Noisy hot water pipe

Ok, but what sort of noise? Bubbling/gurgling? Like a siren? Banging/knocking? etc etc

David

Jon Parker wrote in news: snipped-for-privacy@u13g2000vbc.googlegr oups.com:

If you investigate the large tank in the loft you will find that the problem is most likely the float valve will be causing all the noise.

Turn off the feed to it and replace the washer and clean the jet would cure this problem.

You would probably find it a lot easier to just replace the whole valve they are very cheap.

--- news://freenews.netfront.net/ - complaints: snipped-for-privacy@netfront.net ---

From your later description it sounds rather like the tank in the loft is being refilled.

Not sure the "wasting gas" bit makes much sense - unless the hot water is heated by a combination boiler (i.e. on demand) then all you will be doing is taking hot water from the hot cylinder. That will need to be reheated at some point either by the boiler or immersion heater.

Chances are the valve that refills the cistern in the loft has over time become a little restricted. Its not uncommon in many properties for the refilling process to go on for minutes after a large demand has been placed on the hot water, since its common that the demand outstrips the speed at which it can be refilled (hence why a sizeable tank used in the loft).

Replacing the valve with a fluidmaster or torbek style valve may solve the problem - although some noise as the tank refills is to be expected just due to the noise of the water flowing through the pipe to the tank.

But if it is that, one would need to have no other taps in the house running from the tank and this needs to be known, as running said tap will either prove or disprove this theory. I think my loft tank valve is getting sticky as it can often be heard filling suddenly later after a lot of water has been used, meaning that presumably the ball is hanging in mid air till it suddenly drops with a thwack and it starts to fill! Brian

The tank may be redundant and you may have a mains pressure system.So first check if water comes into this tank when open the hot tap. If not you have a mains pressure system and it is likely the pressure reducing valve sticking. It will be near to your hot water cylinder likely. Put your hand on it while someone operates the taps you willl feel it juddering. The only solution is to strip it down and clean of any scale.

Also check the air pressure in in your expansion vessel.

If the roof space tank is operational, the likely thing is some problem with the float valve in that tank. Again watch it while someone is opening a tap. If there is a valve, turning the water flow down might fix this. A new washer in the float valve may also cure the problem. If not, a new float valve.

Best I could do description wise would be a kind of vibration, very rapid juddering. Starts off quiet but gets to its loudest volume within 2-3 seconds while the hot tap is running. After the running hot tap is turned off the noise continues for a period of say 10-15 seconds and then subsides slowly away to nothing. If a large amount of hot water is drawn, e.g. a bath is run, the noise continues for a couple of minutes after the tap is turned off.

It's not bubbling or gurgling, and it's definitely not a siren. Vibration is the most accurate descriptive I can think of at this hour.

Thanks Jon

Yes, I agree, and I have been up into the loft and observed this behaviour.

No, my mistake. The water is not heated "on demand." Now I have thought about this I can see I was incorrect with the "wasting gas" bit.

Thanks for your suggestion. This tallies with what another poster has suggested. The valve that controls the loft cistern is a bit scaly. I will focus my investigation there in the first instance.

Cheers Jon

Sometimes people fit two valves to the cistern to maximise filling speed...

Ball valve in the tank oscilating. Though it should also do it if you draw off cold water as you say that "The tank begins to refill if any water is used in the house, hot or cold."

Fixing it might be fun, the valve here started doing it and the cure was loosen the pipe clips so things could move but were still supported. A simple change of washer might cure it as an alternative.

If that is done make sure the overflow can cope with the flow rate a torbeck valve can produce. This is mentioned in the instructions...

Yeah, know what you mean. You could try closing the stopcock slightly - sometimes works for that sort of noise.

I fitted a small expansion vessel to my cold water system in attempt to combat this noise; it worked a bit but wasn't wonderful (a Varem model from Toolstation - they don't appear to stock it now though)

I fixed my MiL's one with a bit of string :)

There was a horizontal section about 2ft long leaving the tank, then a right angle bend to another longer horizontal section. I tied the corner to a rafter and that was enough damping. It's outlasted her.

Andy

Wish I could fix *my* MiL with a bit of string...

Solved. Turned out to be the cistern which controls the refilling of the loft tank. Shut it off, took it out, de-scaled it, stripped it, cleaned it, put it all back together and now no noise at all.

Thanks to all for your suggestions.

Jon