Boiler keeps cutting out

Mahuga

Our boiler (kerosene) had taken to cutting out leaving us with no heating. The oil level is fine and the boiler can be re-started by opening it up and hitting the reset button. It then fires up for a while.

We had a new rad installed a couple of weeks ago and the plumber checked the system for airlocks but found nothing. I still think this may be the cause.

Would an airlock cause the boiler to shut down?

Many thanks.

Royal Seahawk

Sounds like a problem with the circulating pump to me, get that checked.

Micky Dolenz

What reset button are you pressing?

Mahuga

Micky Dolenz wrote: »

What reset button are you pressing?

The reset button in the boiler outside the house. In a little grey box, a small button to depress with a screwdriver.

What? Oh Rly!

There still could be an airlock in the boiler. Open up the boiler (ours uses a screwdriver) and then use a spanner or a vice grips, let the oil out, then tighten back up and hit the reset button.

Micky Dolenz

Sounds like the high limit stat is tripping. So it's either a faulty control stat or pump, as mentioned before.

meercat

agree with the lads
most likely pump problem
you could try turning down the thermostat beside the high limit stat if the pump is not the problem

Bruthal

Try turning the temperature setting of the boiler down a few degrees and see does that stop it happening. If it does not stop ot tripping then it may be airlocked, or not enough water in the system, or pump not running properly or at all.

Bruthal

meercat wrote: »

agree with the lads
most likely pump problem
you could try turning down the thermostat beside the high limit stat if the pump is not the problem

Just seen you already suggested the temp reduction.

Buford T Justice

It could be an airlock at the top of the boiler, or the circulating pump.

Is there an air vent fitted to the top of the boiler?

Its the High limit stat that's tripping out, so poor or no circulation would be the problem imo

Billy Bunting

Is your system a dual fuel heating system ?

Mahuga

robbie7730 wrote: »

Try turning the temperature setting of the boiler down a few degrees and see does that stop it happening. If it does not stop ot tripping then it may be airlocked, or not enough water in the system, or pump not running properly or at all.

Sorry, I'm not so hot on this stuff, where would I turn down the boiler temp setting?

Mahuga

Billy Bunting wrote: »

Is your system a dual fuel heating system ?

No, just kero.

Bruthal

Mahuga wrote: »

Sorry, I'm not so hot on this stuff, where would I turn down the boiler temp setting?

Its beside the high limit stat which has the reset button on it. Like the others have said, because a new rad was added its likely an airlock problem, or maybe the pump, as overheating usually means the water is not flowing properly, Put your hand on the pump and see can you feel it running. But turning the boiler temperature down can be a test to do on it to see does that stop it tripping.

Mahuga

Ok, next to reset button was a rotary dial marked 1-5, it was on three and I turned it down to 2. From what you say though it does sound like an air lock or water is low. In the hot press there is a vertical pipe that terminates with what looks like a bike valve, is this where airlocks would gather? Sorry if my lingo is all wrong!

Bruthal

That is probably the automatic air release if its a sealed system. If the boiler was only set at 3 then its probably a water flow problem alright,

Buford T Justice

Sealed or not, best practice would be to have an automatic air vent sited at the flow from the top of the boiler. If you get an airlock, which I suspect might be the case here, then this would take care of it straight away without any problem

Firstly, Check if the system is open or closed.. If its open, then fine, but if its sealed, take note of where the pressure gauge and the filling valve are.

Go to the boiler and locate the Pressure Relief Valve (PRV) Turn this valve less than half a turn and see what comes out. If air comes out of it, then its an air lock and keep it open until you get a steady flow of water, as it will drain all the air from the boiler.

If you do open it and you get water straight away, then thats not the problem and it could be the pump.

A couple of words of warning though.

DO NOT do this after you have fired the boiler and it has switched itself off, as the steam or the water from the boiler will scald you very badly.

Also, PRV's have a habit of failing if they are used for the wrong purpose and if they're old, so its possible that if you take these steps, that it will leak and continue to do so, and will need replacing. Therefore, OP bear in mind that you do this entirely at you're own risk, and are aware of the possibilities.

IF you have a closed system, then go to the filling loop and top the system up to what it was before, and then fire the boiler.

DoneDL

95% sure Fingers is right. is the boiler level

Bruthal

DoneDL wrote: »

95% sure Fingers is right. is the boiler level

Well just about everyone mentioned pump or air in the system, so he probably is right.

