Mr. Heater F260550 Big Maxx MHU50NG Natural Gas Unit Heater,Black

Hopefully this review is useful for other, it was hard to find real examples of use like this to get an idea of how well this unit will heat my space. I am heating a 21'x33' garage with an 11' ceiling. Walls are insulated at about an R15 but ceiling with unfinished attic above it is not insulated. Overhead garage door is insulated. Here's the data: Outside temp: 28F Garage Inside temp when heater was turned on: 40F 30 minutes after heater on inside temp: 53F 1 hour after heater on inside temp: 59F 2 hours after heater on inside temp: 65F The heater was able to get the temp inside the garage up to 70F after about 2.5 hours after not being used all day with an outside temp of 20F the other day as well and it keeps things very nice and comfortable. I cannot speak to reliability as I just purchased, but installation was easy (check Menards for their category 3 horizontal venting kit as it is half the price of the manufacturers kit), and the price was insanely good compared to all of the other options. I was quoted $3500 installed for other brand units from several different local HVAC companies and I was out the door installed (had a local company do part of the install) for around $900 total. I put the unit up and ran electrical but had the installer do the gas line and vent kit install. Since the unit was so inexpensive, I did add the 4 year Amazon protection plan. Hopefully it lasts a long time but if it doesn't, at least it will be easy and free to replace. All in all a good value and it gets the job done.

Update April 19, 2026 Alright guys, forgot to update you all last fall. I got frustrated last fall when I hit the switch and got the clicking to fire up the gas and nothing.. Turns out there was a little piece of fuzz or spiderweb plugging up the vacuum line that that needs to be clear to engage the solenoid that opens the gas valve. Cleared out the fuzz from the line and BOOM, it fired right up. So mechanically it was fine, just a little cleaning required. Still love this heater, it’s April in upstate NY and it’s snowing..So had to fire it up to work on my lawn tractor (a different issue, always something required to keep life moving forwards) and it reminded me I hadn’t posted an update. I still highly recommend this heater.. Update Feb 9. 2024 Still going strong. Absolutely NO issues.. Update: October 17, 2023 I flipped the heater on today after leaving it off since sometime in April.. Its been in the low 50's so I just wanted to take the chill out of the garage and sort out my tools for a fall project. The unit fired right up, warmed up the garage, no issues, just did its job. This unit has been very reliable for me, and I continue to recommend this heater for a garage. ------------------------------------------- I bought this heater in September of 2019 when I retired. I live in western NY where the winters are long, dark and cold. Since the wife doesn't want to snowbird in the south, I figured I better heat the garage, so I had a place work on projects. If you can run some natural gas lines and stick a vent through the roof, you will love this heater. I stuck a cheap thermostat on it from one of the big box stores, a separate house switch on it to flip it off for the summer months. I have had NO problems with it. It runs for 6 months during the cold months, then I flip it off at the end of April, when October comes, I flip it back on and it fires right up. It doesn't make any vibrating noise like some have said, vents out the garage roof using the double wall vent duct with a hat to keep the snow out. I insulated my garage walls and ceiling with standard R19 from HD, and drywalled it as well. My garage is 24' x 24' x 10' with concrete floor. This unit heats it with no problem. I should have installed one years ago. Also, I did not use an isolation relay to isolate the unit that protects the house wiring from "a pulse" from the unit when the solenoid kicks on and I have experienced no issues with the unit interfering with the house electric. I have broadband internet, smart switches, smart lights, Alexa, etc.. and have experienced no issues. If you're like me, live in the north and have some DIY skills and are sitting on the fence, just pull the trigger and buy it. You'll get a whole new play area for the winter months. :-)

So worth the price, and very easy to install. Yeah the exhaust duct work costs almost as much as the unit itself. But We'll Worth It!!! Heats up the Garage almost instantly, my Garage is a 1 1/2 car garage. It's 12°outside currently in Buffalo NY. 01/20/2020. Turned the heater on and it was warm in 7 minutes, about 60°. The fan is quiet, don't listen to the other reviews. Not saying that their unit was loud but maybe they had something wrong with their fan?? My garage is a Gym and to work out in the winter it's great to have the Garage Heated. This unit goes ABOVE and BEYOND my EXPECTATIONS. Im VERY PLEASED with the performance, the ONLY advice i can give is that THE DIRECTIONS SAY TO pitch the duct work UP a quarter inch per foot. DO NOT pitch it UPWARD!! the CONDENSATION will run right into the heater. Their is a Fan their inside the unit that will get wet and ruined. I had to fix this because for 1 i could not find a 4" piece that's shown in the instructions that had that DRIP HOLE where you have to attach a drip hose to. I don't know why you would want a hose hanging down from your exhaust anyway with nowhere to drain it to... "PRO TIP" So angle the duct work downward and this way the sweat/ Condensation will run outside - out of the exhaust. If not you're going to have sweat and condensation running towards the heater ruining and rusting the inside of the heater. That's the only thing that I seen in the instructions that were horribly wrong. Everything else was a breeze. The gas line, the electrical, the thermostat simple work. I am installing a smart thermostat so I can control it from my phone, So when I wanna go out there and work out I will turn to thermos son 5 minutes before I go out their. Thank you, hope this review helps someone.

