Whining noise occasionally when CH on, Potterton Suprima 60

Hi,
Our house has a Suprima 60 boiler, approx 10 years old. Had a problem last year where the boiler made a sound like a jet taking off every so often when CH was on. The Scottish Gas engineer (we're on Homecare) replaced the pump and this stopped the problem.

Since the summer, had a different prob where a loud high pitched whine comes from 'the system' about 5 mins after the CH is turned on (never with the hot water) and lasts for about 30-45 seconds, then stops. The pitch varies slightly too. It then occasionally afterwards (e.g. after 30 mins) repeats this noise but not always. You can basically hear it throughout the house, although it's obviously loudest in the area of the boiler itself. Oh, it does this regardless of time of day, obviously we now have the timer coming on about 5am, but same noise comes on when manually turning on CH at other times of day.

Basically, the SG engineer who came out in the Summer seemed unsure about the noise (even though he did luckily hear it whining), he replaced (I think) the front(?) of the pump but no difference. Because our house is 37 years old and has all the original rads, obviously some are either lukewarm or are cooler at the bottom, indicating sludge (if I'm correct). I know about SG/BG engineers and tendency to recommend powerflushing, to be honest it probably does as a few of the rads are like that.

However, point of this long-winded message - during the above visit, the engineer muttered about a powerflush, then seemed to me to be VERY nervy about it, went off to van and came back with a quote (£749) and was literally shaking as he handed me the quote - poor eye contact etc.

So.... ignoring the fact I think we could do with a flush, but are about to put the house on the market, so don't want to fork out for one, could any sludge build up in 'the system' or rads cause the whining problem described? This was what the SG guy suggested, but I had severe doubts about it, due to his nervousness.

I want to get them back out again (hopefully, different guy) to try and fix it before someone buys the house, but don't want to end up down a road of SG insisting powerflush is the answer....

Any thoughts most welcome, sorry for the rambling

flush is the answer,but 700 quid i would put it towards a newer more efficant boiler ,when they fit it they will cleanse the system as well.

Bit more info. I noticed after posting that my boiler temp was still on 'summer' setting (about number 5 to 6 out of the 14 dots on the temp scale), so I turned it up to about 8 and put the CH back on manually. Whine lasted longer and seemed to have more vibration in addition to the whine. So I turned the temp down to 4 of 14, noise was barely audible.

This morning, I've just set it to 11 (it's one louder, y'know? ) and the whine/vibration was very loud and lasted for a few minutes.
From what I could tell, noise was loudest out of the top of the boiler but still heard throughout the house. Noise stopped when the red 'temperature' light came on, so guess this is when the boiler reaches correct operating temperature, so perhaps accounting for the 3 of 14 setting being barely audible?

Any thoughts? (thanks for previous reply, but I obviously am away to try and sell the house, and want to be armed with enough facts to avoid an 'unrequired' powerflush, since I am paying for homecare anyway). Quite happy to pay for one if it really is required (and would just end up getting stung for it via purchaser's solicitor anyway, I'm sure, if the whine was still there when they move in), but the SG engineer's body language said to me "haven't got a clue about the whine, but let's charge you for a power flush anyway"

Thanks.

Do you have two 2port valves with an autobypass valve by any chance?

Not sure, how could I check that? (work in IT, not heating, sorry!)

if the flush dose not cure the noise then they cant charge you ,if thats what they advise

Maybe off on a tangent but I had a similar noise in my system a few weeks ago, it happened when heating or hot water was called for, and again when he boiler cycle finished, in each case for about a minute. the fault turned out to be the valve actuator motor, I assume the bearing was worn and the rotor was rubbing against the stator. Holding the actuator housing at switch on you should be able to feel vibration.

I used to get a strange Whining noise when my heating was OFF it was the Missus!!!

gordongas said:

if the flush dose not cure the noise then they cant charge you ,if thats what they advise

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I'm sure that BG,in their terms and conditions won't guarantee to stop boiler noises,but will ensure circulation problems are addressed.Some boiler heat exchangers are impossible to silence after contamination.If thats what they claim then get it written on the quote.

Having re-reaad your OP and this might sound silly BUT has anyone checked the Fan?? they can make a hell of a din whch sometimes comes & goes at random???.....just a thought!

Yes. My fan sounds like Concorde at times. I think it's corrosion on the blades making it 'flutter'.

I had a quote for £150.