single pipe upgrade

[dexion]

hi all,

thanks for your help on a previous post which has helped me determine that my house has a single pipe system. i'm fitting new rads throughout and some of the older ones did not get hot (possibly they were on the end of the ring) and want some advice about this please.

1) having read a little about the piping of dual pipe systems it appears that the furthest rad with the longest piping from the boiler should have the shortest return pipe in order to balance the relative pressures to all rads. why does this apply if all rads have TRV's as surely adjustment of these would give the same result whilst significantly reducing the work involved in modifying the piping?

2) can i use the current single pipes to best effect for changing to dual piping and use microbore for all the returns as this will be much easier to slip through the current holes in joists etc?

3) where all the microbore returns meet is there a manifold i can buy which will simply join them all together and then into the large pipe which returns to the boiler?

4) the new TRV's expect a 15mm pipe. are there 15mm to microbore solder adaptors which i can fit under the floor boards?

5) does it sound like i don't know enough about what i trying to do???

many thanks

 

[kevplumb]

1) having read a little about the piping of dual pipe systems it appears that the furthest rad with the longest piping from the boiler should have the shortest return pipe in order to balance the relative pressures to all rads. why does this apply if all rads have TRV's as surely adjustment of these would give the same result whilst significantly reducing the work involved in modifying the piping?

how does that work ??

2) can i use the current single pipes to best effect for changing to dual piping and use microbore for all the returns as this will be much easier to slip through the current holes in joists

you could but its not advisable

3) where all the microbore returns meet is there a manifold i can buy which will simply join them all together and then into the large pipe which returns to the boiler?

yes

4) the new TRV's expect a 15mm pipe. are there 15mm to microbore solder adaptors which i can fit under the floor boards?

yes but dont do it

4) the new TRV's expect a 15mm pipe. are there 15mm to microbore solder adaptors which i can fit under the floor boards?

you can get trvs for microbore but don't do it

5) does it sound like i don't know enough about what i trying to do???

no

 

[Nige F]

hi all,

thanks for your help on a previous post which has helped me determine that my house has a single pipe system.
1) having read a little about the piping of dual pipe systems it appears that the furthest rad with the longest piping from the boiler should have the shortest return pipe
2) can i use the current single pipes to best effect for changing to dual piping and use microbore for all the returns as this will be much easier to slip through the current holes in joists etc?

3) where all the microbore returns meet is there a manifold i can buy which will simply join them all together and then into the large pipe which returns to the boiler?

4) the new TRV's expect a 15mm pipe. are there 15mm to microbore solder adaptors which i can fit under the floor boards?

5) does it sound like i don't know enough about what i trying to do???

many thanks

 

[kevplumb]

keyboard broke nige

 

[TicklyT]

1). Balancing is done by adjusting the lockshield valves to control the maximum flow at each radiator. Leaving them wide open means most of the flow will take the path of least resistance leaving little flow to the rest of the system until the first room has warmed up and the TRV has closed. Rooms warming at different rates, or not starting to warm up until others are overheating is a sign of a badly balanced system, whether it is a one pipe or a two pipe system. IIRC that is the symptom you are trying to cure.

2). Microbore is generally considered bad news, especially if you are going to re-use parts of the old system, because it easily gets blocked with sludge.

3) Yes, you can use a manifold, but see point 2).
With a complete change in the system topology, from a 'ring' to a 'star' or a 'ladder', it may be easier to re-pipe everything. You will probably find only the first and last sections are reuseble anyway.

4). You can get microbore to 15mm adaptors, but we're back to point 2). again.

 

[doitall]

There's nothing wrong with a one pipe system, and if, you connected properly it would work just as well as a two pipe system. the only difference is the later is more forgiving if when you get it wrong.