10mm plastic - maximum radiator pipe run?

[nj53]

We have a 300x2000 (7000 Btu) double radiator in our lounge, which is approx 20m from the manifold (40m flow+return). Needless to say it don't work very well !!!

I have tried tuning the system but it's not helped by the fact that the installer used 15mm plastic upstairs and 10mm downstairs.

The pipework is buried in the floor and it would be a right pain to lay new pipes. The easier option would be to add another radiator.

Any advice on what the limits are on maximum pipe runs in 10mm plastic?

Thanks in advance.

 

[mountainman]

I don't know specifically but that is a heck of a run and from an experience point of view I would have used 22mm.

 

[nj53]

I don't know specifically but that is a heck of a run and from an experience point of view I would have used 22mm.

The reason it's 40m is because the manifold is at the back of the house, the radiator is at the front, and the pipework runs all the way around the outside walls. If he'd taken a straight line, routing out the floor, it would have been less than half the distance.

When the C/H comes on it, it takes several minutes for pipe at the TRV to get hot.

 

[mountainman]

I accept your reasons for the pipe run length but it doesn't alter the fact that the pipe is considerably undersized for what it is being asked to do.

There are calculations that could prove this fact in the same way as gas pipe sizing but anyone who knows their job would have had reservations about doing that run in 15mm let alone 10mm.

 

[nj53]

I accept your reasons for the pipe run length but it doesn't alter the fact that the pipe is considerably undersized for what it is being asked to do.

There are calculations that could prove this fact in the same way as gas pipe sizing but anyone who knows their job would have had reservations about doing that run in 15mm let alone 10mm.

I totally agree with you. Had I known at the time what I know now, I'd never have let the plumber do it this way. I also wouldn't have let him put 15mm upstairs and 10mm downstairs.

 

[AWheating]

i would not run 10mm longer than 5m, this will give you 10m in total flow and return length. Most plastic manufactures state around that length for 10mm.

and any rad above 2.5kw i would go to 15mm.

 

[REDSAW]

10mm plastic restricts down to around 6mm internally after the inserts etc. so thats like peeing down a straw!.

are you sure part of the run is not in 15mm then to 10mm?.

further more, i wish i had a sixty foot deep house1!

 

[Best]

I wouldn't use 10mm, but if I had to, I would have more than one manifold so the 10mm has a short run. I would have thought even 5 or 6m of 10mm is a long f & r distance - try blowing through that length!

 

[tamz]

We have a 300x2000 (7000 Btu) double radiator in our lounge, which is approx 20m from the manifold (40m flow+return). Needless to say it don't work very well !!!

:rofl: What can i say :rofl:

 

[nj53]

10mm plastic restricts down to around 6mm internally after the inserts etc. so thats like peeing down a straw!.

are you sure part of the run is not in 15mm then to 10mm?.

further more, i wish i had a sixty foot deep house1!

The house isn't 60' deep. It's 7m deep by 11m wide. The pipes run 8m along the back wall, 7m down the side, then 5m across the front. They are behind the skirting/plaster board.

               8
 ------M--------------
|                     |
|                     |
|                     | 7
|                     |
 -------------R-------
                   5

All the pipes coming out of the manifold are definitely 10mm.

 

[mountainman]

Assuming that your stuck with this pipework then your only realistic option is to increase the water flow through the system.
Can you fit a higher head pump eg a 15/60.

 

[nj53]

Assuming that your stuck with this pipework then your only realistic option is to increase the water flow through the system.
Can you fit a higher head pump eg a 15/60.

My current thinking is to add another radiator. There is room to fit a 600x700 double on another wall which is 6m from the 22mm manifold.

 

[mountainman]

Good idea, the new radiator will heat up quicker if it's nearer the manifold and the other rad probably won't heat up at all.

 

[nj53]

Good idea, the new radiator will heat up quicker if it's nearer the manifold and the other rad probably won't heat up at all.

It doesn't heat up much now, so no loss there.

Thanks to everyone for all the feedback.