air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the upstairs
rads. after expelling it, the pressure rose again over the next few days. i
have checked everywhere for leaks, and found none. i have replaced the
expansion vessels ( i know the domsetic water (( white one)) isnt connected to
the heating system, but i found no pressure in it , and upon disassembly found
a split diaphragm ). The red one had a small amount of water come out the
shrader valve when i emptied the air from it. I took it to mean a possible
split, so replaced. Air pressue in said vessel is correct, but the problem has
got progressively worse each day. Now if i bleed the system,and close the
valve on the last ( and furthest rad ) as soon as air stops coming out, if i
give it just ten seconds, and reopen the valve , there will be no water come
out again for several seconds.
I havent topped up the water in the system since installing the expansion
vessels several weeks ago. If i had a leak , i would surely have needed to.
Its as if the system is creating the air. If the pump was faulty, would that
put air into the system without water loss? I usually bleed whilst the pump
is running ( as suggested by my local plumber ). If i bleed cold, then i can
expel all the air, without finding more, just seconds later, but as soon as
the system is turned on the air reappears immediately..
The system is unvented, and powered by air source heat pump.
Any ideas welcome . cheers

--
for full context, visit https://www.homeownershub.com/uk-diy...s-1261128-.htm

On 04/01/2018 17:44, paul Roberts wrote:
air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the
upstairs
rads. after expelling it, the pressure rose again over the next few days. i
have checked everywhere for leaks, and found none. i have replaced the
expansion vessels ( i know the domsetic water (( white one)) isnt
connected to
the heating system, but i found no pressure in it , and upon disassembly
found
a split diaphragm ). The red one had a small amount of water come out the
shrader valve when i emptied the air from it. I took it to mean a possible
split, so replaced. Air pressue in said vessel is correct, but the
problem has
got progressively worse each day. Now if i bleed the system,and close the
valve on the last ( and furthest rad ) as soon as air stops coming out,
if i
give it just ten seconds, and reopen the valve , there will be no water
come
out again for several seconds. I havent topped up the water in the
system since installing the expansion
vessels several weeks ago. If i had a leak , i would surely have needed
to. Its as if the system is creating the air. If the pump was faulty,
would that
put air into the system without water loss? I usually bleed whilst the pump
is running ( as suggested by my local plumber ). If i bleed cold, then i
can
expel all the air, without finding more, just seconds later, but as soon as
the system is turned on the air reappears immediately.. The system is
unvented, and powered by air source heat pump.
Any ideas welcome . cheers


Are you sure that it's air - and not hydrogen caused by corrosion in the
system. Do you have any corrosion inhibitor, and when was its
concentration last checked?

What happens if you hold a lighted taper in the stream of 'air' being
bled from a radiator? If it's hydrogen, it will burn with a blue flame.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

From the description though that amount of hydrogen should mean a rather
large amount of corrosion, which in the end would I would have thought
eventually lead to a leak.

Brian

--
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"Roger Mills" wrote in message
...
On 04/01/2018 17:44, paul Roberts wrote:
air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the
upstairs
rads. after expelling it, the pressure rose again over the next few days.
i
have checked everywhere for leaks, and found none. i have replaced the
expansion vessels ( i know the domsetic water (( white one)) isnt
connected to
the heating system, but i found no pressure in it , and upon disassembly
found
a split diaphragm ). The red one had a small amount of water come out the
shrader valve when i emptied the air from it. I took it to mean a
possible
split, so replaced. Air pressue in said vessel is correct, but the
problem has
got progressively worse each day. Now if i bleed the system,and close the
valve on the last ( and furthest rad ) as soon as air stops coming out,
if i
give it just ten seconds, and reopen the valve , there will be no water
come
out again for several seconds. I havent topped up the water in the
system since installing the expansion
vessels several weeks ago. If i had a leak , i would surely have needed
to. Its as if the system is creating the air. If the pump was faulty,
would that
put air into the system without water loss? I usually bleed whilst the
pump
is running ( as suggested by my local plumber ). If i bleed cold, then i
can
expel all the air, without finding more, just seconds later, but as soon
as
the system is turned on the air reappears immediately.. The system is
unvented, and powered by air source heat pump.
Any ideas welcome . cheers


Are you sure that it's air - and not hydrogen caused by corrosion in the
system. Do you have any corrosion inhibitor, and when was its
concentration last checked?

What happens if you hold a lighted taper in the stream of 'air' being bled
from a radiator? If it's hydrogen, it will burn with a blue flame.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 04/01/2018 17:44, paul Roberts wrote:
air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the
upstairs

Could be a bad joint just before the pump allowing air to be sucked in.

Mike

On 04/01/2018 17:44, paul Roberts wrote:

air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the
upstairs
rads. after expelling it, the pressure rose again over the next few
days. i

One possible cause of unexpected pressure rise could be the taps on the
filling loop letting by.

However that would not explain the gas...

Corrosion might - not not in the space of minutes.

have checked everywhere for leaks, and found none. i have replaced the
expansion vessels ( i know the domsetic water (( white one)) isnt
connected to the heating system, but i found no pressure in it , and upon disassembly
found a split diaphragm.

That sounds like an unvented cylinder - is it just heated by immersion
then and not from the heat pump?

The red one had a small amount of water come out the
shrader valve when i emptied the air from it. I took it to mean a possible
split, so replaced. Air pressue in said vessel is correct, but the
problem has
got progressively worse each day. Now if i bleed the system,and close the
valve on the last ( and furthest rad ) as soon as air stops coming out,
if i
give it just ten seconds, and reopen the valve , there will be no water
come
out again for several seconds. I havent topped up the water in the
system since installing the expansion
vessels several weeks ago. If i had a leak , i would surely have needed
to. Its as if the system is creating the air. If the pump was faulty,
would that
put air into the system without water loss?

Possibly. Do you still see the pressure rise without the pump running?

I usually bleed whilst the
pump is running ( as suggested by my local plumber ). If i bleed cold, then
i can expel all the air, without finding more, just seconds later, but as soon as
the system is turned on the air reappears immediately.. The system is
unvented, and powered by air source heat pump.


--
Cheers,

John.

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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 04/01/2018 17:44, paul Roberts wrote:
air is getting into my central heating , as fast as i can bleed it out. i
noticed the presssure had risen a few weeks ago, and found air in the
upstairs
rads. after expelling it, the pressure rose again over the next few
days.Â* i
have checked everywhere for leaks, and found none. i have replaced the
expansion vessels ( i know the domsetic water (( white one)) isnt
connected to
the heating system, but i found no pressure in it , and upon disassembly
found
a split diaphragm ). The red one had a small amount of water come out the
shrader valve when i emptied the air from it. I took it to mean a possible
split, so replaced. Air pressue in said vessel is correct, but the
problem has
got progressively worse each day.Â* Now if i bleed the system,and close the
valve on the last ( and furthest rad )Â* as soon as air stops coming out,
if i
give it just ten seconds, and reopen the valve , there will be no water
come
out again for several seconds. I havent topped up the water in the
system since installing the expansion
vessels several weeks ago. If i had a leak , i would surely have needed
to. Its as if the system is creating the air. If the pump was faulty,
would that
put air into the system without water loss?Â*Â* I usually bleed whilst the
pump
is running ( as suggested by my local plumber ).Â* If i bleed cold, then
i can
expel all the air, without finding more, just seconds later, but as soon as
the system is turned on the air reappears immediately.. The system is
unvented, and powered by air source heat pump.
Any ideas welcome . cheers

I remember my mate couldn't bleed his radiators, turned out the flow of
water was pulling air into the system.