Central Heating Problem

opo

Hi folks.

I have a 1995 firebird popular central heating boiler.

It fires perfectly for about 7 seconds and cuts out.

Plenty of kero and no feed problems. Have changed the nozzle, the photocell and reset the electrodes.

Whats left?

Am I into the control box??

Help please!

rooferPete

Hi,

Any chance the air to fuel mix has been interfered with ? too much air could starve the boiler and too much fuel could flood the boiler.

Is there black smoke coming out of the flue after it has fired even a few times ?

Have you checked the thermostat ?

.

Lex Luthor

opo wrote:

Hi folks.

I have a 1995 firebird popular central heating boiler.

It fires perfectly for about 7 seconds and cuts out.

Plenty of kero and no feed problems. Have changed the nozzle, the photocell and reset the electrodes.

Whats left?

Am I into the control box??

Help please!

So have you definatley confirmed there is a flame ?
Its a bit dangerous but try this. Take out the burner but hold the front bit away from yourself. Switch on and for the first 6-7 secs you should see the sparks across the electrodes. If they are good, then after the 7 seconds the burner will want to fire. It does this by letting the oil into the nozzle section and gets ignited by the spark across the electrodes. When this happens you'll get the burst of a flame about 10 inches. If the flame appears, then you have ruled out the pump/motor. Then you are probably looking at the control box as you've eliminated the photocell. If you get no flame, then it could be either the motor, pump, motor to pump coupling or the coil that operates on the pump.

I'd tend to check the coupling first. I've replaced 2 on mine. Basically, when the motor turns, it is coupled to the pump. This coupling are normally plastioc and wear away. Therefore the pump wont turn and force the fuel into the burner.

opo

Firstly thanks for replies,

Lex, I can confirm a flame as I took the unit out (that was fun!)

At this point I might add, there is no delay. Once I hit the reset, it fires instantly. Previously, there was a delay before firiing

As you say, I may be into the control box but I was reluctant to do this before ruling out thermostat etc as per rooferPete's suggestion.

Can you folks give me some guidance on how to do this?

lomb

Sounds like the water pump is gone to me, and its cutting out as a safety as its overheating.

most common things are most common...

give the water pump a bash with a blunt object or rotate it by putting a spanner on its side into the knurl and turn it, that will free it to work for a couple of days till u replace it.

opo

Thanks lomb, but water pump is fine.

Lex Luthor

opo, which reset button are you talking about?

There are 2 on mine.

One for an overtemp caused when the thermostat level is breached and one on the burner called lock-out.

If its the lockout button, it is related to flame not being seen by photocell and normally burner related. You could be looking at control box. At this stage if it is, it might be cheaper to replace the burner.

In the boiler, there will normally be the controllable thermostat and an over temp stat. If the controllable one fails, you have the overtemp as a precaution, normally with a setpoint of about 100-100deg C. There is normally a reset button for this if it is tripped in the control section of the boiler.

davidoco

before you go and change the control box
remember that the fan has an axle that runs the oil pump (do check the coupling as mentioned)
the oil pump runs from the moment the fan starts
the electrodes fire immediately
so in normal operation the reason there is no flame is because there is a solenoid valve attached to a round bar that comes out of the pump which delays the flow of oil, you need to check the wiring carefully on it for damage, remove it and clean it or replace it (less than 20 euro). I’ve seen frayed wires on them which activates the solenoid too early.

This IMO is the reason you have an immediate flame but I can’t see how it shuts off again after x seconds unless the solenoid closes again for whatever reason.

Lex Luthor

its strange that you have an immediate flame, as like Dave said you will only get the flame when the coil energises and opens up the fuel through the pump to the nozzle.

This coil won't energize until it gets a signal from teh control unit which is normally after 7 seconds. It still shouldn't make any difference as to why it cuts out though.

The motor runs from switch on, which spins the pump through the coupling.

It only goes to lockout when the photocell sees no flame. He has a flame so I'm beginning to think its the control box.

You could change out the coil as they are relatively cheap, but I dunno if it will fix your problem.

How big is the flame/colour?

opo

Just to knock out one or two variables, I am referring to the lockout button with the bi-metal strip on the burner. I tried reseting the temp control but suspect it was not tripped.

The flame is bright orange one and about 6 inches in lenght.

