How to Add an Oil Preheater to a Generac Generator System
Obtain the parts., Connect the thermostat., Connect the thermostat wires to the cut in the cord., Install a fuse., Test., Assemble the heater., Mount the hot pad., Wrap the pad and thermostat with tape., Insulate the can assembly., Install the...
Step-by-Step Guide
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Step 1: Obtain the parts.
The parts required are a silicone heating pad, a temperature controller, and a "soup" can.
The heating pad can be obtained from an auto parts store, a pet store (aquarium heater) or online. The wattage needed is low
-- look for ones rated for 110VAC, about 2" X 6" (not very critical), and with a wattage rating of less than 20W.
The cost should be about $20 to $30.
The temperature controller (i.e., thermostat) can be obtained on eBay for about $3.
One rated for NC (normally closed) and about 25C (77F) to 40C (103F) is suitable.
A commonly available part is the KSD301 but it has variants for many temperatures
-- look for one in the lower temperature range.
Any can from your pantry will do; it should fit loosely over the existing filter. (Check your filter and choose a can accordingly.) Three other "parts" are a small amount of fiberglass or similar insulation, a 2 1/2 to 3" hose clamp, and some duct tape. -
Step 2: Connect the thermostat.
Once the parts are on-hand, the next step is to add the thermostat to the silicone pad heater.
The heater comes with a 110V cord and socket.
Separate the two wires close to the pad (a pocket knife works well) and cut the "ground" or neutral side of the cord.
Strip about 1/4" of insulation off each exposed wire.
The thermostat will likely come with stripped leads. , It makes no difference which "direction" the thermostat is connected
-- it is just a simple switch that is "on" below the set-point and "off" when it is above that point.
Twist the pairs of wires together and solder the connections. (Wire "nuts" will probably work but are bulky and may be prone to failure from heat and vibration. Crimp connections may work.) Wrap the connections with electrical tape or use heat-shrink tubing., A fuse is desirable for protection in case of short or other circuit failure.
At 110V, a fuse of .5 Amp is suitable as that will work with heating pads up to about 25 watts.
The fuse is an in-line design and is soldered into the "hot" side of the 110V wiring by cutting off the plug, separating the wires, stripping, and soldering.
Cover the joint with electrical tape or shrink tubing., Testing of the pad can be done very carefully at this stage.
The pad will get very hot very quickly and will burn if plugged into 110V! An appropriate test that is safe is to use an ohmmeter and check for a low resistance when the thermostat is cool (ice bath?) and an infinite resistance when the thermostat is warm (say 80F).
In case the resistance at low temperatures is also high or infinite, recheck the connections!, The can probably will not fit perfectly over the oil filter.
For the Generac system, the can should fit easily but snugly over the mount for the oil filter.
You can cut some small slits in the open end of the can at roughly 90-degrees so that a hose clamp can be used to secure the heater to the mounting plate (or just the oil filter)., The silicone pad comes with a paper backing and has adhesive under that.
The can used was not smooth so the pad did not adhere well., The other problem was how to attach the thermostat to the can.
The solution was to wrap the pad and thermostat with high-temperature tape (duct tape is designed for this).
A perfect thermal path is not required as the temperatures that should be present will be between 60F or so and the operating temperature of the generator oil. During normal conditions when the generator is not running, the maximum temperature should be no more than about 10F more than the thermostat specification. , It is desirable to limit heat loss (but not critical).
Wrapping the can with a layer of fiberglass batting or some similar insulation layer will provide more-than-sufficient heat retention.
There is no problem with over-heating when the generator is running as the oil temperature is automatically limited. You can put a layer of insulation over the can bottom held-on by a couple of strips of tape.
The circumference of the can was then wrapped with insulation and a layer of tape applied loosely so as to not crush the insulation., The side of most Generac systems removes to provide easy access to the oil filter and battery.
Once the side is removed, put the hose clamp around the open end of the can (where the slits are) and slide the whole heater and clamp over the oil filter.
As noted, for at least the test system, the can fit nicely around the mount for the oil filter
-- the hose clamp was tightened with a screwdriver to hold the heater over the oil filter., Usually this will require turning off all power to the home unless there is a local disconnect for just the generator., The Generac system comes with a 110V socket on the outside, but it is "live" only when the generator is running.
To connect the heater to power it is necessary to connect the stripped wires to the N1 and Neutral wires under the generator control panel.
N1 and N2 provide 240V while either N1 to Neutral or N2 to Neutral will provide 110V.
Access to these connectors is under a plastic cover just above the control panel.
Unless you are competent in working with high voltage wiring, this step should be done only by an electrician.
There is a YouTube ("Generac Cold Weather Kit Installation") showing this general installation., Reinstall the plastic cover over the connector box and the metal panel covering the wiring and battery.
Reinstall the side panel., Turn the utility disconnect back to the "on" state., It will be difficult to perform a complete operational test unless the outside temperatures are below the thermostat set-point which will be true for many areas except in the summer.
A primary test will be to test that the heater is operational when the generator is running.
Generac systems have a manual run switch that makes it very simple to start the engine.
Run the system for several minutes to make sure the hose clamp and can are secure from vibration and heat during running.
Let the system cool-down and check that the heater system is still secure.
Replace the side of the generator enclosure. -
Step 3: Connect the thermostat wires to the cut in the cord.
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Step 4: Install a fuse.
