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Almost affordable rotary screw compressor

S

sjones

Member
Joined
Mar 7, 2013
Messages
15
I've been looking at rotary screw compessors for a while and trying to find one I could afford. I considered the Eastwood unit but it has too many bad posts and not enough air output for my home shop needs. I found this Masteraire rotary screw compressor that is made in Canada that I could justify buying if they ever take the 25% tariff off Canadian goods. It ships free to the lower 48 states and has a 10 year warranty that includes parts and service assistance. At 5 hp with a variable speed drive it would be more affordable over time compared to a recip (I'm currently using a Saylor Beall vt-735-80 I purchased used for $500 with a brand new Baldor Super E motor). Current price is $3999.99 US.

I'm not familiar with the brand but I'm going to keep an eye on it.

https://masteraire.com/en-us/collec...sor/products/5-hp-rotary-screw-air-compressor

Model​

MST-3.7VFD

kW/HP​

3.7 kW / 5 HP

CFM & PSI​

24 CFM @ 102 PSI Heavy-duty Industrial Air Delivery

Adjustable Pressure​

Pressure can be adjusted from 50 PSI to 145 PSI

Pressure Rating​

145 PSI

Outlet Size​

¾ Inch

Dimensions​

34 x 21 x 29 Inches (L*W*H)

Weight​

185 lbs

Duty Cycle​

Continuous Duty
(100% Duty Cycle)

Oil Type​

ISO46 Compressor Oil
(Synthetic and Non-Detergent)


  • Full-colour LED Touchscreen Programmable Logic Controller with Variable Frequency Drive which features Soft Start (Preprogrammed Plug & Play System)
  • Heavy Duty Inbuilt Thermostatically Controlled Cooling Fan
  • Heavy Duty Air Filter, Oil Filter and Air/Oil Separator
  • Direct Drive results in low maintenance and high efficiency by eliminating any power transmission losses due to belts and pulleys
  • TEFC IE4 Permanent Magnet Heavy-duty Induction Motor
  • Variable Frequency Drive to adjust the airflow on demand
  • Energy Efficient Design
  • Preprogrammed Plug & Play System; Comes ready to use, connect your electrical, connect the equipment, and turn it on!
 

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M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,422
Location
Richmond, VA
sjones said:
At 5 hp with a variable speed drive it would be more affordable over time compared to a recip
Click to expand...
Not by a meaningful amount and certainly not enough to come near a roi on the added cost, especially in a home shop

What made you think that it was Canadian made? I can't see anything on their website indicating country of origin and just the typical "designed in" BS. They even pull "engineered for north America" like that means something
 
OP
S

sjones

Member
Joined
Mar 7, 2013
Messages
15
They may indeed be Chinese built, but they appear to be a reputable company and their BBB cases show they do stand behind their product. The Canadian tariff does not apply to their products. I'll look into them further and post what I find out.
 
B

Beerhippie

Well-known member
Joined
Oct 13, 2023
Messages
9,679
Location
Far NE Oregon
FInd and download the manual for it. Read the maintenance schedule. Search for the required maintnenace parts and oil.

Now compare to the price of a recip that will give you what you want/need. I'll bet you find the recip is much more affordable. Many current production recips are as quiet as a screw--and generally produce a higher psi output.

I'm skeptical of the claimed 145 psi output on that one--screw comps I've used and researched usually stop at 125 psi. The 24 cfm is also suspicious for a 5 hp. I'd expect more like 18 cfm.
 
S

Steve_P

Well-known member
Joined
Sep 15, 2010
Messages
5,182
There was a thread a few years ago about a lower-cost import screw compressor for home/shop use. You might want to search for that.

I personally feel that it's still too early on these imported units for home shop use to where I'd spend the $$$$ on them- need more data over more time. The fact that the Eastwood one has less than stellar reviews is a red flag IMO.
 
S

surfacepro

New member
Joined
Feb 12, 2026
Messages
4
sjones said:
I've been looking at rotary screw compessors for a while and trying to find one I could afford. I considered the Eastwood unit but it has too many bad posts and not enough air output for my home shop needs. I found this Masteraire rotary screw compressor that is made in Canada that I could justify buying if they ever take the 25% tariff off Canadian goods. It ships free to the lower 48 states and has a 10 year warranty that includes parts and service assistance. At 5 hp with a variable speed drive it would be more affordable over time compared to a recip (I'm currently using a Saylor Beall vt-735-80 I purchased used for $500 with a brand new Baldor Super E motor). Current price is $3999.99 US.

