Expansion tank psi after shipping

jgaudet

I bought a #90 -14 gallon diaphragm expansion tank I think from PEX universe maybe and it had to be shipped to me and said it was pre pressurized to 12 psi but when I checked it it's 28 psi would that be cause it shipped by plane maybe?  Also my fill valve is pre set to 15 psi when I take the air down in my tank should I go to the recommended 12 or go to 15? Thanks.

HVACNUT

Use an accurate water pressure gauge, make sure cold water pressure is at 15 psi (hydro coil in an attic?) and make the extrol 15 psi.

jgaudet

Do I need a water pressure gauge if I'm checking the air PSI?  And I don't have a hydro coil. It's for hot water boiler for heating my house

Jamie Hall

You need an accurate air pressure gauge to set the expansion tank. It must be disconnected from the system -- or at least valved in such a way as to be open to the air. Then set it to your desired system pressure, less about 2 psi. Then reconnect it to the system

Now -- you need an accurate water pressure gauge to make sure that your system is charged to the correct pressure. Not all automatic feed valves are all that accurate... nor are the gauges on boilers or whatever.

jgaudet

Ahh ok got ya. My tank ain't hooked up yet I just got it Im doing my system over and I checked the psi and it's showing 28 psi so I will have to let air out till it gets down to 12 psi then hook hook it all up.. also when I fill my system back up and bleed the zones should I isolate the expansion tank while.i bleed the zones or no? And I put a picture here is my expansion tank good to be piped like this or does it have to be directly under the spirovent? Thanks 

Zman

Assuming that the circ is pumping to the left of the diagram, that location should work well. I prefer to not locate the tank directly below the separator. Sediment tends to end up in that location that will end up in the tank and reduce its life expectancy. If you install a valve like this (or build your own) you can check the pressure of the tank without removing it from the system. https://www.supplyhouse.com/Webstone-H-44672-1-2-Pro-Pal-Full-Port-Brass-Ball-Valve-w-Hi-Flow-Hose-Drain-FIP-x-FIP-600-WOG?gclid=CjwKCAjwk6-LBhBZEiwAOUUDp9YG4yV0LLWxSceQ6sJK8DXsUFAtWxU8fVVwIaqgsGH7zFRUa14ZexoCyUYQAvD_BwE

jgaudet

Yes you are correct it is pumping to the left to the zones. I just wasn't sure if the piping going to the expansion tank could turn like that in the picture! And I actually got the exact same service valve i was going to put it on top of the tank like my picture but I think I will install it right under the spirovent jr. And then just pipe down to the tank with the 1/2 pipe!  Also do you isolate the tank when bleeding the zones? 

EBEBRATT-Ed

You can isolate the tank if you want to when filling, it really doesn't matter

jgaudet

@EBEBRATT-Ed ok thanks I probably won't isolate it I just wanted to make sure, I'm almost done doing my system over and will have to bleed it after I get it filled back up, here's a pic of what my old return manifold looked like and now my new one. Just have to finish up the supply side now. Here's what's done so far.