My mother and father live in a council property. 6 plumbers have now attended in the last week to fix airlock problem. They get the water going again only for me to stop an hour or two later. They have fitted 2 new valves in the roofspace and now don't know what to do. Everything was fine until last weekend. New kitchen extension was put in house 6 months ago as was gas heating. Any help appreciated. Plumbers are now talking about taking hot tank out and refitting new pipes through to kitchen. Would this work and why?

In some cases in the UK city water is pumped up to a storage tank in the attic and then gravity fed to the units, Is that the case in your parents building? Does each unit have its own water heater?

Everything was fine until last weekend. What's been changed since last weekend? Your definition of air lock might not be the same as mine, Can you tell me exactly what's happening? Back to you, tom

Yes the water is pumped up into the attic and gravity-fed as you say. The hot water is heated through a separate coil in the water cylinder and doesn't mix with the domestic hot water supply. We have pressurised the system numerous times as the plumbers have also done using mains water. This cures the problem for a matter of minutes and then the water stops again. Nothing at all has changed since last weekend, this all happened out of the blue. Thanks for replying. Any advice much appreciated.

The hot water is heated through a separate coil in the water cylinder Again, we might have a problem with terms, By "water cyylinder" do mean hot water tank? And this coil. What heats it? Does it look anything like outs? (see image) I'll have more questions, Having never worked in the UK. I have to be sure that I understand every thing. I'll be asking questions about your hot water piping next, You say everything works when tied to the main. Then w2hy not leave it connected to the main or isn't the main pressured all the time? Here's a thought. If the hot water system works under pressure why not simply add a booster pump and pressurize the system? Back to you. Tom

Again, we might have a problem with terms, By "water cyylinder" do mean hot water tank? And this coil. What heats it? Does it look anything like outs? (see image) I'll have more questions, Having never worked in the UK. I have to be sure that I understand every thing. I'll be asking questions about your hot water piping next, You say everything works when tied to the main. Then w2hy not leave it connected to the main or isn't the main pressured all the time? Here's a thought. If the hot water system works under pressure why not simply add a booster pump and pressurize the system? Back to you. Tom

Yes I mean hot water tank. The water in the coil also runs through the radiators but never mixes with the water in the hot water tank. (Sorry but can't see your image). Your suggestion of pressurising the system to me seems very feasible but my knowledge is limited and I will certainly suggest this to the plumbers who are dealing with the problem. I'll let you know what happens. Thanks again. Robert

Since this is a gravity feed you wouldn't need a big expensive pump. A recirculating pump,(see image) comers to mind. This could be installed at the outlet of the heater and just help push the hot water along. Sound like a plan? Cheers, Tom