| If you already use a hot water system to heat | | | | Hot/Cold Coil |
| your home, adding heat to your garage or | | | | When a room thermostat calls for heat, a valve is |
| workshop can be accomplished by installing a fan | | | | opened, allowing steam or hot water to enter the |
| forced hot water unit heater. Hot water garage | | | | unit heater. When the thermostat is satisfied, the |
| heaters transfer heat from the hot water to the | | | | valve is closed. The fan runs continuously. |
| air. | | | | >>Intermittent Fan Operation - Intermittent |
| Operating Principle | | | | Hot/Cold Coil |
| The hot water from your boiler flows through a | | | | When a room thermostat calls for heat, the |
| radiator coil and an electric fan pushes air through | | | | motor is energized. At the same time, a valve is |
| the radiator coil. The air entering the coil absorbs | | | | opened allowing steam or hot water to enter the |
| the heat from the water, resulting in a warmer | | | | unit heater. An aquastat may be attached to the |
| discharge air temperature. The cooler water | | | | supply or return piping to prevent fan operation |
| leaving the coil returns back to the boiler to be | | | | until the coil is adequately heated to avoid cold air |
| reheated for another pass through the radiator | | | | delivery. When the thermostat is satisfied, the |
| coil. | | | | valve closes and the motor is de-energized. |
| Benefits of fan forced hot water unit heaters in | | | | 3) How do I determine how much heat a hot |
| garages or workshops:o Clean heat, no odors, no | | | | water unit heater will generate with varying |
| by-products of combustion to vent.o No open | | | | entering hot water temperatures? |
| flame to worry about.o No messy fuel oil to | | | | ANSWER: Hot water unit heaters are also used |
| contend with.o Efficient.o Easy maintenance.o | | | | with steam. The major hot water unit heater |
| Very reliable. The only moving part is the motor | | | | manufacturers rate their capacities using 2 psi |
| and fan assembly. If a motor fails, it is very | | | | steam. For example, a Modine model HSB33 will |
| simple to replace.o The fan speed can be | | | | produce 33,000 BTUs when it is hooked up to 2 |
| adjusted on many models. This allows you to dial | | | | PSI steam. Another example: A Sterling model |
| in the perfect airflow.o Low clearance | | | | HS120 will produce 120,000 BTUs when hooked |
| requirements on units with side piping | | | | up to 2 PSI steam. Since you are most likely |
| connections.o Horizontal units have adjustable | | | | using hot water in your garage or workshop, you |
| louvers to help direct warm air where you need it | | | | need to know how much heat you will get out of |
| most.o Durable. All unit casings are treated for | | | | the unit with your specific hot water temperature. |
| corrosion resistance and finished with a | | | | Call us. Within minutes we can tell you the exact |
| gray-green baked-on, high solids paint.o Compact | | | | output for every sized heater under any condition. |
| and lightweight for simple installation.o Tapped | | | | Do not fall for advertisements that claim 290,000 |
| holes in the units casing allow for simple | | | | BTUs!. A size 290 unit heater will produce 290,000 |
| suspension using inexpensive threaded rod.o Large | | | | BTUs ONLY if it is supplied with 2 PSI steam. If |
| electrical junction boxes allow for simple power | | | | you are using 160F water, this same heater will |
| wiring.o Huge range of sizes to match the heater | | | | produce 152,000 BTUs, almost half the capacity |
| to your heating load. If selected properly, you | | | | shown on the advertisement. |
| don't have to worry about under or over sizing.o | | | | 4) Can hot water unit heaters be used with |
| The fan can run in the Summer to help circulate | | | | outdoor wood furnaces? |
| air. | | | | ANSWER: Absolutely. The coil doesn't care where |
| Drawbacks of fan forced hot water unit heaters | | | | the hot water comes from. As long as the water |
| in garages or workshops:o Water in a cold garage | | | | is warmer then the air, the unit heater will |
| can easily freeze if there is a failure.o A home | | | | transfer heat from the water into the space. |
| boiler system is required. If your boiler is down, | | | | 5) What are the different piping configurations on |
| the heater will not produce heat.o Hot water | | | | hot water unit heaters? |
| piping is required to distribute the water from | | | | ANSWER: The most common hot water unit |
| your boiler to the hot water unit heater.o Controls | | | | heater for a garage or workshop is the horizontal |
| can be slightly more complex due to the | | | | model. Most major manufacturers offer side piping |
| integration of your hot water boiler and the unit | | | | and top and bottom piping arrangements on |
| heater. See the commonly asked questions | | | | horizontal units. The side piping connection models |
| section for typical control sequences.o Fan forced | | | | allow you to install the heater closer to the ceiling. |
| units move large volumes of air which can kick up | | | | The top and bottom piping connection models |
| dust in your garage or workshop. | | | | allow you to easily rotate the unit if you need to |
| Unit Configurations: | | | | change the direction it is pointing. |
| Hot water unit heaters come in horizontal or | | | | 6) What is the best location in my garage or |
| vertical models. The "horizontal" or "vertical" | | | | workshop to install my hot water unit heater? |
| describes the direction of airflow. A "horizontal" | | | | ANSWER: The hot water unit heater in your |
