More on hot water supply dying..

[The Natural Philosopher]

Some weeks ago I asked here if anyone knew what was going on with my hot water supply essentially drying up after a few minutes when running a bath.

Well it wasn?t such a big deal as mostly I shower, but today whilst shaving after a shower the hot tap basically stopped altogether.

Cold tap worked fine, so it had to be something in the HE circuit

This prompted me to take up the matter again and lo! the internet is FULL of stories about pressurised cylinders where the input pressure regulator fails in some way.

I didn't even know these things HAD a pressure regulator!

It appears that the cold feed comes in via a preset 2.1 bar regulator and filter assembly and that?s what the tank should run at. There is an air bubble in the top that is the 'pressure vessel' and an 8 bar 'overpressure' dump into the tundish. If something goes wrong with the air bubble.

If flow is restricted the pressure will be there and as long as the air bubble does its job, it will be 2.1 bar slowly falling until expansion is complete then sweet fanny adams. I think that this probly means that the pressure valve is doing its pressure thing, but the input filter is so clogged with scale it can't handle replenishing water at the rate needed.

Which raises the question as to whether the water softener is in fact working properly.

I did have root around inside the salt bit to see if that was OK, and found a drowned mouse....what!!!!???? yes. A drowned mouse.!

This also would explain why I have been getting air in the hot water taps. The bubble has expanded so MUCH that some of its air is getting into the hot water outlet which is near the tank top...

Anyway although a qualified plumber is supposed to do this, I have ordered a replacement regulator which, after switching off the leccy to the immersion and CH system, turning off the inflow to the tank and draining down the tank (open the lowest hot tap in the house and push the tundish test thing to let air in: also will remake the 'bubble'), should be unscrew and refit, corrosion permitting...

Wish me luck..

[Cynic]

I suppose I should know as I have an unvented cylinder "installers" CITB certificate but I'm not sure maintenance demands the same bit of paper. As long as renewal with like for like is involved and you dont compromise safety critical components what's the problem? No one in officialdom will know unless you tell them. Most of the unvented cylinders I've met have a diaphragm type "cushion" vessel but the principle is the same. I'd be looking for a restriction on the input as first port of call.

[The Natural Philosopher]

Well to all those who didn't wish me luck, I didn't need it. I did however find the old manifold impossible to take apart so refitted a new complete assembly.

That didn't quite fit either - it came in two halves screwed together with a weird plastic washer inserted in a groove in the male thread that simply wouldn't allow it to be screwed up tight. In the end I cut that out and fitted the two halves with PTFE tape.

Still too long but there was enough wiggle in the pipework to fit it all.

Instant proper hot water flow.

So the knock on effects of not getting the pressure vessel replaced were two gland leaks that knocked out the electrics and needed a new gate valve, a new ball valve, and a new motorised valve.

And the knock on effects of not using the water softener were completely clogged/seized hot water inlet regulator/filter assembly to the HW tank.

No hot water.

I hope that is the end of the plumbing problems, but I wouldnt mind betting there are a few more. Cold mains pressure seems a little low. And not 100% sure the softener is working though it feels like it when soaping hands...

[Dave Liquorice]

Can you get some water before it's gone through the softner? And compare with water that has. Hard water and soap (proper bar soap not a detergent hand wash) will be reluctant to lather up and will tend form a scum in hard water.

[The Natural Philosopher]

yeah. I have one inside and one outside tap that are unsoftened.

I managed to feel behind the unit, and the bypass is closed allright, so water miust be going through it,

It IS using salt, but at about 1/5th the level it used to.