I'm not familiar with the brand but I'm going to keep an eye on it.

https://masteraire.com/en-us/collec...sor/products/5-hp-rotary-screw-air-compressor

Model​

MST-3.7VFD

kW/HP​

3.7 kW / 5 HP

CFM & PSI​

24 CFM @ 102 PSI Heavy-duty Industrial Air Delivery

Adjustable Pressure​

Pressure can be adjusted from 50 PSI to 145 PSI

Pressure Rating​

145 PSI

Outlet Size​

¾ Inch

Dimensions​

34 x 21 x 29 Inches (L*W*H)

Weight​

185 lbs

Duty Cycle​

Continuous Duty
(100% Duty Cycle)

Oil Type​

ISO46 Compressor Oil
(Synthetic and Non-Detergent)


  • Full-colour LED Touchscreen Programmable Logic Controller with Variable Frequency Drive which features Soft Start (Preprogrammed Plug & Play System)
  • Heavy Duty Inbuilt Thermostatically Controlled Cooling Fan
  • Heavy Duty Air Filter, Oil Filter and Air/Oil Separator
  • Direct Drive results in low maintenance and high efficiency by eliminating any power transmission losses due to belts and pulleys
  • TEFC IE4 Permanent Magnet Heavy-duty Induction Motor
  • Variable Frequency Drive to adjust the airflow on demand
  • Energy Efficient Design
  • Preprogrammed Plug & Play System; Comes ready to use, connect your electrical, connect the equipment, and turn it on!
Click to expand...

I’m posting this as a warning so someone else doesn’t waste their money the way I did.

The “Canadian manufacturer” claim is, in my experience, deeply misleading. What I received was clearly white-label equipment that can be sourced directly from Alibaba for 4–8 times less. The markup would almost be impressive if it weren’t so blatant.

Let me be clear: I have no issue with Chinese manufacturing. China produces excellent products across industries. The problem here is not the country of origin; it’s the quality tier and the pricing strategy. The equipment I received was at the very bottom end of the spectrum. Within one week of purchase, the compressor started malfunctioning. It was already leaking oil, and the controller screen began throwing random errors. The finish, durability, and overall build quality felt closer to a hobby project than industrial-grade equipment.

If you think they haven’t made enough money off you, they’ll sell you cheap Chinese parts at even crazier prices. For example, I was quoted around $150 for a simple pressure sensor that is available online for $12–15. That’s more than 10 times the actual cost for the exact same part. The problems just kept coming. At this point, I’d probably sell this unit for scrap and invest in a reputable brand instead.

If you value your time, money, and peace of mind, look elsewhere.
 
Last edited:
S

surfacepro

New member
Joined
Feb 12, 2026
Messages
4
51dueller said:
I can tell you it's not Canadian made and their location is in a strip mall. They apparently also sell construction equipment like loaders and back hoes. Using Wayback machine their website has only been around for 6 months. I imagine anything they sell is drop shipped from China.
Click to expand...
Absolutely, drop-shipped from China, junk quality at premium prices; their ‘warehouse’ looks less like a facility and more like a graveyard.

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M

moemc

Well-known member
Joined
Mar 12, 2025
Messages
356
I got an Eaton screw compressor like 4 years ago and it’s been great so far. They aren’t too expensive.

at my friends shop, when I was working there maybe 10 years ago, they picked up a used Kaeser locally for a hell of a deal. That thing was beautiful. I maintained it while working there. We were talking about it a few weeks ago, he told me he isn’t sure if anyone’s given it maintenance since I left :D but it’s still trucking along. I would look for one of them locally before buying anything else.
 
V

VolkCNC

New member
Joined
Mar 2, 2026
Messages
1
Hey everyone, I joined just to let you all know to run as far away from this company as possible. Chinese junk with zero after sales support. DO NOT BUY!!!

After looking around for a rotary compressor, I found Master Air. The price was very attractive, as was them having a "sale". Spoke with their sales guy, they are located in Canada so I wasn't dealing with someone who barely spoke English way over in China. I knew they were Chinese made products but figured the price was worth the gamble and being from a Canadian distributor I could talk to also helped sway my decision.

