On 24/11/2019 10:32, Lee Nowell wrote:
Hi All,
Well I think that's what it is. It looks similar one of these
That is NOT a pressure relief valve. It is a pressure REDUCING valve.
Designed to keep the whole unvented system from going over 2.1 or maybe
3 bar.
https://www.unventedcomponentseurope...-95605886.html
In my situation the large black bit is positioned to the left and
the other ports are Top - cold water feed to house
that will be one 3 bar feed.
Bottom - mains water feed from outside
Unreglated input
Right - connected to top of h/w cylinder (it is a mega flo type thing
for mains pressure hot water)
Another 3 bar feed to the sylinder
The leak is coming from the big black bit but not at the end
somewhere between the brass bit and the end.
Replace the sodding thing. Mine failed in a different way and a
neighbours is alos dripping like yours is.
I have done some googling and there seems to be a mix of views 1.
This is normal and that's what happens when the pressure is high.
Seems odd to me and mine continually drips. Also not sure what
pressure is too high - boiler circuit is set at 1.5 bar and inbound
pressure is not great
********.
2. It is because the expansion vessels have run out of air. I appear
to have 2. One in the inbound supply side and one on the circuit
coming out of the boilers.
That may be becuas yourr cylinder doesnt have one. Ther are tow pressure
zones - one is te DHW/CH *primary* that has an expanosion vessel in or
near the boiler usually and the other is a DHW secondary in the
'pressuerised' part of te hot water that is regulated by that valve.
i.e cold wetra enters tank till pressure is 2.1 - or maybe 3 bar -
depemndiong on te tank.
That water then gets hot. Pressure ises in te tank. So there is an
expansion vessel. In mine its a bubble at the top of the tank. Looks
like you have a separate vessel
Some people seem to say to just check them
and if low too them up (not sure to what) with a tyre inflator
(presume the little compressor thing I use to pump tyres up).
Yes. If they have not failed. If when you try and deflate them WATER
instead of air comes out, they have failed.
Pump up to usially a couple of bar - 28 pisi or thereabouts
Others
say this is very dangerous.
The world ois full of ignoirant snowflakes
Also TBH not sure what the purpose of
either is and therefore which one is likely to be it.
It will be the one vonnected to te hotr weatr tank outlet not the
primary heating circuit
If safe, I could do both of course.
No bad plan to check em all.
3. The valve is faulty and it needs to be changed by a qualified
person as could be dangerous.
The valve is almost certainly faulty but that may be becauise the tank
has overpressured due to a faulyy expansiuon vessel on the hot water side.
I have done a lot of plumbing including designing and fitting the
whole plumbing (obviously no gas work!) in our last place and adding
to the current one so am pretty able but some of the "this is
dangerous" is making me think twice.
It is only dangerous if you are a typical thick British plumber or a
snowflake.
That valve is there to regulate mains pressure down to a safe level for
the tank. As long as it is fitted cleanly with no leaks thats it, job
done. Mine got scaled up and failed. I had NO pressure at all! It was
cocered in scale outside so had been leaking like yours
Any thoughts appreciated. Also if anyone know why I have 2 expansion
vessels and what they do that would fill a void in my understanding
too.
One for the boiler primnary circuit, one for the domestic hot water tank
Thanks in advance
Lee.
how to fix this.
1/. Check all expansion tanks. This is something you should do annually
anyway as failed expansion tanks cause a LOT of damage. Whilst my Ex
had the house this happened and I lost three gate valves and two
motorised valves as pressures went mad and blew seals everywhere.
The key sign is that water comes out where air should be. These tanks
are essentiually made in tow halces with a rubber membrane between. Air
is then pumped into one half to allow expansion of water in the other
half. They fail because the membrane tears or leaks or whatever allowing
water everywhere. The air ends up in the water an you bleed it out and
then its all gone.
If at all unsure replace the sodding things. £50-£150 is the going rate.
2/. Replace the valve. £42 quid - mine was £100 - is a cheap price to
pay to fix a nasty plumbing problem. Obviosuly you need to depressurise
everything first by turning off te mains supply and then opening hot and
cold water taps still it all stops gushing
Try and get exact replacement. Mine wasnt and I had to mess with cutting
olives off pipes to get the old one totally out, and then adding pipe
section to nake it all play nice again.
So factor in that you make need to do this and get some 22mm pipe
couplings and pipe in case you need to essentially cut the old one out.
If you are prepared you wont get so upset when it all turns out to be
corroded and scaled to ****.
--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€
ۥ Lao Tzu, Tao Te Ching