Balancing after flushing

[Basils57]

Hi Folks

Due to cold bases on some radiators, and others which just weren't getting warm, I've just had our combi heating system flushed with a MagnaCleanse unit.

Despite this, there appears to be a minimal improvement in the situation, with the majority of the affected rads still in a similar state, and I think I might have been somewhat duped. Upon finishing, the gas engineer has deliberately left all of the lockshield valves fully open, and has made no attempt to balance the system, which seems very strange to me, as the affected rads appear to be those at the back end of the run. Obviously those at the beginning of the run are red hot. He's implying that there must be a blockage in the pipework, but I don't see how he can conclude this without balancing the system?
All of the TRV's seem to be working OK, with no apparent stuck pins.

Your comments would be appreciated.

 

[Jurassicspark]

He's implying that there must be a blockage in the pipework, but I don't see how he can conclude this without balancing the system?

Sounds rubbish. What is the boilers pressure reading at right now?

Obviously those at the beginning of the run are red hot. He's implying that there must be a blockage

Restrict the lockshield by about 80% of its possible amount (i.e. lockshield valve only about 20% open) on the rads that are getting hot quickest and wait about ten minutes. Now feel the rads that were cold. They should have improved a bit but you will then need to restrict the second quickest rad to get hot and so on and so on...

The idea is you need to stop the water simply taking the route of least resistance. So a distant radiator may be harder for the water to get to so you have to make it harder for the water to get to the nearer (easier) rads.

 

[Basils57]

Thanks for that, it's what I thought - I didn't realise that he hadn't balanced the system afterwards.

The pressure is 1.8bar. I have already reduced the first rad to about 1/2 turn open, and that seems to have improved matters. Seems that I'll be having to do a further bit of amateur balancing and see how it goes?

 

[Jurassicspark]

Yes, a bit of trial and error and you'll soon be there.

Do you know where the last radiator is located? If you do, turn the lockshield fully open on that one.

 

[Basils57]

Thanks Juassicspark; yes, I'm pretty sure I know which is the last rad, so will do.

It's damned annoying though, this guy wasn't cheap - It's a bit of a lottery these days. My previous plumber who was superb unfortuately died, so as I say it's a lottery, and FB recommendations can't (obviously) be relied upon!

 

[Jurassicspark]

Yes, give it a try. If it still doesn't work, chances could be that you got air in the system. Have you got a vented system?

Almost forgot above, go around and bleed the radiators.