I need a service manual for a Lennox Model E10Q37512P. Need to install and rewire a thermostat for a Lennox. Furnace not igniting. Need service manual for Lennox model G11Q5E165V-2. Please help find the manual for this Lennox International Inc. Guide Specifications. Covering our extensive line of rooftop units, split systems and heating units, these detailed guide specifications provide helpful product information you can depend on. Lennox® Furnace Service Manuals The Adobe Acrobat Reader® Application is Needed to Read '.pdf' Files Click Here to Get a Free Copy of Acrobat Reader® Click on Your Model Number Below to View the Service Manual for Your Unit. Click Here to Watch a Video on How to Locate your Model Number. O23/OHR23/OF23: 80MGF Series: 80UHG Series: 90UGF. Lennox G12, G12R & G12X Series GAS FURNACE MANUAL PDF (8/1990) Lennox G12-G12E FURNACE MANUAL PDF (10/1987) Gas Furnaces; Lennox G24-200 Series Upflow Gas Furnace Manual, Lennox # 503.614M,1998; Lennox G26 Series Gas Furnace Manual, 1998, #503.533M; Lennox G32V Series Gas Furnace Manual, 2001, #504.391M. Looking for more information about your Lennox product? Find your owner’s literature, like product manuals, by searching your product’s model number.

Lennox G8 Furnace Manual

Heat exchanger can crack for various reasons and should be checked every time furnace is repaired or maintained.

Visually check heat exchanger for cracks

• You will find most cracks form near the back and where the heat exchanger metal bends, Since this is where it will be weakest due manufacturer weakening the metal by bending it.
  Watch the flames as the furnace fan starts if you see the flames are blowing around or out the front of the burners then you will need to take a closer look at the heat exchanger

Water test

• This test worked best on the old Lennox G8 and would find cracks or pinholes on the heat exchanger that sometime could not be seen.
  If there is no air conditioning then it will be easy to access above the heat exchanger through the humidifier. Once the heat exchanger cools down spray water on the heat exchanger from the top insuring full coverage and being careful of the electronics and motors. Then watch inside the burners for water to seep through, A good heat exchanger will not let moisture into burner chamber

Lennox G8 Furnace Parts

Using carbon monoxide detector

• Test for carbon monoxide at return air as well at supply air and compare the two readings or test at supply air with burners on then off making sure furnace is not back drafting and compare.
  If you take reading once and only at supply air you will not be 100 percent sure the problem is with the heat exchanger. You are testing the accumulation of carbon monoxide over a long period of time from other sources like the furnace or hot water tank back drafting also it could be from outside sources like a vehicles near the intake air.

Reasons for cracks

• If the furnace does not have enough combustion air it will cause the furnace to run hotter then designed. Then with more expansion and contraction in the heat exchanger it causes cracks. The gas pressure must be set as per furnace name plate derated for location altitude if too much gas heat exchanger will run too hot.Blower speeds must be checked by comparing furnace temperature difference to name plate rating if running too hot increase fan speed and recheck temperature supply air minus return air.

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Any crack in a heat exchanger is dangerous and the heat exchanger must be replaced when crack is found

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Lennox Gas Furnaces Specifications

Tagged: carbon monoxide, cracked heat exchanger, heat exchanger