What is this below the automatic air vent valve?

[fullel]

The (apparently rotated) picture shows my badly scaled up automatic airvent valve just a few cm downstream from the pump. I have some water hammer (hydraulic shock) when the pump goes off and this scaled up air vent is my prime suspect. I am ready to drain the system down and screw this old vent off. By the look of the amount of nipple, I will have to cut the olive off, clean the pipe and replace with the new compression 15mm auto air vent.

What I don't know is what the object is immediately below the air vent sticking out to the left and whether I need to replace that too. Is it a manual bleed valve for example?

Thanks.

 

[Dotty]

Pressure relief valve.

I'd replace it with one of these. You want 3bar.

 

[Dotty]

And that's an oil boiler you have, yes?

 

[fullel]

Thank you. So it is a manual version of the same thing? Twist to relieve pressure and retighten?

 

[Ermintrude]

No sir it's gas I'm playing wiv

 

[fullel]

And that's an oil boiler you have, yes?

Yes. Grant 140 160 Kerosene.

 

[gassafe]

I can't see a prv valve, looks like it was once a tee piece & its been capped off maybe?

its best to fit an isolater before an auto air vent, saves draining down to change or service the air vent!

 

[Centralheatking]

It all looks a bit old and crusty to me - I would be tempted to
cut out as much as I can see on your post and replace the prv and
mt cock all in one go.

Now is the time - summer bbq season dont wait till November CHK

 

[Dotty]

Thank you. So it is a manual version of the same thing? Twist to relieve pressure and retighten?

No, it's automatic but I've seen the type you have there fail too often. Don't trust them.

I can't see a prv valve, looks like it was once a tee piece & its been capped off maybe?

its best to fit an isolater before an auto air vent, saves draining down to change or service the air vent!

It's definitely a PRV buddy, I agree with the isolator but it must be fitted so it isolates the AAV only.

 

[fullel]

Looks like a pain to fit an isolator because there's little room without taking off the T going to the right with its own lever ball valve (primary feed to second HW cylinder) and little room below that where it all gets a bit 32mm.

 

[happyflyer]

I can't see a prv valve, looks like it was once a tee piece & its been capped off maybe?

its best to fit an isolater before an auto air vent, saves draining down to change or service the air vent!

My money is on you gassafe

 

[happyflyer]

Please send a better photo so we can bottom this one out, we like to be spot on on this forum

 

[Dotty]

We are spot on already Tony. He has one of these.

Spring Safety Valve 1/2" - EPS-BF440 - Supremeplumb.com

 

[happyflyer]

We are spot on already Tony. He has one of these.

Spring Safety Valve 1/2" - EPS-BF440 - Supremeplumb.com

Yep that's better Crops, it looks like that, I have never seen one like that before in the trade 55 years

 

[Ermintrude]

Seen a few in void adjacent to bbu!

 

[lame plumber]

aaaugh thought we might get some entertainment there,🙂

 

[fullel]

Yes, that's the one. Here's the reverse angle replay for confirmation. Now what does it do? 🙂

 

[plumber0808]

Under the auto air vent... I can see 7 clothes pegs.....

 

[Dotty]

Yes, that's the one. Here's the reverse angle replay for confirmation. Now what does it do? 🙂

View attachment 19061

As I said earlier, it's a safety valve designed to release pressure should something go pears. It releases around the 3 bar mark.

Don't like them. Don't trust them. Seen too many fail.

 

[AWheating]

Crops spot on

Used to fit loads of these years ago mainly above heat only boilers. You can adjust them, but they always leak over time and need replacement.

 

[happyflyer]

Now that.s a better photo, well spotted Crops, you know all about blowing offs

 

[fullel]

So why are there two valves? The normal one is a 6 bar trigger and this little thing is 3? Is there any reason I can't leave the suspected broken spring safety valve and put another new one on 15mm above it with the new auto air vent on top of that? I'm a bit worried that trying to replace the SSV will lead to a cascade all down the tree requiring repiping the 22mm piece to the right _and_ the 35mm section and...

 

[happyflyer]

Crops spot on

Used to fit loads of these years ago mainly above heat only boilers. You can adjust them, but they always leak over time and need replacement.

AW, as Crops says they are Tosh, nothing to them, when they blow off where does the water go on the floor, on the OP photo wash the wall down, hell that's before the Ark design, can we see one in bits and learn the folly of our ways..:rofl: you can just imagine one of those in the bottom of a Kellogs Rice Crispies

 

[happyflyer]

So why are there two valves? The normal one is a 6 bar trigger and this little thing is 3? Is there any reason I can't leave the suspected broken spring safety valve and put another new one on 15mm above it with the new auto air vent on top of that? I'm a bit worried that trying to replace the SSV will lead to a cascade all down the tree requiring repiping the 22mm piece to the right _and_ the 35mm section and...

Fullel,

Where is your 6 bar coming from, surly not domestic.....

 

[Dotty]

If you've a 6 bar on that then either your system was installed by a diyer or you're looking at your unvented cylinder which you can't touch anyway.....

 

[jtsplumbing]

Left over from old system, probably solid fuel BB, what boiler do you have now ? if you have a pressurised system you will have a more up-to-date PRV, so you can cut out and remove this old fitting

 

[fullel]

Fullel,

Where is your 6 bar coming from, surly not domestic.....

The tall auto air vent at the top is 6 bar, isn't it? There was also one attached to the primary return from the HW cylinder which was weeping and replaced.

 

[Dotty]

No no no no no.....

That means it can be used on systems with pressure up to 6 bar.

 

[fullel]

Ah yes. Well, still don't know why there are two. So, just replacing the top one should work then? I kind of thought the water hammer was caused by air not being able get _in_ to fill the 'vaccuum' when the pump stops.

 

[Dotty]

The top one is an Auto Air Vent. It vents air out of the system automatically (see what I did there?) but doesn't. or shouldn't, allow air back in.

The bottom one is a Pressure Relief, or Safety, valve. It automatically releases pressure over a given point which, in your case, is 3 bar.

Neither the failure, nor the operation, of either component would result in the noise you say you have.

I'd suspect a sticky flapper type none return valve to be honest.

They have two completely different yet vital functions

 

[fullel]

Right, I'll leave them alone then. 🙂

 

[happyflyer]

Hells Bells!!! :sweatdrop: I think they are going to make Plumbing a trade next week