Boiler stopped, water pouring out the overflow

MackDeToaster

Just before Christmas I noticed my boiler was making an unusual whining sound, plus it was no longer heating up the hot-water cylinder, and putting on the immersion only heated up the top five inches or so of the cylinder.

I just came back after being away for a week and the boiler refuses to start. There's plenty of oil and I don't think it's frozen. I've pressed the reset but nothing doing, but water pours out the overflow under the gutter.
I had a look in the attic and water was flowing out of a u-shaped pipe into the main tank at a rate of knots, and this was then overflowing.

Any ideas what's going on ? Could it be something like the coil in the cylinder has split, or the pump on the boiler has gone ?

Help much appreciated coz I'm freezing and had to turn off the water because I did not like that it was two inches away from flooding my attic even though it was venting properly.

mullingar

Im not a plumber, but I do know how those systems work.

There are many many thing that can go wrong.

First, is you system pressurised (more probably) or gravity fed? If pressurised what pressure is it reading?

Can you isolate the hot water tank's heating coil (BOTH of the 2 pipes that go into the tank around the middle)

Could your system be airlocked?

MackDeToaster

Thanks for the reply. Nope, it's not pressurized. And there doesn't seem to be any way of isolating the coil, as in there's no valves or anything there.

What would be the best way to get rid of an airlock, should the pressure release valve near the boiler not have sorted that ?

items

Sounds like your heating system is pitching, when you run boiler and circulation pump it should only happen then.

Has anything changed recently, turned off any valves? have you done anything at all with heating system? Adjusted pump speed?

MackDeToaster

No, nothing has been done to it. How can it be pitching if the boiler isn't firing, that's what's confusing me ?

steamengine

You mention in your post that you were away for a week. Consider the possibility, that due to the freezing weather, some part of the circulating pipework has frozen up. When you fire the boiler it doesn't start but the pump activates and possibly a slug of ice in the pipe creates back pressure, thus sending water up through the goose-neck vent.

I would suggest you use a fan heater/s to heat up whatever part of the heating system you consider the freezing weather has affected, (including the burner unit) and see if that sorts it out.

items

MackDeToaster wrote: »

No, nothing has been done to it. How can it be pitching if the boiler isn't firing, that's what's confusing me ?

If your system is entirely gravity, something mechanical has to be forcing water out vent pipe, on gravity system water will only travel back to level of water in attic tank.

How is your system fed? mains water could be over filling system. Are you sure heating is open vented, not sealed?

Also, hot water, gravity fed or pressurized?

Have to ask more questions before making suggestions etc.

MackDeToaster

Hi Steamengine. It had actually stopped working Christmas Eve morning, shut itself down after working about half an hour and the rads were hot, so I'm not sure that could be it. However I'll certainly give it a lash, but I've had to leave again so it'll be next week before I can check.

items

MackDeToaster wrote: »

Hi Steamengine. It had actually stopped working Christmas Eve morning, shut itself down after working about half an hour and the rads were hot, so I'm not sure that could be it. However I'll certainly give it a lash, but I've had to leave again so it'll be next week before I can check.

Boiler could be shutting down but pump still running if its wired in such a way.

I've replaced pump the other day which blew purely from bad weather, another poster here had to replace pump, experiencing same problems as you've mentioned.

steamengine

items wrote: »

Boiler could be shutting down but pump still running if its wired in such a way.

I've replaced pump the other day which blew purely from bad weather, another poster here had to replace pump, experiencing same problems as you've mentioned.

Indeed Items, there seems to be a few regulars alright associated with this freezing weather. The pumps might have been frozen, and burned out due to non-rotation.

We also have the high limit stats tripping due to the primary stat being wound up for increased heat, the system is then shut down and the residual heat in the boiler trips the high limit stat.

In your case MackdeToaster there is also the possibility that the primary coil is fractured due to ice expansion, this could be diagnosed by isolating it - fitting plugs or blanks.

Another thread last week was about a condensate drain frozen up, which had caused the trap to fill up and trip the boiler.

items

steamengine wrote: »

Indeed Items, there seems to be a few regulars alright associated with this freezing weather. The pumps might have been frozen, and burned out due to non-rotation.

We also have the high limit stats tripping due to the primary stat being wound up for increased heat, the system is then shut down and the residual heat in the boiler trips the high limit stat.

In your case MackdeToaster there is also the possibility that the primary coil is fractured due to ice expansion, this could be diagnosed by isolating it - fitting plugs or blanks.

Another thread last week was about a condensate drain frozen up, which had caused the trap to fill up and trip the boiler.

True, a lot of these systems are well settled, in for years. Weather is well different than norm, both oil and water are different temp than system is used to so boilers are working harder than before to move and heat everything, small bit of weakness in system will fail as boilers are pushing harder.

