Second floor zone won't heat unless the first is on


Old 01-30-16, 05:20 AM
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Second floor zone won't heat unless the first is on

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Hi guys, we have 2 zone heating (oil furnace) and the past few days noticed that the second floor won't heat when working by itself. The unit is located in the attic and it turns on by the thermostat, but it's blowing cool air. The strange part is when we turn on the heat on the first floor, warm air starts blowing on the second floor as well. When it's working by itself the incoming water pipe is cold. As is the pipe above the zone valve (the one on the left in the attached image). So it seems as though water is flowing by it's not warming up. I would think the boiler is working fine since one zone works. We had a repair guy come in who checked the pumps by the boiler and everything was working. He thought it was the air so he ended up draining a couple of buckets of water. I wasn't home when he was here, but my wife said it started working. When I got home from work later in the day it was back to where we were - cold air blowing upstairs. Any ideas what the problem could be? Attached some pictures. Let me know if you need any others. Thanks in advance.

Last edited by lawrosa; 01-30-16 at 10:32 AM. Reason: spaced pics.....
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Old 01-30-16, 08:17 AM
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Welcome to the best DIY forum on the Internet. Next time do a double line feed (press ENTER twice) between pictures so they don't all run together.

I suspect that the "end switch" in the upstairs zone valve is not actuating the circulator relay.
Old 01-30-16, 03:51 PM
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Set Thermostat to low,
Move the Manual open lever on the zone valve to AUTO,
raise thermostat,
observe valve and boiler.
95-6983_A V4043, V4044 Valves; V8043, V8044 Zone Valves[pdf]

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