New hot water system no flow

[fidom]

I have ripped out all the old rusty iron water pipes in my bungalow and started again from scratch using push fit plastic and copper pipes. I have also taken out the old mains pressure electric water heater and put in an indirect cylinder system. This is intended for use with a solid fuel boiler on pumped CH, gravity DHW. I have raised the cylinder to just above the top of the boiler. The cold tank sits directly on the loft floor, which is concrete. Pipe from cold tank to cylinder is 22mm as is the hot and gravity cold plumbing to the shower mixer/bath taps. I get a good flow on the cold at the mixer but only a tiny trickle on hot. There is no flow at all at the wash basin on hot. I'm wondering if the problem is that the hot pipes are too high up. From the cylinder the pipe goes up through the ceiling then runs along the loft floor then down into the kitchen then through the wall into the bathroom. The kitchen hot is currently blanked off as the sink unit is not fitted yet. I thought it would work as the water level at the top of the cold tank is still higher than the hot water pipe but perhaps not? Could it just be an air-lock?

 

[gasmanstu72]

sounds like its air locked, that pipe that runs along the loft floor will probably be half full of air as its just under the tank.
the way to clear it would be to open a mixer tap with both hot, and cold mains and let the mains water blast it through whilst you hold your hand over the tap outlet.
but you say you kitchen tap isn't fitted yet, could you temp something up to allow you to try this?

 

[fidom]

Thanks Stu, yes it is now sorted. I took off the blanking plug in the kitchen and fitted a bibcock and it flowed fine through that and the other taps now work.