I’m adding a microbubble air separator to my hydronic heating loop to cut down on the time it takes to clear air pockets out of the system. One book says to install it on the main return line to the boiler, but the Honeywell data sheet shows it on the output side of the circulating pump right before the zone valves. The boiler is a wall-hung unit with a built-in pump, expansion tank, and air vent.
My question is does it matter which side of the pump it’s on?
Thanks in advance
Edited 10/13/2006 6:46 pm ET by TJK
Replies
Actually they should be installed between the output of the boiler and the pump. In your case (where everything is package plumbed) you probably don't have much choice except to install it on the output run of the boiler where the water is the hottest.
Thanks for that advice. Yes, the air vent built in to the new boiler is between the heat exchanger and the circulating pump. On our old cast-iron boiler, the air separator was located on the return side.I suppose it makes sense to put it where the water is hottest and the air is easier to remove. The built in vent does it's job removing large bubbles but we have a few baseboard runs with air pockets that persist for weeks and I'm hoping this microbubble vent will clear those out quicker.
Have you force bled the runs to the baseboard units? Do you have air bleeders on each baseboard unit?
You should be able to easily eliminate any air "pockets" from a run if you have the system plumbed correctly.
We live in an older house and the baseboards runs are what they are. Short of tearing it all out and re-plumbing, there isn't much we can do. Two of the three loops do have bleeds, and I even tried using them once. It was a mess because one wouldn't close after it was opened and I had to drain everything and replace that elbow. Now I just flush the system and get 95% of the air out and let the vent do the rest.We're done with remodling work so (hopefully!) I won't have to drain the system again, just add make-up water now and then when the pressure gauge drops below the minimum.
There is a problem if you have to add water. Hydronic heating is a closed loop system - once you add water is in there it shouldn't be coming out. If you have to add any water after the air is worked out, that means there is a leak - water just doesn't evaporate from a closed loop.
A micro scrubber air removal device will do wonders for your system. More importantly, and the cause of many air problems is the location of the circulating pump. You want that pump to pump away from the expansion tank . Most older systems have a pump on the return pumping into the tank, the tank is the point of no pressure change PONPC , causing a negative condition in the rest of the system, and can actually pull air in from those bleeder valves on the baseboard.
Install the micro scrubber air removal device, on the supply pipe from boiler, on the bottom there is a tapping, tie in your water make up line and expansion tank there. After that install your circulator. You will never have to bleed a system again after the initial purge.With wall hung boilers, install on the supply outlet, the built-in pump is there to assure flow thru unit, and you may need a second circulator for your system side. visit http://www.heatinghelp.com and look for the book and info on "pumping away"Good luck.Devan Singh
http://www.singhmechanical.com
Edited 10/14/2006 4:06 pm ET by singhmech