Modine Hot Dawg® HD45 Unit Heater

Modine Hot Dawg® HD45 Unit Heater


$1,175.55 Regular price
  • Ships in approximately 2 weeks

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
  • 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

Model Application Input BTUH Output BTUH Vent Size Weight (lbs)
HD30 1 to 1-1/2 Car Garage
or up to 250 SF Greenhouse.
30,000 24,600 Requires 3" Vent Pipe 55
HD45 2 to 2-1/2 Car Garage
or up to 350 SF Greenhouse.
45,000 36,900 Requires 3" Vent Pipe 60
HD60 3 to 3-1/2 Car Garage
or up to 550 SF Greenhouse.
60,000 49,200 Requires 3" Vent Pipe 80
HD75 Large Garage
or up to 650 SF Greenhouse.
75,000 61,500 Requires 3" Vent Pipe 85
HD100 Up to 1000 SF. 100,000 82,000 Requires 4" Vent Pipe 125
HD125 Up to 1200 SF. 125,000 102,500 Requires 4" Vent Pipe 125


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

Specification Modine HD-Series Sterling RF-Series Comments
BTU Range 30 - 125 MBH 30 - 90 MBH Modine covers more applications
Minimum Efficiency 80% 80% Same non-condensing high efficiency
Blower Fan Units
(HDB model only)
60 - 125 MBH Not Available Modine covers more applications
Casing Paint Polyester Powder Wet Enamel Modine units will look better longer
Quiet Swept Wing Fans 100 and 125 MBH Not Available Larger Modine units are quieter
Heat Exchanger Gauge 18 Gauge 20 Gauge Modine heat exchangers are heavier gauge
Optional Stainless Steel Yes Not Available Modine covers more applications for corrosive environments
T.E. Fan Motor Standard Yes No Modine motors are protected for longer life
Power Vented X-Changer Warranty
(HDS and HDC models only)
10 Years 10 Years Same 10 year heat exchanger warranty
Sep. Comb. X Changer Warranty
(HDS & HDC models only
10 Years 5 Years Modine separated combustion units warrantied longer
Component Warranty 2 Years 1 Year Modine 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.


This item ships via Motor Freight Carrier - almost anywhere in the Contiguous United States

Motor Freight Requirements

  • The shipment must be delivered to a business or residence (a PO Box is invalid)
  • The delivery address must be able to accommodate a tractor/trailer as much as 70' in length
  • Someone must be present to receive and unload the shipment from the truck
  • Shipments and/or locations requiring a lift gate, inside delivery, and/or with limited access may incur additional charges by the carrier

Please contact Greenhouse Megastore Customer Service at 1-888-281-9337 if you have any questions about delivery to your specific address so we can ensure the smoothest delivery possible!

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Customer Reviews

Based on 14 reviews
Legacy Review
Love this Little Guy

I installed this unit in my garage so I could have heat to work in there for the winter. It's a 30'x60' and this little guy has NO problem heating it to 70F. I kept on at 45F for the winter to keep the cars and tractor warm and melt snow, and it didn't even make a noticeable bump in the heating bill. It was easy to install and just works. I would recommend this many times over.

Legacy Review
fantastic heater

This was purchased to heat an attached 3 car garage (almost 800 sq/ft). It does a fantastic job; it's quiet and heats up to whatever temperature i've set so far. It's definitely a high quality heater. I looked at the local brands of heater available at menards and I was concerned that in the future parts availability may be a problem, but modine is an established brand and should be around a long time. Its cheap to upsize the unit but i reccomend sticking to manufacturer recomendations for sizing

Legacy Review
Modine HD45 Unit Heater

This little heater is amazing. I wish I had found this years ago. We will install many more of these in the future. Easy installation, works great, nice looking, it has it all!!!

Legacy Review
Great Heater

I bought this heater for my 10x20 foot greenhouse. My husband got in installed right before we had the coldest weather in over 30 years. It did a great job! I would recommend this heater to anyone needing to heat a greenhouse, shop or garage.

Legacy Review
Great service and price

After fully researching my needs for a heated 2.5 car garage I selected the Modine Hot Dawg propane heater supplied by Greenhouse Megastore. I learned to spend the extra money on the Modine as opposed to Mr. Heat. The unit arrived promptly with no shipping defects. I did not order the extra complete set of venting components, believing I could purchase units from a home supply store for less. That was not case. I will now be placing an order with Green house for the quality vent pipes.

Legacy Review
As expected

Great service and fast shipping. High altitude kit was shipped after the fact at no charge with fast shipping time. Thanks!!

Legacy Review
Worth The Price!

Purchased for our restaurant, whisper quiet, great heat. Keeps our whole 30 X 40 building warm. Very easy to install, completed in about 2 hrs.

Legacy Review
problem solver

I purchased the 45,000 BTU HotDawg. The compact size ,ease of install and purpose for this unit will work perfectly for my residential application. I will use this heater , NG forced vent in my large attic to keep me warm during the cold winter days and evenings .When not in use I will turn the thermostat to 45 F. With in 5 minutes of the unit being on (very quiet) I'm back in business. Thank you Modine,Big Bear

Legacy Review
Best Purchase EVER!!!

When I purchased my Modine Hot Dawg Natural Gas furnace a couple of years ago, I got it for my greenhouse. I actually got a low-profile one for garages, as that is what I needed for the ceiling height, yet still be above the water sprayers, and it has worked marvelously. In Oregon these heaters are priced at $1000 and up, yet even with shipping I was able to save 45% by purchasing it through MegaStore! My husband installed it and we've had no problems's the BEST purchase for my greenhouse we've made yet! I LOVE IT!!!

Legacy Review
Great Garage Heater

I ordered this product online and was impressed by the reviews about the product and the Mega Store satisfaction comments. When I received the billing information the invoice showed that the heater would need a high altitude conversion kit. The box was delivered well packed with a sticker that said additional parts included. The conversion kit was included, sized for the altitude of my garage (thanks Google) and the installation was a snap. In short I recommend the product, my garage shop is a large two car and the heater keeps it toasty even in very cold conditions; I also highly recommend the Mega Store.