Air in Rads

Blowheads

Hi All,
Firstly my system looks like:
9 rads upstairs, 9 downstairs. Large new 300L cylinder, large and small tank in the attic. 4.5 bar pump to 1 tap and 2 showers. Stove with circulating pump for rads and water.

Few weeks ago the oil boiler would not fire unless I reset the limit switch on the thermostat on the boiler. Then it would fire OK.

I asked the plumber to do 3 things, 1 fit a valve on boiler so I could drain the system without flooding the place, 2, replace the ballcock in the big tank as it was allowing water overflow, 3, fit an auto bleeder to one rad upstairs as I had to regularly bleed it. this was in advance of asking the sparky to replace what could have been a faulty thermostat. Plumber duely did all requested.

Today I have to bleed 4/6 of the rads upstairs that I never had to bleed before. I do this every 3-4 nights. Oil boiler is now working fine and fires every time.
Plumber is puzzled. No obvious leak. Lot of gurgling/fizzing in the rad with the auto bleed.

I was up checking the levels in the big tank and set it to higher that the plumber had after replacing the ball cock, I noticed when using the pump (we have one tap and 2 showers on a 4.5 bar pump) that the overflow pipe kind of spat up a drop. Further there is a little black cap on a valve on the cylinder which when opened vented some air the other night

Any ideas to find the root cause of all this air?

Thanks,
Paul

corkgsxr

any signs of pitching?

or if you tie up the ballcock in the morning. has it dropped anything in a few hours?

Blowheads

Hi,
I didnt try that yet. Was a next step, but was half expecting to see water leak somewhere showing at this stage (ceiling or other) but since we are there now 3 years I didnt see anything I kinda ruled that out.

Could you elaborate further on "pitching". I get the basics, but what is causing it and how could it be stopped? The 4.5 bar pump is beside the cylinder on the grounf, the big take is directly above the cylinder and the small tank is above that again

corkgsxr

when the stove or heating is on you get water coming out the vent over the small tank.

as for leaks some you will never see as they will just drain away

Blowheads

OK, any ideas how to fix this issue, based in Galway. Cant be bleeding the bleeding rads day and night ;-)

Dtp79

finneranpaul wrote: »

OK, any ideas how to fix this issue, based in Galway. Cant be bleeding the bleeding rads day and night ;-)

Auto air vents can also suck air into a system. I'd never leave one open. They can suck air in and almost guaranteed to leak at some stage

sullzz

finneranpaul wrote: »

OK, any ideas how to fix this issue, based in Galway. Cant be bleeding the bleeding rads day and night ;-)

No ideas on how to fix it until you do what CORKGSXR said first , then report back with your findings.

sullzz

Dtp79 wrote: »

Auto air vents can also suck air into a system. I'd never leave one open. They can suck air in and almost guaranteed to leak at some stage

They only suck in air if you have water getting out , they are designed to be left open , if you leave them closed it would be cheaper to use a blank cap instead of fitting one at all , they leak as you are using cheap ones , use better quality ones or else use a penny valve before it so you don't have to drain down when replacing them , some people might even call it a maintenance valve:o

Dtp79

sullzz wrote: »

They only suck in air if you have water getting out , they are designed to be left open , if you leave them closed it would be cheaper to use a blank cap instead of fitting one at all , they leak as you are using cheap ones , use better quality ones or else use a penny valve before it so you don't have to drain down when replacing them , some people might even call it a maintenance valve:o

I don't use em at all sullz. I've seen good ones leak too

sullzz

Dtp79 wrote: »

I don't use em at all sullz. I've seen good ones leak too

What about on the flow to cylinder coil , or on high points of heating circuits

Dtp79

sullzz wrote: »

What about on the flow to cylinder coil , or on high points of heating circuits

Always manual vents. Usually 12 inches of 3/4 copper out of the tee and manual vent into that. The 12 inches of copper will accumulate any air trapped. Never had any problems so far. Once the air is out of the system it stays out

sullzz

Dtp79 wrote: »

Always manual vents. Usually 12 inches of 3/4 copper out of the tee and manual vent into that. The 12 inches of copper will accumulate any air trapped. Never had any problems so far. Once the air is out of the system it stays out

Nah you need auto vents , why do you think they are in system boilers

shane0007

Dtp79 wrote: »

Always manual vents. Usually 12 inches of 3/4 copper out of the tee and manual vent into that. The 12 inches of copper will accumulate any air trapped. Never had any problems so far. Once the air is out of the system it stays out

What do you use on open vented gas boilers or on oil boilers?

corkgsxr

The flamco aav's don't leak.

The also come with a valve to close when you take it off in future.

About double the price

sullzz

Yeah I tend to use the flamco flexvent ones , never once had an issue with them

corkgsxr

Aib bank in blackpool has 4 flamcos in the ceiling over the main foyer. Not a hope of getting at them without ripping down the ceiling.

Theres trust for ya

shane0007

corkgsxr wrote: »

The also come with a valve to close when you take it off in future.

Do they? I didn't know that.
Mine just come in a red & white narrow box but no valve!

sullzz

shane0007 wrote: »

Do they? I didn't know that.
Mine just come in a red & white narrow box but no valve!

Mine dont come with a valve either , I presumed he was talking about a different one from flamco .

corkgsxr

shane0007 wrote: »

Do they? I didn't know that.
Mine just come in a red & white narrow box but no valve!

Maybe bad description. If you unscrew the body from the hex bolt it has a rubber spring valve that closes as you split it

sullzz

:eek: I'd be waaaay to afraid to try that , ill take your word for it;)

corkgsxr

sullzz wrote: »

:eek: I'd be waaaay to afraid to try that , ill take your word for it;)

No they work really well feck all comes out. Its abit redundant. You only need it if they give trouble. But they don't.

