relief valve or boiler thermostat

[pspec]

Hi
This is a mix question both pluming and oil boiler so which forum to put it in ..
Let’s try this one……

My oil boiler heats my hot water and where the boiler hot pipe enters the electric boiler there’s a relief valve with max 120c on it where the pipe exits there’s another.

For the last week the top one has been dripping so I put a 2 litre container under it. As it was just a few drips I thought it would just stop. However overnight it filled the container and over flowed and started dripping into the down stairs bathroom. By morning it was back to a slow drip fun stuff ah.
Now I’m thinking……

1. The boiler is heating the water up past 120c
If that's it there must be a thermostat that could be turned down is that something I could do or would I call (1) a boiler engineer or (2) a plumber (oh just thought could the thermostat be faulty.. if the boiler has a thermostat)

2. Could the relief valve be faulty or in need of cleaning ..
If you unscrew the red cap there’s a button like thing could that be pushed down to clean it out. The top also looks like it could unscrew is that away to clean it out or would it just need replacing.

Thanks

 

[stevetheplumber]

its an automatic air vent eitherscrew the red cap down and forget about it or change it doesnt need system draining as it should have a built in valve just hold against on the first nut below it

 

[Riley]

Good work Steve

 

[pspec]

Thanks for the info I got a new one bolted it on then went on holiday…

Now I’m back I want to fit it a bit better..

I removed the old one as it was easy to isolate then turned the water on to give it a quick flush out then screwed the new one in.
I took the red cap off as I thought a may need to clear the air out and thought I would wait until the water came out the top but no water did.

so does that mean I’ve done something wrong????

Also how tight should the red cap be should I screw it halfway down or all the way down????

Thanks

 

[jonnyswamp]

From what you say it's working correctly, no water should come out through the top, only air
Leave the red cap loose to let any air, that may collect later, to escape

 

[AWheating]

The cap should really be left closed once the system is cleared of air. Water should not come out although a little bit of moisture may make it out when it's releasing air.

 

[GrahamM]

As AWheating Flamco actually state to open red cap when filling system to release air and then close the cap.

 

[pspec]

ok thanks....

I've now removed the cap to allow the residual air from fitting the vent to escape.

so I presume I'll know the air has gone when he top has some moisture on it ????

also does the water in the system need to be cold to do this ????

Thanks again guys for taking the time..

 

[jonnyswamp]

As AWheating Flamco actually state to open red cap when filling system to release air and then close the cap.

Ah, every day's a school day, I've always left them loose
If the cap is tightened, how is it an AAV
Are these only designed for filling a system and not continual operation?

 

[PhoenixServices]

The manufacturers state usually they are for filling only then once it's done to close.
Otherwise they leak everywhere once they get the tiniest bit of sludge in them.

 

[lame plumber]

The manufacturers state usually they are for filling only then once it's done to close.
Otherwise they leak everywhere once they get the tiniest bit of sludge in them.

funny all the MFIs I read they say open 3 turns and nothing else, so you leave them open, after all they are there to remove air that builds up during operation, otherwise they could just fit a standard rad valve.

 

[SimonG]

I leave them open. Unless dumping pressure to do some work on system, then I close them.