inhibitor + gravity issue

[mk2phil]

I've just renewed most of my central heating pipework, replacing an old microbore setup with 22mm and 15mm spurs accordingly. #

All the old rads have been disconnected from the system, and so far I've only been able to connect 3 new rads to the new pipework - waiting for the next few weekends to install the remaining 5 onto the system. I haven't put any inhibitor in the header tank yet, just refilled the system to check for leaks and have been running on normal water since Sunday. How long can I leave it before I should add some inhibitor to the system (X100???)?

I'm also getting a 'rushing water' sound in the pipes - is this air that needs to still be bled?

Also, because the HW is gravity fed, when the HW is selected the radiators are getting hot but the gravity pipework isn't. The only way I can get it to work is by running the CH and HW together.

Is this largely due to the fact that I only have 3 rads on the system at present? When I had the old microbore system this didn't really seem to be a problem so I assume the smallbore pipework didn't offer a prefereable route for the gravity heat, but now I've upgraded all the pipes to 22/15 its choosing this pipework to travel instead of the 28mm gravity pipes.

I'm planning to change the system to fully pumped at some point anyway, but in the meantime I'd like to solve this issue if possible.

Thanks

 

[gas4you]

Certainly sounds like serious air in the system. Has it filled up correctly?

Is the f&e tank full. Are these 3 rads upstairs or down? I wouldn't leave it more than a few weeks before you complete, then put a cleansing chemical in , run according to MI's then darin and refill with inhibitor.