Airlock? in hot water system

[Scotsmale]

Some time ago we had a condensing boiler fitted literally should have been one out one in, but ever since then our hot water gradually slows to a trickle.
We called the plumbers who fitted the new boiler and they sent another sefl employed guy round to look at it, who told us to hold our hand over the mixer tap in the bathroom blocking the outlet and then slowly turn on first the hot water then the cold water and hold that for as long as we could or until we heard the air bubbling into the hot tank.
Obviously we were not happy so called the original firm who then denied any responsibility and despite numerous attempts would not even call round,so this is the fix we have been doing for the last few years but now it doesnt seem to work for as long or as well as it used to.
I am plumbing novice so any helpful suggestions welcomed.

 

[Armo74]

Check the water level in the header tank.
Check that the gate valve is fully open on the cold feed that goes into the bottom of the cylinder.
Check all isolation valves are fully open.

 

[jeff the gasman]

It's unlikely to be the fault of someone fitting a boiler. Due to the fact they don't drain hot water systems when fitting them.
Sounds like an air lock in the cold feed to the cylinder. Get someone to have a look.

 

[ALCPlumbing]

I once attended a job with a similar problem. Flow from the hot outlets had reduced to a trickle. I assumed an air lock but actually the outlet on the cylinder had scaled to the point of nearly stopping the hot water all together. Does this sound similar to what you are experiencing? This effects all outlets. Air lock or poor head may effect the upstairs bathroom on its own.
J

 

[stardanny]

Did they replaced the cylinder when they done the boiler? If yes, they should come back and sort out.

I once went to a job on a call out where there is no hot water at all and on inspecting, found a bit of foam, from lagging on cylinder fell in thru imm boss during replacement work. It got stuck up the outlet connector.

Daniel.

 

[Scotsmale]

Thanks guys will take all your ideas onboard