Any plumbers?
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slowmotion
Quite dreadful
- Location
- lost somewhere
The red tank is a pressure vessel which has a closed reservoir of gas that puts pressure on the water in the heating system. It's like a spring. When you introduce more water by opening the valve, more water is introduced and it compresses the "spring". If there is even the smallest leak in the heating system, the pressure gauge runs down to zero fairly quickly as the "spring" decompresses
In brief, you have a leak in the heating system.
In brief, you have a leak in the heating system.
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Levo-Lon
Guru
Sounds like the PRV is past it,they lose there effectiveness and leak .
if it is the pressure relief valve a new one is cheap ,and you can fit them quite easily.
but use a plumber if you are even slightly unsure.
Look like any of these?
https://www.google.co.uk/search?cli...e&source=browser-suggest&qsubts=1450134476690
if it is the pressure relief valve a new one is cheap ,and you can fit them quite easily.
but use a plumber if you are even slightly unsure.
Look like any of these?
https://www.google.co.uk/search?cli...e&source=browser-suggest&qsubts=1450134476690
slowmotion
Quite dreadful
- Location
- lost somewhere
[QUOTE 4056187, member: 9609"]Another question for any plumbers out there - how do I know if there is an inhibitor in the system ? I bled a radiator the other day and the water was clear, I had expected it to be very dirty blackish colour.[/QUOTE]
I'm sure that there is a simple chemical test you could do out there somewhere....but why bother? If the water's clear, you don't have a problem.
I'm sure that there is a simple chemical test you could do out there somewhere....but why bother? If the water's clear, you don't have a problem.
ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
I hope you don't mind if I add another heating question ...?
From time to time, a central heating system with a combi-boiler makes a loud juddering sound. It only happens when the heating is on, and at random intervals. If left alone, I think that the noise would continue until neighbours banged on the wall to complain, or some part of the system shook itself to pieces! I discovered that if a hot water tap is run for even a second or two, that stops the vibration.
I can't figure out what causes the noise to start or how the separate hot water system interacts with the heating system to stop it.
Any suggestions? (Apart from the obvious 'Consult heating engineer'!)
From time to time, a central heating system with a combi-boiler makes a loud juddering sound. It only happens when the heating is on, and at random intervals. If left alone, I think that the noise would continue until neighbours banged on the wall to complain, or some part of the system shook itself to pieces! I discovered that if a hot water tap is run for even a second or two, that stops the vibration.
I can't figure out what causes the noise to start or how the separate hot water system interacts with the heating system to stop it.
Any suggestions? (Apart from the obvious 'Consult heating engineer'!)
slowmotion
Quite dreadful
- Location
- lost somewhere
It's "water hammer". It happens when a valve shuts off suddenly and a flow of water comes to a sudden halt in a pipe. The water pressure wave bounces off the dead end and reverberates back down the pipe like an echo. If the pipework is not well clipped to walls/floors, the pipes start rattling/hammering.
The solution is to fix the pipework better and/or arrange for the valve to shut off more gently. You can get hammer controlling devices as well, but they are not cheap and have to be carefully located. The reason why opening a tap elsewhere fixes the noise is that it disturbs the reverberating pressure regime.
ColinJ
Puzzle game procrastinator!
- Location
- Todmorden - Yorks/Lancs border
I was getting water hammer when taps were opened and closed unless that was done very carefully. The water pressure into the house was stupidly high, enough to blast my coffee mug out of my hand when I tried to rinse it. I half closed the stop cock to reduce the effective pressure and that problem went away completely.
Aaargh - it has just done it again!
I thought that the central heating system in a combi-bolier is closed off from the hot water system and the same water just circulates round time and time again? If that is true, I don't understand how the hot water system affects it. Opening and closing the cold water tap does NOT stop the vibration.
It is a nuisance when I am in, but it means that I am afraid to leave the heating on when I am out. I don't want to risk a joint failing due to the stress of repeated shaking, and I don't think it is fair to inflict the noise on my neighbours either.
The pipework probably is a bit dodgy but it could be expensive to get at a lot of it. (New ceiling below, tiled floor above, pipes in between!)
slowmotion
Quite dreadful
- Location
- lost somewhere
The central heating circuit on a combi system is isolated from the mains cold and hot water system. I think it would be unlikely that any part of the CH circuit would be the cause of water hammer unless the circulating pump is trying to circulate the CH water into a rapidly closing valve. Circulating pumps usually work at much lower pressures than mains water which usually causes hammer. However, it could be a possibility. One way of testing it would be to see if the hammer still appears even when nobody operates the hot or cold taps in your home.
