I have never believed it acceptable to have cold water cisterns made of materials which can't take heat. I've known of primary heating systems to pump over hot water and distort the tank. Why a heat resistant plastic can't be spec'd I don't know!
Bob, this is understandable, but if it is the thermostat (2hrs after heater goes on is plausible for water to be causing noise), then it is potentially serious.
Maybe. I could try closing the valve down slightly to reduce the pressure. It's opened quite a bit just now and the day time pressure is too high really anyway.
What are these and where would it be? The main valve is just a gate valve I think
These sometimes
I'll try closing the gate valve up a bit tonight as the pressure is too high in the daytime anyway. Sombody over on free.uk.diy.home said that night time pressure is even higher due to lower demand.
Cheers Dave, I'm going to try closing the valve a bit for tonight to see what happens
Thanks Chip. I was fitted about a year ago
Many thanks Aidan, this seems to be the theory that's gaining popularity.
OK thanks Andy. I'll work with the night time high pressure theory first then rig the timer to run during the day to see if it happens, then I can get up there at a reasonable time
A double check valve is a non-return valve which stops dirty water being sucked into the mains supply if the mains fails. Typically they look like
Sadly, part-closing the valve will have no effect on the night-time pressure. In order to get a pressure drop across a part-open valve, you need a high flow through it - which you clearly won't have in the midle of the night - so the full pressure will still be present throughout your system.
Isn't the cutout part of the (replacement) stat?
Get real.
It's because the incidence of it actually being a problem is so low that it just isn't worth bothering about.
Why not ban all aircraft from flying over any dwelling, ever, to reduce the very low risk of one falling out of the sky and killing people on the ground?
It's all about assessing and managing risk within a finite budget. Would you rather be forced to spend extra on a fancy tank with approaching zero paybeck in terms of your longevity or spend it on, say, a CO detector which could very well save your life?
MBQ
They will take the heat, providing they have continuous support, i.e., WBP or marine ply base, as per the manufacturer's installation instructions. I think that one didn't, it was inadequately supported by the joists & so collapsed.
OK - I recall one which was badly distorted by pumping over. Yes it held together but would rather not use plasticine as a container.
I am real, a DIYer not in the trade who has seen 2 examples of tanks distorted through pump over. I'm sure there are many more and can't believe it's such a rare occurrence. If these two cases were the only ones in existence then I would agree with you.
On Mon, 07 Nov 2005 11:00:27 GMT,it is alleged that spake thusly in uk.d-i-y:
It may well be, yes. I haven't dealt with immersion heaters in ~10 years (they went out of favour round here due to southern electric's ridiculous pricing)
No I fitted it myself and just adapted the original plumbing
They're
'Closing the valve a bit' won't affect the pressure when there is no flow.
It acts as a restrictor, causes a pressure loss due to increased friction and so reduces downstream pressure when there is a flow.
You'd need a proper pressure reducing valve to limit the static pressure.
Yes I know a little about hydraulics. But since shutting the valve seemed to cure it I'll try it closed down a little just to see.
Do you still get the moaning if the immersion is left off (I know that's a really inconvenient test!). I'm reckoning that the immersion has nothing to do with this but possibly an increase in water pressure at night.
Another possibility is that there is a slight problem with the float valve on the storage cistern. When the HW expands it raises the level in the cistern a bit, possibly interfering with the operation of the float valve (which should have been off and be staying off). Suggested causes of action:
1) Check for air in dead branches of the mains cold water plumbing. 2) Renew washer/diaphragm in the cistern float valve. 3) As (2) but also for any mains WCs.
Don't know Ed. I've a few things to try tonight before trying that. Cheers.
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