Noise in system and two rads cold after a system flush

[Dom2010]

Hi all,

I am posting here because I can't find an exact answer online to my issue. I know very little about DIY on heating and water systems so my apologies if I miss anything important.

I was getting kettling and boiling noises from my boiler so after a bit of online investigation I decided to drain my system and add some cleaner. I've lived here for 8 years and I've never cleaned the system (which I know is too long). I bought some Sentinel X400 Restorer (and also some inhibitor for later use). I found about 6 cm deep thick brown sludge in the feeder tank in the loft so I opened a drain point downstairs and flushed through the feeder tank and gave it a clean until it was clear water (I had shut off the water feed first). I drained the whole system, it seems that the down stairs radiators all feed directly from above and don't have a circular circuit so I had to drain each one from a ball cock by each radiator. Once the system was clear, I added the system cleaner, turned on the feed to the header tank, I let the water fill up, bled all downstairs radiators and then upstairs and then turned on the heating. I was planning to leave the cleaner in the system for a week or so - the bottle says for up to 4 weeks maximum.

The issue is now that the radiators in the kitchen and dining room downstairs are stone cold - although the other two radiators downstairs are very hot. I tried turning the pump up from 2 to its maximum of 3 but this didn't change things. What's more there is a really loud humming and vibrating from the pipes leading from the boiler to the hot water tank (which is in the airing cupboard). The humming comes on with hot water or heating and is constant and seems to be vibrating all around it. I can hear it all round the house but mostly from the side it's coming from.

Sorry for all the detail. Anybody have any ideas what to check first? Any advice will be very much appreciated.

Many thanks in advance,

Dominic

 

[Andygasman2010]

The rads that aren't working are probably air-locked, just turn the others off until they come on.

It sounds like your system might be quite bad, you say there was 6cm of much in the header tank.... A decent flush is a professionals job so you probably won't get the desired results doing it yourself.

Doing what you've done won't do any harm though, X800 for a few weeks then a dran down will get plenty of muck out.

The pump may be off balance and causing the humming noise, it's difficult to advise on that. try putting the pump speed back on 2

 

[Dom2010]

Many thanks for your reply.

I have turned all the rads off except the two which are cold and I will see what happens.

I have turned the pump down but the noise is still present but just not as loud - still loud enough to be a real nuisance though. The hot water has gone off now and I've just noticed that the humming / vibrating is no longer constant but comes in cycles. It gets loud for a while then fades away but after a couple of minutes it comes back - and so on. It only seems to be constant when the water is on.

I will keep on eye on these rads for a while and see if they heat up now. Once they're sorted it's only the noise to worry about!

Thanks again.

 

[Dom2010]

Quick update:

The radiator in one room got hot after about 10 minutes when only the 2 cold ones were on. The radiator in the kitchen stayed cold so I turned the other one off leaving only the kitchen on. I checked the valve (the one without the screw cap, and I don't have TRVs) and it seemed stuck so I turned it off (which needed only a turn and a half) and then opened it again fully. Both valves were open full and It seemed to get very slightly warm after a while but not much. Every 5-6 minutes the pipes upstairs in the airing cupboard make a sound like water bubbling and then a large scratching sound as if they are forcing something through. It passes within maybe 4 or 5 seconds

I am not sure what to make of this. The radiator is not getting hot still after about 45 minutes of it being the only one on. I don't know if I should just turn it off again due to this horrible sound every 5 minutes.

Any ideas would be very much appreciated. Many thanks!

 

[Andygasman2010]

Sounds like it's full of air or sludge. Seeing as you said you were a novice i think it might be best to get a pumber in, he'll be able to make sure it's configured propperly too.

 

[Dom2010]

OK, many thanks for all your advice. I will make a call tomorrow.