No HW or even flow on primatic system.

Hi, I am in the middle of replacing an old primatic system to a condesing combi system. (With help from a friend who is Corgi). Since I'm living in the house and working I want to do it in stages. I shut off the supply to the single header tank and drained the system (Rads and HW), blanked off the Boiler Feed and return to the cylinder. The plan was so that I could keep hot water for the kids etc and just rip out all the heating/rads/pipes etc first. The boiler feed and return are now capped and the header tank & cylinder full (it has an immersion) but there is no flow at the HW outlet. I know primatic systems use the air bubble do I need to bleed the air locks on the 2 capped pipes ? Any help to restore HW appreciated. I can just crack on with the new system but it will mean a couple of weeks of no HW by the time i'm done.

I guess what I'm asking :-

a) is it because theres an airlock in the HW system, if so can connect mains CW via a hose to the HW (Washing machine) to blast the air lock

or

b) is it because its primatic there is an air lock on the Boiler Feed/Return I've capped

Thanks in advance

I can't see how air trapped in old flow/return pipes could have any bearing on problem. I suspect it is just an air lock in the pipework where it runs slightly uphill (under floor?). Usual way of clearing air lock is to force mains pressure water back along hot water pipes. Use hose to link up mains cold and hot at, for example, washing machine valves, sink taps, etc.

thanks Chris, I mentioned that in my "edit" of the post.

Much appreciated, I just thought that with it being primatic, and me obviously interfering with the air bubble seperation I have someway interfered with it.

I will link the washing machine CW to the HW and give it a blast tomorrow.

I appreciate your prompt response.

Couldn't resist giving it a try, after several seconds blast from the mains CW into the HW via washing machine hose the air lock has cleared.

Boy am I glad I found this forum (No more hassle off the missus now).

I was perhaps being a little over cautious due to my lack of knowledge of primatic systems. I've heard a few horror storys on the net about collapsing cylinders or over-pressurised cylinders (not sure how though since it has an open vent.

Thanks once again for taking the time to reply.