Modine HD75 Unit Heater

Item No. HD75A-01
Free Shipping See Details Model HD Hot-Dawg Unit Heaters: For applications requiring a low profile unit. The Hot Dawg may be installed in residential, greenhouse or commercial applications just one inch below the ceiling. Don't be fooled by cheap Chinese manufactured heaters currently flooding the
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Model HD Hot-Dawg Unit Heaters: For applications requiring a low profile unit. The Hot Dawg may be installed in residential, greenhouse or commercial applications just one inch below the ceiling. Don't be fooled by cheap Chinese manufactured heaters currently flooding the market. Since 1916, Modine has provided quality heating solutions that are made in America to the highest possible standards. The superior quality matched with the following features makes the Hot Dawg unit heater an easy choice for a variety of applications.

Standard Features

  • Made in the USA Made in the USA
  • Certified for residential, agricultural and industrial use.
  • Quiet operation.
  • Attractive low-profile design and neutral paint scheme assure that Hot Dawg will blend inconspicuously into any garage decor.
  • Durable polyester-powder paint maintains life-long good looks.
  • Standard power exhaust simplifies side-wall or roof venting with small-diameter vent pipe.
  • Versatile design allows for right or left-hand piping and installation. Gas, electrical and flue connections can be changed from one side to the other by simply flipping the Hot Dawg over.
  • Lightweight, easily installs from ceiling with only 2 angle brackets (included).
  • Installs quickly and easily with field wiring connections and knockouts for quick access to gas and electricity.
  • Designed for natural or propane gas.
  • Sealed, permanently-lubricated motor for trouble-free dependability.
  • Full 10-year warranty on heat exchanger.
  • 24,000 thru 75,0000 (HD25A - HD75A) BTUH Heaters will include ceiling mounting brackets. Ceiling mounting brackets for the 100,000 & 125,000 (HD100A, HD125A) BTUH Heaters must be purchased separately.

Dimensions and Diagrams

Dimensions, Diagrams and Specifications (PDF)

Modine Greenhouse Heating Solutions (PDF)

Wiring Diagrams (PDF)

Performance Specifications

ModelApplicationInput BTUHOutput BTUHVent SizeWeight (lbs)
HD301 to 1-1/2 Car Garage
or up to 250 SF Greenhouse.
30,00024,600Requires 3" Vent Pipe55
HD452 to 2-1/2 Car Garage
or up to 350 SF Greenhouse.
45,00036,900Requires 3" Vent Pipe60
HD603 to 3-1/2 Car Garage
or up to 550 SF Greenhouse.
60,00049,200Requires 3" Vent Pipe80
HD75Large Garage
or up to 650 SF Greenhouse.
75,00061,500Requires 3" Vent Pipe85
HD100Up to 1000 SF.100,00082,000Requires 4" Vent Pipe125
HD125Up to 1200 SF.125,000102,500Requires 4" Vent Pipe125


Many of our customers happily report that purchasing a Hot Dawg heater from the Greenhouse Megastore helped them save 50% or more off the unit price received from a local HVAC installer.  However, for safety reasons and to minimize installation problems Modine strongly recommends having a licensed HVAC technician install your Hot Dawg heater.  Although we are happy to offer limited technical support for your Hot Dawg purchase, we can NOT install the heater for you over the phone nor are we able to troubleshoot problems you may experience if you choose to install the heater yourself.  By purchasing this heater from us, you accept sole responsibility for installation and agree to abide by Modine's limited Warranty


Based on our experience in selling Modine Hot Dawg Heaters, we have written up a troubleshooting guide that deals with the issues we most commonly hear from customers. - Troubleshoot a Modine Hot Dawg

If you still need help, check out Modine's own troubleshooting guide.

Comparison Chart

Modine HD-Series vs. Sterling RF-Series

SpecificationModine HD-SeriesSterling RF-SeriesComments
BTU Range30 - 125 MBH30 - 90 MBHModine covers more applications
Minimum Efficiency80%80%Same non-condensing high efficiency
Blower Fan Units
(HDB model only)
60 - 125 MBHNot AvailableModine covers more applications
Casing PaintPolyester PowderWet EnamelModine units will look better longer
Quiet Swept Wing Fans100 and 125 MBHNot AvailableLarger Modine units are quieter
Heat Exchanger Gauge18 Gauge20 GaugeModine heat exchangers are heavier gauge
Optional Stainless SteelYesNot AvailableModine covers more applications for corrosive environments
T.E. Fan Motor StandardYesNoModine motors are protected for longer life
Power Vented X-Changer Warranty
(HDS and HDC models only)
10 Years10 YearsSame 10 year heat exchanger warranty
Sep. Comb. X Changer Warranty
(HDS & HDC models only
10 Years5 YearsModine separated combustion units warrantied longer
Component Warranty2 Years1 YearModine parts warrantied longer

Additional Information


Residential Owners Manual (PDF)


Modine offers a 10 year limited warranty on the heat exchanger and a 2 year limited warranty on all other components.  Please note this warranty covers parts only and does not cover any labor costs associated with repairing the heater. View Warranty (PDF)

Product Video 

Heater Warranty and Return Policy

It is the customer's responsibility to carefully inspect heaters for damage before accepting delivery since heaters are usually not returnable once delivery is accepted. Obviously damaged heaters should be refused and Greenhouse Megastore customer service contacted to make arrangements for a replacement unit. Once delivery is accepted Greenhouse Megastore will gladly provide replacement parts under the manufacturer's warranty to repair damaged or defective heaters; however this warranty does not include any labor costs associated with installing these parts. Warranty issues should be diagnosed by a certified HVAC technician since parts deemed not to be defective by the manufacturer are not available for credit back to the customer. Specific warranty policies vary by manufacturer but typically cover replacement parts as indicated above up to one year after purchase. Please contact Greenhouse Megastore customer service if you have any questions about the warranty for your specific heater.


