My ongoing, intermittent Wallstar oil boiler problem AGAIN!

[MM]

Sorry to have to bore you chaps yet again with my woes. The boiler is, as ever, unreliable at starting, frequently going into lockout when the Danfoss timer calls for heating.

Yesterday evening the heating was due to come on at 20:00 so I went out at 19:57, took off the boiler cover and watched the DKO 970 control box closely.

At precisely 20:00 the LED came on and stayed on. No flash code.

There was NO OTHER activity inside the boiler. No sound of the pump, no movement of oil in the supply pipe, no sound of any spark, no clicks, no nothing. The ONLY thing that happened was that the LED came on.

I pressed the reset button and the boiler started.

However, now I am noticing that the boiler is locking out DURING the cycle. This morning at 04:30 am it started okay. The Danfoss timer is timed to come on at 04:30 and go off at 07:30.

But at around 04:50 (yes, I'm not getting much sleep!) I noticed that the rads were going cold again, so I went out and checked and, yes, the LED was ON constant. I pressed the Reset button and it started again.

But just now, at around 06:00 am, the same thing happened. Rads going cold, boiler locked out, LED ON. I've just pressed the Reset button for a second time.

Is perhaps the temperature set too high? What about the knob on the white boiler housing inside the garage? It's turned to MAX.

By the way, the current heating session is for HEATING only.

As a way of explanation, can anyone please clarify the typical start-up process of an oil boiler for me?

I assume that the flame is ignited by means of electrodes, similar to a spark plug?

So I further assume that the electrodes are set to start sparking BEFORE any oil is sprayed into the combustion chamber?

I further assume that if the control box detects no flame AFTER this initial sequence, it goes into lockout mode?

Is this how it proceeds? Please excuse my lack of knowledge. I am a motor fitter by trade, not a heating engineer!

Many thanks to all who respond. I'm at my wits end with this Wallstar.

MM

[harry]

I assume you are talking about a pressure jet oil burner

Normally when a boiler locks out, a red light comes on. Is this the case with you?

A boiler locks out on startup when for some reason the flame fails to establish or if the flame detecting device fails to see the flame. So the cause can be

No/insufficient oil. Polluted oil (water). Low oil/air pressure/faulty pressure switch for measuring them. Worn jet, oil not atomising, hard to ignite. No spark-Faulty transformer, (dirty)sparkplug Faulty sequence controller.

Flame failure device doesn't "see the flame"- faulty/dirty.

Start up sequence is Purge (fan runs for 10-15 seconds, clears any fuel vapours present) Pressure tested (fuel and air) Spark Fuel valve(s) open Flame is established Flame sensor sees flame.

On shut down Fuel is cut off Post purge (fan clears combustion gases)

If these things don't happen/fail for any reason you get a lockout. You need to establish at what point lockout occurs. This gives a clue as to what is faulty.

[MM]

I don't know what type it is. It is a Wallstar 15/20 oil boiler. It has a pump that sucks oil from the tank in the garden. It is approximately eight years old. This is the handbook that came with it:

>Normally when a boiler locks out, a red light comes on. Is this the >case with you? Yes.

There is plenty in the tank.

Engineer used dipstick smeared with special gunge that changes colour if water is present. There is no water.

Engineer has checked the above exhaustively over the past month and cleaned whatever components needed cleaning. New transformer, control box, solenoid and photocell fitted in the last two weeks. The pump was replaced in 2010 because it was diagnosed "noisy".

New photocell fitted (see above).

No fan can be heard to start. There is NO noise of ANY kind when the LED comes on. I have had the boiler cover off and stood in front of it listening intently for any signs of life. Zilch.

Would one hear that sparking?

Ditto?

These would give SOME indication of activity on observation, would they not?

That's the problem. There IS no clue! The LED comes on and stays on. There is no flash (diagnostics) code on the LED. The control box is a DKO970. This is the manual:

yet the Reset button ALWAYS starts the boiler immediately! In fact, that is when I *DO* hear the fan going, whereupon the burner fires up a few seconds later.

When the LED first lights up, it's as if the sequence you describe isn't even starting at all -- as if there is an "OK" box waiting for a click in Windows to acknowledge something!

Like I said, it's a total mystery, both to me and the heating engineer, and I have it on good authority from other residents that this chap knows what he's doing.

A previous correspondent in this ng stated a few weeks ago that this kind of intermittent problem can be damned difficult to fix sometimes.

Thanks for your response!

MM

[Allan Mac]

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Another problem I've seen is a tight spot on the motor bearings. Ie the motor always stops at the same position ( the tight spot) when it comes to restart there is'nt enough oomph available to get it spinning again. Intermittent at first, getting gradually worse.

