Radiant Heat Boiler Plumbing Question

[Ezzie]

I am doing the plumbing to connect my hydronics boiler to the distribution manifolds for my in-floor radiant heating. I am a little confused about which side of the system the air seperator/microbubbler needs to go and the expansion tank location. The installation manual seems to contradict the installation notes that came with the Honeywell seperator I got. Maybe it doesn't matter but perhaps their is a radiant heating "pro" on here that could explain this a little clearer for me??

The boiler is a Triangle Tube Excellence which had an integral DWH tank. It has a built in Grundfos circulator pump that is on the "supply" side pushing the fluid through the floor. I am going with only this circulator and using zone valves on each of my 3 zone manifolds to control the flow. The manual says to install the air seperator/microbubbler in the supply line between the boiler and the supply manifolds. It shows the expansion tank and auto-fill on the return line between the return manifold and boiler. The instructions that came with the Honeywell air seperator/microbubbler show the expansion tank hanging off the bottom of it (there is a 1/2" NPT tap to allow this). Does it really matter which side of the floor the air seperator is on??

Any thoughts??

 

[MattFirebird]

Eezzie
Compression/expansion tanks in a sealed system (what you have) goes at the point of lowest pressure. Typically that's near the pump inlet side. Same for air scoop or vent. Here's a couple of links,
http://www.bellgossett.com/BG-TechTalk.asp will tell you more than you ever want to know.
Here's a pretty good pdf http://www.amtrol.com/pdf/EXTROLAXSeries9017-093.pdf .. The pictures on page 3 show the pump drawing through the boiler, just put the pump on the inlet side of the boiler and you should have a good idea of how to plumb your system. Lowest pressure is at the suction side of the pump, and that's where you want your expansion tank and air separator.

Good Luck.

Matt