>no header tank then how would this system be topped up?
when you can have a look at the copper cylinder if it has a label on the side saying primatic it only has one header tank instead of two that is for your water supply for the copper cylinder and heating. it is seperated by a air bubble in the copper cylinder. the air bubble is easerly lost when draining system, the art of keeping the bubble when refilling is to fill the system slow.
they are an horrible system fitted when central heating first got going in the early 70s, very few about now.
and to stop it filling while draining just surport the ballvalve in header tank. (tie it up so it don't drop)
to get a better understanding type primatic systems in to google.
>Does the header tank have to be directly above the boiler?
no can be anywhere, as long as it's higher than the
>straight joint without a stop so it slides along the pipe
don't use plastic pushfit. brass compression joints that have the olives will be ok
or if your soldering yes you can get a straight coupler that slides they are called slip couplers. they don't have the indent in the middle to stop it sliding.
where are you located ?
don't try b&q, go to plumbcentre or any descent plumber's merchant. they help you better with the slip couplers.
hi-spec plumbing, June 2007