Plumbing advice PLEASE! Boring hot water problem.

[trinni]

I have a 30 plus year old Baxi Bermuda back boiler and a gas central heating system which is regularly serviced. The hot water tank is in the airing cupboard upstairs. No roof tank.

The problem is running a bath. The hot water starts ok when the tap is turned on but soon drops to a dribble but the water is still very hot.

Previously we could run a couple of decent baths - now we're lucky to fill one.

Any ideas before I call a plumber please?

I don't know your system, but does it run at pressure. Some systems need a small amount of pressure in them to run, and you need to top them up from time to time. There should be a tap somewhere to do this.

Oh that's an interesting and new take on the problem and sounds quite straightforward too.

As for running at pressure...All I can tell you is historically, our cold water pressure has been brilliant but the hot water not so good ie: it isn't possible to use a mixer tap (we just get a blast of cold!)

That probably isn't much help is it?

If you don't have a roof-tank then it will most likely by under pressure. The roof tank tops up the water automatically on unpressurised systems, but you have to top up pressurised ones yourself.

It's not the same "pressure" as the pressure of the hot water running, but it could be connected, if it's not high enough the system won't be running quite right. If it was ok when first installed but has got worse over time, it's certainly a possbility.

Our system has a round red thing as part of the installation, with a little dial on the front. You have to turn on a tap (actually two little taps, like the ones for washing machines) to get the needle to point to the right level, or in the righ range. Do you have anything like that?

I've just been up and had a look. No little red dials, just a white box (says Drayton on it) which is the temp thingy I think.

I'm going to need to call a plumber I think but thanks, you have been so helpful.

when you say "no roof tank" but you have a hot water cylinder, is there a cold tank on top of it? Does it have a close-fitting plastic lid?

is the cylinder copper with a red ribreglass jacket; or copper with a yellow, blue or green coating of rigid plastic foam, or is it in a white casing with a maker's name on it?

Could it just be the tap in the bath? Does the sink one work ok?