Frequently Asked Questions

All internal combustion engines and their components, including pistons, cylinders, bearings, and lubrication oil, are factory-designed to operate within an optimal temperature range. While the engine is running, the engine’s dedicated cooling system safeguards the equipment to ensure that temperature range isn’t exceeded.

When an engine is shut down or is in standby, these components will gradually cool to the ambient temperature, whether it’s a room-temperature facilities area, an outdoor generator enclosure, a locomotive rail yard, or a mining operation. Without a dedicated heating system that preheats and circulates critical fluids, an engine must bring itself up to optimal temperature before accepting a heavy load, or risk unnecessary wear and tear. Each time the engine has a cold start, costly problems occur over time, including increased emissions, lack of lubrication, and other issues. To help avoid these problems, engines often idle continuously during downtime—but that comes with the drawbacks of wasting fuel and increasing costs.

Continuously heating an engine during downtime, or preheating it immediately before starting, eliminates cold starts and the problems encountered from repeated hard starting—without wasting fuel or shortening the engine’s operating life. When your engines are critical to providing key services, such as applications in data centers, hospitals, municipalities, universities, and other critical facilities—engine heating systems are the first step to ensuring reliability and safeguarding your bottom line.

While most of us think of cold engines in extreme arctic winters or high-altitude mining sites, cold engines needing engine heating systems are found in any location that falls below a typical engine’s operating temperature – usually any temperature lower than about 100 °F (38 °C). A data center in the tropics still requires an engine heating system as one in a cold climate—as the system will need to keep the engine warm during the night when the temperature falls, or during brief cold spells during the normal season. Additionally, engine heating systems can also be found in relatively warm, high-humidity environments such as shipping ports or gas compression facilities to prevent condensation in the engine cylinders and oil sumps during standby periods.

In short, engine heating systems are a cost-effective solution to promote maximum engine reliability and operating life—no matter what the ambient conditions are.

Hotstart heating systems come with a wide range of model and heat power options, so selecting the right system for your engine may seem overwhelming.

Heat power is almost always the most important consideration. Too little heat power, and your engine heater will struggle to keep the engine block at the optimal temperature—incurring a lot of electrical costs in the process. Too much heat power, and you may be paying for heat you simply don’t need, shortening the life of your hoses and seals.

When selecting your heating system, it’s important to have a good understanding of your engine size and the overall amount of coolant in the engine’s water jacket. You’ll also need to take the following factors into consideration:

• The lowest temperature you expect your engine to be exposed to
• If your engine may be subjected to wind or other factors that will reduce heating effectiveness
• If you intend to use multiple systems (coolant and oil or a dual-fluid system) to heat the engine
• If you intend to install either a thermosiphon (convection-based) or a forced circulation (pump-driven) heating system

For thermosiphon heaters and HOTflow® heating systems, these factors can be simplified into one basic rule that uses the engine displacement size and the lowest expected temperature as a starting point. For most small- or mid-sized engine applications (5 to 50 liters), this rule will produce a good working estimate for heating power.

• If your engine location’s temperature will remain above 0 °F (−18 °C):

o   3 × [your engine’s cubic inch displacement] = your heater’s wattage requirement, or

o   183 × [your engine’s liter displacement] = your heater’s wattage requirement.

• If your engine location’s temperature will fall below 0 °F (−18 °C):

o   5 × [your engine’s cubic inch displacement] = your heater’s wattage requirement, or

o   305 × [your engine’s liter displacement] = your heater’s wattage requirement.

For larger or more complex applications, especially those requiring multiple heating systems, larger volumes of liquids or other factors, it’s best to work with a Hotstart representative directly to specify the heating system that will provide the heat power you need.

You can reach our customer service team directly at 509-536-8660 or contact our Customer Service team to get started.

Hotstart heaters are designed to accommodate small installation spaces, using a minimal footprint area while providing maximum heating power. They may be either threaded into the engine block directly or externally bracket-mounted, foot-mounted, or plate-mounted depending on the type of heater.

In most cases, Hotstart does not recommend fastening heating systems directly to the engine itself. When exposed to engine vibration without dampening, heating systems can suffer problems over time, including electrical connection problems or leaking. The exceptions to this rule include in-block heaters or oil heaters (OW/OE series) that must be installed directly in the water jacket or oil sump.

