Strange Pipe Run. But Will it Work?

[stem]

We are having a new bathroom installed by a local company that are highly recommended and so far their attention to detail and quality of work has been excellent.

However, the plumber has moved the bathroom radiator which is on a one pipe system. My understanding is that the pump circulates water around the one pipe loop and the radiators sit atop it and the water circulates through them more or less by gravity. The plumber has used the existing 15mm tee for the flow, but instead of going up to the radiator, it now goes down and underneath the one pipe. I would like to mention this before he finishes the system off in the morning, but am I missing something?

The top diagram shows how I imagined he would change the system, but the one underneath is how it has been done.

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• stem
• 19 Feb 2013
• 1

 

[ALEC1]

It will work, assumng he uses the right valves..however, your method would be far more preferable than the one installed.

He may be using tees that have a "scoop" to ease the flow of water to the radiator..

and being single pipe it begs the question is the radiator correctly sized?

 

[stem]

It used to work fine, as does the whole system. I was going to change it to a two pipe when I bought the house 15 years ago but as we're always warm and toasty and the bills are smaller than our neighbours, I've left it well alone.

No the tee's are normal, they were the ones I installed when I added the original radiator.

I still don't see how when warm water rises it will manage to fall, and the pump won't help as the pressure on the rad flow and return are equal being off the same pipe, but I'll keep quiet if you think it's OK and we'll see tomorrow.

 

[ALEC1]

single pipe installs rely pn the pressure dfferential between the two teed off ppes...

The way the new radiator has been installed will work, but it will take longerto warm up than the others which I assume are installed as per your drawing..

NOTE it is very important that the right valves are used...is this the case?

 

[stem]

single pipe installs rely on the pressure differential between the two teed off pipes...

Exactly! I don't see that there will be any differential the way it is piped. The pressure on the flow and return tee's will be virtually the same, as they are close together. How much pressure drop is there on 0.5 metre of 22mm pipe. Certainly not enough to overcome the the resistance of the 15mm flow to the radiator IMHO.

I don't know about the valves, they are not there yet. Before it was a Terrier II TRV and standard lockshield, and the radiator was too hot to touch when it first came on.

 

[Whitespirit66]

The golden rule with one pipe, is short tails from the main flow pipe. Your top diagram looks right. The bottom one doesn't look right for one pipe. The output from the rad will be affected.

 

[stem]

So now is the time for me to eat humble pie. Got home tonight and bathroom radiator was hot with the pipework as it was. but at least it was a happy outcome.

 

[gigz]

So now is the time for me to eat humble pie. Got home tonight and bathroom radiator was hot with the pipework as it was. but at least it was a happy outcome.

Good of you to tell us this, too many customers just slag us off and don't tell the full story.