I was surprised to received the Hitachi EC12 a day early. Unfortunately it had a broken filter box case. I called the company and the part was in the mail no questions. So far I have had this unit for over 3 years. The pressure control knob fell apart in my hand but a quick to the shop fixed that. I don’t know if the knob failure was my fault or worn part. I do wish I had purchased a compressor with more horsepower but this one is a keeper. It does 87% of jobs I need.

I run 3 framing nailers on the one compressor. No problems, runs great.

What would have been a great compressor (aside from regulator placement) is spoilt for me by 2 things: 1) for about $1.50 a muffler could have been put on to reduce noise by 25-30 dB (to less than 1/4?) and 2) the unloader valve that is supposed to relieve pressure from the cylinder head after the compressor cycles off is poorly designed. When it fails, the motor has to try & start with the head under pressure, which mostly it cannot do. This is also likely to burn out the motor. This same thing may also be the cause of all the poor starting in cold weather etc. I have a simple fix. If you (or Hitachi Co.) want it, email paul@pthompson.com I have since bought 2 Makita 3.5hp compressors, and now having fixed this I shall probably sell it.

I chose the Hitachi three years ago because it has a fine compressor and motor, solid construction, and overall good design. It has been entirely reliable and three years later I still am using it both in my cabinet shop and on the job for residential remodeling. The only significant design flaw is the position of the gauges. They are subject to being knocked off. I found this out the hard way one day when I had to slam on the brakes in my van and a sliding tool box sheared one of them off. Despite this one flaw I would still by another Hitachi in a heart beat. The Hitachi is not only reliable, but, unlike many compressors, it truly works on 15 amps. This compressor has never blown a fuse on me, which is something of a miracle considering the wiring in many of the older homes I remodel.

I got hooked on Hitachi tools several years ago and I have several Hitachi electrical and air tools in my toolkit. I bought this EC12 Oiled Air Compressor about 5 years ago and really like it. The reviews warned me to take care of the vulnerable gauge and pressure switch housings, so no probs. I installed a single 3/8″ female air coupler onto the compressor and only use one 50′ 3/8″ hose and fittings to a reserve air tank modified from a portable (125 psi max) tire-filling air tank. My idea was to keep the heavy compressor out of harm’s way. The reserve air tank can be repeated every 100′ to extend the range of the work from the compressor, if needed. The reserve tank allows the static pressure to regain, and feeds the next line segment.

A 1/4-turn 1/2″ pipe ball-valve closes off the male air inlet of the remote tank. This tank can be plumbed with 1/2″ pipe (3/4″ pipe tee or cross with appropriate 3/4-to-1/2 reducers)and short pipe nipples, etc., for one or more hoses out and will serve multiple nailers on a roof; I reused the gauge and 1/4″ tire filler fittings so I can still use it for a portable tire tank. Plumb the tank to the branch of the tee or cross and the 3/8″ air inlet and outlet(s) on the straight-thru run. The 3/4″ gauge fitting can go directly onto the vertical branch of the cross.

Each nailer can be fed with a lightweight 10′x1/4″ whip on the end of a 3/8″ hose of any length, but no nailer is starved by being a long way away from the compressor. Line loss is just NOT a problem with the reserve tank and 3/8″ hoses: all my major air tools have 3/8″ male air fittings. I have had no problem with two framing nailers. Three may work as well, depending on your nailers and the compressor’s 4.0 SCFM capacity. Taking the reserve tank up onto a roof is easier than fighting with long-line losses due to friction and long extension cords and the voltage drops incurred. Attaching a couple of short 4×4 “feet” (or plastic pipe with clamping bands) to the metal legs of the tank allows the tank to straddle the roof peak and feed the work.

I experienced an occasional burst of air loss when the compressor shut off which would bleed the tanks. I found the spring-loaded rubber check valve poppet had hardened up and I replaced it using a 19mm hex socket, NOT a 12-point socket which can slip, to remove the cast brass hex nut on the top of the compressor check valve housing. This check valve housing is located on the side of the top tank where the metal line feeds from the compressor cylinders and a new poppet cost me $7 at a local tool repair parts house. Air pollution will harden them, so buy them fresh.

I blew a circuit breaker a couple of times on start-up until I figured out my garage outlet powers my freezer and my home office (all on a 15 AMP circuit breaker: I don’t have that problem anymore.) I only use one 50′ 12/3 AWG extension cord (20 amp), and only connect to a 20 AMP circuit, either wall outlet or generator with no other tools on the circuit.

The black tube which runs from the cylinder to the power switch is the unloader tube and when the pressure switch shuts down, the unloader valve bleeds off the line pressure so the cylinder starts only against atmospheric pressure. If this tube is mashed, blocked or kinked it will not unload the compressor, the compressor will kick-off the circuit breaker when it starts, and if the check valve is hardened, all the air will bleed out of the tanks when the pressure switch shuts off.

This compressor is very useful and gives me 25 more psi than my fixed compressor which has a max output of 100psi. It is a great tool, and reliable, but it won’t save you from yourself. As with any machine, there are mechanical and electrical limitations which cannot be exceeded.

Very fast up-to-pressure time
Deilvers on the nose pressure as set on the regulator.
It ran two framers full bore with no issues in drive pressure or overheat.
Easy to carry unless you are under 15 years old.
Easy to drain moisture (just place a scrap 2×4 under the front feet and tilt foward.)

The are a few downsides to this heavy compressor. It is very loud. Although most of it is made of cast iron or metal there are several key components that are made of delicate plastic. Such as the components nearthe regulator, which include the on/off switch. And the filter housing. There is nothing wrong with them being pastic but if you transport your compressor regularly in the back of your truck, then you can count of them breaking almost everytime and the compressor stops working soon after that. If your compressor stays in your garage then this is okay. But for twice the money, you can buy a thomas compressor that has more power, is a lot less noisy, and a much better machine.