How to Open a TPR Valve

[Topslice]

Temperature and Pressure Relief (TPR) valve made by Reliance.

How do you open and close it.

I believe its a twist one. Do you just twist it anti-clockwise

or do you have to pull it out a bit first

 

[russell armstrong]

If it has a "cap" it twists anti clockwise, if it has a level you pull the level up or down.
However, can I ask what are you wanting to do (is it part of a service check or are you just making sure its opening correctly?

 

[Topslice]

so twist anti-clockwise - and that's it - no pulling?

can I just test the TPR valve by opening it - check that water flows through tundish.

and also to replenish the air cap at the top of the unit - opening the TRP is part of this procedure

 

[russell armstrong]

Yes, just turn it anti clockwise.
If you are replenishing the air gap, rather than sit there holding it open whilst it glugs away, put a one pound coin between the cap and the brass (sometimes the coin falls out though!) or use a special tool to hold it open.
Dont forget to isolate the cold supply to the unit before trying to replenish the air gap (you probably already know this anyway)

 

[Topslice]

Thanks

Not sure how the air gap works - hot water from the cylinder is from the
very top of the unit - but is'nt the air gap at the top?

How is the air gap formed and if the air gap is at the top of the unit
how does the hot water get to it from the top pipe?

Thanks in advance

 

[RBG]

What model is your unvented cylinder. You mentioned a reliance

 

[russell armstrong]

What model is your unvented cylinder. You mentioned a reliance

I think he means that the T or PRV is a reliance valve

 

[russell armstrong]

Thanks

Not sure how the air gap works - hot water from the cylinder is from the
very top of the unit - but is'nt the air gap at the top?

How is the air gap formed and if the air gap is at the top of the unit
how does the hot water get to it from the top pipe?

Thanks in advance

Hi
Most "air gap" cylinders have the draw-off pipe extends inside the cylinder and below the baffle plate so what you see on the outside is not the whole story. Otherwise, as you are probably correctly thinking is, if there is air there, how does water get up the pipe!

 

[Topslice]

Its a Megaflo unvented indirect hot water cylinder 120L CL, I think

 

[Chuck]

Its a Megaflo unvented indirect hot water cylinder 120L CL, I think

Just twist anticlockwise. It will snap shut if you go too far, i.e. more tha about 1/4 of a turn. They have sharp knurling and are pretty stiff so wear a glove to give a more comfortable grip.