Allan

[Dave Liquorice]

But is there a big enough hole down the supply pipe? If it's been well below freezing for a while I'd suggest slush in a low point of line, that can stop enough oil getting to the boiler. Has the line been cleaned? By that I mean disconnected at both ends and a wodge of cloth on a wire pulled through in the same direction a few times. Just flushing through with oil won't get suffcient flow to purge water or muck from a low point. BTDTGTTS...

Filters clean, no blocked orfices in filter housing, same with the fire valve? Doesn't take a very big flake of paint or insect carapace to act as a butterfly valve over/in a small hole. Such a little bit can take a while to be drawn to the place where it causes problems then fall away again once the flow stops.

New jet?

So it looks like it is powering up in "lock out". Fairly that state is remembered across complete power downs, that would be the safe thing to do.

Possibly, the noise of the fan can mask it. Should start about 10s after the fan and last about 5s before it decides that there is no flame and locks out. Flame detection turns off the spark.

Doubt it, never heard it on ours, to much other noise. An acoustic probe on the right bit might pick it up.

Or the previous shutdown was a lock out and is remembering that state. As almost everything else has been changed recently I'd be looking at a complete strip down and check for free flow of oil through of every component in the fuel line and all sections of the line itself are clear of muck/water. Any flexible hoses, has that been changed?

As the boiler starts and behaves everytime the lockout is cleared I don't think there is anything fundemental wrong with boiler. It looks as if it's going into lockout at some random/indeterminate period after running for a while. This could be a fault in the shutdown procedure, does the boiler have a permenant live or just a single "call for heat" live? I don't find that very likely TBH.

I suspect fuel starvation hence the full dismantling and checking of the complete fuel line. Sorry about the thoughts being a bit random, sure you can sort 'em out though.

[MM]

it:

>>>>>

manual:

>>> And yet the Reset button ALWAYS starts the boiler immediately! In

Well, my problem DID start intermittently back in June, then got gradually worse until by beginning of October it is happening almost

50% of the time. Since I started *actively* monitoring *all* events from 19 Nov I counted a total of 45 heating cycles when the boiler was supposed to come, stay on for a period from 30 mins to 2.5 hours, then switch off. Of those 45, 26 were successful, 19 were failures (needed reset button).

The boiler had a new pump in 2010, but I suppose the motor is what drives it, and that hasn't been replaced (yet!)

The engineer is going to replace the capacitor today or tomorrow. What does this component do exactly?

MM

[MM]

There IS no fan noise! There is *no* noise of any kind. The LED on the DKO970 comes on. That's all.

When the boiler starts successfully (on its own), the LED does not come on at all. There are a few seconds which elapse since the Danfoss timer triggered its ON event, then the fan starts, then a few seconds later the burner starts and everything is hunky dory.

But it's when the boiler *does not* start, that's when there is NO fan noise, no other noise, no other signs of life -- and then the LED comes on and stays on. It's as if you had an LED wired across a battery through a resistor and simply completed the circuit. The entire boiler is otherwise dead.

Yes, that is how it happens (approximately) when it starts automatically. I do hear the fan noise. I hear it even from outside the garage with the boiler cover in place. Hearing the fan start is always indication to me that the burner itself will fire in the next few seconds, and it *always* does. It's when the fan doesn't start and the LED comes on, that's the mystery.

Dunno about a *complete* strip down, but he has had the whole caboodle in bits at least once. He checked for no water in the tank, but the actual line itself has not been removed/blasted through. Perhaps it should? The distance between the boiler and the tank is approximately

12 metres. The boiler is mounted on/in the outside garage wall, the pump being approximately 190cm above the base of the garage.

The hose has been replaced.

The motor, however, hasn't been changed. Allan Mac just now mentioned a possible problem with a 'tight' spot on the motor bearings.'

I don't understand that last question. Don't have the technical knowledge.

Yes, many thanks, I'll put all of the above points to the heating engineer.

I just did a test start (manual override on the Danfoss) and the boiler started fine. I'll leave it on for 15 minutes, then wait a couple of hours and repeat the test.

MM

[Dave Liquorice]

Enables the motor run. But the motor does run when it gets power after you hit the reset button... It's not getting power as the boiler has entered lock out for some reason.

[Chris Holmes]

Hi MM,

Sorry if i'm stating the obvious, but it sounds like either....

The fan motor isn't getting voltage, or if it is, it's not turning when that voltage is applied, and therefore the Danfoss doesn't get the messge that it's running and goes into lockdown.