Free Shipping 

This item ships free via Motor Freight Carrier - almost anywhere in the Continental United States!

On rare occasions addresses with limited access such as islands or major metropolitan areas (ie: New York City) may incur additional delivery fees; if so, you will be contacted to confirm the extra shipping cost before your order is processed. Shipments to Alaska or Hawaii qualify for free shipping to any West Coast port. Please contact us for special shipping rates from the West Coast to Alaska or Hawaii.

Motor Freight Agreement

  • Full Size Semi: Your location must be able to accommodate a full size semi-truck trailer of up to 70ft. in length.
  • Someone Must Be Present: You or someone else authorized must be present to unload the shipment. Exact delivery date will be arranged via phone by freight company.
LTL Freight Type FREIGHT
Standard Drop Shipment Code DROP SHIP
Replenishment System Purchase
Available for Drop Shipment Yes
Item Tracking Code PARENT
Reviews (19)
  • nice
    install went smooth, nice product
  • ?
    fast delivery , easy to install , fired right up
  • Excellent Heater
    This heater came with my greenhouse and so far it is doing a great job. It's early Feb 2012 in the NW and I'm busy getting seeds started in the greenhouse. The Modine Hot Dog heats the place up in minutes and the optional thermostat is working like a charm. Just ordered another one for my new shop :)
  • Great Heater
    Ordered on Monday and the unit was delivered on Wed. It was very easy to install. Used a drywall lift to raise it to the ceiling and bolt it in place. Hooked up the gas and electrical and it fired right up. The unit heats great! Very high quality product compaired to the big box stores. Love it!
  • HD75 Modine Heater
    Great price, fast shipping and the heater is wonderful...
  • hd 75 heater reveiw
    Easy installation and hook up. Unit started and ran on 1st try.Wind chill outside today -30 degrees below zero. I set heater at 50 degrees and kept garage warm to clean car today.
  • HD 75
    Hi all just purchased and hooked up 12-11-10. The whole purchase was absolutely painless. Install was easy. Shipping was as I was told it would be. Arrived on time and well packed. Heater fired right up first try and has been heating my 30x40x10 high garage since. Has been in the teens and lower hear lately but is nice and toasty in the man cave. Thanks for an easy transaction Steve
  • modine 75 heater
    Thank you for a prompt and careful delivery. heater is operating according to specs.
  • great heater
    Have used in my woodshop for 3 years now and wouldn't consider anything else. Great heater and takes up no usable space.
  • hot dawg hd75 heater
    FAST shipping, Great product!! NO damage in shipping, and fired up first try.
  • Yes...Best Purchase Ever!!!
    I was amazed how trouble free this unit was to install! The unit fired quickly and cycled as advertised. The unit has performed flawlessly. It is very quiet compared to the unit I replaced it with. Thanks, Greenhouse Megastore!
  • Smart purchase
    I just finished installing my new Unit Heater and I am very pleased with the operation and will welcome the heat in my garage.
  • Fast heater!
    Just finished installing the heater yesterday.. Fired it up, took a few minutes to purge but once it kicked in, I finally was able to feel my frozen feet again!! All the liquids in my garage were frozen before and now I can finally use them!
  • Great product
    I am using this product in my work garage where I have to build cabinets and do painting and refinishing. I have to keep my garage at a certain temperature in order to work and for my cabinets to dry. This heater does a great job in keeping my garage at the required temperature.
  • Hot Dawg Is great
    We moved into our house about 6 months ago and there was a HD-75 heater already in the garage but it was not working correctly. Upon further checking it was the Nat. Gas version probably 5 yrs. old. The problem is that it was hooked to Propane and I don't think it was converted. The problems were: Not heating very hot and sometimes it would light and sometimes it wouldn't. Anyways, After installing the HD-75 Propane today I was amazed at how much hotter the air was, it went from 45 to 55 in about 5 mins. Also The Greenhouse Megastore had the best price around and the Shipping was extremely fast. I will be back for my heating and gardening needs, Thanks IGC!
  • Heats quick
    Its been a real cold winter in Wyoming this winter and the hot dawg heater has kept my shop nice and warm
  • Super Dawg is more like it.
    I'm presently finishing my three car garage in a man cave fashion with all the goodys. The Modine H D75Unit Heater started this project off just right. Janurary in Ohio is pretty cold so I needed a good supply of heat to stay warm while working in the garage and the H D 75 did the job.
  • Bill Fortney
    After researching for about a year, My mind was made up to purchase the Hot Dawg HD75. IGC by far offered this unit at the best price. I was surprised and pleased when it arrived in only two days. It took some effort to run the new gas line and install the vent but all in all the unit was easy to hang and has worked perfectly since the first time I turned up the thermostat. Thanks so much for selling a quality product at a reasonable price. PS. I am heating a very well insulated 1728 square foot garage / shop with this unit Thanks Again, Bill
  • modine hot dawg 75K
    great heater, easy to install. the only bad thing i could say is the way they ship the louvers. being spring loaded is the only way the stay on. during shipping, three of them were off. after seeing how they work, they were quickly and easily replaced. no big deal. it is so nice to walk into a shop where is is warm.