Water was recently cut off for Southwest water works with no problems but on last day when water came back on no water came out of hot water tap. We have an immersion tank.Could this be air?

Are you saying that you have no water in any hot water faucet or is it just one? Do you flush your heater on a regular maintenance schedule? Regards, Tom

Thanks for answer, there is no water from any hot tap at all. We've only been in this house 7 months but I don't think the tank has ever been flushed. When I first turn any hot water tap on a dribble comes out but then nothing ! Could it be that there is no water coming into tank from the mains ? Could this be because of the recent water works?? Blocked? Do I need to get a plumber?? Oh dear :confused:

there is no water from any hot tap at all. I don't think the tank has ever been flushed. If it were just one or two faucets affected I would suggest starting at the faucets but with the entire hot water system down I would start checking at the water heater itself. The fiirst place I would check is the inlet and outlets on top of the heater. If you have heat trap nipples, (see image) installed then shut the water off to the heater and change the nipples for 3/4" brass nipples and nsee if you don't get your pressure back.
I'm going to take a guess here. What might have happened is when the city worked on the line some dirt fell in. The first house making a draw, You, sucked the dirt up intop your service line and the next time you made a hot waterb draw it got sucked into the cold water heat trap nipple where its clogging the flow. Or it could simply be mineral build up clogging the hot water heat trap. But that's where I'd start to check. You should set up a monthly maintenance schedule to keep wour heater clear of mineral buildup.
Let me show you how.
For long life and fewer troubles you should keep your heater clear of mineral build-up by FLUSHING NOT DRAINING on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures that are affected . Now pull each aerator and clean the screens. Be sure you put them back together the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps, Tom