These Wallstars SHOULD have both a permenant live connection from the mains (if it's the same as my 13 YO Wallstar, this would mean that the orange power light would be permenantly on I think). And then it would get a "calling for heeat" live from the programmer/thermostat and this is what would start the iginition sequance.

Mine has been wired incorrectly, and doesn't have the permenant live, the ony "issue" I know of with this arrangement is that the orange light only comes on when the boiler is actually running.

It's been irregularly serviced during it's 13 years, and aside of a couple of lockouts has always fired first time.

Be assurred, I have other less relaiable appliances which cause me headaches.

IANAHE

Chris

[Dave Liquorice]

Because it's gone into lock out.

That is to be expected, the time switch ON is probably opening a valve some where, this takes a few seconds, the auxillary switch in the valve then turns the boiler on when the valve is open, the boiler should then start it's ignition sequence of fan on for 10 s or so, spark, ignition, flame detection, run...

Because it's in lock out.

You have that arse about face the LED comes on because the boiler is latched into lock out. The fan won't run in this state until the reset is pushed.

Well as virtually everything else has been changed or looked at there is little else to do, I doubt it's the motor capacitor, if they go the motor just won't run or will be horribly noisey.

I'd get him to throughly check the fuel line from the tank isolation valve, open that with the outlet disconnected to get a good flow into a bucket to flush any debris out of the valve. Then look at and clean every item and pipe. This will require a complete dismantling to check for a bit of crud on say the inlet of the filter. Remember what I said about bits taking a while to be drawn to where they cause a problem and then falling back. Just beacuse the inlet to a device is clear when you look at it doesn't mean there isn't a bit of crud way back down the feed pipe...

Not likely IMHO.

How many wires feed the bolier just live, neutral, and earth or is there an extra wire that becomes live when the time switch is on and any room stats calling for heat?

[Grimly Curmudgeon]

Defective or dirty flame detection photocell is a common cause of your symptom - although, it might be a defective control box.

[MM]

Would a dodgy capacitor have that effect?

MM

[MM]

Assuming you mean the orange neon light on the white-painted boiler housing INside the garage, this only comes on when there's a "call for heat".

I will mention that the house was new in 2004 and until 2010 the boiled behaved 100% correctly year in, year out. Then in Spring of

2010 a faulty/worn pump was diagnosed and replaced and the boiler ran since then until June 2012 when the current intermittent problem started.

As mine does. I'll mention this "permanent live" condition to the engineer when he turns up.

Thanks for the response. Here's hoping we'll eventually get to the bottom of it.

MM

[MM]

So much for Wallstar's diagnostic procedures! What the heck can one read into an LED that just comes on? According to the DKO970 spec sheet, it's supposed to flash in a certain sequence to indicate possible areas of failure. Beats me why the ruddy boiler doesn't have some kind of "engine management system" that could be connected to a PC temporarily and then a log run of all desired values and the actual values.

I don't know about the technical stuff re wiring. Above my head, I'm afraid.

There are no room stats. Each rad is fitted with a fancy Honeywell knob thingy. The ONLY control is the Danfoss timer in the utility room at the back of the garage. (Okay, there IS the round knob on the white-painted boiler casing INside the garage. This has MAX and MIN settings. The boiler handbook recommends MAX for heating and hot water and MIN for hot water only. It's currently turned to MAX.)

I'll put your other points to the engineer in due course. Thanks again.

MM

[Dave Liquorice]

It could if the motor failed to start when told to but as you say it never fails to start when you hit the reset I find that unlikely.

[Dave Liquorice]

Downloads manual that you linked to earlier (should have done that before, sorry). That manual covers several different models/designs but I see that some of them have a "limit" light and associated seperate reset button as well as the "lockout" light with integrated reset button, or the reset button located on the burner control box itself.

Which reset button brings it back to life?

If it's the "limit" one then we have been barking up the wrong tree, try turning the thermostat down a notch or two, this should make the boiler shutdown before it overheats. If this cures the problem then there is another set of potential problems that ought to be looked at and sorted out.

If it's the "lockout" reset one then carry on with what we have been saying this morning.

[Tim+]

Could it be that the timeswitch isn't switching cleanly causing the controller to lock up? The fact that it always fires up properly using the reset button may support this.

Tim

[MM]

This is the button/LED:

If it's the "limit" one then we have been barking up the wrong tree, try

MM

[MM]

Well, that's something else to be mentioned to the engineer. Thanks. I just don't know enough about heating electronics to be able to say, but it sounds entirely reasonable.

Mind you, I'd have thought a Danfoss timer/programmer would last longer that eight years. The model number is CP715:

[Grimly Curmudgeon]

It snips posts, dozy bollocks.