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Zone running too hot

Old house with a new (less than 2 years old) hydronic, base board heat. 4 zones, Lux programable thermostats. One zone is running hot 72 deg (started a couple of days ago) when the thermostat is set @ 62. I switched thermostats (though kept the same baseplate) and still no change, so I don't think its a thermostat. Any ideas? :confused: Any and all info much appreciated.

Re: Zone running too hot

Could you advise if you have zone valves or zone circulators as your zone controls at the boiler.

If you have zone valves, please specify the brand name and model #.

Also, note if you have a control panel that controls the zone valves or the circulators.

If, as you say, you substituted the t-stats and the problem didn't go away, the fault may well be at the zone valve.

If you have zone valves, put your nose right up close and smell the power head for any "burned" odors; sometimes if you shine a strong light at the valve, you can see some signs of burning/overheating; sometimes a foul-smelling brown liquid oozes down over the bottom of the valve.

Also advise if you have 2 wires connected to the t-stats.

Check the literature that came with the t-stats, or take the cover off the t-stat to see if you can locate the "heat anticipator", and check its setting.

Some zone valves will only function properly if the t-stat heat anticipator is set at or close to the operating amperage of the zone valve (often 1 amp).

Please post back.

Re: Zone running too hot

Jacktheshack - Thanks for the quick reply. I did some additional research on the system in place. There are zone circulators and flo-check valves (TACO).

Last night, I unhooked the thermostat to see if the rooms still stayed heated, they did. After a while I went to check on the make/model info, I put my hand on the zone pipe in question - it was cold. While I was still in the basement, a different zone called for heat, and a few minutes later, the questionable zone pipe was now quite hot.... which led me to the flo-check valves . I hand turned the thumbscrew and heard a distinct "clink" (assuming the valve closing), and reset to original position. The renegade zone is now in control... What could cause the flo-check valve to stay open, and in such a new system, should I be worried about other valves? Thanks for any additional information you can provide.

Re: Zone running too hot


Looks like you found the problem--good work!

Circulator zoning is preferred by professionals over zone valves.

If one zone fails, you can still prop open the other flow control valves and get heat to the other zones on a cold winter's night.

Ocasionally, flow contol valves will "stick open" (especially if you have hard water) when a bit of crud prevents the valve from opening and closing normally with hot water flow in the supply piping.

This may well be what happened here: the flow control valve remained stuck open and you got what is known as "ghost flow" in the problem zone everytime the other zones called for heat.

As part of periodic maintenance, it's a good idea to "exercise" the flow control valves by working the little tabs on top.

Opening and closing the top tabs, you can listen to hear the telltale "clink" as the valve opens and closes.

Turning the top tab clockwise closes the valve; turning the tab counterclockwise opens the valve.

Quite often, if you have an indirect hot water heater for your hot tap water (recommended); the flow control valves are put in the closed position for the summer months to prevent hot water from migrating to the heating elements.

Re: Zone running too hot

Jack - Thanks for the help /reply. I'll go and give my other flo-checks some exercise....

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