mison midas bf - pilot light going out

[rinkydink]

hi , i have a mison midas bf boiler which works fine - all rads hot, hot water etc, the problem is if i run a bath afterwards the pilot light will go out & then its a pain to relight. this happens not every time, but most times i run a bath - or use alot of hw. the ch works fine & the pilot light doesnt go out if the ch is on

any idea what the problem is?

 

[ChrisR]

Overheating perhaps.
Peculiar boiler - two pumps.

After HW drawoff the fan should stay on for 10 minites and the HW pump (left one I think) for 30 seconds. Is that happening? If so, posibly scale in the secondary heat exchanger

 

[rinkydink]

fan & pump seem to be staying on ok. How do i deal with scale??

thanks

 

[Agile]

Its not a procedure that many professionals attempt or perhaps even know what to do.

You need to introduce sulphamic acid ( Fernox DS3 ) and circulate it through the main heat exchanger for about 20 minutes at about 70 C. Its likely to need repeating two or three times.

Very messy too! And rather dangerous handling hot acid !

Tony

 

[Softus]

Very messy too! And rather dangerous handling hot acid.

It is if you make the mistake of handling it, but it takes about 10 minutes to knock up a home-made kit for circulating the solution, using a UPS 10-50, a 4 gallon cistern, a few lengths of 22mm Hep2o and some pushfit fittings...