I'd consider myself a fairly handy guy so I decided to take this installation on myself. This is a big job, but it can be done by just about anyone who's handy with tools and is willing to do their research. The install took me about 20 hours total over the course of about 2 weeks. I didn't have to run gas line or electricity though, I had a contractor do that a few years ago when we had a new furnace installed, so the extent of gas piping I had to do is what you see in the photos: a gas line connector and a drip leg attached to the heater. The job can be broken down into a few phases: 1) Hang heater from the ceiling 2) Run gas line and electric line to the heater 3) Run exhaust vent Each one of these is a project on its own, especially if you have to run gas pipe through the walls, so it'd be good if you know what you're getting into before you get started. Hanging heater from the ceiling What I did was mark out where I wanted to install the heater (bearing in mind gas line and electric line locations, chimney location, location of roof truss, and code regulations for distance from the wall), then built a wood frame out of 2x4 ripped in half. I drilled mounting holes that matched the brackets on the heater and put carriage bolts in the frame facing threads down. Then I screwed the frame up to the ceiling and into the roof truss. Then, lit the fire inside of me, that one that thinks I can hoist a heater up above my head and hold it there while my wife put nuts on the carriage bolts to support the heater. It hurt. It hurt a lot, but we got it done. I recommend a drywall lift for this task instead. That or an ice pack. Run gas line and electric line to the heater This is pretty straightforward. Use lots of pipe dope. Since my gas was already run to the wall, all I had to do was build a drip leg (required), then run a gas line connector used for gas appliances from the wall to the heater. Keep in mind these need to be short due to code. Electric is pretty straightforward, I chose to put mine on a 15 amp outlet instead of hardwiring it for ease of disconnection. Run exhaust vent This was the hardest part for me. It's not that it's hard, it's that I had never done it before so I had to read a lot, watch a lot of videos, and then make some mistakes. First, B-vent is fairly easy to work with, but DO NOT put any screws into it. I made that mistake and had to trash a few pieces. I fumbled around a bit to get my fire stop in the right spot, then fumbled around a bit getting things routed through the attic, then fumbled around a bit getting the hole in the roof in the right spot. At the end of the day it looks good, works good, and I maintained 1" clearance from combustibles as required by code, it just took a lot to get there. Tools I used for the install were: Drill Sawzall Table saw (for ripping 2x4s) Circular saw (for building wood frame for fire stop) Screwdriver(s) Wire stripping tool Plumb bob Tin snips Ladder Jigsaw (for cutting hole in the roof) Hammer Ratchet/wrench (for tightening carriage bolts) Hex bit impact (I used hex head screws to attach wood frame to truss through drywall) Channel locks/pipe wrench (for assembling black pipe) Crescent wrenches (for assembling gas line connector) Here are some things you'll probably need, and end up running back and forth to the hardware store for: B-vent, fire stop, flashing, storm collar, cap, vent strap/support 14/3 electrical wire (and plug if you decide to use an outlet) Electrical twist caps Black pipe/tees/caps Pipe dope Roof flashing sealant Wood (if mounting on an angle to the truss, otherwise you can mount it through the drywall directly to the truss if square) Wood (for fire stop support) Thermostat (not included) Thermostat wire (2 wire red/white) Lastly, a word on quality of the product. You get what you pay for. This is a very simply designed, very bare-bones, very low-BTU heating unit. Honestly, that's exactly what I wanted. It is a tad bit undersized for my extra deep 3 stall garage, but it heats the garage from 30 degrees to 60 degrees in about 90 minutes which is slower than my torpedo heater, but plenty fast enough for me and without the nasty smell and fumes from the torpedo. So its great, except, like some other reviewers on here, my unit came with a number of deformed panels. This didn't bother me much, I straightened out what I could and you don't see the rest up there on the ceiling, but nevertheless the thing was all bent up so if that bothers you I'd recommend a Hot Dawg. But, for what this thing costs compared to other units, I'm fairly happy with the end result.

