Generac 5616 Extreme Cold Weather Kit for 25 kW (1800 RPM), 22 kW, 27 kW, 36 kW, 45 kW & 60 kW (2.4L Engine) Standby Generators

works as expected , it is thermostatically controlled , keeps the engine on my 35KW gen set between 120F and 145F . easy to install , comes with quality heater hose .

Arrive very quickly and was as described. Using it as a block heater for my outside generator

Second Update 12/15/25 The heater failed after two years. It was powered from a temperature-switched outlet so during those two winters it was only energized when the air temperature dropped below 20 deg. F. It developed an electrical leak between the hot side of the plug and the ground prong, perhaps from fluid ingress into the bottom around the electrical contacts. The leak only appeared when it was hot. When cold, it measured > 5 Megohms with a DVM, and did not trip the GCFI outlet. As soon as it heated up, the GCFI tripped, and it measured about 115 kOhms. (The AC impedance at 60 Hz may have been lower. DC resistance measures involving metal/electrolyte interfaces are not reliable.) The disassembled heater showed no signs of deterioration or fluid residue around the electrical connections (see photos), so it’s not clear where the electrical leak developed. The heater was replaced, and the replacement unit does not trip the GCFI. Note: See UPDATE below for performance at temperatures down to -15 degrees F. Original Review 10/22/23 I installed the 5616 block heater on a 32 kW Protector QS. Installation per the enclosed instructions went fairly smoothly, with a couple of plumbing issues noted below. Instructions can be found on the Generac website, but they’re hard to find. Try Googling “MANUAL 2.4L G2 CPL BLOCK HTR” including the quotation marks INSTALLATION Electrical The heater draws a nominal 1500 watts when active, so it needs a dedicated branch circuit. I used the recommended 20-amp breaker and 12-gauge wiring. I installed a weather-proof box and GFI outlet w/switch inside the generator enclosure. The cord on the heater (~6 feet) is longer than necessary for the recommended outlet placement - maybe to provide for connection to alternate pre-existing outlets. I was concerned that if the GFI or the breaker tripped I would never know about it. So I also mounted a small LED pilot light on the exterior generator panel adjacent to the box, and plugged it into the outlet. That way I can tell at a glance while walking by whether the outlet inside is live. Plumbing I ran into two issues with the plumbing. First, after threading the 45-degree NPT adapter nipple into the engine block it started to tighten with the nipple at about the 7:00 o’clock position. It bottomed out at about the 4:00 o’clock position – I couldn’t advance it to the full down 6:00 o’clock position. I was still able to get the tube connected to it and keep it clear of the exhaust. Second, the coolant temperature sensor was mounted to the intake manifold with some kind of brittle red sealant. After removal, its threads were filled with the stuff. I picked out as much as I could from the threads, but they were not completely clean. So when threading it into the adapter tee block I used a high-temperature pipe dope to fill the gaps around the remaining bits of sealant. I used Teflon tape on all the other pipe fittings. If I were doing it over again, I’d replace the provided spring-type hose clamps with screw-type hose clamp bands. PERFORMANCE The heater certainly keeps the engine block warm to the touch. As far as I can tell, Generac does not publish the heater’s switch-on and switch-off temperatures. Ordertree dot com lists them as 80 degrees F and 100 degrees F respectively. I was curious about the how the on/off durations and duty cycle would vary with ambient temperature, so I monitored the heater current over a 24-hour period in early October. I used an All Sun 263 passive current probe clamped around the hot lead in the breaker panel, and connected its output to a Siglent SDS1204X-E scope in measurement data logging mode. It measured AC RMS current once per second for 24 hours. I didn’t bother to set up an automated temperature measurement – just manually logged the AWOS (Automated Weather) report at an airport 2 miles away once each hour (except from 11:00 PM – 5:00 AM while I slept!) Results are shown in the attached figures. When on, the heater drew 11.9 Amps RMS, or 1428 watts. Note: The non-zero values in the graph during “Off” times represent the noise floor of the current probe – not actual current. Over the 24 hours, average current and power were 1.86 Amps and 223 W respectively. The following minima and maxima were recorded: • Temperature 32 - 66 degrees F • Heater On Time 164 - 234 seconds • Heater Off Time 710 - 1875 seconds • Duty Cycle 9.0% - 22.6% As expected, duty cycle was inversely related to ambient temperature. Temperature was interpolated between hourly readings to determine the value at each switch-on time, which defined the end of a cycle. A linear regression through the duty cycle/temperature points produced the following relationship: duty cycle (%) = 33.8 - 0.375 x temp (deg F) Extrapolating the fitted line to 0% duty cycle (where the heater never switches on) yields 90.4 degrees, which is not too far from the 80 degrees cited above. In the other direction, even at a temperature of minus 10 degrees F the duty cycle would be only 37.6%. So the power drawn would average 537 watts over a cycle. The heater seems to have ample reserve for very cold temps. As far as I know the physics of this system should be pretty much linear, but I plan to repeat these measurements in February to see how the linear extrapolation holds up. UPDATE 1/22/24 Additional data at lower temperatures were collected over two additional periods of 20 and 25 hours respectively. For the new measures temperatures were logged every 10 seconds with an Elitech RC-4 Data logger using the external probe in a shady location about 20 feet from the generator. Ranges for the aggregate data set were: • Temperature -15.5 — +66.0 degrees F • Heater On Time 144 — 358 seconds • Heater Off Time 266 — 1875 seconds • Duty Cycle 9.0% — 51.4% • Power Consumption 129 — 739 Watts The scatter plot of Duty Cycle vs Temperature for the full data set is shown in the attached figure. The original data are plotted with red symbols, and the two subsequent sets in blue and green. The right vertical axis represents the equivalent average power where 100% duty cycle represents consumption of 1440 watts (12 Amps x 120 V). Extrapolation using the original regression line underestimated the low-temperature duty cycles somewhat. A regression through the entire data set produced the following relationship: Duty Cycle (%) = 42.0 - 0.510 x temp (deg F) corresponding to an average power consumption of: Power (W) = 605 - 7.34 x temp (deg F) Extrapolating the new regression line to 0% duty cycle (where the heater never turns on) yields 82.4 degrees which corresponds well with the 80 degree turn-on temperature cited above from the Ordertree website. Variability in the data probably arises from at least two sources. None of these measures was taken in the “steady state” after soaking the generator at a fixed temperature until duty cycle stabilized. Temperatures were rising and falling most of the time (sometimes abruptly), and there was inevitably some lag in the heater response. The generator was also exposed to sunlight during some morning hours which could have affected the temperature within the enclosure.

Great product. Must have for motor longevity and reliability. Highly recommended.

My Son, being a professional tech on Emergency Generators, installed the kit for me and it has operated jest fine for months now