Any help with radiators?

[lathany]

Does anyone have any useful tips on calibrating radiators?

Our house has a crap complex pipe structure for heating with various sets of radiators running on various different loops and we thought we would try and calibrate them all this evening to try and get something resembling an even heating effect throughout the house. Any tips on which radiators to start with (we also have some idea of where the loops start, although not completely) would be met with gratitude!

Comments

[undyingking.livejournal.com]

Do you have radiator thermometers? One, or preferably two, is pretty essential. Or some other thermometer that you can fasten to the pipe. And NB it's to the actual radiator inlet and outlet pipes you fasten them, not to the main system pipes.

And you will definitely need to know the exact sequence of the loop(s).

The canonical way is to start with the system cold. Open the valves fully on all radiators. Turn on the system, and close the lockshield valve on the first radiator. (You'll need to make sure you can access all the lockshield valves!) Once the heat's come back up, open the lockshield valve gradually until there's about a 12 deg C drop across the radiator. Move on to next radiator, repeat, etc.

It's pretty straightforward but rather laborious I'm afraid... do say if more detail wanted.

[bateleur.livejournal.com]

Thanks for the tips!

Once the heat's come back up, open the lockshield valve gradually until there's about a 12 deg C drop across the radiator.

That step sounds completely irrational - do you know the justification for that? I would expect the settings for an individual radiator to need to depend on the rest of the system.

[undyingking.livejournal.com]

This drop is set to allow the radiator to optimally heat the room, rather than as a measure of how much heat it's taking out of the system. Remember that the main system flow and return pipes don't actually pass through the radiators, but alongside them.

Of course the radiators do take heat out of the system as well, so you may find that you get to the end of the loop and find that the last radiator (or last few...) aren't able to achieve that drop even with the lockshield fully open. Which means your boiler is probably not big enough... in that situation, reducing the 12 deg C should help to spread the suffering evenly through the house rather than just making the last rooms heatless. (Although I've never tried this.)

Oh and, I forgot to say, make sure the radiators are all thoroughly bled first.

[bateleur.livejournal.com]

Seems to me that opening the valves on a given loop will reduce its resistance and thereby influence current, which will in turn throw out the settings on the already-set radiators.

But maybe this effect is too small to matter?

Only one way to find out...

[undyingking.livejournal.com]

Mm, I hadn't tohought of that, but I suspect it is too small to matter or else they'd have amended the 12 deg rule of thumb to compensate.

[lathany.livejournal.com]

We don't have radiator thermometers - do you need to find a specialist to supply them or might you get them from a high street shop of some sort?

I think I'll start by acquiring some and then re-read your comment ('cos I think I follow it, but I'm not yet trying to do it!). I may then email you with a plea for further help if that's OK?

[bateleur.livejournal.com]

do you need to find a specialist to supply them

Doble's will have them.

[quisalan.livejournal.com]

Would you like me to phone later with Russell since he is of the building persausion? It'll be after 6 but he would probably be the most practical and helpful person I can think of...

[lathany.livejournal.com]

I think see how we do first; if our plan ends in disaster, you'll be hearing pleas and whimpers from me! Although if you'd like to wave this page at him and ask him if he has any other comments, that would be much appreciated.