10mm pipe for radiators max length

[Rich]

As the title suggests I'm trying to find out the max run of 10mm pipe to supply a radiator from a manifold. 

As a rule of thumb Im sure I remember being told 7m, however would that be 7m flow + 7m return or 3.5m for each?

 

would appreciate any input from the collective? 

 

Thanks.

[PeterW]

never heard the 7m rule - think I have seen them at least 10-12m in some properties

[scottishjohn]

your main problem will be balancing the flow  across the whole system if you have small bore and std size piping 

,but that you can sort out when you are done with the flow valves on the rads

the water will take easiest way to flow  so you will need to cut flow to std piped rads  to make it go round small piped ones

I had same problem as builder had used 10mm upstairs and 15mm on ground floor  + just left all flow valves fully open ,so a lot of messing about to get even temp on all rads .

It had a 15mm to upstairs then split off to 10mm to go to bedrooms 

and of course sod all insulation on 10mm copper -so part of the heat was going into the building before it got to rads

 

 

Edited April 3, 2019 by scottishjohn

[SiBee]

Never heard that 7m rule either?

For what its worth, our existing house is a relatively new build  (4/5 bedroom) and all the rads are fed off and return to 22mm branches. These branches have been made as long as is practicable though. I replaced the boiler last year and two of the nearest rads have since  been run in 15mm. Yes it takes a bit to balance the system and the new fancy designer panel rad which happens to be furthest away from the boiler takes a while to heat, even now. So, it can be done. Thing with microbore is that a poor bend will restrict the flow massively as will not de burring cut ends and poor soldering. For anyone not used to plumbing, its easy to not get a good seal on the compression joints such as at the rad valves. its too easy to over tighten the joint. 

All our plumbers (old boys) hate micro bore, say it can block up easy like?

Did I put you off☺️ its easy to run in though.      

[Rich]

7 hours ago, PeterW said:

never heard the 7m rule - think I have seen them at least 10-12m in some properties

 

5 hours ago, SiBee said:

Never heard that 7m rule either?

For what its worth, our existing house is a relatively new build  (4/5 bedroom) and all the rads are fed off and return to 22mm branches. These branches have been made as long as is practicable though. I replaced the boiler last year and two of the nearest rads have since  been run in 15mm. Yes it takes a bit to balance the system and the new fancy designer panel rad which happens to be furthest away from the boiler takes a while to heat, even now. So, it can be done. Thing with microbore is that a poor bend will restrict the flow massively as will not de burring cut ends and poor soldering. For anyone not used to plumbing, its easy to not get a good seal on the compression joints such as at the rad valves. its too easy to over tighten the joint. 

All our plumbers (old boys) hate micro bore, say it can block up easy like?

Did I put you off☺️ its easy to run in though.      

 

I was told This on 2 separate occasions however it was some time ago. Just to clarify it is 10mm plastic I was planning to use not copper, not sure if that makes any difference, hopefully I have been missinformed as it would make life much easier. 

 

 

6 hours ago, scottishjohn said:

your main problem will be balancing the flow  across the whole system if you have small bore and std size piping 

,but that you can sort out when you are done with the flow valves on the rads

the water will take easiest way to flow  so you will need to cut flow to std piped rads  to make it go round small piped ones

I had same problem as builder had used 10mm upstairs and 15mm on ground floor  + just left all flow valves fully open ,so a lot of messing about to get even temp on all rads .

It had a 15mm to upstairs then split off to 10mm to go to bedrooms 

and of course sod all insulation on 10mm copper -so part of the heat was going into the building before it got to rads

 

 

 

Im using a underfloor heating manifold to distribute so I'm hoping to use the flow valves on that to balance. 

[Nickfromwales]

OK, why 10mm ? Lets start there  

[Rich]

16 minutes ago, Nickfromwales said:

OK, why 10mm ? Lets start there  

 

If I'm honest, purely because it's easy to work with/no joins from the manifold to rad. 

The last time I tried a coil of 15mm plastic it was a nightmare or am I missing a trick? 

[Nickfromwales]

20 hours ago, Rich said:

 

If I'm honest, purely because it's easy to work with/no joins from the manifold to rad. 

The last time I tried a coil of 15mm plastic it was a nightmare or am I missing a trick? 