For external heating systems, Hotstart recommends installing the heater on a vibration-isolated skid or in a similar location protected from engine vibration. The Hotstart CTM heating system offers an optional vibration isolation kit for installations where vibration isolation is not available, such as a vehicle engine bay or a confined generator enclosure.

Full-flow isolation valves are ideal to add to a heating system’s plumbing during installation. These valves allow the heating system to be serviced without needing to drain the engine coolant. 

Consider heating system orientation when identifying the system's location. Some systems, such as the TPS, CTM and CSM, have a single orientation option. However, the TPS and CTM systems are designed to allow the inlet and outlet port adjustment for easier hose routing.

Other Hotstart heating systems, such as the CKM and our Tank-Style heaters (CB/CL, SB/SL, WL and EE series) may be mounted horizontally or vertically. Vertical installations require care when routing hoses as all dips and horizontal hose runs must be eliminated to prevent air pockets. In rare cases, Tank-Style heaters may also be mounted at a slight incline, to raise the outlet above the inlet, and promote heated fluid flowing through the system, resolving fluid flow issues. To properly install your heater, please refer to your model’s installation manual.

Direct immersion heaters, including the OW and OE series of oil heaters, should be mounted on the side wall of a fluid tank or sump with a minimum clearance from the bottom of the container to avoid sediment build-up. Immersion heaters must always be fully immersed in fluid during heating to avoid burning out the heating element; immersion heaters must never be installed the the heating element pointing upward from the bottom of a tank or sump, as the heating element may be exposed to air if the fluid level changes.

Some direct immersion heaters, such as in-block heaters, are designed for a specific engine port and must be installed in this location to properly operate. The location of that port can be found your model’s installation manual.

For coolant heating systems that are installed externally from the engine water jacket, such as thermosiphon heaters or pump driven heaters, proper port selection is important to ensure heater longevity and reliability. Two ports on the engine, the supply port and return port, should be dedicated to the heating system. Both ports must meet the minimum required size for the heater you intend to install. Check your heater’s installation manual for minimum port size requirements.

Supply Port

The supply port allows cold coolant to flow from the engine to the heating system. The supply port should be located as low on the engine’s water jacket as possible to ensure the coldest coolant is drawn into the heating system. For most engine configurations, the ideal lowest point is located toward the front of the engine, near the lower radiator hose.

Return Port

The return port allows heated coolant to flow from the heating system back into the engine’s water jacket. This port should be located high on the engine’s water jacket to:

• Ensure the return port is as far away from the supply port as possible for coolant to travel through the entire engine block, reducing extreme hot spots and cold areas.
• Allow heated coolant to flow with gravity downward through the engine water jacket as it cools gravity. Placing the return port low on the engine jacket will result in heated coolant traveling upward, cooling rapidly and flow downward before it reaches the top of the water jacket, creating cold areas that reduce heater effectiveness.

The return port must also be positioned away from the engine’s thermostat, which is typically located near the top radiator hose and toward the front of the engine. If placed near this thermostat, the heated coolant from the return port may trigger the engine thermostat, permitting heated coolant to flow to the radiator instead of the engine block. Warm coolant traveling through the radiator will cool rapidly and result in drastically reduced engine heating as the radiator continues to move heat away from the engine block.

Placing the return port high near the rear of the engine block prevents the possibility of triggering the engine thermostat and ensures that the return port is located as far from the supply port as possible, maximizing engine heater effectiveness.

For V-type engines, fluid flow across the entire engine block is important. To promote cross-flow, the supply port may be installed on the opposite side of the engine as the heater. By drawing from the lowest point on the opposite side, heated engine coolant will flow across both the length and width of the block, maximizing engine heater effectiveness while minimizing heat loss. If the return port is located on the opposite side of the engine instead of the supply port, the extended return hose length may increase heat loss and result in dips and bends that collect air pockets—reducing heating effectiveness and heating system longevity.

For thermosiphon, pump driven heaters, and larger forced circulation systems, ensuring plumbing lines and fittings meet the minimum size requirements maximizes the flow of heated fluid throughout the engine block, sump or compressor.

Thermosiphon minimum port fitting sizes:

Thermosiphon minimum hose inner diameters:

Pump driven minimum port fitting sizes:

Pump driven minimum hose inner diameters:

Forced Circulation Heating Systems

Plumbing requirements for forced circulation heating systems vary by model, depending on the system configuration, installed pump and fluid type. Check your Installation & Operation Manual for your specific minimum requirements. However, all forced circulation systems will require that:

• At a minimum, the supply line must be the same size as the pump inlet. Hotstart recommends using the largest practical inner diameter size hoses to maximize flow.
• The suction port for coolant systems must be installed as low on the engine’s water jacket as possible.