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Step 5: Assemble the heater.
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Step 6: Mount the hot pad.
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Step 7: Wrap the pad and thermostat with tape.
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Step 8: Insulate the can assembly.
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Step 9: Install the heater on the Generac.
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Step 10: Disconnect the generator from local power.
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Step 11: Connect the heater.
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Step 12: Reassemble the generator.
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Step 13: Reconnect the power.
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Step 14: Test your system.
Detailed Guide
The parts required are a silicone heating pad, a temperature controller, and a "soup" can.
The heating pad can be obtained from an auto parts store, a pet store (aquarium heater) or online. The wattage needed is low
-- look for ones rated for 110VAC, about 2" X 6" (not very critical), and with a wattage rating of less than 20W.
The cost should be about $20 to $30.
The temperature controller (i.e., thermostat) can be obtained on eBay for about $3.
One rated for NC (normally closed) and about 25C (77F) to 40C (103F) is suitable.
A commonly available part is the KSD301 but it has variants for many temperatures
-- look for one in the lower temperature range.
Any can from your pantry will do; it should fit loosely over the existing filter. (Check your filter and choose a can accordingly.) Three other "parts" are a small amount of fiberglass or similar insulation, a 2 1/2 to 3" hose clamp, and some duct tape.
Once the parts are on-hand, the next step is to add the thermostat to the silicone pad heater.
The heater comes with a 110V cord and socket.
Separate the two wires close to the pad (a pocket knife works well) and cut the "ground" or neutral side of the cord.
Strip about 1/4" of insulation off each exposed wire.
The thermostat will likely come with stripped leads. , It makes no difference which "direction" the thermostat is connected
-- it is just a simple switch that is "on" below the set-point and "off" when it is above that point.
Twist the pairs of wires together and solder the connections. (Wire "nuts" will probably work but are bulky and may be prone to failure from heat and vibration. Crimp connections may work.) Wrap the connections with electrical tape or use heat-shrink tubing., A fuse is desirable for protection in case of short or other circuit failure.
At 110V, a fuse of .5 Amp is suitable as that will work with heating pads up to about 25 watts.
The fuse is an in-line design and is soldered into the "hot" side of the 110V wiring by cutting off the plug, separating the wires, stripping, and soldering.
Cover the joint with electrical tape or shrink tubing., Testing of the pad can be done very carefully at this stage.
The pad will get very hot very quickly and will burn if plugged into 110V! An appropriate test that is safe is to use an ohmmeter and check for a low resistance when the thermostat is cool (ice bath?) and an infinite resistance when the thermostat is warm (say 80F).
In case the resistance at low temperatures is also high or infinite, recheck the connections!, The can probably will not fit perfectly over the oil filter.
For the Generac system, the can should fit easily but snugly over the mount for the oil filter.
You can cut some small slits in the open end of the can at roughly 90-degrees so that a hose clamp can be used to secure the heater to the mounting plate (or just the oil filter)., The silicone pad comes with a paper backing and has adhesive under that.
The can used was not smooth so the pad did not adhere well., The other problem was how to attach the thermostat to the can.
The solution was to wrap the pad and thermostat with high-temperature tape (duct tape is designed for this).
A perfect thermal path is not required as the temperatures that should be present will be between 60F or so and the operating temperature of the generator oil. During normal conditions when the generator is not running, the maximum temperature should be no more than about 10F more than the thermostat specification. , It is desirable to limit heat loss (but not critical).
Wrapping the can with a layer of fiberglass batting or some similar insulation layer will provide more-than-sufficient heat retention.
There is no problem with over-heating when the generator is running as the oil temperature is automatically limited. You can put a layer of insulation over the can bottom held-on by a couple of strips of tape.
The circumference of the can was then wrapped with insulation and a layer of tape applied loosely so as to not crush the insulation., The side of most Generac systems removes to provide easy access to the oil filter and battery.
Once the side is removed, put the hose clamp around the open end of the can (where the slits are) and slide the whole heater and clamp over the oil filter.
As noted, for at least the test system, the can fit nicely around the mount for the oil filter
-- the hose clamp was tightened with a screwdriver to hold the heater over the oil filter., Usually this will require turning off all power to the home unless there is a local disconnect for just the generator., The Generac system comes with a 110V socket on the outside, but it is "live" only when the generator is running.
To connect the heater to power it is necessary to connect the stripped wires to the N1 and Neutral wires under the generator control panel.
N1 and N2 provide 240V while either N1 to Neutral or N2 to Neutral will provide 110V.
Access to these connectors is under a plastic cover just above the control panel.
Unless you are competent in working with high voltage wiring, this step should be done only by an electrician.
There is a YouTube ("Generac Cold Weather Kit Installation") showing this general installation., Reinstall the plastic cover over the connector box and the metal panel covering the wiring and battery.
Reinstall the side panel., Turn the utility disconnect back to the "on" state., It will be difficult to perform a complete operational test unless the outside temperatures are below the thermostat set-point which will be true for many areas except in the summer.
A primary test will be to test that the heater is operational when the generator is running.
Generac systems have a manual run switch that makes it very simple to start the engine.
Run the system for several minutes to make sure the hose clamp and can are secure from vibration and heat during running.
Let the system cool-down and check that the heater system is still secure.
Replace the side of the generator enclosure.
About the Author
Sandra Mitchell
Specializes in breaking down complex practical skills topics into simple steps.
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