Gonna see of I can find the solenoid.

Lex Luthor

opo wrote:

Just to knock out one or two variables, I am referring to the lockout button with the bi-metal strip on the burner. I tried reseting the temp control but suspect it was not tripped.

The flame is bright orange one and about 6 inches in lenght.

Gonna see of I can find the solenoid.

do you know where to locate the coil?

It'll be attached to the pump and you'll have 2 wires connected into it

JamesM

opo wrote:

Hi folks.

I have a 1995 firebird popular central heating boiler.

It fires perfectly for about 7 seconds and cuts out.

Plenty of kero and no feed problems. Have changed the nozzle, the photocell and reset the electrodes.

Whats left?

Am I into the control box??

Help please!

What make burner ?

opo

Just to close and hopefully for others sake,

Changed the control box (landis & Gyr) - failed to solve the problem, thankfully, I was given a refund.

Back to square one, I tried a setting on the pump. It's a Suntec pump with an allen key which I wound in. Fired it up and it's working like a hero since!

No idea what this setting does but I hope to find out.

Thanks for the help guys!

davidoco

opo wrote:

Back to square one, I tried a setting on the pump. It's a Suntec pump with an allen key which I wound in. Fired it up and it's working like a hero since!

That’s brilliant, the bypass plug might have been loose and letting in air and air locking the pump. It’s too cold to go out and try this myself just to prove it.

opo

davidoco wrote:

That’s brilliant, the bypass plug might have been loose and letting in air and air locking the pump. It’s too cold to go out and try this myself just to prove it.

As a matter of curiousity, any idea what this plug is for?

davidoco

bypass on oil pumps

if your oil tank is lower than your burner or your not getting a flow you can fit a second line (return line) to the tank in this port and get the oil pumped from the tank

Lex Luthor

opo wrote:

As a matter of curiousity, any idea what this plug is for?

its for the oil pressure setting on the pump

JamesM

opo wrote:

Just to close and hopefully for others sake,

Changed the control box (landis & Gyr) - failed to solve the problem, thankfully, I was given a refund.

Back to square one, I tried a setting on the pump. It's a Suntec pump with an allen key which I wound in. Fired it up and it's working like a hero since!

No idea what this setting does but I hope to find out.

Thanks for the help guys!

The allen screw is for the oil pressure. You should not wind it in fully. With kero, it should be at least 3 turns (probably more) back from that position. Are you sure that you don't have black smoke with that much oil pressure ?
You may have a dodgy nozzle - extra oil pressure can compensate, but maybe you should change the nozzle.
The reason the flame was coming on straight away was because you were pushing the button too soon after it had locked out. Is the photocell clean and facing the flame ?

Jim

davidoco

We should get opo to check the model of that sunvic oil pump. The pressure regulator that the previous two guys mentioned is usually adjusted using a flat head screwdriver and the allen key is used for the bypass plug.

JamesM

If the bypass plug was loose, there would have been oil all over the place. The only screw which can be "wound in" is the oil pressure.

Jim.

opo

Photo cell is new. The nozzle is also new.

The burner did not start because of premature pressing of the reset.

Even when left it off for days, it would do what I said it did.

I have no black smoke.

As I cannot rule out the allen key bolt being oil pressure, I have wound it off three turns in case.

I suspect this is oil pressure as I cannot conceive how it would become loose if it was locked down.

A bolt on the side of the pump looks like a good candidate for a bypass.

Everything is still working fine.

For what its worth, I had arranged for a "expert" to look at it in my coldest hour, but this being Ireland, the b*****d never turned up, nor rang to explain.

My wife spent all day at home waiting.

As stated, I am closing this post to hopefully help others caught in this trap.

Again, thanks for input.

Hellrazer

It does sound like an oil pump problem.

Same problem here last year.Firing away and then cutting out.I dismantled the entire burner,replaced nozzle,filters, control box and still the same problem.Increased the pressure on the oil pump and it worked for about 6 months.

New oil pump was €180.00.
A new Lamborghini 90,000 btu burner(uses all riello parts) was only €220 incl vat. from Dublin Providers in Inchicore.

Bought that(came preset for Kerosene) and havent looked back since.
Economy wise Im saving 50% on what my old burner was using.Obviously the increased oil pressure and fecked oil pump was making the burner use more oil than it should have.