One zone not working


Old 01-27-17, 08:59 PM
Thread Starter
Join Date: Dec 2008
Location: Mass
Posts: 310
One zone not working

I have hydronic baseboard forced hot water with 2 zones and taco zone valves. The upstairs zone there's no problem. The downstairs won't call for heat. I tried a second thermostat and also jumping the wires but it won't turn on the furnace. Hot water seems to get to the first two rooms without the furnace getting turned on then doesn't make it around to the rest of the house. The pet tubing coming out of the zone valve has really hot water too and the first baseboard in the zone is really hot. Always worked fine but this just started happening. Troubleshoot? I manually opened the taco valve but it's still not heating. The waters not getting pushed through.
Sponsored Links
Old 01-27-17, 09:30 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 51,393
Upvotes Received: 210
The waters not getting pushed through.
You did say it's getting to the first baseboard so some water is moving thru.

Try running just the problem zone. Shut the other one off.

You may need to bleed air from the problem zone.
Old 01-27-17, 09:38 PM
Thread Starter
Join Date: Dec 2008
Location: Mass
Posts: 310
I did have the working zone off. I can try bleeding but why would air not make the furnace go on?
Old 01-28-17, 08:50 AM
Join Date: Oct 2013
Location: United States
Posts: 2,698
Upvotes Received: 11
From your description it sounds like you may have a bad end switch in your zone valve.
You have a couple options to test it. The simplest way is as PJ suggested only you must have the other zone calling also because that zone will activate the pump. So put the unworking zone on manual at then turn up the working zone's stat which will activate the pump and burner and send heat to both zones, essentially making your house a single zone system.

The other way to test is with a meter if you have one. With your stat calling you should have 24V or a little more at terminals 1 & 2 on the ZV, which will make the manual lever move with no resistance, and make an end switch which turns the pump and burner on. Once the ZV opens and you have verified power to 1 & 2 remove the wire from terminal 3 and check for continuity between 2 & 3.

If you don't get continuity or your meter does not beep your end switch is bad and the head must be replaced.

The upside to using ZV's is that you don't have to go without heat until you replace the head by just putting on manual and using the working stat to heat both zones,

Hope this helps a little.
Old 01-28-17, 09:28 AM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
If you don't have a meter, you can swap zone valve heads. If the problem follows the valve head, it's almost certain the end switch is bad.
Old 01-28-17, 12:14 PM
Thread Starter
Join Date: Dec 2008
Location: Mass
Posts: 310
Thanks for the replies. It ended up being a bad zone valve.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes