Cleaning central heating from combi boiler

[bl86]

Hi

My central heating has been getting progressivly colder for the past few years. I've taken each radiator off and cleaned a lot of black sludge out of them, which has improved things slightly. I've also cleaned the magnetic filter on the boiler. However I'm concerned that there may also be the same sludge in some of the pipes.

I understand that the next step is to run cleaner through the system for a couple of weeks, before draining it out and replacing with inhibitor, so I've bought a universal cleaner at Toolstation

However it states that it's "for use in indirect systems only". I'm not sure how I can check if mine is direct or indirect. While googling, it seems easy to get confused between direct/indirect heating and hot water. I don't want to run anything through which could damage the system or make things worse.

Can anyone tell me how I'd know if my heating is direct or indirect? It's a Glowworm Betacom2 24 combi boiler.

Many thanks

Craig

 

[Razor900]

It's fine to use in your boiler. Direct is something that's mostly from the distant past.

 

[bl86]

Thank you Razor900.

I put the cleaner in on Monday night and have been running the system ever since, but with no noticeable difference in temperature. I think it's reaching the stage where I need to admit defeat and call someone in, but just wanted to see if anyone here had any other suggestions of things I could try?

So far I've:

• Taken each radiator into the garden and flushed through, shaking and rotating until the water runs clear
• Ran water from the filling loop to each outflow valve until it runs out clear
• Put cleaner into the system and ran for 5 days
• Completely drained the system and refilled
• Attempted to balance the system as best I can

At best, I can get 2 or 3 rads hot at the same time, but only the ones closest to the boiler. When trying to balance, I've found that if I turn the first 3 lockshields right down, I can get it so that the first 4 are lukewarm, but I can never get it any further, and it always results in the hot ones going cold. When attempting to balance, most guides suggest that there should be around 12 degrees difference in temperature between the inlet and outlet pipes, but in my case, the outlets are always cold. The bottom corner of the rads nearest the outflows also never heat up.

I'm wondering if it could be something to do with the pump? However this being a combi boiler, I'm not sure if that's something I'm able to check. Failing that, it could be a blocked pipe?

Anyway like I say, I think it's about time I got in a pro, but if anyone here can think of anything obvious that I'm missing, any advice would be much appreciated!

 

[jeff the gasman]

Not sure if the betacom has an in-line filter in the return or not. Are the valves fully open on the boiler?
Pump could be lethargic.

 

[bl86]

Thanks Jeff, I'm not sure if that's something I can check without opening the boiler? Not very confident at doing that. I'm in a soft-water area if that's any help?

I should have mentioned that there is a magnaclean filter on the boiler which I have also cleaned.