M380 Hurricane Heater

[pgchin]

OK Chuck, Thanks
So I studied the picture again. I see the yellow handle after the tee which is what I think you are talking about. The other 2 yellow handle tees directly under the red handle valve, is each one the return side of each zone? The reason for the question is if they are, then you can attach a hose to zone 2 and put it in a pail, shut zone 1 and see if the circulator is pushing fluid though zone 2 or not. You still won't be able to determine if it is a blockage or an air pocket if it isn't, BUT it will determine that you will have to amp it up and actually isolate zone 2 and back flush it or physically inspect it, all big deals of time and effort. They always say when something stops working, go back to the last thing you touched. I presume you can't do that as I reread your first post and you stated this was an issue from the start but did the prior owner or dealer happen to mention any interior work? If they did some, maybe they kinked a hose or register accidentally in zone 2 and you can examine that one first????? I'm stretching here ole pal, this appears to be a duzzie!!!!! And I hate calling in a professional only as a last resort!!!!!!!!