Buford T Justice

robbie7730 wrote: »

Well just about everyone mentioned pump or air in the system, so he probably is right.

Yeah, but not everyone mentioned how to get rid of it though....

Micky Dolenz

Fingers McGee wrote: »

Yeah, but not everyone mentioned how to get rid of it though....

I would be slow to advise a house owner to interfere with a safety device. Go at a PRV at your own peril.

How many times has it happened to you where the thing just won't stop letting by after being disturbed. too much of a risk for me unless it is fairly new.

Bruthal

Micky Dolenz wrote: »

I would be slow to advise a house owner to interfere with a safety device. Go at a PRV at your own peril.

How many times has it happened to you where the thing just won't stop letting by after being disturbed. too much of a risk for me unless it is fairly new.

And it can often let only water out even if the system has a lot of air in it. Its tricky enough for a house owner to sort out air lock problems if they have no experience of it. It could also be a vented system with the header tank not filling or full. There are plenty of problems that can cause it. Air lock, main feed or return pipe blocked with sludge, pump faulty, overheat stat faulty which is why suggesting turning down the boiler temperature is worth a try, a leak, all zones closed, no pump over-run etc.

Out of all them the air lock is probably most likely. Filling with the filler valve into a sealed system is not always as simple as just turning on the filler valve, often the rads need to be bled then too.

Buford T Justice

Micky Dolenz wrote: »

I would be slow to advise a house owner to interfere with a safety device. Go at a PRV at your own peril.

How many times has it happened to you where the thing just won't stop letting by after being disturbed. too much of a risk for me unless it is fairly new.

Too many times for it to be a once off or a co-incidence. They have a habit of failing when messed with.

I agree, that I would be skeptical to advise on this, but at the same time, I'm not the internet police either if you know what I mean. I mentioned the risks and dangers my earlier post. Its up to the OP if they want to tackle it now after being made aware of the risks.

Fingers McGee wrote: »

A couple of words of warning though.

DO NOT do this after you have fired the boiler and it has switched itself off, as the steam or the water from the boiler will scald you very badly.

Also, PRV's have a habit of failing if they are used for the wrong purpose and if they're old, so its possible that if you take these steps, that it will leak and continue to do so, and will need replacing. Therefore, OP bear in mind that you do this entirely at you're own risk, and are aware of the possibilities.

IF you have a closed system, then go to the filling loop and top the system up to what it was before, and then fire the boiler.

Micky Dolenz

Fingers McGee wrote: »

Too many times for it to be a once off or a co-incidence. They have a habit of failing when messed with.

I agree, that I would be skeptical to advise on this, but at the same time, I'm not the internet police either if you know what I mean. I mentioned the risks and dangers my earlier post. Its up to the OP if they want to tackle it now after being made aware of the risks.

I completely agree.

This started to happen a boiler I had. Once boiler was anywhere near max heat and switched off, it would trip the high limit stat, because of course the pump died as soon as the burner did.

I rewired a permanent live through a pipe stat and to the pump, to create an overrun. It worked a treat.

Buford T Justice

robbie7730 wrote: »

And it can often let only water out even if the system has a lot of air in it. Its tricky enough for a house owner to sort out air lock problems if they have no experience of it.

If the PRV is fitted to the top of the boiler, (and it should be) and there is a substantial volume of air at the top of the boiler, this will trap the water from flowing out of the boiler. Opening the PRV, may give a little water, but would release the air from the boiler. As I've said, I've had this happen a few times, and without an AAV on the boiler, this is the only way that i know of getting rid of it easily.

robbie7730 wrote: »

It could also be a vented system with the header tank not filling or full. There are plenty of problems that can cause it. Air lock, main feed or return pipe blocked with sludge, pump faulty, overheat stat faulty which is why suggesting turning down the boiler temperature is worth a try, a leak, all zones closed, no pump over-run etc.

I agree, that these are potential issues, but if a new rad has been fitted, then this is the likely problem. In fact, i fitted a new rad to a system about four weeks ago, and this was the exact problem I was faced with, when I fired the boiler after refilling. There was no AAV on the boiler.

Most stats will go to around 80 at the max, and the high limit is at about 90, so even if the stat is 3/4 of the way up, it still shouldn't trip the high limit. When the boiler boils the water within it, which it can't circulate, the vapors rise, which will be hotter than the water temp as its vaporised and will trip the high limit stat, which sits at the top of the boiler.

robbie7730 wrote: »

Out of all them the air lock is probably most likely. Filling with the filler valve into a sealed system is not always as simple as just turning on the filler valve, often the rads need to be bled then too.

