AIRLOCK .... I THINK....HELPPPP !!!!

[Hangarpilot]

My sister's son broke a pipe which comes off the inlet of the immersion tank. There is a reducer from 22mm to 15mm which has a 15mm pipe and is capped by a bleed valve. The 15mm pipe fractured at this T junction and after draining the system down, i managed to re solder the joint. After closing everything up and opening the water mains, I cannot get water flow into the hot taps in the bathrooms. I seems like there is an air lock. Could anyone pleas3e advise what to do to clear the airlock.
The boiler is a CREDA and is used for Hot water only as they have duct heating and no C/H.

 

[Space cat]

I would expect to find four pipes going into the cylinder. There must be one on the top. That's the one where hot water comes out and goes to your taps. There must be another one somewhere very close to the bottom. That's where cold water comes in from your cold tank to replace the hot water coming out at the top. If nothing goes in at the bottom, nothing can come out at the top!

The last two are the flow from and return to the boiler. This water goes through a coil of pipe inside the tank and does not mix with the tap water. These pipes will be low down on the cylinder, one higher than the other. It is here that I would expect to find a bleed valve.

I would also expect to find two cold water tanks: a big one that goes to the bottom of the cylinder and a smaller one that connects somewhere into the boiler pipework. Do you have two tanks and did you drain them both?