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Mr. Heater MH42T Utility Product F273900 Key FeaturesType Utility / PortablePower Source GasHeating Levels ...

When you need heat like a jet engine, think Reddy Heater and think small. - Reddy RLP30 Utility Heater Reddy Heater RLP30 BTU Propane Forced-Air Heater Heat Output in BTUs: 30,000 Capacity: Heats up to 700 Square...

Mr Heater MH42T Triple Tank-top Propane Heater

Heat output in BTUs: 8, 12, 14, 16, 24, 28, 36 and 42,000 BTU/HR Setting

Safety features: Heater shuts off automatically with loss of flame

MSRP $120

—– A great solution for medium area heating —–

Garages are very unique spaces for most people as they can vary from an unheated, un-insulated storage area to a fully finished workshop. Mine falls somewhere in between the two, it’s mostly a workshop and is insulated very well yet has no built-in heating system. This is because I seldom work out there in the winter, but when I want to work I can heat it up pretty fast and it will stay warm for a while. This winter has been extra cold at times, so much so that my old 30,000 BTU Reddy Heater wasn’t up to the task. I found this Mr. Heater three-head heater at Lowe’s and decided to give it a try.

Unpacking Mr. Heater is very simple as no assembly is required, just open the box and remove. Mounting it on a full 20lb propane tank is also easy thanks to the slide-&-tighten fastening system. You simply slide Mr. Heater onto the propane tank’s upper collar and tighten the locking knob until the mount is secure. Even thought the three-head heater isn’t lightweight, it never makes the tank tipsy or in danger of falling over even when only a few pounds of propane remain. Tighten the MH42T gas line fitting into the propane tank and remember propane tanks are reverse thread.

—– Using the MH42T heater —–

To fire up this unit you’ll need either a match, lighter, or torch to ignite each burner. I recommend a long gas match like you’d use to light a gas grille, you don’t want your hands near the burner when it fires. First thing to do is turn the propane tank on full, then set the three-stage gas regulator on the MH42T to the setting you desire. Low setting distributes 8,000 BTUs to each burner, Medium gives you 12,000 BTU, and High pumps out 14,000 per burner. To light each burner you’ll need to hold in the Safety Valve button for that burner and hold a lit flame over the burner where Light Here is written on the heat reflector. Each burner will light with a pop, so don’t be surprised. Once all burners are lit they will take a bit to heat up to full burn, when they do you’ll see them glowing bright red.

It takes about 1.5 hours to heat my 20×24 workshop to 50 degrees, which works out to about a 30 degree rise in temperature. This is quite an improvement over the 30K BTU Reddy Heater I used last winter, and although the MH42Tis only 12K BTU higher on the output scale it makes more useable heat per BTU. After than initial 2.5 hours of full-burn heating I always turn one burner off and leave the other two on medium heat. This setting maintains temperature quite well even when I’m going outside quite a bit via the side door. I did get pretty close to the manufacturer-claimed 10 hours of operation on one propane 20 pounder, although I did have a few hours of two-burner operation in there. After using two 20lb tanks over December I switched to a large 100lb tank (the double tanks you see outside mobile homes) and haven’t had to refill it in the two months since then.

—– Bottom line and a few things to watch for —–

First of all I must stress strongly that this can be a dangerous unit and it should not be used near small children of any age. Not only is this an obvious fire hazard but also the heat reflector gets extremely hot and will cause 3rd degree burns to any skin that touches it. Watch very carefully where you place your heater since anything above it will get hot. When I switched from the short 20lb propane tank to a much taller 100lb tank I forgot to look above the heater. I have 6 bikes stored in the garage over winter, all hanging from the ceiling on rubberized hooks. The tire on my road bike happened to be hanging above the Mr. Heater unit and actually started to blister from the heat after a couple hours. This tire was about 30” above the heater and I didn’t even think about it when I fired up the unit. Since there’s no blower or heat circulation with this unit the 42K BTUs of heat go straight up until the hit the ceiling. Remember to check the area every time you light any portable heater, someone may have moved or set something down since you last used your heater. Precaution is much safer and cheaper than a fire.

Another thing to watch out for is the obvious need for ventilation while using this unit. This three burner heater emits a considerable amount of combustion fumes over an hour (or more) of use, if you don’t have some fresh air coming in you risk being overcome by the byproducts of combustion (CO2 & CO). Not to mention if you’re using it in a sealed area it burns oxygen and will at some point bring the oxygen level down to a dangerous level. The manufacturer recommends having a 6”×6” fresh air source near the top of the area and near the floor for optimal air circulation.

NOTE: On the subject of Carbon Monoxide (CO) output from this unit I was able to test it while on full three-burner operation. Using my Fluke Digital CO Meter I found 9-11 parts-per-million being emitted by the MH42T. 9 PPM is listed as OSHA approved and ASHRAE standard for living areas. What this means for the average Joe is this doesn’t pump out lots of CO while running, just keep some fresh air flowing in from time to time and you’ll be fine.

Speaking of air circulation I’ll share what I did to make the most of my MH42T heater. Hopefully we all know that heat rises in a cold room, right? My garage area has a 12’ high interior ceiling with 12” of insulation that holds the heat very well. To keep the heat in the lower 6’ of my shop where I’m actually working I installed a high-output 8” squirrel-cage style blower at the highest point of the ceiling, which blows down at the floor from the center of the ceiling. This causes the air to circulate back up the sidewalls and warms the room up much faster than if all the heat collected up high.

I’ve been quite happy with my MH42T heater and recommend it for anyone looking for a good radiant style heater for a workspace or small construction site. This should NEVER be used inside a house as it’s not designed to shut off if it tips over. It’s also not safe for kids as it’s an open burner design with a very hot heat reflector in the open. For specific needs this is a great purchase as long as the user understands the dangers and is responsible with its use.

Related Links:

Reddy Heater RLP30 Utility Heater

Thanks for reading and feel free to comment!

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