True, but the OP hasn't said if its a sealed or vented system yet.

Bruthal

Fingers McGee wrote: »

Most stats will go to around 80 at the max, and the high limit is at about 90, so even if the stat is 3/4 of the way up, it still shouldn't trip the high limit.

It can if there is no pump over-run.

When the boiler boils the water within it, which it can't circulate, the vapors rise, which will be hotter than the water temp as its vaporised and will trip the high limit stat, which sits at the top of the boiler.

Thats not entirely true, water vapour can only go over the 100 degrees c when under pressure (enclosed), and if it is under pressure, the waters own boiling point will itself be higher than 100 degrees c. The steam coming from a kettle will be no higher than 100 degreec c.

When the water can not circulate or does not, it just needs to go above the 90 degrees to trip the overheat stat, and this happens in boilers when the water suddenly stops flowing. It is really the metal in the heat exchanger heating up due to no water flow transfering the heat away that causes overheat trip rather than the water turning to steam and overheating it. Although the metal cant increase in temp once the burner is off, so it could be said the water now increases in temp alright.

What could actually be said is the area with vapour will now be less effective at keeping the heat exchanger at least down at 100 degrees c, than water would be even when the water is at 100 degrees c.

Water at 10 degrees c will take a lot more heat from a person in it than air at 10 degrees c, even though in effect, the air is vapourized gas, but with a far lower specific heat capacity than water at the same temperature.

Bruthal

Fingers McGee wrote: »

If the PRV is fitted to the top of the boiler, (and it should be) and there is a substantial volume of air at the top of the boiler, this will trap the water from flowing out of the boiler. Opening the PRV, may give a little water, but would release the air from the boiler. As I've said, I've had this happen a few times, and without an AAV on the boiler, this is the only way that i know of getting rid of it easily.

Yes in the case of outdoor oil boilers where the pipes go underground after leaving the boiler, this is certainly right, i was more thinking of boilers installed inside the house itself so your right there.

Buford T Justice

robbie7730 wrote: »

Yes in the case of outdoor oil boilers where the pipes go underground after leaving the boiler, this is certainly right, i was more thinking of boilers installed inside the house itself so your right there.

Sorry, was talking about an external boiler. Over here in the wesht we have very little oil boilers indoors. Generally all outdoors.

P.S. I've no overrun on my circulating pump, and i've never had a problem with it. Its controled by the timeclock in the same fashion as the burner.

Bruthal

Fingers McGee wrote: »

P.S. I've no overrun on my circulating pump, and i've never had a problem with it. Its controled by the timeclock in the same fashion as the burner.

Yea a lot of oil boilers will work without it alright, but with a pump over-run the boiler can be run at a higher temperature closer to the cut out level without cutting out when the pump stops.

I dont doubt at all its likely an airlock here, i agree completely with your views on it.

jimmytheface

Hi there I,m new to this boards.ie thingy, was looking for info on something else and ended up here . I,ve read a few threads on oil boilers and felt I have to say something . In regards to your boiler cutting out if there is and airlock in the heating this would not cause it you just bleed the rads to get rid of the air . A boiler cuts out for various reasons from faulty oil pump or control box , a blocked oil pump , too much air , too much oil , blocked nozzle , dirty photo cell and even a circulating pump thats not working plus lots of other reasons but an airlock unlikely . Get an OFTEC tech to look at it .

sullzz

jimmytheface wrote: »

Hi there I,m new to this boards.ie thingy, was looking for info on something else and ended up here . I,ve read a few threads on oil boilers and felt I have to say something . In regards to your boiler cutting out if there is and airlock in the heating this would not cause it you just bleed the rads to get rid of the air . A boiler cuts out for various reasons from faulty oil pump or control box , a blocked oil pump , too much air , too much oil , blocked nozzle , dirty photo cell and even a circulating pump thats not working plus lots of other reasons but an airlock unlikely . Get an OFTEC tech to look at it .

I wouldn't think it is any of the problems mentioned , although they are problems which would cause a boiler to cut out I wouldn't say the are the problem here , the OP mentioned that he just had a new rad fitted and then started to have this problem , so it points towards what the lads suggested ( an airlock) , I'd say that if he was to fire the boiler and monitored the temp of the flow and return pipework at the boiler he could tell easy enough , it may just require the pump to be bled