Mr. Heater Big Maxx 45,000 btu gas heater

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Review by Nicky posted 02-13-2013 07:38 PM 24050 views 0 times favorited 13 comments Add to Favorites Watch
Mr. Heater Big Maxx 45,000 btu gas heater No-picture-s No-picture-s Click the pictures to enlarge them

A heater is an integral part of my shop. If the temperature falls below 50 degs I can’t work comfortably. Yes, I’m a wussy boy.

During the Christmas break my Peerless heater stopped working. Seems that it developed an electrical problem. The fan had been on its way out. Estimate for repairs about $300. It was 30 plus years old so I thought it was time for a new heater.

After a bit of research and reading through some reviews I ordered the Big Maxx 45,000bu heater. I paid $399 plus $40 for shipping from Northern Tools. Heater delivered in 5 days, box was in relatively good shape. I opened the box and the heater was well packed and all parts were there.

My old heater was hung from two ¾” pipes. Although it would have been easy to just loosen the unions that held the old heater in place, I was working alone and wound up taking the old heater apart. Lots of cast iron, unit weighed about 150 lbs..

The new heater is ceiling mounted. I made a plywood mounting board and installed carriage bolts that would hold the heater after the plywood was installed on the ceiling. I also installed two large eye hooks on each side as aids to help mount the heater to the installed plywood board. This worked out really well. I used a simple rope system to help lift the heater to the ceiling to attach to the plywood. My honey helped with the lift, and I was able to quickly attach the new heater to the new plywood ceiling mount. Gas connection was easy using the same fittings, with some new sealant. The exhaust on the heater is 3”, my existing vent was 4” but a simple reducer, and some foil tape I had this connection done.

The unit did not come with an electrical cord. This is my only complaint. Took an old extension cord and installed the power. I then connect the thermostat, and plugged in the unit. Turned the thermostat on the unit started right up. First the power vent blower, followed by the heating elements being lit and then the main blower. Shop was back in business.

The unit had excellent instructions. The vent could be configured either vertical or horizontal. I’ve been using for about 6 weeks. Temps here have been in the low teen. The unit heats my shop quickly. It has an auto ignition where my old one used a pilot light. The circuit board has a diagnostic LED that should help troubleshoot any problems that may arise. Manufacturer claims that is about 85% efficient and the loss is due to the power vent.

Overall I’m very satisfied with the purchase. The installation was a breeze. The unit is very quiet compared to my old heater. Hope that someone may find this useful.

-- Nicky

View Nicky's profile


711 posts in 5211 days

13 comments so far

View Bogeyguy's profile


548 posts in 3187 days

#1 posted 02-13-2013 10:07 PM

I guess they were thinking hard wired. Now get busy.

-- Art, Pittsburgh.

View RonInOhio's profile


721 posts in 3983 days

#2 posted 02-14-2013 09:49 PM

How large is your shop ? And is it insulated ?

View Nicky's profile


711 posts in 5211 days

#3 posted 02-14-2013 11:49 PM

Bogey, been spending a lot of time working in the shop.

Ron, Shop is 24×22, two car garage. It is insulated.

I leave the thermostat set at 55 (it’s lowest setting) when not working, and when working in the shop set it for 65.

-- Nicky

View helluvawreck's profile


32122 posts in 3985 days

#4 posted 02-15-2013 04:53 PM

Thanks for the review. I’m fixing to build a shop and I’ll check it out.

helluvawreck aka Charles

-- helluvawreck aka Charles,

View Hacksaw007's profile


620 posts in 4308 days

#5 posted 02-16-2013 04:06 AM

How is it on using fuel, how is it handling your shop dust. I only have a shop of about 12×12. How would that be, to little?


-- For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. John 3:16

View adamjohn's profile


7 posts in 3041 days

#6 posted 02-20-2013 06:06 AM

I just installed this heater for my garage office, puts a required heat on the garage as my garage is a triple size.It is working well as said and still no problems. Pro-Easy installation. Puts out great heat. The unit is rather loud, but I anticipated it to be… just the nature of being a unit heater.

Heating repair Manassas VA

View Nicky's profile


711 posts in 5211 days

#7 posted 02-22-2013 08:15 PM

Hacksaw, I can’t speak to the fuel usage. I have all other gas appliances, stove, hot water heater, house heater etc… The heater is rated for up to 700 sq ft. Maybe overkill in your space, but would warm it up in a hurry.

Adam, compared to my old gas heater, this is quiet. All a matter of perspective. Hope it lasts for the long haul.

-- Nicky

View Holbs's profile


2379 posts in 3148 days

#8 posted 02-24-2013 09:25 PM

i have a 60k btu reznor rated for residential garage to install.
did you also install the previous heater… peerless? i’ll try to tackle running electrical to the reznor, running the ‘B’ pipe out the side wall and thermostat, but have to hire the HVAC to slice into the house gas line for a leg to the reznor and then city inspector to come out to sign off (dont want to cause a fire to house when something that was supposed to be inspected, not inspected as my house insurance folks would not be in a favorable mood).

do you have a picture before / after installation?

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

View brunob's profile


2277 posts in 5288 days

#9 posted 02-24-2013 09:30 PM

I have one. Love it. Had it for 5 years. No problems.

-- Bruce from Central New, if you'll pardon me, I have some sawdust to make.

View Nicky's profile


711 posts in 5211 days

#10 posted 02-24-2013 10:19 PM

Holbs, sorry no “before pics.”

The old heater was professionally installed in 1983. A gas line, an electrical circuit and vent were needed. I did plan on having a plummer install the new heater, but could not (did not) wait the 2+ weeks quoted for installation. I would not have installed the new unit without having all the pre-requisites in place. The gas line uses the same connection type as a standard kitchen stove. The vent lined up perfectly with the addition of a 4” to 3” reducer. I did thoroughly clean the vent before installation. I installed a new flexible gas supply line.

Here is a pic of the type of unit that I replaced (pulled from the web)

Here is my installed heater

-- Nicky

View Holbs's profile


2379 posts in 3148 days

#11 posted 02-24-2013 10:28 PM

i’m too skittish to play with gas lines :)
does your B pipe go straight up after that first 90? i have stone tile, and luckily this reznor is rated for horizontal B pipe runs.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

View 8iowa's profile


1591 posts in 4880 days

#12 posted 02-24-2013 11:30 PM

My Upper Peninsula “Workshop in the Woods” is a well insulated 24×28 free standing building. It was a garage package from Menards, however I chose to install double doors instead of the typical overhead door, which has poor thermal efficiency.

For heating I have a 35,000 BTU Reznor propane unit with the separated combustion feature, thus there is no open flame. I’m not U.P. there in the winter, but on cold spring days in the 40’s, the Reznor brings the inside up into the high 60’s in about 15-20 minutes.

Sizing of your unit depends a great deal on how well insulated the shop is, more so than the size. The amount of tools and their size also acts as a thermal “sink”. Several hundred pounds of cast iron can slow down the warm-up time considerably. Once I have my shop up to about 68 degrees I leave the heater running, maybe turning it down a little bit during the night and times when I’m going to be away. Thus I don’t have to bring the “sink” up to temperature every day.

Non vented heaters spew a lot of moisture into the air and many shops report rust problems, not to mention breathing the products of combustion. Personally, I would not choos this type of heater.

-- "Heaven is North of the Bridge"

View Nicky's profile


711 posts in 5211 days

#13 posted 02-25-2013 12:53 AM

Holbs, straight shot though the roof after the 90.

-- Nicky

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