Vertical Rad issue on a 1 pipe heating system

[Sfc]

Evening guys, Just wanted to pick some brains about an issue i'm currently having with a vertical rad on a 1 pipe heating system.

Kitchen that has been converted into an open plan kitchen diner. We've taken out a large double rad and installed 2 single verticals in different locations. One rad isnt getting any heat at all. Have tried balancing the system even closing all lockshields throughout the property and can't get any heat to one of the rads. I thought it was an issue with a blockage or air lock inside the rad as when i opened the nut of the lockshield and pulled through with the wet vac it heated up straight away. Both radiators are exactly the same and fitted in the same way with the same valves etc. Can't quite work it out!

Boiler is a new Vailant heat only fitted by an engineer around 6 months ago.

 

[SimonG]

Not going to balance anything on a 1 pipe system

Need to look at how you've piped it.

 

[Sfc]

Not going to balance anything on a 1 pipe system

Need to look at how you've piped it.

Kicking myself now after reading up elsewhere too. Have teed off a run around 3 metres to the new rad. Have a feeling ive broken the loop and should've taken pipework around to the rad and back. Seems like its just bypassing the tee now and not sending any heat that way.

Any thoughts on trying to rectify or attempt to balance without taking up a lovely herringbone flooring thats been laid

 

[ShaunCorbs]

Nope sorry vertical rads arnt suitable for single pipe systems

Tbh should of been converted to a two pipe system years ago

 

[Sfc]

Nope sorry vertical rads arnt suitable for single pipe systems

Tbh should of been converted to a two pipe system years ago

To be fair their are 2 others in the house that work perfectly ok. It is a nightmare of a system to work on mind you!

 

[Basher]

You may already know this - Caleffi make thermostatic valves for one pipe systems, that can divert the flow to the radiator by throttling the straight through path. I think there are differential models that open the rad valve and throttle the straight through path simultaneously.
This sort of thing, but different models available:

https://www.caleffi.com/sites/default/files/file/01323_en.pdf

It would mean you would have to close off the 'straight though' path to route the one pipe through the valve, which may not be practicable given your new flooring?

Everybody slags-off one pipe these days, but my experience is it can and does work with a bit of patince and the right components (maybe with the possible exception of some 6kW tall radiators )

 

[Last Plumber]

The rads on a one pipe system work by gravity so the route of the 'loop' as you call it is important and the position/distances of the connections that supply it are important too.
You can't balance it as you think. The only thing you could do in my opinion, which would definitely work without altering the pipework or rads to that radiator is to convert the system to two pipe. Obviously I haven't seen it.

 

[Sfc]

The rads on a one pipe system work by gravity so the route of the 'loop' as you call it is important and the position/distances of the connections that supply it are important too.
You can't balance it as you think. The only thing you could do in my opinion, which would definitely work without altering the pipework or rads to that radiator is to convert the system to two pipe. Obviously I haven't seen it.

Cheers for the reply! What would be the best way to convert to a 2 pipe without touching the existing run or rad pipework?

This could be achieved if it’s something that can be done off the boiler or cylinder.

Cheers

 

[Last Plumber]

Cheers for the reply! What would be the best way to convert to a 2 pipe without touching the existing run or rad pipework?

This could be achieved if it’s something that can be done off the boiler or cylinder.

Cheers

You would need to convert all of the system really. I have seen a few where there is a mixture but they do not work correctly.
You would generally need to run a second pipe around the property to all rads.
Have a look at this diagram. The top system is a one pipe, the bottom is two. It isn't a DIY job in my opinion but I suppose it depends on your level. There is more involved than an additional pipe.

 

[Basher]

You could try one of these!

 

[Ric2013]

#6 should not be undervalued as advice and I'm just going to expand on it. There are a lot of one-pipe systems still in use abroad, but they work them rather differently from how Last Plumber is describing them.

One pipe systems can exist in two variants:

One type, as described by Last Plumber, may have a pumped loop (though that could be gravity too, in the unlikely case it's out of the ark) but gravity circulation through each radiator as shown in #9.

The other type has the flow run in series through each and every radiator. This is common in Italian appartment buildings which have a single heating system for multiple dwellings. To allow individual householders control over their individual radiators, the valves used are similar to the Caleffi ones Basher has linked to. When turned OFF, the valves do not stop the flow through the one pipe loop, but merely allow the water to bypass the individual radiator. In this case, the water flow is pumped through the radiators as they themselves form part of the loop.