extension radiators stay cold.

[rh2705]

I have a central heating system with a piping layout that is obsolete - big bore pipes that go in one big feed/return loop (1" or 3/4" imperial pipes I believe). The radiators are tapped off the big bore pipe with 1/2" 'off shoots'.

The house is very warm in the winter and I don't have any issues with the pipes - they seem to work well - however...

A couple of years ago we had an extension built above the kitchen and garage - two additional rooms were added, two radiators were fitted but they don't really get very warm, and this winter these rooms have been decidedly chilly.

These new radiators were tapped off the big bore pipe using plastic 10mm push fit piping and my own view is the distance from the big bore pipes are just too great for them to circulate any useful heat.

Can anyone advise on plan A, B and C below:

Plan A - Fit a gate valve after the feed to the extension rads to restrict the big bore flow to force circulation to the extension and close it off bit by bit by trial and error until the rooms are warm

Plan B - Fit a Zone Valve controlled from a room stat placed in one of the extension rooms (i.e. divert full flow to extension til temp achieved then close extension pipes, reverting to original flow path)

Plan C - Rip up floor boards, dismantle archaic big bore system and install feed and return pipes

...or is there an easier more efficient fix? Any plumbers in the Swindon area interested in quoting me for this work I would be glad to hear from you.

As usual all help hints suggestions and advice very gratefully received.
Some (very basic) flow diagrams are hopefully attached if they are of help.

Once again, thanks in advance!

My CH piping layout

• rh2705
• 21 Feb 2010
• 1

As far as I can tell without ripping floor boards up, this is how the pipes in my CH system are...

My Extension radiators (blue pipes)

• rh2705
• 21 Feb 2010
• 1

Currently these radiators dont work very well. I believe the distance from the feed/return loop...

basic diagram - radiator connection

• rh2705
• 21 Feb 2010
• 1

A basic view without showing compression fittings or lock sheld valves that shows how the...

 

[tamz]

Firstly 10mm will never work off a one pipe unless the main pipe is directly below the rad.
15mm min.

You could change it to as shown where it "should" work as a 2 pipe to the extension.

Plan A - If you put a valve between the 2 extension tees it will seriously effect the rest of the system due to the 10mm.
Plan B - Rest of house would cool too much while waiting on extension to get to temp.
Plan C - Not really necessary.


View media item 19900 [/img]

 

[stem]

Some of the pipework looks strange on your existing one pipe diagram. On some radiators you don't show the pipe underneath, so turning off that radiator would stop all of the others on the loop working.

If it was me, I would just break into the loop and run it into the extension like this.

Untitled

• stem
• 22 Feb 2010
• 2

Often connecting a two pipe extension to a one pipe doesn't work too well. Keeping it all as a one pipe will maintain the flow consistecy through the system.

Radiators on a 'loop' work best where they are installed directly above the pipe, as in your third drawing.

 

[75pete]

You could try, if not already fitted, changing the tee offs too and from the rads to swept bends/tee but as said, 15mm min.

 

[Bon]

Water will always travel along the "easiest" route, i.e. the route of least resistance. It sounds as if your heating water isn't getting down the newly installed feeds at the required flow rate.

Assuming your existing boiler and pump are capable of coping with the extra demand, the best layout should be to tee off your main to the new rads wherever is most convenient, but connecting the pipe from rads back into the main after the last rad in the system (i.e. before the pipe returns to the boiler).

You can then valve the system so that you're diverting some water down to the rads in the extension without causing problems to your existing system.

 

[rh2705]

Thank you to all posters for your suggestions - it seems the 10mm pipes are totally unsuitable - I remember the plumbers subcontracted by the builder seemed to be in a bit of a hurry and had the work done in one day. Oh well, lessons learned!

Bons idea seems the best starting point in terms of being the least difficult mod, if that doesn't work, tamz idea seems favourite of the other three.

75pete and stem's suggestions would involve a good deal more work - probably best left til summer time methinks!

Your responses, as ever, are truly appreciated - many thanks!!!


Rob H

 

[stem]

If you're going to replace the existing 10mm pipe for 15mm anyway, I don't see much less work involved in any of the solutions.

 

[rh2705]

Stem - I was thinking of trying to reconfigure the 10mm 'to see if it would work' but having had time to mull it over that would be potentially a waste of time - what deterred me was the upheaval of all the furniture in the rooms. On reflection I quite agree with you.

15mm is the way to go!

 

[rh2705]

The more I look at this the more extending the one pipe system appeals - the hard part being laying under the landing floor boards - I can go above floor level in the rooms and box in with those upvc pipe covers.

'Soblem Prolved'! - just need to wait til June when we turn off the CH and I can drain the system.

I wish someone would invent the 'electronic pint' so I can at least buy youse guys a credit for a foaming ale down your preferred hostelry.

in the meantime as a token of my esteem:



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