Levo-Lon
Guru
[QUOTE 4056217, member: 76"]Yes, it is a bit like that. I will have a look into it, are they easy enough to fit then? I can follow instructions well enough, thanks very much.[/QUOTE]
takes me about 15 mins to do mine,as its the 3rd in 10 yr.
its a case of "can you shut off all the heating valves ",if yes then its easy.
if your flow and returns are siezed its a drain down system ..
but no gas work involved and its your boiler.
turn off the flow and return valves at the boiler, electric to boiler etc
use the prv to drain the boiler..change valve..be carefull not to stress joints etc.
Hold valve with a set of grips when undoing the old one as they get tight after a few yrs.
refit with a smear of plumbers paste to ensure a good seal.
open valves..fill to pressure..usually 1bar then check for leaks.
if its all dry and pressure holding Swith on.
you should be ok bleed wise as the boiler has a air vent but a quick rad bleed wont hurt after a day or too.
then check pressure after any bleeding.
good luck @User76
takes me about 15 mins to do mine,as its the 3rd in 10 yr.
its a case of "can you shut off all the heating valves ",if yes then its easy.
if your flow and returns are siezed its a drain down system ..
but no gas work involved and its your boiler.
turn off the flow and return valves at the boiler, electric to boiler etc
use the prv to drain the boiler..change valve..be carefull not to stress joints etc.
Hold valve with a set of grips when undoing the old one as they get tight after a few yrs.
refit with a smear of plumbers paste to ensure a good seal.
open valves..fill to pressure..usually 1bar then check for leaks.
if its all dry and pressure holding Swith on.
you should be ok bleed wise as the boiler has a air vent but a quick rad bleed wont hurt after a day or too.
then check pressure after any bleeding.
good luck @User76
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Levo-Lon
Guru
[QUOTE 4056187, member: 9609"]Another question for any plumbers out there - how do I know if there is an inhibitor in the system ? I bled a radiator the other day and the water was clear, I had expected it to be very dirty blackish colour.[/QUOTE]
sludge is at the bottom..so the bled off water looks clear.
Usually thers a inhibitor added sticker on the boiler or inside the drop down cover? Date added etc.
have a look and see if there is one..or check service record book if you have one
sludge is at the bottom..so the bled off water looks clear.
Usually thers a inhibitor added sticker on the boiler or inside the drop down cover? Date added etc.
have a look and see if there is one..or check service record book if you have one
Levo-Lon
Guru
[QUOTE 4056454, member: 9609"]No stickers or record book - I drained it myself and refilled it a few years back when I moved some radiators, I remember not having any to put in and planning to do it the following week. I have a sneaky feeling I probably didn't.. I suppose I could drain and refill, but would rather not spend the £15 if there was an easy check.[/QUOTE]
we have terible limescale here..so if your water is soft you may be ok..but its worth having it.
i can smell the inhibitor in the water if a drain a bit into a jug via bleed point..its a chemical smell
we have terible limescale here..so if your water is soft you may be ok..but its worth having it.
i can smell the inhibitor in the water if a drain a bit into a jug via bleed point..its a chemical smell
Levo-Lon
Guru
subaqua
What’s the point
- Location
- Leytonstone
I used fernox F1 in all my systems after a proper flush and not had any problems. Rads have very little black in them if I ever take one off.
ArDee
Legendary Member
- Location
- North of Buntingford, Hetfordshire
By shutting the valve you are reducing the pressure and flow rate (speed) of the water and hence reducing the potential for the water hammer to occur. The water hammer is caused by the water stopping as discussed above.
Rather than half close a valve a better approach is to install a pressure reduction valve (PRV). These cost around £30 and are easy to install, should be available from any good plumbers merchant.
A PRV reduces the water pressure under all flow conditions, from no flow to full flow, rather than just high flow and seats in taps, ball cocks, valves, etc. will last longer. Partly shutting the valve to reduce pressure can lead to wire drawing on the valve seat that means when you want it to close off completely it won't.
U
User6179
Guest
It could be the boiler is Kettling and by running the hot tap you let cold water into the boiler heat exchanger cooling it down !?
