One Pipe system

[chestercity]

A plumber was to add some radiators but disappeared so I shall attempt it. However he said something about the one pipe system needing 'swep t's'. Is this the case?

Many thanks

 

[simond]

It will work better with them, but not vital.

I think you will be surprised how much they cost.

Extending one pipe systems would worry a few 'pro' fitters, so make sure you know what you are doing.

 

[75pete]

When I did a one pipe back in the 1970is, it was with swep tee as you say. You need to ensure your flow and return from and to the new rad is not close to each other, think it's 3ft ish but do check. With this tee, you reduce down to the rad to 15mm pipe. Also, this type of tee will give a better flow, reduced turbulence but as said, expensive and don't think you can buy solder ring type, so end feed. I would only use this type on your system.

 

[Agile]

The best and easiest one pipes in domestic places have a pipe bypassing each rad underneath with a restricting valve ( or even just a length of 15 mm between 22 mm ).

But even many professionals are not very confident with this type of system.

Most would advise a DIYer to convert to a two pipe system as that's far easier and does not suffer from any of the problems that a one pipe can give.

Tony

 

[chestercity]

Thank you all for your prompt replies. I think the plumber legged it because he had underestimated the time. He had relied on my guesswork as to where the pipes were located to feed from. I later had a better look under the suspended floor You can crawl under the house easily). I realised he had located a new rad and was going to connect it to the main gas feed! Also I worked out that I would need to break through block walls to feed to the correct pipe. So I think he thought it would take too long and hadn't the time.
He said the Tees were £10 each. Not a big cost if I save on labour!
I can see 22mm is used with 15mm fed to rads. My main concern is draining the system, only because I haven't done it before and if anything leaks etc its v time consuming to do again! Bad weather and idea of it going wrong is a concern but I do prefer, with advice, to do my own work. Only got in the plumber because I had too much other work on the house.
I'll make a decision in the next week.....

 

[St0rmer66]

It will also work better if you put the flow pipe to the top entry of the radiator and return at the bottom.

 

[Agile]

We know nothing about your boiler!

If the one pipe is in 22 mm then I would use standard tees and add an adjustable valve into the 22 mm pipe which bypasses each rad to aid balancing.

Tony

 

[simond]

Oh dear.

 

[chestercity]

My Boiler: Freestanding Ideal Mexico2. Old but regularly serviced and seems fine

I see some rads have been upgraded before and the flow and entry of these are both at the bottom. They work fine.

Its all on one floor (bungalow) so that probably benefits circulation(?)

I am going to go 'underground' and take a look again to see where I can T off from. A drawing may help and the odd photo!

 

[Agile]

You don't "Tee" off in the normal sense with a one pipe.

You reroute the one pipe to the new locations!

Better to measure the flow and return temperatures when it has stabilised.

In many ways it may be better to add new rads as a new parallel circuit ! They will better suit a replacement boiler which may not be many years away.

Tony

 

[chestercity]

Thanks Tony.
Not sure how i would add a new parallel circuit...?
A few images showing ones that have been added after original installation I would think, together with pic of a TCV and drain 'tap' (can i drain whole system from here?)
I need to go under house again and will see how they have taken the 2 rads pictured from circuit

 

[stem]

That doesn't look like a one pipe system. With a one pipe system, the rads all sit on erm...one pipe that runs around in a loop, like this

Untitled

• stem
• 21 Nov 2014
• 1

For comparison, a twin pipe has two pipes that supply the radiators. The clue is in the name.

Untitled

• stem
• 22 Dec 2010
• 1

 

[chestercity]

Thanks. Yes, I get all that but I believe the two pictured are bad examples/confusing. They are taken off main run. I need to go underground and take a pic.

 

[chestercity]

I have crawled about under floor and its One pipe(see photo)

Here is a drawing...is this how i run pipe to one more rad?

 

[St0rmer66]

There's no way that would work on a 1 pipe system unless it was literally in series with the main loop. You must have a 2 pipe.