Oil fired boilers

[Graham Harrison]

Our oil fired boiler locks out far too frequently (at least once a week on average - can come in bursts of 2-3 per day for a couple of days).

Engineer comes, changes various components, adjusts fuel mixture etc. etc. but the problem recurs. (I'm beginning to think that with all the components that have been changed it's turning into "Triggers broom"!)

Digging around on the internet I've come across products like HYDRA VULCAN Heating oil additive

(other sources and makes are available)

The tank was installed about 15 Ayers ago when we first moved here. The pre-existing tank had a manufacturing fault and we got a reasonable deal on the replacement. Not having any knowledge of oil rates of use I just got the same size (about 2300 litres). We've never used more than 50% when it gets topped up (and yes, maybe I should go off regular top ups but I am where I am). I believe we could easily go the best part of 18 months without refuelling.

The question is are these products any good? Perhaps, more importantly, are they bad? I'm thinking of doing one treatment just to find out unless someone here knows better.

[Theo]

I have no experience with such products, but I would want to know *why* the boiler is locking out.

For an analogy, the lockout is a bit like the 'check engine' light on your car. Adding something to the fuel is unlikely to solve a problem like a faulty coil pack which stops a cylinder firing. It might marginally change the way the fuel burns which might affect efficiency or power, but if the car has decided something is wrong a bit of additive in the fuel is not going to fix it.

Lockouts suggest that something is out of ordinary range: not a good flame (which could be related to fuel supply, air supply, mixture or ignition problems) or maybe temperature problems (overheating, lack of water flow, problems with thermocouples). The actual control box is usually relatively simple, but a bad input can cause things to go awry.

It sounds like you need a proper diagnosis of why the fault occurs, and a technician who is just randomly swapping parts is not doing that. Really you want something to log what happens during a lockout event (does the spark voltage look good, is there a good flame signal from the photocell, etc) which would tell you what the real problem is.

Theo

[Andy Burns]

wind related?

[The Natural Philosopher]

That is the usual case when mine pops

I should have built a chimney instead of a balanced flue

[Andrew]

biofuel growing bugs ?

[Martin Brown]

I live in a very windy spot and mine only really locks out for wind when it is in a particular direction and strong gusting to 50+ mph. A couple of times each winter this may happen but no more than that.

If it is locking out more often than that then diagnosis depends on exactly when it locks out and why. Over the years we have probably had most of the things that can go wrong including the control board.

Most common failure is sooting up of the optical flame sensor so that the unit shuts down because it thinks there is no flame (or there really is no flame). It is easy enough to clean and put back as DIY.

Another which causes lockouts almost every morning is a very slow leak on the oil feed solenoid so that there is too much kerosene in the burner when it first starts with a big sooty flame. There may even be drips of kerosene inside the bottom of the case. After a reset it will apparently work fine all day only to fail again the following morning.

The last one is much less benign. If the exhaust pipe for the hot gasses is beginning to fail and leaking somewhere then that can also cause inexplicable frequent lockouts as the flue isn't balanced. Inspect it carefully for signs of corrosion and/or soot on the outside.

Keep a log of when and how it fails and the wind direction and speed. It might just be wind related - it has been very windy this week.

It matters whether it locks out after a few hours running OK or at start of the day or only when there is a howling SW gale.

[Tim+]

Interesting. I wonder where your boiler would get it?s air from then?

Tim

[The Natural Philosopher]

separate intake of course

[John J]

Don't waste your money on snake oil. Find out why the boiler is locking out and fix it. Make and model of boiler plus which variant of burner it uses would help. Also is the fuel supply clean and dry? Water/condensation in the fuel tank can cause problems as can clogged fuel filters. Firestop valves or other fuel shut off valves can create restrictions as can kinks in fuel pipes. Drops of water in fuel pipes can form ice plugs in the pipe. If fuel is not a problem is the fuel pump and it's solenoid ok? Odd faults can occur with pump solenoids which only show up when the coil warms up some of the danfoss models were known for this. Is the combustion chamber clear? I've had carbon build up in the flame path which gets hot, glows and the photocell thinks there's a flame present when it shouldn't be so the burner trips on false light lockout. Lots of other problems it could be but those are a start.

[Max Demian]

From the room?

(I used to live in a bedsitter with a gas fire; the higher I turned it up the more cold air came in under the door, so (somewhat) defeating the purpose.)

[Tim+]

Not a balanced flue then. My point being you can?t just change a balance flue boiler to using a chimney without making major changes to the boiler.

Tim

[The Natural Philosopher]

IRC my balance fule boiler could be fitted with either a balanced flue or a device that sucked air down one tub and pushed the exhaust up a chimney

i.e. the balanced flue was a bolt on to the boiler. Not integral

[Graeme]

In message [e-mail], Graham Harrison [e-mail] writes

Just read this thread. Sorry.

We have a Worcester oil fired boiled and had exactly the same problem. Cutting a very long story short, a young-ish guy turned up, and couldn't find anything wrong. Frustrated but not wanting to admit defeat, he eventually phoned an old timer who said check the fan carefully. Sure enough, he dismantled that and found that a plastic or nylon gear (I think) on the spindle had cracked just enough that it gripped the spindle well enough most of the time, but not all of the time, hence the lockouts. Changed that and problem cured.

[John J]

The motor shaft of many oil burners has a "flat" which is located under the flexi-drive connector. It's not uncommon for the plastic drive dog on the end of the flexy-drive to become worn and provide unreliable drive to the oil pump. It's not normally something that comes and goes intermittently so I wouldn't discount your theory but it's rarely found as an intermittent fault. Riello burners used a plastic drive dog which also failed from time to time in a similar manner. A lot of early model low level flue oil boilers were susceptible to adverse wind conditions whereby at the instant of shut off the cloud of hot combustion products were blown backwards from the combustion chamber into the burner and cooked the photocell, leading to unreliable operation. Frequently this also damaged the ignition electrodes while at the same time causing a stink in the house. Later models employed a fan run-on timer to purge the combustion chamber and overcome the problem.