The suction port for oil systems must be installed as low as possible in the engine or compressor oil sump. However, it must not be installed on the bottom of the sump or in a location low enough that may allow debris or sediment into the heating system. Hotstart recommends installing a swing-type or full-flow check (non-return) valve as close to the suction port as possible to prevent oil flowing back into the sump.

Ordering a Hotstart heater is quick and easy.

First, select the heater you’ll need for your application. You can specify a heater using the following resources:

• For in-block heaters, use our In-Block Heater Tool.
• For a product overview, read the Which heater is right for my application? FAQ post.
• For a list of our most popular models, view our Product Catalog.
• Search and filter our product listing with our Product Search.
• Contact our Customer Service team directly for assistance in selecting a heating system.

Once you know the heater model, operating characteristics or part number, you can purchase a heating system by:

• Contacting our Customer Service team to order direct from Hotstart.
• Working with one of our worldwide Hotstart Distributors.
• Ordering through your local OEM Hotstart Dealer, including Cummins, Detroit Diesel, Generac, Kenworth, Kohler, MTU Onsite Energy, and Peterbilt.

Heater installation procedures and tools vary depending on heater model and type. At a minimum, you should expect to prepare for installation by draining the system's coolant and/or lubrication oil before installing the heater. You’ll also need to have selected the supply and return ports on the engine block or sump to meet the placement guidelines and minimum size requirements. For thermosiphon or pump driven installations, you’ll need to run the engine to purge air from the system before energizing the heater for the first time, so ensure you have access to start the engine once the heater is installed.

Before installation:

• For coolant heating systems, drain the coolant from the engine block and radiator
• For oil and dual-fluid systems, drain the lubrication oil from the sump or pan.
• Select engine block or sump ports for each heating system's supply and return port
• Select a heater installation location and add appropriate vibration isolation if necessary
• Plan the hose routing from the heater installation location to each port

General tools:

• Basic mechanic’s tools, including drivers, wrenches and sockets.
• Basic electrical tools
• Basin or bucket, rags
• Eye protection and gloves

Plumbing:

• Hoses (see your instructions for minimum inner diameter)
• Port fittings (see your instructions for minimum sizes)
• Full-flow isolation valves (recommended for maintenance)

Electrical:

• A suitably grounded plug-in or hardwired power source compatible with your heater’s specification
• Power disconnection point (recommended for all hardwired heaters)
• A 24-volt engine run signal source for remote automatic operation of CSM models and industrial forced circulation systems (typically the engine’s fuel pump)
• For all three-phase systems, or single-phase systems requiring a contactor and/or transformer, a customer-supplied control box (check your model's installation instructions)
• All additional electrical components as recommended by your model’s instructions, such as a liquid level switch for industrial immersion heaters

Extras:

• A laser or infrared thermometer or similar tool to check operation and troubleshoot the installation

For In-Block, Thermosiphon, and Pump Driven heaters, Hotstart installation instructions recommend running the engine until it reaches operating temperature before energizing the heater for the first time.

When an engine is run to operating temperature, the engine’s thermostat opens, allowing coolant to flow through the radiator and return to the engine block. During this process, the engine’s water pump will move coolant throughout the engine block to the radiator and any air present will be purged from the system.

By using your engine’s own method of removing air from the cooling system, you ensure that the engine’s water pump moves coolant throughout the entire system — including the newly installed heater and plumbing lines — and flushes out any air pockets or bubbles created by the installation process.

If these air pockets remain when the heater is energized, they may block the flow of fluid to or from the block. This lack of flow may cause the heating element to boil coolant, creating a larger air pocket and exposing the element to air, causing immediate failure, requiring replacement of the element or the entire heating unit.

Running the engine is quick, easy, and the best way to ensure your heating system is ready from day one. If you have additional questions about installing and running your heater for the first time, contact our customer service team or all (509) 536-8660.

For fleet vehicles with installed in-block heaters or direct immersion oil heaters installed, saving money often hinges on the weather—since heaters incur electrical costs when plugged in, whether the engine needs to be heated or not. If equipment operators plug them in every night regardless of conditions, you could be paying unnecessary electrical costs. However, leaving activation to equipment operators or timers can create hard starts the next morning temperatures dip unexpectedly, or worse, the heaters were not plugged in at all.

