Connecting flow and return on radiators

[Retroelec]

Hello
I have been told that I can connect a new radiator circuit to the pipe work in the airing cupboard.
I guess the flow can be teed off below the zone valve?
Where do you pick up the return from?
It’s a s plan system and in this forum I have heard about the last tee. Is this where the pipe at the bottom of the cylinder joins onto the the return?
Should it be taken back to the landing and joined there?

 

[Retroelec]

Tried to get a better picture of it all.

 

[ShaunCorbs]

Think the set with the brass reducing tees are your rads

Easy way to tell

Turn the heating onto your rads and see which ones get warm

The shiny ones should get hot in both heating and hot water

 

[Retroelec]

Thanks for the reply.
The left one is the pipe from below the pump and heating valve that goes to the rads so can I tee the new in anywhere below the valve?
The middle one is return from rads and this tees off to the bottom shiny pipe and carries on in 15mm to the tee at the bottom of the tank.
The one on the right goes up to that can shaped thing.
Can the return be teed in anywhere in the airing cupboard or can it be between the on the right hand dull pipe?
The dull pipes are the rads. The hot and cold are just below these.
Thanks again.

 

[fixitflav]

in this forum I have heard about the last tee.

If by that you mean all the rad returns must be commoned before joining the cylinder return, that's right. Otherwise you'll have rads getting warm when HW only is called.

 

[ShaunCorbs]

normally only a problem with 3 ports not 2

 

[king of pipes]

Employ a plumber for a day is it really worth risking flooding your home it may look easy but it not . kop

 

[fixitflav]

normally only a problem with 3 ports not 2

Not with you there. On S-plan, if it's piped wrong and HW only is calling, so the CH valve is closed, there can be reverse flow through 1 set of rads, then forward flow through the other set, and back to the boiler.
From the pics the OP has posted it's anybody's guess where the connections are!

 

[Retroelec]

Thanks for all the replies guys.
I know it’s a nightmare trying to advise diy people on these forums and to make matters worse for you I’m a sparky!😉
Extension was first fixed by a plumber about 4 years ago. 2 rads up 2 rads down and an en-suite.
He has since moved away and I have been let down quite a few times by other plumbers, not sure if they don’t want to connect someone else’s work.
Really just want to make sure the pipe work put in isn’t leaking before it finally gets tacked downstairs as upstairs is all done and all rads are all on apart from one.
If I tee in here which are definitely the rads is this as good as anywhere going from the limited info I have given?

 

[fixitflav]

If I tee in here which are definitely the rads is this as good as anywhere

Do you mean teeing new rads in where marked? IMO impossible to say without seeing the complete system.
Attached sketch shows water flow path if the rad returns are not commoned before joining the cylinder return. Diverter valve DV is in the HW position. You have two 2-port valves but that makes no difference. It's because the water has 2 parallel paths to the boiler, the short way, or the longer way via the rads. It's surprising how big the effect is.
If you follow the return pipe back from the boiler you should find the cylinder return connection, then one rads return, then another rads return, and maybe more if more than 2 zones. If you find one of the rad returns first, then the cylinder return, as in the sketch, there's a problem.

 

[ShaunCorbs]

Do you mean teeing new rads in where marked? IMO impossible to say without seeing the complete system.
Attached sketch shows water flow path if the rad returns are not commoned before joining the cylinder return. Diverter valve DV is in the HW position. You have two 2-port valves but that makes no difference. It's because the water has 2 parallel paths to the boiler, the short way, or the longer way via the rads. It's surprising how big the effect is.
If you follow the return pipe back from the boiler you should find the cylinder return connection, then one rads return, then another rads return, and maybe more if more than 2 zones. If you find one of the rad returns first, then the cylinder return, as in the sketch, there's a problem.
View attachment 35413

Right pipe (dirty) is return
Top pipe going to that is cylinder return (15mm)
Horizontal pipe coming off that is main boiler return

 

[Retroelec]

Yes 2 shiny pipes are from boiler.
Return is teed one way in 15mm to bottom of cylinder then 22 the other that goes to the rad returns on the dirty pipe.
Can I tee the return from the new pipework between the cylinder tee and the return tee or is this too close

 

[fixitflav]

Yes 2 shiny pipes are from boiler.
Return is teed one way in 15mm to bottom of cylinder then 22 the other that goes to the rad returns on the dirty pipe.
Can I tee the return from the new pipework between the cylinder tee and the return tee or is this too close

View attachment 35415

View attachment 35416

View attachment 35417

If the marked pipes are original rad flow and return pipes, and your extensive mods haven't violated the principle of commoning rads return first, it should be OK.
I assume the common boiler return is 22mm, so the 15mm cylinder return must tee into it somewhere. If the rads returns are commoned before that point, it's OK. If a rads return comes in downstream ie closer to the boiler, that's wrong. I can't tell from the photos.
Don't know what you mean by too close, as long as you can install it should be OK, perhaps somebody will comment.