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Honeywell T7400 thermostat

SpeyFitterSpeyFitter Member Posts: 420
I have a Honeywell T7400 Thermostat serving a portable class room. The thermostat controls a Temspec Unit Fan Ventilator with electric elements for heating - serves to ventilate (using some outside air/damper) as well as heat the space. There is an enthalpy controller with no real markings on it inside the unit venitilator with 4 contacts labelled 1, 2, 3,  & 4, which connect to terminals 1, 2, 3, & 4  (respectively) of the above mentioned thermostat. Before I go jumping things to see if the thermostat is the culprit to the problem that the heat doesn't seem to be controlled properly, I want to know if these are just 2 sets of dry contacts (how do they correspond to todays thermostat terminal letters)? I have contacted Tempsec who is looking for a manual for me on their ventilator/wiring which is designed with this thermostat as standard equipment.
Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber


  • EmpireEmpire Member Posts: 2,343

    I tried to look up the configuration on the T-7400 stat with no luck.  I am assuming the HW T-stat cam w/ the heater.  Do you have the manual?  stupid question or you wouldn't be asking.  sorry.  Is this stat the older version say,...2000 or so?  Thinking about your problem in hindsight, the wiring diagram on the unit itself should tell you what the designations are for the given #'s 1/2/3/4.  Can you post the Wire diagram from the equipment?


    Mike T.
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