Question about Lite On Laars Lite 2 Heaters: 250,000BTU MV Heater

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Pilot is lit but the heater won't fire up - Lite On Laars Lite 2 Heaters: 250,000BTU MV Heater

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Chandler Ede

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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

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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

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tcwlsn

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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

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protek480

Craig Butler

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SOURCE: Patio Heater

The pilot light has to heat up the thermocouple. Is the thermocouple in the flame? If so, the them. could be bad. Replace

If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

Posted on Jul 02, 2009

Anonymous

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SOURCE: warm morning propane heater. new thermal couple.

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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1 Answer

Rheem rp4036m


Under the gas valve is a removable panel. On models of that era there should also be a second panel behind the first. remove both.

the pilot light should be clearly visible.

If no pilot, turn the gas valve to OFF. wait 60 seconds. locate the tubes from the gas valve to the pilot location. turn the valve to pilot, and with a long match or grill lighter lit, place flame at the pilot location and press down on the pilot button beside the main valve.

pilot should light. If not shut off the gas and call a technician. If yes, hold the pilot button for 60 seconds, then slowly release. Pilot should stay lit. If not, shut off gas and replace thermocouple, start relight sequence over. If pilot stays lit, replace inner cover and adjust temp to 120 deg. If heater fires up, replace outer cover. Done.

If heater does not light, replace gas valve or entire unit. Water heaters have a limited life expectancy, and if my recollection is correct your unit is 10yrs past warranty.

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1 Answer

My laar hot shot natural gas pool heater pilot says lit but wont fire any more replaced pilot generator pilot that whole unit nice pilot but wont fire


problem isnt with the pilot generator. you have either an open safety withing circuit, lose wiring connection, or tstat issue

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1 Answer

Rheem 22V50F1 pilot won't stay lit. Changed thermo couple & it lit, ran then went out. Let it sit overnight & it lit, ran then went out. What next? p.s. The unit is 5 years old. Thanks


If pilot lights and flame is robust and clear blue, and pilot goes out later, then some suspects can be excluded: air in gas line, low gas pressure, thermocouple is overtightened (finger-tight + 1/4 turn), thermocouple not positioned correctly in the flame, dirty pilot tube.
If flame is yellowish and small: then clean pilot tube and combustion parts.
http://waterheatertimer.org/How-to-install-gas-water-heater.html#clean
Remaining suspects can include: air in gas line, low gas pressure, bad gas control valve, tight house so household vent fans pull air down water heater vent that blows out pilot, hot attic with inadequate ventilation, water dripping down vent.

Open following links to read troubleshoot resources.
http://waterheatertimer.org/pdf/Pilot-light-will-not-stay-lit.pdf
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

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Water not hot even thermostate turned to high. The pilot light is on. Shoulder I be able to visualise the burner actually firing.,or hear it firing. I can see the pilot light clearly. Please help


If you have cold water now, you should hear the unit fire up and run while heating water. Proceedure would be; pilot is lit with thermostat at pilot setting. Once pilot is lit, you turn up to desired temp setting and you should hear the heater running. Depending on lighting, you should be able to see it slightly brighter and may flicker some while heating.

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1 Answer

My honeywell gas suspended garage heater will not come on when the t'stat calls for heat. It is a heat only unit and neither the fan nor the blower motor will come on. The Heater is getting power to it...


The pilot light has to be lit before gas valve will operate. That's a safety feature so the valve won't open and fill the garage with gas and possibly cause an explosion or fire. If you have a standing pilot and can't get pilot to stay lit, it's usually the thermocouple and it will need to be replaced. Once the pilot is lit, the gas valve comes on and heats the combustion chamber up to approx. 100° to 125° a thermostat controlled fan switch will close and bring the blower on.

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1 Answer

Pilot light is lit, but heater will not fire


Make sure thermostat is set higher than water temperature. Make sure pump is running and water is flowing through unit. If gas valve is not opening then flame sensor or gas valve is bad.

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