Interested myself to see what problem is, if can figure out how system is set up, might be able to find some solution. Coil could be cracked but only way it could pitch that way is, pressurized hot water.

Just on high limit, user should be able to set user stat full up all day and night without boiler locking on high limit, they are designed to do so. Any that happen to lock out are doing so just as you've mentioned, pipe stats go a long way, defo should be a requirement here to have pipe stat fitted, that way you would'nt see these problems here, pump will still run on until lower temp is reached. Its real efficient also.

Mad_Mike

On the issue of the boiler itself, it seems very likely that the motor has seized. That's going on what you are saying about the "whining" noise. That would be typical when a motor is failing in a burner. More than likely it ran on Christmas eve and cut out when temp was reached and when it went to cut back in, the motor had seized, which would then trigger the reset and cut out.

steamengine

items wrote: »

True, a lot of these systems are well settled, in for years. Weather is well different than norm, both oil and water are different temp than system is used to so boilers are working harder than before to move and heat everything, small bit of weakness in system will fail as boilers are pushing harder.

Interested myself to see what problem is, if can figure out how system is set up, might be able to find some solution. Coil could be cracked but only way it could pitch that way is, pressurized hot water.

Just on high limit, user should be able to set user stat full up all day and night without boiler locking on high limit, they are designed to do so. Any that happen to lock out are doing so just as you've mentioned, pipe stats go a long way, defo should be a requirement here to have pipe stat fitted, that way you would'nt see these problems here, pump will still run on until lower temp is reached. Its real efficient also.

I came across a fault many years ago, an immersion heater in contact with the coil - had abraded through the coil over a period of time. The OP's boiler could be a sealed pressurised unit, with the heating water crossing over via the coil into the domestic sytem at a lower pressure - ie - head pressure of the attic tank.

Pipe stats definitely a good idea, also a combined inhibitor/antifreeze that would protect down to -10 deg C. I would hazard a guess that a lot of the older oil fired domestic systems wouldn't have this protection.

items

steamengine wrote: »

I came across a fault many years ago, an immersion heater in contact with the coil - had abraded through the coil over a period of time. The OP's boiler could be a sealed pressurised unit, with the heating water crossing over via the coil into the domestic sytem at a lower pressure - ie - head pressure of the attic tank.

Pipe stats definitely a good idea, also a combined inhibitor/antifreeze that would protect down to -10 deg C. I would hazard a guess that a lot of the older oil fired domestic systems wouldn't have this protection.

Heating's not pressurized in this case, its wrote up their somewhere. Having a coil crack under frost in a house which people live in would be rare, if anythings pushing water up vent, can only be dodgy circulation pump or dodgy mains connection if heating's connected to mains. Having said that, anything is possible.

Duel immersions and coils can be troublesome, coils seem to be different over different cylinders, some cylinders take immersion no problem, others its hard to thread in immersion with out hitting coil, even damaging it, seen many cylinders thrown to scrap man, threads for coil messed up after trying to fit immersion.

Pressurized/ un vented cylinders don't need duel immersion, two singles go in from side, never a problem.

Copper cylinders can have side single immersions but most of those cylinders will only be installed in houses with no fuel heating, no coil in cylinder.

Systems here should be flushed and filled with inhibitor after installation, not many do it, should boiler have problem, if system has not been flushed or inhibitor introduced, might not be cover under boiler guarantee in some cases.

Fernox is some stuff, they have great range, cleaner, flusher, inhibitor, leak sealer. Anyone reading this should look into Fernox range, best DIY heating job I can think of, easy done, all instructions you need to know come with fernox products.

Household plumbing systems never cleaned or flushed after instilation here, schools hospitals public buildings and so an have to have lines cleaned out and tested before allowing public use.

Seen two bad cases for homeowner after buying new house, 1st was poisoning, flux is used while soldering plumbing joints, home owner was brushing teeth etc with water diluted in flux which led to poison. 2nd, sometime during house new constrction, leak in attic, someone cleaned up leak with attic insulation, squeezed excess water from insulation back into attic tank. Family moved in, entire family had to go to hospital after using water full of fiberglass particals.

Worst I've seen is some lazy person took a you know what in attic tank, lucky no one in house, fired attic tank into skip.

We have a great system here.

MackDeToaster

Hi all, very interesting stuff there and thanks for the suggestions. I'll post up what it was once I get back and have it sorted.

One quick question, when it's suggested that the motor seized, that would be referring to the pump off the boiler would it ? As in, there's not some sort of motor in the boiler itself ?

Mad_Mike

Regarding the motor, I am referring to the one in the boiler itself that drives the oil burner and not the motor on the circulating pump. Having said that, I'm assuming the whining was from the boiler itself and not the circulating pump?