Further Boiler Problem - Ideal Minimiser

[XrayDave]

Hi again,

Just had this boiler repaired after a week of no c/htg or hot water!

Heat exchanger replaced for 2nd time in 3yrs on an 11 year-old boiler along with a few other "bits & bobs".

Since completion of the repair at around 2-2:30pm this afternoon, the boiler has repeatedly refused to light after the boiler overheat protection has activated. This is due, I believe, to air in the system?

All the rads have been bled repeatedly (with the pump off) and each time the boiler cut-off needs to be re-set, the rads are checked again for air, so I'm quite happy that there is little (or no) air left in the radiators.

The only thing that hasn't been bled is the hot water tank (and I wouldn't know how to do this if this needs doing as I don't know where the bleed valve is if there is one).

So far, the boiler has tripped (if that is the correct word for this overheat protection) 9 times since 2:30 and the heating has been on since then.

Boiler thermostat was on "3", I've now turned it down to "2" (out of a range from 0 - 6).

EDIT: Overheat still tripped. Now set to 1 1/2. Here's hoping.

EDIT2: Radiators are too hot to grab and hold on to - ie over 60˚C. They aren't glowing mind you, just a bit hotter than "hand hot". Symptom that boiler is over specified (but then why hasn't it done this during the past 11 years)??

If I press the reset button, the boiler will relight straight away.

So, likely problem & possible remedies?

Thanks in advance.

Dave

 

[Agile]

You talk so much about bleeding rads but dont say anything about repressurising the system?

Whats the pressure?

Tony

 

[XrayDave]

Hi Tony

The system is not pressurised as far as I know and there is no pressure meter on the boiler so I have no way of knowing what the pressure may be.

Incidentally, the problem with the boiler turned out to be a faulty boiler thermostat (this must have been one of the extra bits that was installed along with the heat exchanger yesterday).

This should be all fixed tomorrow.

Dave

 

[Agile]

Most of the Minimisers I have seen have been on a pressurised system.

Presumably if yours is not pressurised then its acceptable to fit them on an open system.

These were never a very reliable boiler and most have by now been replaced.

I am glad that its now getting fixed again.

Tony

 

[XrayDave]

Hi again Tony

It turns out that not only was a replacement thermostat needed but the water leak from the broken heat exchanger has also corroded connections on the pcb (a No. 37).

Thermostat & pcb now replaced & system now working properly

It has taken 5 engineer visits over the last 8 days and lots of parts - would heve been cheaper for British Gas to have put a new boiler in methinks!

Thanks for your help

Dave

 

[Agile]

BG engineers are meant to make 11 visits a day so each visit is relatively cheap for them.

The way they work is to keep each visit short and to do as little as possible by prescribing a new part which they, or someone else, will fit another day.

Tony

 

[Temprise]

I hope BG have diagnosed the fault properly.

Water can get onto pcb 37 because of a heat exchanger leak but more commonly it can happen if an inner flue seal has deteriorated. The condense then runs down the outside of the heat exchanger and onto the components that you have mentioned.

I hope you don't have any more problems.

Regards.

 

[nickso]

BG engineers are meant to make 11 visits a day so each visit is relatively cheap for them.

you know very well they are not

The way they work is to keep each visit short and to do as little as possible by prescribing a new part which they, or someone else, will fit another day.

and that isnt true either. back to making big assumptions again glazier, was that your new years resolution?

 

[nickso]

Flue tube rots and drops condensate onto the bottom of the combustion chamber, it then gets to the pcb through the wiring loom hole in the bottom.

Flue tube is near impossible to see properly if its the larger h/e and seeing as all minimisers run badly a check with your FGA is unlikely to yield any clues.

 

[Agile]

How many visits are BG expected to make a day then?

And the longest that are they expected to spend at a job?

Tony

 

[XrayDave]

Thanks Temprise, agile & nickso

Boiler seems to be running sweetly at the moment, but I'll keep an eye out for flue seal problems. Thanks.

PCB 37 has obvious corrosion around some resistors & diode between relay RL2 and capacitor C14 (see photos).

Impressed by the BG engineer who came to sort this out - same engineer throughout. Very pleasant & knowlegable. Nothing was too much trouble.

Showed me how to re-set the boiler overheat sensor (so that we wouldn't be without heat), fitted a non-standard thermostat to keep us going whist he ordered the correct part & rang us each time before he turned up and kept appointntments - even to the exent of turning up at 9am on Wednesday (through thick snow) to fit the new h/exchanger assembly.

Richard, you are a star. Thank you.

Dave

 

[boabcelt]

When I used to work for them, the focus was not on the volume of jobs but on first time completion rates. If you were stuck on a job, you were expected to contact the office to allow the planners to alter their allocation of jobs. I was never a fan of the minimiser and I have to say I'm glad that most of the ones in my area have been replaced. I havn't worked on one for months. Touch wood.

 

[Agile]

I am sure that I have seen a minimiser with a newer design of PCB with a higher density of components.

Was the 37 replaced on later boilers?

Tony

 

[Ihavenojob]

now uses pcb 41,same as response

 

[XrayDave]

Hi guys,

From reading the forum, I was surprised when I saw a 37 pcb. Was expecting a '41.

No idea what has been fitted though as I was at work when the engineer came.

Dave