In October of 2025, I purchased a 5hp screw compressor based on the advertised 24 CFM at 100 psi. I also purchased the refrigerated dryer. Both arrived in a timely manner. I plumbed the compressor into the 60 gallon tank of my existing piston compressor. Right from start up, the compressor didn't seem like it was performing as advertised. It had weird vibrations and resonance. It would run constantly all day when my CNC mill was turned on. The CNC mill has a constant air purge that is listed as needing 4 CFM at 80 psi air supply. The problems really started when I tried to do more demanding jobs like putting air in tires. By the 4th tire, my tank was almost completely drained and I had to wait for the pump to refill the tank. I have a small blasting cabinet that needs around 10 CFM. It would drain my air tank below 50 psi after 3 to 5 minutes of operation. I did some timed pump up tests (formulas available on the internet) and was calculating around 10 CFM output from the pump. The only positive was it heated my shop when running.

At this point I contacted Master Air and the run around started. They just kept kicking the can down the road. They gave next to no help, making excuses of my piping is wrong, I need a bigger tank, try bypassing the air dryer, "our CFM ratings are based on laboratory conditions", etc. My entire shop is plumbed with 3/4 piping, my 17 CFM piston compressor handled all my air needs just fine (but I needed 100% duty cycle for bead blasting). It went back and forth for weeks, promises of "we will check on this and call back". I'd wait a week with no calls and then call them. Whoever I had spoken with before wasn't available, so I'd have to explain everything all over again. They'd email back and forth for a bit asking for picture of my setup, every time it would get sent off to the next person up the chain, they'd ask all the same questions, ask for all the same pictures. Then not respond to emails for another week until I'd phone. I could tell they were not interested in helping and were very dismissive of the timed pump test results to get CFM.

I finally had enough with the excuses and purchased a 4-50 CFM flow meter for $300. I plumbed it in directedly after the compressor outlet and it was showing a flow of 8 CFM while filling the air tank. I placed the flow meter on the outlet side of the air tank to read my shop use. Even when bead blasting, I never went over 10 to 12 CFM of air use. We discussed swapping it for the 10hp unit because I still need a compressor. I even offered to pay the price difference if they covered the freight for each unit.

It is now March of 2026 and I have given up on this company. I purchased a Hyundai 7.5hp rotary with 80 gallon tank from Princess Auto (basically Canadian version of Harbour Freight) at an insane sale price. Yes, still a Chinese compressor (with the exact same control screen) but it works amazing! It's also from a major national chain, so after sales will be easier. Zero complaints so far.

I am now struggling to return the Master Air compressor and get my money back. I am continually having to phone because emails aren't answered, phone calls aren't returned, no one will tell me the steps to return it. I have a feeling when it is returned, I won't be getting my money back. I have since found numerous Better Business Bureau complaints with essentially my exact same problem. By all indications, I'm going to get screwed. I've read 25% "restocking fees".

The air dryer seems to work, but is now starting to ice up a lot around the compressor motor. Seems also like it is icing up inside the heat exchanger. It might just be from lack of use over the last few weeks. I'm keeping it but also would not recommend.
 
T

tarbellb

Well-known member
Joined
Apr 17, 2011
Messages
5,741
Location
Oregon
VolkCNC said:
Hey everyone, I joined just to let you all know to run as far away from this company as possible. Chinese junk with zero after sales support. DO NOT BUY!!!

After looking around for a rotary compressor, I found Master Air. The price was very attractive, as was them having a "sale". Spoke with their sales guy, they are located in Canada so I wasn't dealing with someone who barely spoke English way over in China. I knew they were Chinese made products but figured the price was worth the gamble and being from a Canadian distributor I could talk to also helped sway my decision.

In October of 2025, I purchased a 5hp screw compressor based on the advertised 24 CFM at 100 psi. I also purchased the refrigerated dryer. Both arrived in a timely manner. I plumbed the compressor into the 60 gallon tank of my existing piston compressor. Right from start up, the compressor didn't seem like it was performing as advertised. It had weird vibrations and resonance. It would run constantly all day when my CNC mill was turned on. The CNC mill has a constant air purge that is listed as needing 4 CFM at 80 psi air supply. The problems really started when I tried to do more demanding jobs like putting air in tires. By the 4th tire, my tank was almost completely drained and I had to wait for the pump to refill the tank. I have a small blasting cabinet that needs around 10 CFM. It would drain my air tank below 50 psi after 3 to 5 minutes of operation. I did some timed pump up tests (formulas available on the internet) and was calculating around 10 CFM output from the pump. The only positive was it heated my shop when running.

