No hot water after draining tanks

[Andrew]

Dear All

Today I have drained all the water from the house both Hot and cold, to allow me to replace the mixer tap in the kitchen. Following the successful replacement of the mixer taps in the kitchen I turned the watee back on and waited round 30 minutes for the tanks to fill. The cold water is ok once the airlocks cleared. How ever i now have no hot water in the house, kitchen or bathroom. The hot water is heated by a combination i think of a back boiler and a copper water tank with heater in. I think there is another airlock some where

Any recommendation on how to clear it.

I have already tried connecting a hose between the cold and hot taps. When the cold water is turned on I can get water from all the hot taps , so the air lock i guess is between the cold water tank and the hot water tanks.

Any help would be appreciated

Andrew

[Bob Minchin]

I think you are on the right track. Connect the hot and cold as before and working from lowest to highest, open the hot taps one at a time until they run free then close them. whenyou have done the highest one including any showers etc. wait for the coldheadertank overflow to run. Shut off the hot-cold link and you should find the airlock has cleared.

hth

Bob

[Bob Minchin]

I should have written - use the cold mains not the tank fed cold as it will be quicker and higher pressure.

[IMM]

Failing that, drain down again and fill with all hot taps open. When water comes out of a tap at full flow turn it off.

[BigWallop]

You might just have a blocked expansion pipe on the hot water tank outlet side. Have a look in the loft for a pipe that loops back over the top of the cold tank, or the header tank of the hot water system. Make sure it is perfectly clear by sealing your mouth around the end of it and blowing.

[Andrew]

Thanks for the answers i tried various thing including, draining the water again then leaving the hot tap open

forcing water up the hot water system

both failed

In desperation

I drained the water once again

Tied bull c*ck up in the main tank

Opened all the hot taps

Took the hose (which was connected to the mains) up in the loft.

Got the wife to turn on the hose, when all the air in the hose had gone I held the hose up against the output from the cold water which fed the boiler. The Hot taps immediately started to run and the there seemed to be some sort of hot water backwash into the main tank as the water felt slightly warm.

Got the wife to close all the hot taps. The overflow from the copper hot water tank sputtered a bit them began to immediately over flow.

Untied the bull c*ck and left all the tanks to fill and now every thing is ok.

My Question is why did he copper water tank over flow so quickly, did it not empty when i drained the water ???

Andrew

Andrew wrote:

[BigWallop]

Probably a block in the expansion pipe then. :-))

[Andrew]

Big Wallop

What i called the overflow pipe from the copper water heater, is what you correctly are calling the expansion pipe. Sorry i using the wrong term.

Andrew

BigWall>

[BigWallop]

LOL !

I knew what you meant. :-))

Most people forget that you have to let air in to the hot tank pipework on a gravity fed system. It's the best way to let you get water out of the taps. So when it blocks, even slightly, it causes an air lock.

Glad to hear it's sorted.

[Christian McArdle]

No. You can't drain a hot water cylinder just by opening taps. It must be drained off by syphoning, or using the drain valve at the bottom. This is because the hot water outlet is at the top of the cylinder. The water only comes out of the top when pushed by a supply of water at the bottom. Cut off the supply and no water comes out of the top.

Christian.