expansion tank orientation

Nom_Deplume

Hi…homeowner here, planning some reorganization of the piping in our hydronic system. My question is about whether I need to invert the current placement of the expansion tank, which was installed many years ago (not by me) with inlet down (Extrol).

(a) The Extrol tank instructions say to only mount with the inlet up. Is it a big deal if we keep an Extrol tank mounted the wrong way? Of course, the tank will in any case need to be pumped out before it can be taken off. And some air gets stuck in the water side, but if I understand correctly, it's not a whole lot of air since the bladder is inflated to start. Is there any other issue?

(b) Watts tanks say they can be mounted vertically or horizontally. They don't say anything about not mounting with inlet down. Are Watts tanks made differently?

Many thanks!

hot_rod

Nipple up is preferred. I think the Amtrol Engineering Handbook still shows horizontal as the second option.

Zilmet use to show nipple up, sideways and down as acceptable in their manual.

It's the warm moist air in the steel part of the tank can cause them to rust through.

Or undersizing which causes the diaphragm to fail.

Personally I would use the Amtrol Extrol Pro tanks, they are a lined steel tank, so rust and corrosion is not an issue. It's basically the DHW expansion tank with a 1/2" stainless nipple.

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