Get some LayFlat JG or Hepworth and it’s nowhere near as a pita as the generic push fit stuff is. 

I’ve just put about 400m of 15mm through a 2-storey TF and it was a doddle ( with a pair of helping hands ). 

The flow rate with 10mm is very low, and you’ll notice a house piped with a mix of 10 & 15 will show just how different they are. If you’re going 22mm backbone to 10mm legs throughout then you’ll be fine, but you should choose one discipline and stick to it.   

Hepworth ( aka Hep2O ) also uses wafer thin stainless inserts so the internal bore isn’t compromised. The JG ones are terrible by comparison and choke the pipe at every joint / junction ?

[Rich]

On 04/04/2019 at 18:56, Nickfromwales said:

Get some LayFlat JG or Hepworth and it’s nowhere near as a pita as the generic push fit stuff is. 

I’ve just put about 400m of 15mm through a 2-storey TF and it was a doddle ( with a pair of helping hands ). 

The flow rate with 10mm is very low, and you’ll notice a house piped with a mix of 10 & 15 will show just how different they are. If you’re going 22mm backbone to 10mm legs throughout then you’ll be fine, but you should choose one discipline and stick to it.   

Hepworth ( aka Hep2O ) also uses wafer thin stainless inserts so the internal bore isn’t compromised. The JG ones are terrible by comparison and choke the pipe at every joint / junction ?

 

I used a roll of 15mm hep as a bit of a trial earlier today and wow! What a difference. 

Thanks for the advice it really is so much easier to use.

 

now I'm thinking 15mm from the manifold, then a 15mm st with a 10x15mm spigot elbow under the rad, bringing the last 1m up in 10mm for neatness (10mm out of the wall behind the rad to keep pipework out of the way)

is this an acceptable solution? All individual feeds/returns fed from a ufh manifold with 15mm Eurocones allowing each room to be zoned. 

[Nickfromwales]

On bigger radiators you'll need to balance well, but yes, should be fine reducing at the radiator. I've done it a bunch of times as it does look a lot neater.

Why go with the grief of the manifold? Hepworth stuff is bombproof, so you could just plumb generically ( series, descending in size 22 > 15 ) with tees at each rad. Then for zoning go for an open-source TRV system with a central hub + wifi.?

[Rich]

On 07/04/2019 at 10:15, Nickfromwales said:

On bigger radiators you'll need to balance well, but yes, should be fine reducing at the radiator. I've done it a bunch of times as it does look a lot neater.

Why go with the grief of the manifold? Hepworth stuff is bombproof, so you could just plumb generically ( series, descending in size 22 > 15 ) with tees at each rad. Then for zoning go for an open-source TRV system with a central hub + wifi.?

 

Open source trv system? Do you have a link?

ive just had a quick google and i can only find the big brand systems which seem a little limited for how expensive they are. 

 

I would appreciate the simplicity of installing the heating in the "standard" way. But ideally would like to zone each room independently. 

Maybe wired actuators at each rad and a stat in each room all wired back to a central wiring centre? Or would that be a bit old fashioned in the wireless world ? 

 

Edited April 8, 2019 by Rich
Typo

[Nickfromwales]

9 hours ago, Rich said:

 

Open source trv system? Do you have a link?

ive just had a quick google and i can only find the big brand systems which seem a little limited for how expensive they are. 

 

I would appreciate the simplicity of installing the heating in the "standard" way. But ideally would like to zone each room independently. 

Maybe wired actuators at each rad and a stat in each room all wired back to a central wiring centre? Or would that be a bit old fashioned in the wireless world ? 

 

It’s just binary, on or off. A TRV operates proportionally so offers smoother heating curves. I’ve done one house as you’re proposing, but tbh I wouldn’t do another like that as the room is hostage to the hysteresis of the stat. That’s fine for a centrally mounted room stat with a decent reference of the ambient, but not so great for a room with say 3 outside walls and big windows etc where a finer degree of control ( TRV ) would perform better. 

I don’t have links, but a bit of searching on here will dig up info on what others have used.   Heatmiser gets a few mentions, but Honeywell, Nest and Hive etc seem quite robust solutions, just I’m not familiar with them as I’m mostly now servicing passive ( ish ) clientele on single central stats.