At this point I contacted Master Air and the run around started. They just kept kicking the can down the road. They gave next to no help, making excuses of my piping is wrong, I need a bigger tank, try bypassing the air dryer, "our CFM ratings are based on laboratory conditions", etc. My entire shop is plumbed with 3/4 piping, my 17 CFM piston compressor handled all my air needs just fine (but I needed 100% duty cycle for bead blasting). It went back and forth for weeks, promises of "we will check on this and call back". I'd wait a week with no calls and then call them. Whoever I had spoken with before wasn't available, so I'd have to explain everything all over again. They'd email back and forth for a bit asking for picture of my setup, every time it would get sent off to the next person up the chain, they'd ask all the same questions, ask for all the same pictures. Then not respond to emails for another week until I'd phone. I could tell they were not interested in helping and were very dismissive of the timed pump test results to get CFM.

I finally had enough with the excuses and purchased a 4-50 CFM flow meter for $300. I plumbed it in directedly after the compressor outlet and it was showing a flow of 8 CFM while filling the air tank. I placed the flow meter on the outlet side of the air tank to read my shop use. Even when bead blasting, I never went over 10 to 12 CFM of air use. We discussed swapping it for the 10hp unit because I still need a compressor. I even offered to pay the price difference if they covered the freight for each unit.

It is now March of 2026 and I have given up on this company. I purchased a Hyundai 7.5hp rotary with 80 gallon tank from Princess Auto (basically Canadian version of Harbour Freight) at an insane sale price. Yes, still a Chinese compressor (with the exact same control screen) but it works amazing! It's also from a major national chain, so after sales will be easier. Zero complaints so far.

I am now struggling to return the Master Air compressor and get my money back. I am continually having to phone because emails aren't answered, phone calls aren't returned, no one will tell me the steps to return it. I have a feeling when it is returned, I won't be getting my money back. I have since found numerous Better Business Bureau complaints with essentially my exact same problem. By all indications, I'm going to get screwed. I've read 25% "restocking fees".

The air dryer seems to work, but is now starting to ice up a lot around the compressor motor. Seems also like it is icing up inside the heat exchanger. It might just be from lack of use over the last few weeks. I'm keeping it but also would not recommend.
Click to expand...
Did you buy it with Credit Card
They offer refunds, as does my bank if you get slimy company like this
 
J

jblnut

ALLIANCE MEMBER
Joined
Jan 17, 2015
Messages
6,979
Location
In the Middle of MN
OP there are two members with units that have had major issues. I’d run.

I have personally serviced and maintained around 100 Kaiser Compressors and while not inexpensive to keep running they will last a loooooooooooooong time if cared for. The oldest one I service just rolled over 100,000hrs. Spendy little buggers but they preform as the nameplates state and the service is amazing.

Another option we’ve done for a few customers is to put in a larger than needed piston pump and run it slower. Say a 5hp pump is needed. Well install a 15hp head and pulley it down so it runs more at a 5hp output speed. It doesn’t run as fast, stays cooler and lasts longer. Plus they’re way quieter running slower. They sound like an old 2cyl John Deere lol

Yet another option we’ve done a few times is to install a smaller than needed rotary with a piston pump as a topper. The rotary can sit there and run its brains out and the piston pump will cycle on and off keeping it happier than running all the time.

No matter how you approach this all things rotary are expensive. Purchase price and maintenance costs are absolutely higher per running hour than a piston pump if you compare brands of the same quality. We’ve been installing mostly IR with a few Quincy units mixed in on the piston side with almost exclusively Kaiser with a few GB units on the rotary side. Rotaries absolutely have their place of course and when needed are the best option by far.

Another option would be to look at a scroll compressor. They’re not inexpensive either but they run quiet and produce nice clean air. We’ve installed hundreds of Hitachi and Atlas Capco units over the years that will see as high as 95% run time. With proper maintenance they’ll last a long time as well.
 
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P

PhantomEB

Well-known member
Joined
Feb 6, 2006
Messages
6,707
Location
Medicine Hat, AB, Canuckistan
Myself I would be very Leary on Atlas Copco. We got one at the plant the size of a small sea can and it was down for the better part of a year to wrong motor, bad VFD…. So wish they would stick it outside under a roof like the transformers.

If I had the money it would be Hyundai screw. But even still I just rather spend the money on a 5hp 60-80 gallon IR compressor then take the money saved for an auto drain.F35A1767-2AC6-495D-A593-6F4E7B196839.jpeg
 
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