Ferroli Sigma 40 Boiler Shutting Down

[PeteSpringfield]

Boiler has been progressively shutting down after shorter periods. Problem applicable to CH, HW and Both. Pump has become very noisy.

Shutdown warning LED on boiler does not come on (but never has!)

Switching off mains supply or turing boiler temp to lowest appears to reset the boiler.

Pump run on never ends until boiler is \\\"reset\\\".

My logic is:

Option 1: System is sludged up (especially pump)increasing the frequency of boiler overheat due to low flow rate.

Option 2: Boiler PCB is faulty causing false shutdown and pump run on.

Observations:

3 Way valve appears to be working correctly
Don\\\'t think there is a blockage as very hot water arriving at tank heating coil (but only until boiler shuts down)

Is it worth removing and disassembling pump to determine how bad the sludge problem is or whether pump bearings etc are shot, before any further action?

Depending on the state of pump and pump contents, a de-sludge, flush and de-scale treatment are highly likely anyway.

All suggestion welcome and apologies for the length of post.

Cheers,
Pete

 

[bripl]

sounds like thermister to replace you need to drain boiler,make sure you get the right one gold colour,on early models pcb falls apart if you keep resetting,poor solder connection,these boilers are noisey but ferrolli do a kit which helps a little.check resistance on thermister in the installation man.

 

[PeteSpringfield]

Thanks for that swift and helpful reply.

'tis much appreciated,

Cheers, Pete

 

[ChrisR]

While the boiler's drained I would do as you suggest and at least look in the pump. If its noisy then it must be quite worn. I dunno for Ferroli but many combi pumps use adaptations of standard pumps, so you can just change the head (remove allen screws) for a standard one - of the same make. Usually Grundfos, Myson (= Circulating Pumps ltd) or Wilo. Usually the 6 metre version.

 

[bripl]

chris sigma is not a combi,poor attempt by ferroli at a conventional boiler.
these boilers are very prone to ketteling noisey heat exchangers for some reason.i have come across ones which have been power flushed correctlyand still the noises return after 9/12 months

 

[ChrisR]

Righto ta. Hardly ever see Ferrolis. What's in their "kit which helps"?

 

[bripl]

plates/baffles i believe never fitted any.

 

[PeteSpringfield]

Thanks again Guys,

Pleased to see I'm on the right track.

The Ferroli would never have been fitted had I not needed a fan assisted flue to go over a conservatory. It may be noisy by today's standards but it's hidden in a cupboard so it's one of the problems I don't suffer.

£12 for overnight shipping of a small item. More money in that than selling the damn boliers !!!

Cheers All,
Pete

 

[PeteSpringfield]

Hmmm - The mystery deepens!

Stage one, drain system ready to replace boiler thermistor but unable to refill system. To cut a long and emotional story short, finally found a blockage in the header / expansion tank cold feed.

The 15mm pipe joing the 22mm hot feed from the bolier and before the pump was totally blocked with what appears to be a rust like material (not the black sludge that normally drains).

I'd be interested to know whether this is a common problem related to chemical reaction (unflushed flux etc) or a thermal issue ???

Having replaced relevant pipe, I'm almost back to square one in that heating and water together run fine but water only results in a short (5 mins) burn before boiler shutdown and continuous pump overun.

My thoughts now are:

1. Cylinder coil is partially blocked although hot water with heating on is fine.

2. Boiler is almost too efficient requiring minimal bolier temp setting and minimal 60c cylinder stat setting.

3. Boiler thermistor or main PCB is still faulty

4. Pump (which haven't replaced yet) is not circulating well enough to keep water temp in the boiler to acceptable levels.

Any further comments are most certainly welcome.
Cheers,
Pete

 

[dan21mag]

The blockage u came across is very common, its where the cooler water meets the hotter, espec' in poorly maintained systems( lack of water treatment), it could do with a powerflush me thinks, which would also clear the crap out of the pump. good luck

 

[ruthedwards1]

Hi. We've just moved into a new flat and the heating was working OK. However, after coming back from a weekend away we now have a problem with the boiler shutting down after about 1/2 hour.
The boiler starts OK and heats the radiators and hot water, but then just shuts down which results in the radiators going cold.
Have resleased air from the radiators which makes it less noisy when it does shut down, but still having the initial problem.
Any clues? Am a total novice with these things, so want to know what to check when I get someone round to fix it.

Ruth

 

[pete1055]

chris sigma is not a combi,poor attempt by ferroli at a conventional boiler.
these boilers are very prone to ketteling noisey heat exchangers for some reason.i have come across ones which have been power flushed correctlyand still the noises return after 9/12 months

The Ketteling is the easy one to solve just use the timer from a timed bathroom fan to run the pump on for a few seconds after the boiler cuts out

the wiring is self explanitory same as for the fan