Purging Air from the Storage Tank

[rickh1001]

As I am in the middle of cutting pipe and finishing off the plumbing for the EKO 60, it suddenly dawned on me (as in Duh!) that the 500 gal LP storage tank will also be a massive air collector. I am piping the supply into the top. Any air during initial startup or later, will accumulate at the top of the tank, and never make it out of the system at the bottom return. So it will inadvertantly be creating an air reservoir in the LP tank, with the only exit being slow dissolution back into the water, where the air separator could pick it out.

With that, I decided to add a valve to one of the available ports on the top of the storage tank. I will just open it during the system fill, and periodically thereafter, to remove any air lingering at the top of the tank. However, in all of the discussions I have followed over the past 6 months or so here, and the various system setup pictures, I have never found this issue mentioned, and I have not seen a purge valve on the tanks of pictures in the various setups. Am I missing something here, and will any air trapped in the top of the tank just remove itself naturally, without needing to worry about it?

 

[Willman]

Good call IMHO. No system needs any more air than what is contained in the water. I would think about a short nipple prior to valve for a small accumulation area between purges. Maybe even an auto air vent. Hopefully some of the pro installers will weigh in on this aspect.

Will

 

[machinistbcb]

I put a pressure releif valve at the top of my tank and used that to bleed any air out. When I filled the tank I loosened up a few fittings to allow all the air out as the tank filled up.

 

[jebatty]

I use the auto air vents at all high points in my system, just to make sure there are no air locks. A manual valve at the top of the tank is a good idea for initial filling. Once the system is pressurized, and if pressure is maintained, and all air is purged, the air issue should be over.

 

[rickh1001]

Thanks for the excellent feedback. I think I will use all the ideas. I have an extra 3/4" port on the top of the tank. I will put in a short nipple+T, with a purge valve, plus a small air separator on top. That way I can easily purge the tank of air during the initial filling, and continuously get rid of any air that somehow makes it way into the tank. I am also making sure the tank is very level, so no air will get trapped at either end.

 

[jebatty]

I don't think you need to be very concerned about a small amount of air being trapped at an end of the tank because the tank is not level. It won't take too long before that air is absorbed into the system and replaced with water. Rather than an auto air vent at the top of your tank, if you have plumbing that rises from the top, such as your hot water inlet, any air will rise through that plumbing when the tank is not charging to the plumbing high point. That would be a good place to put the auto air vent. The purge valve at the top of the tank is good for any large quantity of air.