Hi,
hopefully someone can give me a quick straight forward answer to this one. Im re running the old one pipe circuit in my house with a flow and return system and new rads. At the last rad on the system which out of the following do i do?

1: terminate the flow into the last radiator and commence the return out of the other side

2: t into the last radiator at the flow, continue the pipework , turning it into the return and then t into the return from the rad and carry on back picking up the rads?

ive had two sets of advice. My thinking is if i do the first option then any alteration i make to the feed during use on that rad via the valve will affect the return to all the othr rads.

Any answers appreciated and quick as im starting it today!!!

If it's a completely new installation then method 1 would be used with a pressure relief valve between flow and return so the pump can still circulate in the event of all rads being turned off.

chaps maybe i didnt make myself clear, at the moment the rads are all plumbed up on a one pipe system. It doesnt work very well and the rads are old and some need replacing. I am therefor ripping them all out and the pipework. I am then going to pick up the pipework from just after the pump run it as the flow and then pick up the return from the last rad and take it back to the boiler. That will then leave me with a two pipe system.

Hope it now makes sense, so back to the original question!

The hot water is gravity I assume.

below is a basic crude layout for a fully pump system, for gravity primary's a slight alteration is needed.

also need info on the system, is its open vented or sealed, new regs say the the boiler should be interlocked.

for bigger and better drawing send me a email.
scruff

In this case  Jerry he is intending to use 2 x 2port valves so a by-pass would be needed.

scruff

I am then going to pick up the pipework from just after the pump run it as the flow and then pick up the return from the last rad and take it back to the boiler. That will then leave me with a two pipe system.

If you do as you say Thermo that is a one pipe system

gentlemen,
thankyou all so much for your help, especially scruff for going the extra mile. It was all pretty much as i thought and having been scrabblin around under the floorboards the existing one pipe system was well beyond its useful life and a complete botch job. The re-running of it is going well, apart from fighting with that damned coiled up speedfit pipe, its a nightmare to get staright for a pipe run. I am a traditonalist and would normally use copper, but ive got very restricted access so speedfit it is, but im not sold on it yet!

cheers once again for all your help. I hope to be able to repay it with some advice you all may need some day.

thermo

thanks for the tip, but made my own out of bamboo canes, some stirng and wire (sounds a bit heath robinson but hey it worked!) The ain problem i found with the stuff is trying to straighten out the rolls of barrier pipe, as it wants to stay coiled. Ive come to the conclusion that using the straight lenghts is easier for a rehash job, but then you end up with joint in it!