Central heating OK but no hot water

[Kevsy1]

Hi, Any help much appreciated by this novice! Yesterday I had to change the kitchen tap washers, so I shut off the rising main and turned off the hot water supply. Although I eventually achieved this by locating and turning off the hot water feed under the kitchen sink, I had originally tried by closing the valves in the hot water cylinder airing cupboard (noting and marking the original position of each, and turning them back when that had no effect). Following the washer replacement I reenabled the hot water supply to the kitchen. Yesterday evening and this morning I heard a load throb from the plumbing (about 2-3 seconds), and only unheated water comes from any of the hot taps in the house. Both water and central heating are controlled by an electronic Honeywell timer which came on as usual yesterday evening and this morning. The airing cupbaord pipe for the hot water is no longer warm, tracing this back to the cylinder I cannot see an obvious valve , just a large nut connecting the pipe to the top of the cylinder. Can anyone think of anything I might have done to disable the hot water? ALl suggestions very welcome! Cheers Kevin

[Kevsy1]

A couple of updates:

- when I turn up the thermostat downstairs, which activates the CH(with both CH and HW set to 'Contant') the load throb/groan happens again.

- There is an unusual (to me) connection between the boiler and the hot water cylinder. This piping enters the cylinder at the bottom, about 6 inches before it enters the cylinder there is what appears to be a tap, but instead of a handle there is a small nut with a printed metal foil collar behind it with the 'Close' direction. When the HW was working yesterday this nut was loose and could be fmoved by finger. In a naive attempt to stop the HW supply to the tap I closed this tight with a spanner, later undoing it back to the original position. Boiler to here, the pipe is warm, from here to cylinder, pipe is closed. So I guess that's the problem, is there a good chance that I've damaged this by overtightening it? Many thanks!

[Kevsy1]

The 'unusual' fixing I mentioned above is a compression gate valve (BS5154) but dows not have the red turning dial on it! Just the loose nut at the end. Turning this just makes the nut go up and down the thread.

[purple pete]

stuck on hot water only? There is a 2 or 3 way valve which is operated by a motorised switch and this switch turns the valve depending on whats required - so, ie if its just hot water the motorised valve will turn the valve to allow only hot water to run to the taps and when heating is required it moves again to allow the flow of water just to the radiators. I think tere is also a mid posistion to allow both if needed. In my mind I think either the motorised switch has packed up or the valve that it turns has got stuck. Just my thoughts.

Good luck

[purple pete]

So I guess that's the problem, is there a good chance that I've damaged this by overtightening it?

It may be stuck - half closed

[Kevsy1]

Hi Pete, many thanks for the reply. The problem was that the compression gate valve was closed - so by opening it with a spanner (there was no red dial) hot water got into the cylinder from the boiler. The mystery was that I hadn't closed the valve yesterday...I'd only spun the nut which is there to retain the red dial on its thread?! Anyway, all working now so thanks for your time!

[mike ring]

"Kevsy1" wrote in news:1128242615.721875.124780 @g44g2000cwa.googlegroups.com:

Your hot water is driven, (in a vented system) by water from the cold tank above entering the cylinder and pushing hot water out of the top.

This is where your handle-less gate valve is.

It sounds buggered, it certainly needs a handle.

To replace it you need to empty your cold water tank by turning off your stopcock, and opeing the lowest tap in the house. (and any others for speed)

You can then remove the gate valve by unscrewing the nuts, and fit a new one.

It can be a good idea to leave the old nuts and olives(little collars) on the pipe and just use the new body. If you're a wuss you can smear Fernox LS-X on the olive to make sure of a watertight joint with the new body, also a smear of grease on the threads acn help.

HTH

mike

[mike ring]

I fergot to say, cause it was dinner time, that if you're lucky you may be able to work it with grips on the stem of where the wheel useter be.

Try to grip the shaft; you can also try to unscrew the bigger nut at the bottom to ease the shaft a bit. this may start to weep a bit, just retighten it after you've got the valve open.

Aand of course, it's the cold taps you open. I fitted a drain c*ck at the lowet point in the cold supply to your cylinder, if you're lucky you may have one, which will cause less spillage when you replace the gate valve.

And when you replace it, consider doing it with a full bore lever operated ball valve

(you can also get them in yellow!)

mike

[kitchenman]

There was no handle on purpose to stop the valve being turned of unintentionally as you found out.