Quick question on heating pipe sizes

[skenk]

My central heating pipes are currently all in 8mm copper microbore. The flow and return go from the combi coiler to a manifold(?) in 22mm copper then branch off on 8mm to the individual radiators under the floor.

I am thinking of buying a plinth heater for the kitchen which has 15mm connections. Am I ok to tap off the 22mm flow and return for the plinth heater in 15mm for connection to the plinth heater or will this draw heat away from the rads? Would I be better tapping off the flow and return before or after after the connections to the rads or does it not make any difference?

Boiler is a Vokera compact 25HE. Only 4 small radiators at the moment.

Thanks for any help
Tim

 

[namsag]

perfectly ok your boiler is more than big enough to cope
Should not matter where you tee in you may have to tweak the balancing

 

[skenk]

thanks mate

 

[muggles]

Why not run 8mm from the manifold (if access is possible) to the plinth heater then increase to 15mm when you get to it? That should sort out balancing issues

 

[kevplumb]

you ever tried undoing a joint on an old manifold muggles

View media item 14390

 

[muggles]

Hehe err no I haven't to be honest, never yet needed to and it seems that you're hinting this may not be simple, I'll remember that. Could still tee into the 22s and run 8mm from there though...

 

[skenk]

Thanks for the input. I just wasn't sure about mixing pipe sizes but the system can be balanced when it's all done. Think I would prefer 15mm for the plinth heater or is it a waste of money on pipe? System will have 1xlarge rad 1x plinth heater (space saver 7) 1x medium rad, 2x small rad and 1x medium towel rail when it's done. Don't have BTU values atm but I believe it's within the boiler spec. Flat is approx 50m^2, 3m high ceilings. Plinth heater ordered

 

[Terrywookfit]

Plinth heaters need a high flow rate due to the low water capacity.

Use 15mm to ensure adequate performance.

 

[skenk]

Yeah that's how I was thinking, thanks