Radiator balancing results... Can someone cast an eye over my homework?

[Mathew Newton]

It seems radiator balancing is all the rage at the moment so apologies if this is getting a bit boring...

Following on from my plea for help

regarding boiler cycling and suspected poor central heating performance it was suggested that I gave balancing a go. So, armed with an IR thermometer I spent this morning doing exactly that and seem to have got somewhere.

My results are at:

they seem to show some interesting patterns. I say 'interesting', but my girlfriend's eyes were clearly glossing over when I showed her the results but I'm hoping those here will be a bit more understanding... ;-)

It was clear from the first round of measurements that my system wasn't at all balanced, and indeed the smallest radiators (downstairs loo, en suite and dressing room) were only showing 2-3C drops, whereas the bigger rads were more towards 10C. Given the former it is perhaps no wonder I was getting cycling even when not upto temperature.

Following several iterations (I've learnt the long way not to be too conservative closing down the LSVs!) I've got my drop difference to around 4C. Should I aim for closer? I'm almost certainly going to be doing some plumbing work on the rads soon (including fitting a towel radiator etc) so I'm mindful of not doing too much nugatory work just now.

Given that the overall average drop is now ~6.5C I thought I could try dropping the pump speed from 3 to 2 however this only increased it to ~7.5C. Is this the wrong thing to do, or should I drop it further to up it even more? As you can probably tell I'm stabbing in the dark with this particular point. Incidentally, my boiler is a condenser and the installation instructions says to aim for an 11C drop through balancing however it doesn't mention lowering the pump speed to do this.

My final question is I note that whilst the conservatory radiator now gets a hotter flow than before (nearly 10C higher) it still has the largest drop over it (9.9C). Could this be a consequence of its location (i.e. cooler room therefore more heat extracted) or should I continue throttling the others increase the flow rate through it? Second highest drop is the adjacent lounge (9C) which again is a cooler room at the moment given the doors to the conservatory are open.

Thanks for your continued help with this - it is really appreciated.

Mathew

[Roger Mills]

And very impressive they look, too!

Yes, try it on 1, to try to increase the overall drop a bit - probably plus a bit of fine tuning on the rads.

These higher drops are indeed due to more heat being extracted from these rads. However, they are closer to what you should be aiming at so yes, throttle the others a bit more - but to increase *their* drop rather than to reduce the conservatory and lounge drops.

Don't worry about getting them all *exactly* the same. As long as the boiler's flow/return differential is reasonable, and as long as no radiators have excessive drops, you are home and dry!

[Mathew Newton]

Yeah, curiosity got the better of me... I've now replaced the original sheet to give the latest (final) results:

the pump on the lowest setting, and some final tweaks made to the LSVs, the boiler is drop is within the 11C target (10C) and the radiator drop variation is 3.5C from 7C to 10.5C.

Think I'll leave it there for now... Now just need to locate some LSV caps so I can remove the knobs without losing the aesthetics!

It took me over 4 hours... *now* I can see why professional installers sometimes don't do it particularly thoroughly! ;-)

Cheers,

Mathew

[fred]

It does get quicker when you've done it a few times :-)

It's now the smaller radiators that have lower drops so you're on the road to diminishing returns but there's nothing wrong with going a bit further.

To speed things up, for anything that is 7degC drop I'd immediately close them by a half, eg 1 turn becomes 1/2 and so on. For those at 8 I'd close them by a quarter (of the current setting). Then tweak again from there.

Btw, for ease of recording and setting, I record the setting as the number of quarter turns opened from fully closed, it saves writing fractions and is a very easy setting to visualise when you make the change. For settings at 1/4 turn and below, expect to have to come back and re-balance the system in a while, that is a very small gap at the lockshield washer and it can close up through washer swelling accumulation of crud.

[Mathew Newton]

I might wait until I've added the towel radiator (and possibly bigger lounge radiator - I'm sure it's undersized) in case that upsets the whole lot and puts to waste any minor tweaks now.

I'll try that next time. It sounds like it'd get me to target quicker rather than making turns in absolute numbers regardless of current setting.

Thanks again Fred (and others) for your help, here and in my previous thread. I am more confident now that I'll get the most from this heating system and am starting to understand some of the shortfalls of how it was previously set up (or not!).

Mathew

[fred]

Oh ffs, just get on with it, it's only one more iteration and it sounds like you need the practice :-P

You know you want another play with that IR thermometer.

Forgot to say, some lockshield caps lock the posn of the lockshield valve when they are fitted and some don't. On those that don't (including Peglers) you can find that tightening the cap fixing screw (if present) can change the lockshield setting. I found this on my chum's system and just left the screws off when I refitted the caps.

Good luck.

[Roger Mills]

Well, you did it thoroughly, using an IR thermometer. But I'm sure that when you've done a few - so you know what you're at - you can get somewhere close much more quickly, just by using a calibrated hand!