A great heater! Good install instructions. Make sure you read them and follow them! Lots of good guidelines. Heater itself is heavy but seems to be built well. I added a nest thermostat. Easy to wire a power cord on and easy to get exhaust and gas line hooked up. This is going to be a game changer for when I get back from plowing in the winter! I have natural gas and it came set for that. They do include the kit to switch to LP. I’ve tested this a few times when it’s been cooler recently and the garage heated up extremely fast! FYI I did a lot of research before install, but as I said the instructions are laid out well.

Update 2021: starting second winter with the 50k btu unit. After a 4 month summer nap she fired right up. No issues. Super happy with its performance so far. See my original post below for details. Original post 2020: I’m heating a fully insulated 700sqft shop with an insulated 18ft garage door and 9ft ceilings. I installed the 50,000btu unit 2 days ago. Install of the unit itself it easy. I screwed two 48” 2x6 to the ceiling making sure to hit ceiling joists. I was able to hold the heater in place while a friend lag screwed its brackets to the 2x6’s. I’d recommend using a sheetrock lift, it was all I could do to hold it in place. It calls for 1” of top clearance and 36” of rear clearance. It also recommends 8ft clearance from floor. With 9ft ceilings I’m only 2” from 8ft. Obviously running the gas line and roof vent are the hardest parts. I won’t get into that work other than to say be sure you use 4” B-Vent for the roof vent. Do not use single wall vent pipe. It’s very quiet and works well. It’s a little deceiving because it quiet and doesn’t blow very hard but it heats my space quickly. 10 degree rise in about 15-20 minutes. I left it on overnight last night. It was 30 degrees outside. I set thermostat on 58 degrees. It only ran for a total of 1hr and 49 minutes over 12hrs to maintain that temp. And that is total time, including cycle on and off time, burner lit time would be even less. The Wifi thermostat I recommend below tracks run time. I also purchased a Wifi thermostat from Amazon. It’s the Sensi ST55. It’s an easy 3 wire hookup with this heater and allows you to download their app and control the thermostat from your phone. Very handy to be able to kick up the heat from the house before I head out to the shop. It also keeps track of how long the heater runs daily. Nice to know how hard your working it. I’ll update this post with any changes over the next year. Final thoughts. The performance of any heater is dependent on not only the size of the space you are heating but the condition of the space; insulation, draft, if there’s a ceiling or not, etc. The 50k btu unit works great in my space (as stated in my first paragraph). Hope this helps others with their decision.

I was able to raise this heater to the ceiling and to install it all by myself. I also install the new gas line across my garden and in my shop. The heater works as expected and it i quiet. I love it. Jan 17 2021. 3 days ago my heater died. The heater is warranted for 3 years (36 months) and I have it for just 28 months. So it still is under warranty. My shop was freezing. I contacted the manufacturer by e-mails and phone numerous times. I was never able to talk to anyone and no on answered my emails. No knowing what to do I contacted Amazon customer service ( no an easy thing to do) who told em there is nothing we can do, you are on your own. I have ben a maintenance mechanic all my life. I took the heater apart and I determined that the control board was fried. I called a local gas heater specialist to see if he could do something to help me. He charged me $79.00 to tell met that there was nothing he could do to help me. I find on the Internet a reference number for the faulty C.B and I found one to buy locally. I replaced the C.B and my heater is working again. I also determined that I am able to repair the original C.B to keep it as spare. My total cost for the repair is about $160.00 in addition of my time. I do not expect to ever hear from Mr Heater so before buying on of these heater beware of the total lack of customer service and support.

Just what you would expect from Mr Heater. Was easy to install and has been heating my Minnesota three car garage for about three years now without any issues. I keep it at 50 degrees most of the time and the gas bill only went up like $7 a month. Highly recommend it.

Great for a shop or an area where heat on demand might be required. Parts are readily available and now they offer a direct vent package a separate cost. I bought this unit with the intention of installing in another building as the one that I purchased in 2012 is still working fine other than a circuit board that I had to replace this year that was also available on here at a fair price just like the heater.

Very good

Had the unit professionally installed in a new workshop space. Went in without problems, worked when first fired up, and ever since. Puts out a lot of heat in a short time, but without scorching its mounting or surrounds.

Became intermittently noisy after about 3 days in operation and very noisy after about a week. Mr.Heater wasn’t much help. Amazon replaced it on the 29th day. New heater was shipped to me but without prepaid return shipping. I had to pay return shipping but was credited the shipping cost onto my account. New heater has been working great since the install. Very quiet. Heats my 24x26 garage nicely. I did find the exact same heater in town on sale for $100 less with a regular price equal to Amazon. Do your homework and check locally first. Edit: September 4/19. Tried to start heater to test for the upcoming season and nothing. Verified 120acv and thermostat to be ok. Will attempt to contact Mr.Heater to resolve this issue.

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