Plumbing: Replaced hot-water tap, now no hot water

[Justin C]

I've replaced a hot-water tap on our bath. I did this by turning off the boiler, turning off the mains and then draining the hot and cold tanks and then replacing the tap. I've turned the mains on again and have cold water at every tap, but I'm getting no hot water. The cold tank has filled, and stopped filling. If I turn all hot taps off and wait a while, say ten minutes, I can get about a pint of water out of one of the hot taps, but that's it.

I though that perhaps when I drained the cold tank there may have been some gunk sucked into the hot-tank feed, but I've had a look in the cold tank and can see nothing.

There are two gate valves in the airing cupboard (where the hot-tank is) and I've closed and opened one in case some debris had become lodged there, but that didn't help. The second valve will not move either direction more than about 16th of a turn.

Any ideas how I might solve this?

Our hot-water tank is not separate from our central heating, and if it's empty I don't feel safe running the central heating, am I being foolish or sensible? I'm cooling down from the doing the job and it looks like it will be a chilly night.

Justin.

[The Medway Handyman]

Not sure what you mean by that?

[charles]

I assume he meant the CH boiler also heats the water

[Justin C]

I had no idea how I could attempt Harry's suggestion. Our only mains tap is the kitchen sink and that's a mixer. All others are off the tank. How I'd get a hose onto the mixer and then to another hot tap I had no idea, but this sounds perfect.

Thank you, and thanks to Harry for the suggestion.

I'll let you know how I get on.

SWMBO doesn't want me to do it tonight in case I somehow make matters worse... and what with me being tired and, probably, irratable due to the lack of earlier success, that could be a good idea. So, first thing tomorrow!

Justin.

[MuddyMike]

The simple solution is.

Hold your thumb on the outlet of the mixer tap whilst you firstly turn on the hot tap and then the cold tap thus forcing cold water back up the hot system.

Many hot water systems need to be re primed in this way after draining, I had to do it every time after we left our holiday cottage drained down in the winter months.

Mike

[Brian Gaff]

Sounds like an air lock to me. Can you without destroying the system, get a good pressure from the cold main into the tap with the problem in order to force the air to come out somewhere?

Brian

[ARWadsworth]

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[Tony Bryer]

Standard fix is to put a hose between the kitchen sink hot and cold taps and turn both on.

[The Medway Handyman]

[MuddyMike]

:-) I should have written, GENTLY turn on the cold tap whilst keeping your thumb on the spout! But never mind a bit of water on the kitchen floor is no big deal.

I had these instructions careful printed and laminated at the cottage when we owned it as part of the "opening up" instruction for friends and family using it. It often produced a phone call asking. Do I really have to turn both taps on with a thumb over the outlet? "You won't get any hot water without" I would tell them.

The water there came from a spring up the hillside so the pressure was not too great.

Mike