Gloworm Ultimate 120 FF kettling

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Hi,

My CH system is playing up. (Gravity fed system with Gloworm Ultimate 120FF, two motorised valves, bypass valve and TRVs on each rad.) The symptoms are kettling every 10-15 minutes. This has only started in the last couple of weeks. I have read the FAQs and checked a few things and I think the most likely culprit is sludge build up in the heat exchanger. I have about 20 rads in the house and some have the tell-tale build up in them but we have just lived with it for a few years. My plan is to remove them 1 by one in the spring and flush them through with a hosepipe. I have tried power flushing twice before with little success (once myself and once with a plumber).

I thought that the problem was air in the system initially as I have had some building work done and rads removed. I have bled the air though with little improvement. I also guess that the inhibitor strength will be low as this has not been topped up since the builder left.

I have checked the pump, the motorised valves and bled all the air out of the system but I still can't get the rads very hot or the kettling to stop.

I am loathed to touch the system for a few days as HW is OK and the rads get warm (and I mean warm only) which keeps the chill off. (I have two small children so I need some heat and HW).

My plan is to drain down the system partially and add some Central Heating cleaner & sludge remover (I have some stuff called Flushex which recommends being in the system for 4 weeks). Then flush through and refill with Sentinel Inhibitor.

Am I wasting my time or do you think it is worth a go? I also need to find a decent plumber in the Basingstoke area. I have only ever got two from Yellow Pages and they had no idea.

Thanks in advance for any advice.
 
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Maybe worth trying something stronger . X800 would be a good place to start. Doesnt need 4 weeks either and works great with the heat.
 
Happy to give anything a go. I just happened to have a couple of cans of the stuff I mentioned. No chance my whole system will dissolve then? Thanks for the reply
 
Pitty that when given good advice to use a quality product ( X800 ) he still wants to use something that we have never even heard of !
 
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Porker said:
No chance my whole system will dissolve then?

Yes probably :D ...only joking.

Reading instructions your system should require two litres, but maybe give one ago and leave in for a day or two. Id be surprised if you didnt see any improvment.

Im assuming basic checks i.e gas pressures have been checked and are ok. A 120k btu boiler is probably well oversized, how big is the system?
 
Agile - you must have read my post differently to what I meant to convey. I WAS going to take the advice and use what was suggested. I just mentioned that I had some of this stuff around. The answer might just as easily been that you had heard of the stuff and it was OK.
 
rob - this is in a very large house 7 bedroom and 3000 sq feet.
 
Flushex is a Purimachos product, a quarter the price of most of the others. I suppose you could try it as a weedkiller, but I wouldn't want to use it for anything else...
 
I was sceptical about the price as well. As the job will take me ages and be a pain I have bought 2ltrs of X800 @ £30.
 
Just an update on the work today -
I spent all day cleaning out the header tank then adding X800. I fired everything up and lo and behold no banging and the system warmed up the rads perfectly. Much better than I expected. A perfect cure. Drained down and refilled with water only to flush the X800 out. (Small amount of scale but nothing much) Powered on for about 1hr.. again perfect. I was very tempted to add the inhibitor and be done. But no, I thought I will drain down again. So did this and refilled and added the X100. Then powered back up and guess what the clanking returned. I am now convinced that there is an airlock somewhere in the system that I can't find that somehow I cleared the first two times. The only way I can think of curing this is to drain down again (wasted 2ltrs of X100), refill, bleed and hope!!

Basically the boiler comes on for a few minutes and then you can hear the water rushing as if the return cannot supply fast enough, then the heat cuts out and then the banging and kettling. When the system was working OK i.e. the previous two times today, the boiler stayed on for ages until the rads were hot and worked normally with no noise.

Does an airlock sound right to anyone else?
 
If I had been you, I would have circulated the x800 for more than an hour - if thats what you did. Can you be sure there is no air in the boiler?
 
Sorry post must not have been clear. The X800 circulated for around 3 hours. The flush through with water only was 1hr. Unfortunately my woes are not over. I left the system on Xmas Eve looking pretty good after a 2am finish. I was away over Xmas and although the system was still working when I got back yesterday the rads weren't that hot (although they were still getting warm) and some banging which occurs about 2 minutes after the boiler fires up. I still suspect the flow is the issue but why would the system work OK for around 6-8 hours initially and then get steadily worse?

Actually, I dont think the X800 did any good really, I think this was a red herring.
 
sorry to go down another root but i'd of put 2 ltrs of x200 descaler in & left it to chug 4 a couple of weeks to see how it faired, x200 can be left in & is a slowly slowly catch the monkey cure. that scale took years to build up it cant be cured over night without a new heat exchanger, c if it dont work.
 
Could try treating as an air lock - open just 1 rad at a time, hw off.

Sometimes backfilling through a drain cock helps.

How old's the pump? Maybe it's going a bit slow, but liked being flushed in the elixir?
 
Thanks ChrisR. The backfilling is also on the list. My father suggested this as well, this has worked for him once on a large system he has on some flats. The pump is a brand new 6m one. I took the old one off and the impeller was blocked by some scale. I think the pump was OK apart from this but I replaced anyway as I had a new one spare.

I'm a bit worried that I have shut down the whole system, rebled and then left for around 1/2 hour. The header tank is still taking water!! I tied up the ballcock and the 3" of water disapeared in around 10 minutes. All the CH pipework for the ground floor is buried in concrete. My main worry is that the leak is coming from under a floor where my builder relocated a radiator this summer. It now has a new oak floor installed on top of it. Might need to rig up some sort of pressure test to see if there is a leak. :cry:
 

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