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[tunnie]

So MrsT just called to inform me the boilers not working 

Fault lights indicate:

Lack of burner ignition (no
ignition signal from the full
seqence ignition device)

So am I right in thinking Spark plug? Or is more complicated than that 

Anyone recommend someone in West London? 

[Marks DTM Calib]

Not very conclusive, do you know the boiler make/model?

No spark plug as such, its much more likely to be something else in reality.

If its a condensing boiler then we all know the common fault (hopefuly) given the weather and the general low quality installs but many of the experts.

The fault hints that the request for boiler ignition has not been reached from the sequencing device.

The basic sequence of events is;

Stat demands heat
Motorised valve moves to the correct position
Motorised valve calls for boiler to fire
Boiler starts fan
Once flue pressure differential is confirmed via pressure switch (e.g. fan running and no significant air leaks) then gas is turned on.
Ignition signal sent to ignite gas.
If gas ignition is succesful then keep gas valve open, if not then shut off gas (some repeat a few times before reporting a fault)

There are a few other interlocks on some setups e.g. condensing units where there are condensate level sensors which will also stop the boiler firing. Its often these that cause issues this time of year because way to many gas fitters dont follow (or choose to ignore - delete as appropriate) the building regs when installing condensate drains so they freeze up!

[tunnie]

Its a Biasi Combi boiler (M96.24SM/C), just sparks up on demand when hot water is requested. Works well in a 1 bed flat really, had no issues until now.

Can it do this because of low pressure? I think its at 0.6 bar now, the book says it should be around 1.1 bar.

Just called a few "Plumbers" first 5 never answered phone 

Next one wanted £95+vat an hour, next £120+vat     Parts on top of course! 

Fluck that, I'll put myself through a course for that kind of money. 

[tunnie]

Oh and many thanks for the information above, most of it goes way over my head 

But understand the basic flow 

[Marks DTM Calib]

If pressure is low then it also wont fire. 

[tunnie]

If pressure is low then it also wont fire. 

Ah, I'll look at it when I get back then. Recall there is a valve underneath which will allow more water to flow into the boiler, which I have done once, possible as its been used a lot recently its just boiled off some of its water?

Hopefully thats the cause, as I can't get anyone for less than £100 an hour   

As always many, many thanks Mark 

[Nickbat]

If pressure is low then it also wont fire. 

Ah, I'll look at it when I get back then. Recall there is a valve underneath which will allow more water to flow into the boiler, which I have done once, possible as its been used a lot recently its just boiled off some of its water?

Hopefully thats the cause, as I can't get anyone for less than £100 an hour   

As always many, many thanks Mark 

The water in the system does not boil off. If it's starting to need regular water top-ups to maintain the 1.1 bar pressure, you must have a leak somewhere. 

[acope]

SOMETIMES, on a combi,when its very cold the external vent pipe can freeze and that will stop it dead.

Is your external pipe well lagged (nothing personal) it only takes a slight frozen blockage on a bend etc to cause a problem.

[Marks DTM Calib]

SOMETIMES, on a condensing,when its very cold the external vent pipe can freeze and that will stop it dead.

Is your external pipe well lagged (nothing personal) it only takes a slight frozen blockage on a bend etc to cause a problem.

 Not just restricted to combi's

[tunnie]

If pressure is low then it also wont fire. 

Ah, I'll look at it when I get back then. Recall there is a valve underneath which will allow more water to flow into the boiler, which I have done once, possible as its been used a lot recently its just boiled off some of its water?

Hopefully thats the cause, as I can't get anyone for less than £100 an hour   

As always many, many thanks Mark 

The water in the system does not boil off. If it's starting to need regular water top-ups to maintain the 1.1 bar pressure, you must have a leak somewhere. 

Nothing I can see, did bleed rads a while ago but that as minimal loss.

It was around 8/9 months ago I last "topped" it up, just had a picture from her, looks like its well down on pressure:

[tunnie]

SOMETIMES, on a combi,when its very cold the external vent pipe can freeze and that will stop it dead.

Is your external pipe well lagged (nothing personal) it only takes a slight frozen blockage on a bend etc to cause a problem.

I'm on the 5th floor, guessing no way to easily check this? 

It was ferking cold this morning!

[Marks DTM Calib]

Indeed, the pressure drops for a reason and there can be a few causes.

Thing to do is top the pressure up and keep a close eye on it, if it drops again and there are no obvious leaks it may be over-pressuring and venting by the relief valve, this is can be a sign that the expansion vessel has an issue.

Note that the expansion vessel should be checked every year to ensure the correct air pressure is present (likely to be 1bar) but this has to be done with the pressure on the water side released.

[Marks DTM Calib]

That pressure is to low.

[tunnie]

Indeed, the pressure drops for a reason and there can be a few causes.

Thing to do is top the pressure up and keep a close eye on it, if it drops again and there are no obvious leaks it may be over-pressuring and venting by the relief valve, this is can be a sign that the expansion vessel has an issue.

Note that the expansion vessel should be checked every year to ensure the correct air pressure is present (likely to be 1bar) but this has to be done with the pressure on the water side released.

I need that to be done then, as I've not had any work done on it.

That pressure is to low.

First thing I'm doing when I get back is letting more water in   

[Marks DTM Calib]

The expansion vessel is dead easy to top up, it simply has a car type schreider valve on it and you add air the same way you inflate a tyre.