Whooshing, rumbling and whistling.

[wingman]

My CH system is driving me potty! It is a Thermal Store with standard condensing boiler supplying CH and HW to a detached 3-bed house with 6 single and 2 double radiators.

When the central heating/hot water turns on the whole system, including the CH pump, is very quiet to start with, although the boiler pops and booms a little. After approx 15 – 20 minutes, the whole system whooshes which gradually increases in volume to a crescendo. This then stops and then there is a loud sound of rushing water and rumbling, accompanied by a high pitched whistling coming from the CH pump, which can be heard throughout the whole house. After a minute or so, this subsides.The whooshing and rumbling repeats every 10 minutes or so with the accompanying whistling from the CH pump. The system as a whole appears to function adequately providing the necessary HW and CH. All the rads have been bled and get hot although a small one upstairs has to be bled every four weeks or so. I have failed to find how air is getting in.

British Gas have said that this is common with Thermal Store systems as they have to run at extremely high temps to provide efficient HW and CH and there is not a lot I can do about it bar fitting a new system!! They did fit a new CH pump a few months back and I had the boiler moved a few feet when a new kitchen was fitted back in April. I have also heard that the CH pump can be bled too (there’s a nut in the middle), but how do I go about doing this without scalding myself and/or flooding the airing cupboard!? And will it do any good anyway?

Would power-flushing and treating the system maybe fix the problem (I live in a very hard water area)? Any advice greatly appreciated.

 

[captain_pugwash]

my boiler used to make horrific noises and really scared me that it was going to blow up. Basically this tends to be because the flow is resticted and it then 'kettles' i.e. boils and bangs like a bag of spanners. I read around these forums and decided to give it a thorough clean. It's now as quiet as a mouse.

I drained it down into a bucket and all sorts of black crap came out - I think this was because the system was never flushed properly when first insalled and so all the crap built up inside the boiler.

My advice is to use the Fernox boiler silencer cartridges - can buy these at Plumb Centers. To get then into the boiler requires a little bit of DIY - I saw the way a guy from British Gas did this. The cartridge inserts into a mastic gun (as used from frame sealants etc). Then use a small piece of hose and use a circlip to tighten on the end of the Fernox cartridge. At the other end of the hose you will need another circlip and a plastic union to attach to the place where the filling loop goes into the system - usually a sliver braided loop near the boiler from the cold feed.

Pump the stuff in with the mastic gun and run the boiler up to temperature for a few hours then drain out. I did this 3 times until the water ran clear from the boiler, then added Fernox inhibitor to stop the soot building up again and, touch wood, everything has been really quiet since.

 

[wingman]

Thanx captain_pugwash for the info. I have a sneaking suspicion my CH is full of cr@p. When bleeding the rads, the water is pitch black, a couple of them are cold at the bottom and the header tank above the thermal store is sludgy when I checked earlier.

Think I'll drain and treat similar to how you suggest, but may leave it until the weather is warmer. Don't wanna beft left freezing if I b@lls it all up!

 

[Agile]

If your system water is like that then I wonder why you posted here in the first place.

It obviously needs power flushing or some appropriate adequate cleansing action. We would charge about £300 to power flush in the London area!

Tony