Its like the lifetime warranty with oil tanks. They only fail if you're base is wrong. He must do nothing

Dtp79

shane0007 wrote: »

What do you use on open vented gas boilers or on oil boilers?

Just manual vents. Once the air is out its out. I only find auto air vents " handy " when filling a system on your own and dont Have to stand over it on the initial fill. Once the system is bled there should be no issue and there never is

shane0007

corkgsxr wrote: »

Maybe bad description. If you unscrew the body from the hex bolt it has a rubber spring valve that closes as you split it

Thanks. I did not know that either. Good to know. I only had 2 faulty ones but they were not leaking, they just would not let air out!

shane0007

Dtp79 wrote: »

Just manual vents. Once the air is out its out. I only find auto air vents " handy " when filling a system on your own and dont Have to stand over it on the initial fill. Once the system is bled there should be no issue and there never is

If you are installing manual air vents on boilers then you should inform your customers that they may not have any manufacturer's warranty. This is a condition of warranty that an AAV is installed on the boiler. What happens if a pump gland weeps beside the boiler? There are many many reasons why air will get into a boiler & if you are not there to remove it every time, then the air pocket will cause extremely high temperatures within the boiler & could result in a warped boiler. This is also why the AAV cap should not be tightened.

Blowheads

Ok, have tired up the ball cock in small tank so let's see. However also a test, whenever the tap runs from the pump then it is pitching back a small bit back into the main tank after turning the tap off

Dtp79

shane0007 wrote: »

If you are installing manual air vents on boilers then you should inform your customers that they may not have any manufacturer's warranty. This is a condition of warranty that an AAV is installed on the boiler. What happens if a pump gland weeps beside the boiler? There are many many reasons why air will get into a boiler & if you are not there to remove it every time, then the air pocket will cause extremely high temperatures within the boiler & could result in a warped boiler. This is also why the AAV cap should not be tightened.

To be honest I've never fit an open vented gas boiler. If there's an aav with the boiler then yes I'd leave that one open. As for oil, I've seen endless aav s leaking, usually down onto the burner in outdoor modules. Probably leaking months if not years

corkgsxr

the glowworm aavs are a fecker for leaking

Dtp79

corkgsxr wrote: »

the glowworm aavs are a fecker for leaking

Not the only ones!

Blowheads

Ok, sorry to come back to the original thread topic, but, after day 1, there is no sign of pitching into the small tank nor has te water level dropped. Slight water came out of the valve on cylinder but only a few dropps.. only oil on,no stove yest. next steps??

Irish Steve

Are you still having problems with air getting into the upstairs radiators?

Blowheads

Yep, thats the crux of the problem

Irish Steve

Ok, living on the edge here, is there any chance that the newly fitted upstairs air release valve is actually drawing air in?

To find out, easiest way will be to tightly wrap the entire head of the valve and the top stem in cling film, and see if that stops the noise etc when the pump is running. If it's the one i think it is, there's a small stem on the top that looks a lot like a tyre inflation valve stem. That's the important bit to seal off.

Yeah, I know it sounds crazy, but I have seen it happen once on a site in the UK, and something has changed for that much air to be getting in now compared to before.

corkgsxr

Why not just close the nipple on top.

Irish Steve

corkgsxr wrote: »

Why not just close the nipple on top.

It might not be there, I've seen more without them than with them

Dtp79

Irish Steve wrote: »

It might not be there, I've seen more without them than with them

That's why I always use manual vents!!

Blowheads

Hi All,
Ok, I have taped over the auto bleed valve.

Rads still rattling / "fizzing" a bit though.

The valve on the cylinder has a drop of water at it, but opened the cap, no air came out.

I will let things cool a bit and re check all tomorrow before the heating comes back on tomorrow evening.

I have attached 2 photos, one of the auto bleed valve and the other of the valve on the cylinder, you can see the staining where there has been water.

back to school tomorrow....

Blowheads

No sign of pitching to the small tank, auto vent sealed, no sign of leak (water level in small tank OK).
Last night with stove lit, the oil came on and good few of the rads upstairs started "rattling", opened the vent on the cylinder and released air..
any ideas?

shane0007

Dtp79 wrote: »

To be honest I've never fit an open vented gas boiler. If there's an aav with the boiler then yes I'd leave that one open. As for oil, I've seen endless aav s leaking, usually down onto the burner in outdoor modules. Probably leaking months if not years

AAV's usually leak because they are either located incorrectly or the circulating pump is located in a poor thought out location. Systems that are in negative pressure will also have the AAV in negative pressure where they are designed to be in positive pressure. The positive pressure forces the float valve within them in the upward position, whereas in a negative pressure location, the float valve is pulled downwards, thus resulting in failure.
They do, of course, leak for the heck of it too but it helps to have them in a positive pressure zone, i.e. in front of the pump.

Dtp79

shane0007 wrote: »

AAV's usually leak because they are either located incorrectly or the circulating pump is located in a poor thought out location. Systems that are in negative pressure will also have the AAV in negative pressure where they are designed to be in positive pressure. The positive pressure forces the float valve within them in the upward position, whereas in a negative pressure location, the float valve is pulled downwards, thus resulting in failure.
They do, of course, leak for the heck of it too but it helps to have them in a positive pressure zone, i.e. in front of the pump.

I'd always have em in the positive pressure zone but as Ye said they will leak just for the heck of it!

Blowheads

closing this one off.. problem solved. seemed the stove was boiling the water in the rads creating the air bubbles. didnt see it as the stove could only get rads to luke warm, but seems oil brought it to hot and stove then carried on to boil