He can't fix it so I'm suppose to replace my oil boiler. Really?

[fadedspark]

Re: Worcester Greenstar Camray External 12/18 oil boiler.

I have an ongoing problem with the above boiler. When set to work from demand via the timer or when manually switching it on the boiler will not run for any length of time unless the boiler control thermostat on the boiler is turned to max. The lower the control is set the short time it will run then stop. If I turn the control up to max it will run again for a short time then stop, I assume this is the boiler control thermostat shutting the boiler off as if left to cool for a while it will again fire up and run. The boiler itself and the radiators will heat up fully.

Also, about half the times it is supposed to fire up via the timer or the one-hour boost the boiler won’t fire up. It sort of locks out but the lockout light on the burner reset button is not eliminated however pressing the burner reset will start the boiler if the boiler the boiler control thermostat is set high enough.

We had it serviced in August and after testing it was not used again until about three weeks ago. The tank is full of oil, new filled in Sep. I have spoken with the oil company and they say they have no reported problem with that batch of oil.

We had the usual service engineer who services the boiler out to look and after spending some time with it basically giving it another service, fitting another nozzle even though the one fitted in the service hadn’t been used, and fitting a new photocell the problem remains and his conclusion is because of various parts being obsolete due to age, it was installed in 2008 he thinks we need a new boiler. Frankly, I’m not buying that and sent him away.

Being an ex-electrician I have looked at the electric side of things and noted, all the in-house control systems seem to be working and are calling for the boiler to turn on and supply 230V for it to do so.

When the boiler has been switched off by the boiler control stat I have linked out this stat and sometimes it will run and sometimes it it still won’t until it is cooler. I’ve checked the continuity switching of the boiler control stat and it appears to work continuity-wise, as for resistance values I have no idea what is normal values with reference to temp.

I’m going to think it is a control box problem but they are very pricy to just buy on the off chance.

In the summer one radiator was removed, this was done by closing the valves and removing the rad. When it was replaced it was filled gently in the usual manner to remove the air and everything worked fine afterwards and the usual inhibitors topped up via the header tank in the roof space.

I’ve checked around the whole system for leaks and bleed it several times. The boiler has no pressure gauge fitted. I was told by You need a new boiler mate man the pressure was OK. But being an open vented system wrong or right I don’t see pressure being a problem unless due to pump pressure but as said once the system gets running it works fine.

Any advice would be appreciated before I go spending reducing funds on having another person look at it and tell me to buy a new one due to age when I’ve checked and parts are still available.

 

[oldbuffer]

I'm not familiar with oil boilers, but if a gas boiler behaved in a similar way I'd suspect some impediment to circulation causing the boiler to cut out as the return temperature was too high. I other words, the heating / hot water (boiler primary) circuit wasn't able to get rid of the heat fast enough. 1. I'd be looking for:
1.1 Sludge in radiators causing poor flow rates.
1.2. Ditto for pipework.
1.3. A failing circulation pump.
1.4. A blockage in the feed from the F&E tank into the primary circuit.
2. For 1.1 and 1.2 you might try adding some Sentinel X400 (cleaner) to the system and let it circulate for a couple of weeks. Then drain the system and flush through with mains water to try and clear any sludge. I would clean the F&E tank before doing this to avoid potentially washing additional crud into the system.
3. For 1.3 there is no real alternative to replacing the pump. You can try removing the central screw and seeing if the the impellor is rotating properly, but it doesn't give much feel for the pump's power. You could isolate the water to it (should be pump valves before and after), dismantling and cleaning it, but again you won't know directly if it was a problem unless the system starts to work properly.
4. For 1.4 you could try tracking the pipework from F&E tank outlet to the point where feed joins the system with a magnet. If there is attraction at some point there could be well be a blockage / restriction caused by magnetite. No use in the unlikely event you have steel pipework.

 

[fadedspark]

Thanks for that info Oldbuffer, All pipework is copper in my house, I made sure of that. The system was all new in 2008 so it might be time for a flush-out.

I was thinking along the lines of there being nothing wrong with the boiler as it works fine when cool, apart from the intermittent lock-out problem which I think might be unrelated to the cutting out at high temp issue. The boiler itself does seem to get very hot and I think it's the safety systems cutting it out as per normal.

