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$250 Order

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$500 Order

$50
gift card

$1000 Order

$100
gift card
  • The promotion will be automatically applied on the Shopping Cart page.
  • To qualify for this offer, your order subtotal must equal $100 or more. Excludes gift cards, free item offers, warranties, Advantage memberships, tax and shipping.
  • Free gift cards will be issued in the form of e-gift cards only, not physical gift cards.
  • E-gift cards will be sent to the email address used in your billing address when your order ships or is picked up.
  • Free e-gift cards expire 11/01/26.
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  • Valid online and in participating retail stores.
  • Limited-time offer. Subject to change without notice.
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Mr. Heater Big Maxx Natural Gas Garage/Workshop Unit Heater, 125,000 BTU, Model# MHU125NG

Item# 57328
New
Mr. Heater Big Maxx Natural Gas Garage/Workshop Unit Heater, 125,000 BTU, Model# MHU125NG

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Mr. Heater Big Maxx Natural Gas Garage/Workshop Unit Heater, 125,000 BTU, Model# MHU125NG

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$999.99

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Heat Output

  • Shipping: 

    Free shipping (lower 48 states) - Available now
    $19.99 Same Day

    Heavy/large item. Lift gate service available.

  • Store Pickup: 

    1 in stock at Fredericksburg VA

  • Requires only 1" clearance from ceiling with 2 included angle brackets
  • Power exhaust allows for vertical or horizontal venting
  • Designed for right or left side piping, electrical and flue connections by simply rotating 180°
  • Aluminum tubular heat exchanger for maximum efficiency and longer life
  • Spark ignition with self-diagnostic control module

See full description

  • Description

  • Key Specs

  • Reviews

  • Q & A

  • Accessories

  • Warranty

  • Compare

Product Summary

This Big Maxx™ Natural Gas Garage/Workshop Unit Heater is designed for residential and commercial use, easily heating a 2- to 3-car garage. Built-in electric high velocity fan pulls cool air into the rear of the heater and over a heat exchanger, forcing hot air into the surrounding area. Item may come in Dark Gray or Tan. Works with Thermostat Item# 173641 (sold separately). Note: Installation requires an 8ft. clearance from the floor and will not pass code with less than 8ft.

What's Included

    (1) Big Maxx Natural Gas Garage/Workshop Unit Heater

Downloads

Product Manual

Key Specs

AttributeSpecification

item#

57328

Brand

Mr. Heater

Manufacturer's Warranty

3 year limited warranty

Ship Weight

65.59 LB

Heat Output

125,000 Btu/hour

Heat Type

Forced Air

Heating Capability

4,167 ft²

Needs Direct Venting

Yes

Blower Included

Yes

Blower CFM

1,475 cfm

Amps

3
AttributeSpecification

Thermostat Included

No

Remote Included

No

Phase

Single-phase

Volts

120

Watts

360

Oxygen Depletion Sensor

No

Fuel Consumption

1.38 GPH

Hardwired

Yes

Product Weight

109.1300 lb

Dimensions L x W x H (in.)

26.89 x 25.43 x 27.17 in

Reviews

Questions & Answers

114 Reviews This action will navigate to reviews.

Questions

1–10 of 52 Questions  
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  1. whats the efficiency percnetage of gas

    whats the efficiency percnetage

    1. It is an 80% efficiency unit which means you loose 20% through the vent exhaust. This is actually really good for this type of unit. The older units would loose 60% which means you loose more than your heating.

      Helpful?

    2. This Big Maxx natural gas heater has an 80% efficiency rating.

      Helpful?

  2. any info on the running dB?

    1. This unit is quiet. Due to lack of industry standards on decibel ratings, the manufacturer does not have a rating.

      Helpful?

    2. I am not sure of the dB's but this unit is quiet. I was very pleased how quiet it was.

      Helpful?

  3. Is there a LP Conversion Kit

    1. Yes, there is. I converted mine to LP and it was easy. You had to switch out the orifices and the spring inside the regulator/valve. There is good directions in the manual included with your unit.

      Helpful?

    2. The LP conversion kit is included with this heater.

      Helpful?

  4. Is this product suitable for installation/use in a damp location? (Car Wash with no direct water contact, but definitely humid. Need to replace a a 22 year old Dayton.

    1 answer

    1. The heater is not designed or approved to be installed in a damp or wet location.

      Helpful?

  5. Do I need a regulator with naturalgas

    1 answer

    1. A low pressure regulator is required for natural gas.

      Helpful?

  6. can this unit be set on its bottom on a wood deck 10ft from the floor

    1 answer

    1. This heater cannot operate sitting on a wood deck. It does minimally require 8 ft. of clearance at the bottom of the heater.

      Helpful?

  7. is this heater available for propane?

    1 answer

    1. This unit comes with a LP conversion kit.

      Helpful?

  8. Is this CSA certified?

    1 answer

    1. The heater is CSA International design certified. The installation must conform with local building codes or in the absence of locals codes with the current CSA B 149.1 (natural gas and propane installation code). All electrical wiring and grounding for the unit must comply with the Canadian Electrical Code CSA C22.1.

      Helpful?

  9. Will the universal Mr heater vertical vent kit f102849 fit ?

    1 answer

    1. The 6" vent kit, model F102849 would not work with this garage heater. It would use the 4" vertical kit, model 4GVKNT, item #28795.

      Helpful?

  10. What size Allthread is needed to hang this unit?

    1 answer

    1. The hanging bracket would have 1/2" NPT threads.

      Helpful?

Accessories We Recommend

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See All Thermostats
Thermostat For Mr. Heater Garage Heaters
3.5 out of 5 stars. 91 reviews

Thermostat For Mr. Heater Garage Heaters

Item # 173641

$24.99
See All Venting
DuraVent Vent Unit Heater Kit, 4in. Horizontal, Model# 4UHK-KVNT
4.4 out of 5 stars. 39 reviews

DuraVent Vent Unit Heater Kit, 4in. Horizontal, Model# 4UHK-KVNT

Item # 29794

$429.99
See All Venting
DuraVent Vent Unit Heater Kit, 4in. Vertical, Model# 4GVKNT
4.5 out of 5 stars. 31 reviews

DuraVent Vent Unit Heater Kit, 4in. Vertical, Model# 4GVKNT

Item # 28795

$279.99
See All Hose Assemblies + Regulators
Mr. Heater 225,000 BTU, 2-Stage Regulator, Model# F273863
4.8 out of 5 stars. 40 reviews

Mr. Heater 225,000 BTU, 2-Stage Regulator, Model# F273863

Item # 25819

$42.99

Warranty

Manufacturer's Warranty

3 year limited warranty

Extend Your Warranty Coverage with a Northern Protection Plan (NPP)

Repair Plan — 1 Year

A Northern Protection Plan is available after adding the product to your shopping cart.

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Mr. Heater Big Maxx Natural Gas Garage/Workshop Unit Heater, 125,000 BTU, Model# MHU125NG
4.8 out of 5 stars. 114 reviews

Mr. Heater Big Maxx Natural Gas Garage/Workshop Unit Heater, 125,000 BTU, Model# MHU125NG

Item # 57328

$999.99