Questions about Caleffi manifold

cckriss

I will probably be posting in this thread with questions regarding my Caleffi Twist Flow Inverted manifold every now and then as I work on my heating project.

Question 1: Do I need these loop caps for an empty port? Can I use a pex fitting with a capped stub-out?

https://www.supplyhouse.com/Caleffi-386500-3-4-Manifold-Cap
https://www.supplyhouse.com/Caleffi-680504A-1-2-PEX-Fitting-for-Manifolds

The cap only has 1 use. The fitting can be re-used when I want to add a circuit.

Thanks

cckriss

Question 2: I'm want to air pressure test my system. I am going to install the baseboard radiators to the hePex risers in their respective locations. Cap off the 1" port of the return manifold. Apply air to the supply manifold. What pressure should I air the system up to? 60-70 psi, same as my domestic water pressure?

Jamie Hall

I really don't like air testing. If something fails, the result can be anywhere from a loud noise to shrapnel all over the place, and I've had enough of both of those.

As a minimum pressure (preferably hydrostatic, pleast) you should go to twice the pressure relief valve setting.

cckriss

At the same PSI, how is air testing different than water testing? I just want to know if there's a leak before I put water in it. If there's a catastrophic failure with air, wouldn't it also fail the same with water?

Jamie Hall said:

I really don't like air testing. If something fails, the result can be anywhere from a loud noise to shrapnel all over the place, and I've had enough of both of those.

As a minimum pressure (preferably hydrostatic, pleast) you should go to twice the pressure relief valve setting.

EdTheHeaterMan

You can use either the Caleffi cap or a regular fitting with a PEX cap or plug. As long as there is a good air seal on the fitting that holds pressure.

As far as air pressure testing, based on the volume of what you are testing, the danger of damage increases the larger the volume of air needed. So a 1000 gallon tank at 100 PSI (per square inch) is a lot of pressure when you add up all those square inches you literally have a bomb ready to explode if the system gives way at just the right spot.

Since you are testing a small diameter tube and the air volume needed to create a 30 or 60 PSI pressure in that relatively low volume system, there will be much less danger in your test. That is not to say there is no danger at all. use common sense and always... SAFETY FIRST!

hot_rod

In the box there should be two plastic caps in a bag, those need to go on the air vents to cap them off tightly. The air vents that are on the manifold have hygroscopic caps, like this, that will not hold an air test. And it will drive you crazy looking for that slow leak. The float vent needs to have water to float and shut off, or a tight cap.

30 psi should be fine for an air test.