1980's Radiators with only one valve

[George Kaplan]

Hi folks, I need to remove at least a couple of radiators in a house that I have recently purchased. I am not a plumber or heating engineer but I am an engineer (mechanical and hydraulics) so I am familiar with the way things work. However this house has radiators that I am not familiar with. The two pipes come into a block at the bottom of the radiator where one side seems to go straight into the rad and the other goes to the top of the rad via a pipe that connects to a TRV.

I need to remove two of them to work out why they are not heating up fully but cant see a way of isolating them. Before I drain all of the pipes can anyone on here enlighten me as to what these are and as an aside why would you use them. I think they date from 1981 when the house was built.

Thanks in advance, George.

 

[ShaunCorbs]

Thanks, I did wonder if it were to boost the water pressure which isnt great here.

I am replacing all the pipes and creating three separate circuits so I can independently control different zones.

Some of the rads are being replaced now although some will have to wait until next year as I have a finite budget this year.



I didnt know that. I thought injector tee's were used with gravity systems.

However I have never come across a single pipe system before.

George.

Be careful if re using existing rads as you will have to alter the pipework later as most likely be imperial sizes eg width/length of them

 

[George Kaplan]

George - I'm not a plumber as you've probably gathered, but thought you might be amused by my experience of 'one-pipe'.
I lived with a one-pipe system for over 30 years, originally with an oil boiler that sounded like the engine room of an ocean liner, replaced by a Potterton when gas arrived in 1990, then updated with a system boiler a few years ago.
Fortunately it had been designed with 5 'zones', so wasn't 23 radiators all on one pipe! Also some attention had been paid to how the rads had been connected, though there were no injector tees. The sort of thing below.
View attachment 84234
But in the process of "maintaining" it, I did come across the Caleffi valves that allowed rads to be connected literally in series
You can adjust the ratio of flow through the bypass to flow through the rad, so get them to similar and adequate temperatures, though as you see below, Caleffi suggest progressively bigger rads!
View attachment 84235

With a Honeywell Evohome programmer and motorised valves on most rads, it worked well.
I admit more trouble than a proper 2-pipe system, but it did the job!!

Best of luck with the improvements to your system.

Hi Basher, thanks for the comment. My existing system has Caleffi valves already. I have adjusted the bypass in them so that it doesn't work (on the rads that are not being replaced immediately) so that they work on the new circuit.


George

 

[George Kaplan]

Be careful if re using existing rads as you will have to alter the pipework later as most likely be imperial sizes eg width/length of them

Thanks for the tip. The pipes for all existing rads come up through the floor in pairs only about 2 inches apart. When I replace the existing rads I know that I will have to modify the pipes anyway and I am OK with this.


Having spent far too long in the crawl space the pipework is 99% complete. I just need a couple of fittings that I will pick up next week. Once it is all leak tested I will have to go back in and insulate everything.

When I was taking out the old pipes I noticed that most of the system was 15mm but one leg of the system was in what seems to be 18mm pipe which is a new size to me. Anyway its now all replaced with 22mm with 15mm tails to each rad.

George.

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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