difference.

What I can't get out of the back of my mind is that with the main burner flame playing up before the main gas valve switches off there has to be something wrong with the gas valve itself rather than the control system outwith the valve.

I didn't notice any fumes being expelled into the room when the boiler case was off but if I can find the spare gaskets I will take the fan out and check that the exhaust is clear downstream of the fan.

The message from Ed Sirett contains these words:

My boiler is fitted with the Honeywell valve. The destructions I have only document the main burner pressure adjustment which is a tiny screw set in the face of the valve casing midway along the bottom edge.

There is also a similar sized screw in a little turret at the bottom left hand corner of the valve which is the pilot flame side. Doesn't seem to want to turn though, at least not easily.

I think you'll find that's a pressure test point: you loosen the screw and stick your manometer tube onto the turret bit.

The message from John Stumbles contains these words:

There are not a problem. I eventually fitted a neon from the NO on the pressure switch to neutral and the switch definitely stays on while the boiler malfunctions. I ran it that way for several days and there was never any suggestion the pressure switch wasn't working as it should.

The message from John Stumbles contains these words:

That makes sense. Presumably needed to adjust the pilot flame.

There is another possible adjustment screw near the top edge but that is more than twice the size of the main burner one.

Much of this morning I spent cleaning the heat exchanger. More muck in there than I expected.

Boiler currently back on to warm the house up again. Wind is relatively light and the boiler is only occasionally misbehaving.

The view through the observation porthole is not very good but I remain convinced I can see the foot of the pilot flame oscillating between the jet and the end of the pilot flame shroud.

Not had time as yet to mess with the pilot flame assembly again.

OK I've been out of the loop on this one. The (flame) lift off I'm referring to is when the pilot flame loses contact with the pilot assembly. It might also accompanied by a small roaring sound (which you probably can't hear inside the casing over the sound of the fan).

What is the gas pressure from the meter at the boiler inlet? Does any similar flame lift happen on the gas rings (if you have them)?.

I don't think there can be any APS problems as you would not even get any a pilot flame.

The message from Ed Sirett contains these words:

I am beginning to forget what I have written on here but while the the casing off and the main gas valve lead disconnected I have experienced a roaring from the pilot flame for a period from just an instant to over a second. During this time the flame foot was hovering around the end of the shroud mark and the ignition still sparking but with the casing back on I didn't get this effect and I have failed to recreate the same situation later.

With the old pilot assembly I just couldn't make out the pilot flame while the main burner was firing but with the new pilot assembly I can see some of the flame. I believe what I see is the flame foot moving from the jet to about the end of the flame shroud and back quite rapidly with turn-off coming when it strays further and the main burner flame hesitating when it doesn't but I can't be certain. It could be that the width of flame is shrinking out of my sight rather than the base of the flame disappearing.

According to my recently bought el cheapo manometer the pressure at the meter is a touch over 20 mb, perhaps 20.4 or 20.5 but I don't think there is a pressure point at the boiler end to check if to see if any different there unless it is the point I initially thought might have been the pilot light adjuster.

Unfortunately the kitchen is dismantled at the moment and the hob and oven disconnected.

Been very windy here recently and there is a slight smell of fumes in the kitchen but perhaps not unsurprising with gusts of 70 mph. Perhaps I should take up smoking again so I can puff smoke round the casing to see if that shows if there is a leak. No feeling of a draft anywhere round the casing seal and a soap bubble test down the two long sides was negative.

The message from Roger contains these words:

As might be expected said point is the requisite test point.

Pressure when no usage a bit variable but always in the range 24 - 26 mb. When the main burner is firing the pressure drops to a touch over 18 mb, perhaps 18.2. (I don't have the scale quite centred so that is 17.8

- 18.4 by my observation).

From what I recall has been said in the past that is an acceptable pressure drop. There is about 9 feet of 15mm copper and 3 elbows between the boiler and the short 22mm feed from the meter but it is no longer than when it used to feed my floor standing boiler back in the 80s.

ISTM that upgrading the feed to 22mm might make the matter worse if the pilot light is getting too much gas so do I mess around trying to adjust the pilot flame (assuming that the other screw I found is the adjustment) or go the whole hog and replace the gas valve as well? With the boiler casing off, which is how I get a good view of the pilot flame the flame is a close approximation to the illustration in the destructions. Perhaps marginally larger but not by very much.

I suppose if I turn the pilot flame down too much the boiler will never light and if I mess with it and can't get it back to where it should be it might mean a new gas valve anyway. Perhaps I should leave that till Monday.

In article , geoff writes

You're right. "Cracked joints" describes them better, though I think any electronics repairman would also recognise them as dry joints.

In message , Mike Tomlinson writes

But it's like "rising to a crescendo" (last heard this morning on CountryFile) you know what she meant, but it's just wrong