Air Locks?

[Chloe]

Hi group

I had to drain the hot and cold systems completely to fit a new bathroom - but so far have got as far as ripping the old one out and preparing the room for the new one, (floor etc). To do this I have fitted valves to both hots and colds in the bathroom and also the cistern feed and separate shower feeds. I Put the mains water back on just now, waited for the tanks to fill, and then found the hot tap downstairs was not delivering, (the cold one is OK as its directly above the stopcock)

Presumably I've got an air lock in the hot system somewhere, but how do I fix it?

TIA

C

[Set Square]

Presumably the cold taps - and possibly the cistern - are fed directly from the mains, whereas the hot water comes from a hot water cylinder fed by a header tank in the attic?

Is the header tank full? Is there a stopcock or gate-valve in the cold feed from the header tank to the bottom of the hot cylinder? If so, has it been turned off and left off? [If there is one, it must be ON to get any hot water].

If it *is* an air-lock, you could start by bleeding the hot supply to the bathroom. You said that you had fitted valves to the pipes. If you open the valves on the hot pipes until water runs out smoothly - hopefully into a container! - you will get any air out of the pipes, and possibly allow water to flow to the kitchen tap.

If that doesn't work, you'll need to connect the hot and cold taps in the kitchen together - with a short piece of hose or somesuch - and force mains water backwards through the hot system. Don't do it for too long, or you'll make the header tank overflow - a minute should be long enough.

[Chloe]

Both tanks are full and no gate valves were turned off in the loft and I tried bleeding the hot valves in the bathroom - not even a murmur...

and , ermm , I have a monobloc tap in the Kitchen!!

What next?

[Andrew Mawson]

In my house, when the hot has been drained down, the only effective way to clear the airlock is to fill the hot system up from the bottom. I temporarily rig a pipe from the rising main to the lowest hot tap and feed cold upwards for about 5 mins to push the air out. This in in a 3 story plus cellar house with quite a few horizontal runs.

AWEM

[Rick Dipper]

Get a bit of hose, join the taps together, turn them both on, slowly, the cold waster will bast through the hot, and clar the lock.

Be carefull not to push too much water through.

Rick

[Set Square]

If there *is* a gate valve in the cold feed to the hot tank, it will likely be in the airing cupboard rather than the attic.

With a monobloc, if the mixing is done *inside*, you simply have to block up the outlet pipe and turn on both taps. If the mixing is done at the nozzle, you need to clamp something like a plastic bottle round the outlet pipe so that what comes out of the cold part of the nozzle goes back in through the hot part.

But if nothing at all came out when you bled the pipes in the bathroom, I still think that something's turned off somewhere. How far is it from the bathroom to the hot tank, and do the pipes go up and over anything?

You can partially back-flush the hot system by connecting the valved hot and cold pipes in the bathroom together, and opening both valves.

[G&M]

Hold a towel over the end, put the hot tap on full and then slowly turn the cold tap on until you can't hold the pressure in any more. If you hear lots of gurgling around the house that's your airlock going.

[Chloe]

Thanks for the guidance folks - I can get on with washing a week's worth of dishes now!

The plastic bag tie-wrapped around the kitchen sink nozzle did the trick in the end...

[The Natural Philosopher]

Even esier. Put a rubber glove or condom over the end, grab tight and turn on both taps.

Unless you have a noin terurn vlave in teh ho supply, this will low any air out.

Or suck on the tap with hot only on, until water flows.

[Set Square]

What language is that?

[IMM]

It's called Snot.

[Set Square]

Ah, I guessed you'd speak it fluently!