Question about Lite On Laars Lite 2 Heaters: 250,000BTU MV Heater
A few things dictate when the main burner turns on. One is a thermocouple not getting hot enough, the other is a bad thermostat ot thermostat wire, and another is the gas valve. First look at the gas valve located on the heater and make sure it is in the On position and not in the Pilot position. Remove your thermostat and jump the two wires together. The heater should light. If not, go back to the gas valve and find the wires up to the thermostat, the should be attached to terminals marked TH and MV or something similar. Jump the terminals. The heater should start. If not, you may need to replace the thermocouple.
Posted on Sep 09, 2009
I had this ame thing happen and it was easy to fix.. I backwashed the filter.. I was told if the filter or pump is plugged the heater wont fire up . Its a protective device to keep the heater from burning up with no water running thru it.. I see your post was back in Sept . maybe you dont need this answer anymore..
Posted on Oct 06, 2009
If the T-couple isn't hot enough, even the pilot won't stay lit. On an MV system it is a pilot generator. The pressure switch, Hi-limits, On/off rocker switch and t-stat are in the circuit. Make sure the P. switch isn't airlocked and you have good pressure. The Rocker switches on these units are horrible. Bypass it and see what happens. Then check continuity on your hi-limits (two white wires going up and to the right to the manifold)
Posted on Mar 28, 2012
There are basically three things that can go wrong with the Warm Morning .
Sensor shut off. There is a sensor button on the back of the unit with a wire going from it to the thermocouple. This sensor turns the heater off if the flue is blocked, however it will also shut the heater off if the wire contacts are dirty, or if the sensor has gone bad.
You can test this by bypassing the sensor. Disconnect the two wires from the sensor and reconnect them directly together. If the pilot stays on, your problem is here. Try cleaning the wire contacts first.
Pilot orifice. If the pilot flame is small and doesnt look healthy, the pilot orifice may need cleaning. The hole is very small and can get dirty. Disconnect the silver tube and clean with electrical parts cleaner. Never try to clean the hole with an object like a pin, you may damage it. You may have to slide out the burner unit to get at the silver tube. (Always shut off gas before disconnecting lines and after you reassemble, spray joints with soapywater and look for small bubbles which may indicate a gas leak. Dont use parts cleaner around an open flame.)
Thermocouple can go bad but this is not as common as the first two problems.
Posted on Jan 28, 2010
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