The TwinStat™ cord easily solves this problem. Heaters equipped with this cord only activate if the outside temperature dips below 40 °F (4 °C). If the spring or fall temperatures stay warm, the heaters remain off and use no electricity. If temperatures fall, the cord automatically energizes the heater, safeguarding the equipment and providing all the benefits of engine heating—including easy starts the next morning.

In a typical backup generator application, the generator will likely consume far more energy over the course of its operating life than it will produce. One of these factors is the engine heating system, installed to meet the NFPA 110 standard for emergency and standby power systems which specifies that a generator must be capable of assuming a full load within ten seconds of engine start.

To satisfy this requirement, many factory-built gensets are equipped with a single or dual thermosiphon heater. These heating systems provide proper engine heating to ensure the genset meets load requirements; however, their single or dual thermosiphon circulation methods are less efficient than a comparable pump driven heater. In many cases, if a genset is equipped with dual thermosiphon heaters, they may be replaced with a single pump-driven unit.

Because a thermosiphon heater relies on convection to circulate the fluid, the heating element must heat the fluid to a very high temperature to produce flow. Over the lifespan of the heater, this increased power demand can add up. Additionally, the higher temperatures produced by a thermosiphon heater may require that plumbing hoses are replaced more frequently, also adding to total ownership costs.

In these cases, replacing a legacy convection-based heating system with a forced circulation system—such as a HOTSTART HOTflow® heater or EVRHEAT® Series 20 heater—can lower electrical costs drastically, in some cases up to 45%. Replacing two convection heaters with a single heater also reduces overall system complexity and may lower maintenance costs. Finally, plumbing lines are not exposed to the high temperatures required by thermosiphon circulation and will last longer between routine maintenance, further reducing maintenance time and costs.

To learn more about HOTflow® and other forced circulation heating systems, visit our HOTflow® solutions page. Technicians interested in becoming HOTflow® certified for installing these types of systems should refer to our HOTflow® Technician Certification Training page for information on attending our webinars.    

Hotstart is dedicated to superior service over the lifetime of your heater. As a part of that commitment, we make servicing and replacing parts simple. You can order replacement parts for your Hotstart heater using any of the following options:

• Contact our Customer Service team and order direct from HOTSTART.
• Work with one of our worldwide Hotstart Distributors near you.
• Purchase through your local OEM Hotstart Dealer, including Cummins, Detroit Diesel, Generac, Kenworth, Kohler, MTU Onsite Energy, and Peterbilt.

When ordering replacement parts, be sure to reference your heating system’s model number and/or serial number found on the identification plate.

Our larger forced circulation systems, including those intended for use in Hazardous Location applications or Marine engine systems, are equipped with connections enabling fault signals and operating states to be transmitted to a user’s system interface—giving operators up-to-date information on the heating system’s status and health.

For users of smaller systems, evaluating heating performance can be done with a few extra tools. A malfunctioning heater can be remedied with simple maintenance procedures. 

For Thermosiphon heaters, technicians can immediately detect heating action by touch, confirming that heated coolant is flowing into the engine block.

Temperatures of the return hose, supply hose, heater tank, and engine block can be confirmed with an infrared laser thermometer. Alternatively, an infrared camera or recording device can capture images of the pattern in the heater and engine block. Either infrared recording devices are excellent tools for troubleshooting problems and improving heater installations, since they can detect both hot spots and cold areas in both Thermosiphon and Pump Driven applications.

Common issues include:

No heat from the heating system.

• Test thermostat and element: If fluid temperature is above the heater’s thermostat range—either due to a warm ambient temperature or a recently run engine, no heating will occur until the fluid cools below the thermostat's temperature setting.
• Check power source: Check the power source and heater cord for damage. 

Continuous heating

• Check for heat loss: Use an infrared thermometer or camera to measure radiator temperature. Thermosiphon systems normally cycle about four times per hour. If your heater runs continuously without cycling off periodically, it may mean that either the heater isn’t powerful enough for the application or the engine is losing heat faster than the heater can circulate fluid through the engine block. Unexpected low temperatures, exposure to high winds, or excessive heat loss through the radiator can affect heater performance. 

If you continue to have problems with heater operation, or you are looking for installation and operation tips or help, contact our Customer Service team directly for service and support or call (509) 536-8660.