Wire a dayton 4lz94a thermostat for turning on a gas fired heating unit?

I found the installation manual for several Dayton gas heaters, including the 4LX62, at Grainger: https://www.grainger.com/product/DAYTON-Gas-Unit-Heater-4LX62 . The direct link to the manual is currently https://www.grainger.com/ec/pdf/4LX68_1.pdf . Since this is a 250,000 BTU unit, the wiring diagram 5C on page 11 is the one appropriate for your unit.

I hope this helps. I could not find separate documentation for the A suffix heater. The suffix may indicate a minor difference (for example - manufactured at a specific facility) and thus the 4LX62 manual is still appropriate.

Cindy Wells

That all depends on how old the system is, wires colors change over the years,.

Thermocouple/flame sensor error

It sounds to me like your thermostat may be bad. I would check power incoming to t-stat then turn temp. setting up and down to see if it is switching on and off. If not then replace. If it does then I would check all wiring to gas valve and if power is shutting off to valve but burner continues then replace gas valve. Thank you.

Sounds like a bad fan switch. The switch is located on the heat exchanger and is 110 volt bi-metal switch. Follow the wires from the blower going back to the heatexchanger. Graingers can get you a new switch if you give them your model number. www.grainger.com.

Hopefully there is a wiring diagram glued to one of the panels to verify but on the transformer you will have 2, 110 volt wires. One is the power coming in (usually black wire) and the other is a common (white wire) and will be connected to other common leads. On the low voltage side of the transformer one wire will go to the thermostat then from the thermostat to the gas valve. The other side will connect to the gas valve. When the thermostat calls for heat it completes the circuit from transformer to gas valve back to transformer.

if you can use a meter check for 24 volts at the valve when you call for heat. If you have 24 volts and no burners then the valve is bad, if you do not have 24 volts then another safety is locking out the valve

Check for a bad thermostat and wire by jumping the red and white wire together at the thermostat. If the unit fires, you have a bad thermostat. If it does not, jump the R and W terminals at the furnace (or where ever the thermostat wires are connected to). If the unit fires you have a bad wire. If it still does not fire, you have an issue with the heating system not the thermostat or its wires.

the stat works using a bi metalic strip so that click you here is making a contact and telling the boiler to call for heating so if you getting no click you need a new room stat. Replace with same model and note the wiring most stats only use 2/3 wires depending on system