New boiler to a single pipe system?

[gas4you]

You do not have to have TRV's fitted to any boiler upgrade job.

I didn't fit any to my job as the valves were all ancient and had to be retained for the 'character' of the house.

I had plenty of exclusions in my paper work though absolving me from any problems later.

 

[outmyway]

How much of an effort would it be to convert to a twin pipe system?

I gues some of the existing pipework can be used, and we are having to run new 22mm HW pipes from the garage (boiler) into the airing cuboard (central location in the house).
So their will already be some dispruption to floor boards etc ...

Plus I'm already having quotes to replace the older 70's rads with modern ones, so already every rad will be off during the boiler replacement.

 

[kevplumb]

i have fitted many boilers into 1 pipe systems and i have never had any problems at all.
it is advised to update to 2 pipe but as long as you give the best advice to the customer then there is normally no problems ..

Bet you havn't fitted a Keston to one then lol

who in their right mind would want to

the things are sheds

 

[tamz]

How much of an effort would it be to convert to a twin pipe system?

I gues some of the existing pipework can be used, and we are having to run new 22mm HW pipes from the garage (boiler) into the airing cuboard (central location in the house).
So their will already be some dispruption to floor boards etc ...

It will be easier and probably cheaper to repipe the lot from scratch.

 

[gas4you]

I didn't have the option with my job. They had had new laminate floors laid before they decided to upgrade the boiler

 

[outmyway]

Could my plumber measure the delta T on my existing setup to see if its within limits for my new boiler?

I guess the delta T is a function of the pipe work and should be the same with any boiler?

 

[simond]

Most one pipe systems will work just fine with modern condensers, we have used Kidd, Bosch and Vaillant front ends on old one pipes with no issues.

The temp loss at the last rad is not really noticeable.

TRVs can still be fitted, you just have to use the full bore derivatives, Drayton and Honeywell have such versions available, in fact I have three on my van!

 

[outmyway]

Thanks simond - reasuring ... Looking at Bosch Highflow 550's

Still would have thought TRV's would potentially block off flow downstream?

 

[tamz]

Still would have thought TRV's would potentially block off flow downstream?

Not at all and as long as nobody has been altering it in the past few years

 

[stem]

If I turn off a rad on a any floor then all the rads on that floor go cold.

Something funny here. Surely, that must mean that the radiators must be connected so that the return from one radiator is piped directly to the flow on the next, (as top diagram below). If you fit TRV's to the system you describe, when one room warms up and the TRV closes, they will all go off. I have a one pipe system where all radiators, bar one, are fitted with TRV's and sit atop a common loop, so turning one off doesn't affect the others, as bottom diagram.

Untitled

• stem
• 12 Apr 2010
• 1

 

[outmyway]

Your diagram sums it up ....

Something funny here. Surely, that must mean that the radiators must be connected so that the return from one radiator is piped directly to the flow on the next, (as top diagram below). If you fit TRV's to the system you describe, when one room warms up and the TRV closes, they will all go off.

Yes - correct - I have removed floorboards expecting to see a pipe underneath each rad but their isnt one!

I have a one pipe system where all radiators, bar one, are fitted with TRV's and sit atop a common loop, so turning one off doesn't affect the others, as bottom diagram.

Thats what I was expecting to see on my system.

Someone has worked on the system in the past, probably to zone my upper two floors into two seperate loops - Each of these loops run into seperate motorized valves near the boiler. But each loop has 5 or 6 rads in series.

 

[stem]

In that case individual control will be impossible. But on a positive note, in theory, I would expect a better temperature differential across your boiler than with the standard 1 pipe layout