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Posted by Heatpro on December 08, 2005 at 20:26:04:
In Reply to: Re: Spirovent placement posted by Dave on December 08, 2005 at 18:48:41:
The place where the air vent is, on top of the vertical supply manifold stub going to the zones is the place to put it. It is coming off the tank, so any air bubbles collected there will go up to the vertical stub and be vented there.
An air scoop of the type of the spirovent that expands to a diameter twice that of the pipe is a place that air can slow down and bubbles rise to the top to collect and go out the vent. The tank is huge in comparison to that, so bubbles will float to the top of the tank. From there the top outlet is the supply pipe to the vertical manifold stub with the vent on top of that, where it will collect bubbles to vent. As the vertical manifold stub is the place where varying slower flow rates will occur due to periodic demand of the zones, it provides the place where water will be slowest in the system, giving the best opportunity for bubble separation - even better than the 24 to 30 gpm flow through a horizontal air scoop separator.
Actually, after the first few weeks of operation in the winter with all zones running, there will be no more bubbles to catch. The water supply can be shut off to the system and the air vents closed, sealing the system. After that, a signal that air got back into the system due to a leak would be bubbling stream noises in the pipes.
I didn't ask if there was a low water cutoff in the system, but the flow switch to kill the burner could be of some help there. It is better to have a low water cutoff above the boiler tubes though, not to just depend on the flow switch, even if the low water cutoff is never used (we hope), just to be sure in case of a problem.