Ferroli Sigma 40-60 boiler

[steveuk1971]

Hi. I have a Ferroli Sigma 40-60 boiler installed March 2005. So is now out of 1 yr guarantee. This is a standard boiler (not combi) on a standard open vented central heating and hot water system with separate circulating pump in the airing cupboard. The boiler is wall-hung in the kitchen.

The problem is that the boiler starts up ok when water or heating calls for heat, but whn it first starts after the boiler has been on for 5 minutes it starts to vibrate itself and the pipework and then turns off! It then relights after a break of about a minute or so and cycles fairly normally after that.

The vibrating sounds like the water inside is boiling??? What may cause this and what may be the solution?

Thanks.

 

[ChrisR]

Suggests overheating - circulation problem perhaps, possibly related to sludge/dirt in the system. Was the pump replaced? Was the system powerflushed? Could be high gas rate when cold - needs checking out.
Temp sensors are known to be short-lived on these sometimes.

 

[steveuk1971]

Hi

System was power flushed when new boiler installed in 2005. Circulating pump was replaced about year before that in 2004.

Thanks.

 

[steveuk1971]

Could be high gas rate when cold - needs checking out.
Temp sensors are known to be short-lived on these sometimes.

When you say "high gas rate when cold" ? What does that mean? Sorry to seem stupid.

Thanks.

 

[HarrogateGas]

The heat exchangers are crap on this boiler and virtualy impossible to change. They kettle unbearable after a while. Ferroli offer a new boiler as opposed to a new heat exchanger.

I went to one that was about 3 years old and way out of warrenty but with a few harsh words from the customer to Ferroli, Ferrolli dropped me off a brand new boiler to fit.

 

[ChrisR]

If the flames are too high the water can boil in the boiler (kettling). Temp sensor can reduce flame when it gets warm.
But I don't know the specific boiler so go with Harrogate's advice. Hopefully you have a decent installer who will come back and look at it, and know something about the boilers he fits. Most installers stick to a few boilers they get to know.

 

[Agile]

Lime deposition in the main HE is usually caused by faulty commissioning or water treatment. I dont see any reason why it should be worse with this model than any other brand.

The only possibility would be when the sensor fails if that allows the boiler to come on with full gas rate until it overheats. Does anyone know if this is the case?

Tony

 

[ChrisR]

I suppose they could have tighter waterways which clog more easily than average

 

[steveuk1971]

I spoke to my boiler installer on the phone (he no longer lives round my way) and he says that the problem sounds like a blockage in the flow system causing the boiler to overheat (not enough water pumping through? ) The pump in the airing cupboard has 3 speeds and it is on speed 2. Not had problems with it before last week. He said to go in the loft and see if the expansion tank fills up if I press down on the ball valve in it. I did so and water does come from the valve but not very fast! Is it supposed to come the same as the pressure in the big water tank in the loft?? It is an open vented system by the way. Any help and advice gratefully received.

 

[bripl]

sigmas are renowned for noisy heat exchangers turn the pump up and the noise will disappear,only cure i can think of is turn the gas pressure down and renew the GOLD coloured thermistor.has the boiler been wired correctly with the pump back to the boiler and a permanent live supply?

 

[steveuk1971]

sigmas are renowned for noisy heat exchangers turn the pump up and the noise will disappear,only cure i can think of is turn the gas pressure down and renew the GOLD coloured thermistor.has the boiler been wired correctly with the pump back to the boiler and a permanent live supply?

Hi

Yes there is a permanent live. and a pump over-run to the boiler too. Is renewing the gold thermistor a heating engineer job?

 

[bripl]

all depends on your plumbing skills and access,isolate electricity to boiler,isolate heating tank, drain it remember the boiler could be a low point undo thermistor and change.if access is good bung the tank and vent and do it live if your quick you will not lose too much water if your slow or it goes tits up you will get very wet very quickly good luck

 

[steveuk1971]

Just for info, it is a small 3 bed terraced house with 4 rads upstairs and 1 downstairs plus water cylinder in airing cupboard.


I was having a look at my circulating pump in the airing cupboard. It has 3 speeds. It was on speed 2. The speed changer is a disc that you turn with a screwdriver or coin. When i touched the speed changer dial with my finger lightly the pump went off whilst the boiler was on and i got the exact noise that i am having problems with - i guess the boiler and pipework was kettling - if that is the term. If i touched it again it came back on - a loose connection i guess?

I put it to speed 3 setting and again a small touch of the finger made it turn off and on again and the vibrating noise etc.

I put it on speed 1 and it was ok. I could not make the pump stop by touching the changer if you know what i mean. I can only assume there is some loose connection on speed 2 and 3 setting but all ok on speed 1???

I am going to see if leaving it at speed 1 resolves my vibrating kettling system.

With my set up as described above would it be ok to leave the circ pump at speed 1 or does it need to be on a higher speed - 2 or 3 - which i guess would need a new pump fitting in the airing cupboard.

Thanks to all so far.... Steve

 

[steveuk1971]

just a bit of further info - my pump is made by circulating pumps ltd (website of http://www.circulatingpumps.net/products/cprange.asp ). Mine is a CP63. Does anyone know if I can get a new speed selector switch rather than replace the pump?

Thanks.

 

[steveuk1971]

Circulating pump replaced by engineer £88 all in. Seems to have cured the noise.