2 Radiators in series?

In article , PeterC writes

No bigee, just treat them as one when balancing ie maintain the drop across the pair rather than each in turn. Technically you will get a better result if you join both top and bottom with pipes but I don't have figures on the difference (I'd expect it to be small).

No. If carried to extreme, eg having all the house's rads in series, the last rad gets lukewarm water and has to be correspondingly huge.

NT

One drawback is that if one rad develops a fault you will not be able to isolate it, and moving the rads as a pair might be fiddly and require care not to get black goo everywhere if you have to loosen the joiner pipe. Minor details but worth thinking about if you have nice carpets. [ Yes folks, I'm stingy, and prefer to empty one rad at a time if I can, rather than keep forking out for expensive inhibitors etc after draining the whole system.]

Thanks for the replies - I'll pipe them in series.

Good point, Spamlet, I've changed the compression tails to in-line valves.

If the radiators are largish, I would avoid putting 2 in series. The second one would be cooler and less efficient. I also can't see how you could fit thermastic valves which would work for both rooms.

If you were hell beint on fitting them both in series I would consider fitting a top pipe as well. Then both rads would have similar top to bottom temperature gradients.

You ought be able to get right angle lockshield valves within 10cm.

In article , Fredxx writes

Two 2m radiators in series with pipes joined top and bottom are no less efficient than a single 4m radiator when the temperature drop across the pair is the same as the drop across the single long one.

I have three towel rails connected in series in my bathroom. I just treat them as one big radiator. Works fine.

Pete

They're 1200mm and within 10cm of each other in the same room. No TRVs as they'd argue with the 'stat.

That's easy to do as a retrofit.

I've done the same sort of thing: needed a 2m single, curver rad. for a bay. It would have been expensive and several weeks to arrive. Use 3-off

I misread some aspects of your post. As you say 10cm is not enough room to put 2 lots of lockshield.

I would plumb in the top pipe as a matter of course. It'll then perform as good as a single rad of the same length.

Done it: increased the distance to ~12cm, 2 angle valves and a 'U' of copper at the bottom. Couldn't join the tops as the rads. have no top unions, only bleed.

In article , PeterC writes

Well done, balance across the pair and the difference in heat output will be next to bugger all.

That's what I've found, Fred: fully open vlves (well, half a turn in) between the rads and the other 2 open the right amount and lots of heat! - but why was I doing this when the temperature in the house was 22C?!!

Added some gunk and filled the system, heated it up a couple of times to get it all mixed in, now leave it for a week, drain down, wash through and refill with a drop more gunk in it - that, I hope, will do it for a few years.

Awkward job getting the additive in as only 1 rad. with top unions. Used a right-angle of pipe on a service valve and a 60ml syringe. Made the mistake of filling the system intending to drain down a bit and add upstairs, then found that I couldn't seal into a bleed hole. Had to turn off all valves except the new one and bow some water out of that to get access.

By the time it needs doing again I'll have forgotten how I did it.