| unit heater is typically placed along a wall and | | | | garage or workshop should be located in the |
| blows warm air into the space. A "vertical" unit | | | | coldest area, and it should be angled slightly so it |
| heater is typically placed along a ceiling and blows | | | | blankets warm air across the coldest wall. |
| warm air vertically down into the space. Vertical | | | | 7) What is the best location to install a wall |
| unit heaters are typically used in very large | | | | mounted thermostat in my garage or workshop? |
| spaces. Horizontal units are typically used in smaller | | | | ANSWER: The thermostat should be mounted in a |
| spaces such as garages or workshops. | | | | location that represents a good average |
| There are several modifications available. | | | | temperature in your garage or workshop. If it is |
| Horizontal and vertical unit heaters are available | | | | located in a cold spot, it will falsely run the unit |
| with "power throw" high CFM fans, high pressure | | | | heater more then it should. If it is located in an |
| tubes, low outlet temperatures (for high steam | | | | area that receives direct sunlight, it will falsely run |
| pressure applications), special motors and custom | | | | the unit heater less then it should. A well insulated |
| coatings. These modifications are rarely used in | | | | interior wall is the best spot for the thermostat. |
| the typical garage or workshop. Call us for | | | | 8) What is an aquastat? |
| information about customizing a unit to meet your | | | | ANSWER: An aquastat gets strapped on to the |
| specific needs. | | | | supply or return hot water pipe. It gets wired in |
| Installation Overview: | | | | series with the fan motor. The aquastat will only |
| 1) Suspend the unit heater using threaded rods | | | | allow the fan to run when there is hot water |
| that thread into the self tapping holes located on | | | | running through the pipes. This inexpensive device |
| the unit heaters casing. | | | | will prevent cold air from circulating throughout |
| 2) Install hot water piping from your boiler or | | | | your garage or workshop when the hot water |
| wood furnace to the hot water unit heater. | | | | pipes are cold. |
| 3) Wire the hot water unit heater's fan motor. | | | | 9) What kind of sound can I expect from a hot |
| 4) Install controls. | | | | water unit heater? |
| Commonly Asked Questions: | | | | ANSWER: While sound is created anytime fans |
| 1) How do I calculate the heating load for my | | | | and motors are used to move air, Modine unit |
| garage or workshop? | | | | heaters were designed to minimize their sound |
| ANSWER: Call us or use our simple heat load | | | | level through the careful selection of motors, fan |
| calculator. Do NOT fall for equipment that is | | | | blades and the design of the air intake opening. |
| advertised as will heat up to 400 square feet. | | | | The information below shows typical types of |
| Heating a 400 square foot insulated garage in | | | | buildings or rooms with a corresponding Sound |
| Florida is a lot different then heating a 400 square | | | | Class rating. For a unit heater with a given Sound |
| foot un-insulated metal garage in Maine. 1 heater | | | | Class rating, when placed in the type of building or |
| can not magically service both 400 square foot | | | | room shown below, the sound of the unit heater |
| spaces. Call us; we are happy to run a detailed | | | | will be relatively comparable to the ambient sound |
| engineering calculation that will help you pick the | | | | level of all sounds within that type of building or |
| perfect heater for your space. You do not want | | | | room. When purchasing a unit heater, ask for the |
| to undersize, and you do not want to oversize. | | | | the sound class rating to be sure you are buying |
| 2) How do I control my hot water unit heater in | | | | something that will fit your application. |
| my garage? | | | | Sound Class Ratings |
| ANSWER: If there is always hot water running | | | | Type of Building or Room Sound Class Rating |
| through the coil, you can simply use a switch to | | | | Apartments, Classrooms, Court Rooms, Executive |
| turn the fan motor on and off when you are | | | | Offices, Hospitals, Libraries, Museums: Class I |
| using your garage or workshop. Automatic control | | | | General Offices, Hotel Dining Rooms, Recreation |
| is preferred over manual control. There are 3 | | | | Rooms, Show Rooms, Small Stores: Class II |
| common methods for automatically controlling a | | | | Bank Lobbies, Grocery Stores, Gymnasiums, Post |
| hot water unit heater in a garage or workshop: | | | | Offices, Restaurants, Service Stations: Class III |
| Common Control Sequences | | | | Factories, Foundries, Machine Shops, Packing |
| The following control sequence descriptions are | | | | Plants, Shipping Platforms: Class II-VII |
| typical for steam/hot water unit heaters in garage | | | | Forge Shops, Steel Fabricating Shops, Boiler |
| or workshop applications: | | | | Works: Class VII |
| >>Intermittent Fan Operation - Hot Coil | | | | 10) How can I compare the cost of heating my |
| When a room thermostat calls for heat, the | | | | garage with different types of garage and |
| motor is energized. Hot water or steam is | | | | workshop heaters? |
| continuously supplied to the unit heater, even | | | | ANSWER: Call us. We will first run a heat load |
| when the motor is not running. When the | | | | analysis, and then we can run an energy |
| thermostat is satisfied, the motor is de-energized. | | | | comparison analysis based on your local fuel rates. |
| >>Continuous Fan Operation - Intermittent | | | | |