 

[Johntheo5]

If the burner lockout light is not illuminated then its not combustion failure (except the light is "blown") and pressing the reset shouldn't do anything. If the boiler is cutting out on the overtemp stat then it doesn't self reset but another button, (normally under a a plastic cap) has to be pressed but there will be no combustion failure light.
How is the air intake arranged on that boiler, is it taken directly from inside its enclosure or piped in from outside, was any flue gas analysis carried out?.

 

[Exedon]

IHow is the air intake arranged on that boiler, is it taken directly from inside its enclosure or piped in from outside, was any flue gas analysis carried out?.

External boiler so air supply through case
Flue gas analysis certainly should have been done.
Which burner is fitted? Picture would be useful

 

[Johntheo5]

If its like this then check the flexible hose between the air intake and the burner, check outside for any obstruction, temporarily remove the hose from the burner intake, leave the enclosure door open and fire up the boiler.
It also shows (3) a flue overheat stat, possibly this?.

 

[fadedspark]

The air intake is via an external flue in the boiler side casing, I've checked it for blockages.
The guy that came out did meter the flow and CO2, not sure exactly what he did there.

there are two reset buttons under two thermostats, one for flu manual reset and the other for boiler manual reset.
the third thermostat doesn't seem to have a button to press just a plastic cap. son there is a button under that cap? it is on the high-limit thermostat.

 

[fadedspark]

If its like this then check the flexible hose between the air intake and the burner, check outside for any obstruction, temporarily remove the hose from the burner intake, leave the enclosure door open and fire up the boiler.
It also shows (3) a flue overheat stat, possibly this?.

View attachment 320659

it is just like that, so i guess the air intake is via the case. All the hoses look in good condition, clean and not blocked.

 

[fadedspark]

External boiler so air supply through case
Flue gas analysis certainly should have been done.
Which burner is fitted? Picture would be useful

The burner is riello the burner head is LD2XSH 12/18.
What do you need a photo of ?

 

[fadedspark]

If the burner lockout light is not illuminated then its not combustion failure (except the light is "blown") and pressing the reset shouldn't do anything. If the boiler is cutting out on the overtemp stat then it doesn't self reset but another button, (normally under a a plastic cap) has to be pressed but there will be no combustion failure light.
How is the air intake arranged on that boiler, is it taken directly from inside its enclosure or piped in from outside, was any flue gas analysis carried out?.

I've just looked at the bottom of the high-limit thermostat and it is just a solid plastic lump threaded with the retaining nut on. No cap or button. Can this not be reset?

 

[fourtytwo]

As a sadly ex-oil boiler owner myself the symptoms you describe are indicative of no or little water flow.
Have you checked the pump has power to it and sounds normal ?
If there are multiple zone valves, are at least one of them powered ? Try forcing them open manually with the lever.
Something might have gotten air-locked when the radiator was removed and re-fitted ?
I moved house and now pay the gas standing ripoff, oil anytime

 

[fadedspark]

If its like this then check the flexible hose between the air intake and the burner, check outside for any obstruction, temporarily remove the hose from the burner intake, leave the enclosure door open and fire up the boiler.
It also shows (3) a flue overheat stat, possibly this?.

View attachment 320659

If it was an overheating problem would not the boiler overheat reset button (38) need to be reset?
I've never had to touch this button.
The only button I've had to press is the lockout reset button (26) when it has failed to fire up on demand from timer and it hasn't been lit up.

 

[fadedspark]

As a sadly ex-oil boiler owner myself the symptoms you describe are indicative of no or little water flow.
Have you checked the pump has power to it and sounds normal ?
If there are multiple zone valves, are at least one of them powered ? Try forcing them open manually with the lever.
Something might have gotten air-locked when the radiator was removed and re-fitted ?
I moved house and now pay the gas standing ripoff, oil anytime

The pump pumping water around the rads seems to work fine. I can feel it working all rads get hot when it is actually working. I thought it could be an airlock from the rad being off but I've bled every rad and boiler several times and never found no air.

 

[fourtytwo]

The pump pumping water around the rads seems to work fine. I can feel it working all rads get hot when it is actually working. I thought it could be an airlock from the rad being off but I've bled every rad and boiler several times and never found no air.

But when it's not working, is the pump still working and the zone valves open ? maybe one or other or both are intermittent.
Actually as it's intermittent perhaps the boiler stat is intermittent, check across the contacts when it's not working if safe for you to do.

 

[fadedspark]

If it is being caused by a faulty thermostat on the boiler when the problem occurs if I link out each thermostat in turn and get no response does this mean the stat is not the problem?

In my thinking, if I link out each stat and the boiler fires up then the problem is that stat, correct or not?