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jeff5may · 12-10-15, 09:29 AM

Here's the thing about electronic expansion valves: They don't all work the same way, and you are relying on an electric over mechanical control layer to regulate how your system acts. If you pony up the money for a turnkey rig, it will do what it was designed to (hopefully well).

There are 2 main types of EXV's: pwm and stepper.

The pwm type work like a super-fast solenoid valve, and I imagine they have some kind of damper built into them.You feed them a square wave, and they conform to the duty cycle of open / closed. Who knows whether they are normally open or normally closed? Who knows how slow or fast the damper is? Not me.

The stepper type are a modified version of a brushless dc motor. They work kind of like the 3-phase compressor you bought, and require a specific motor driver like the VFD you are selecting. They have to be told to move. I don't imagine the EXV have a position sensor built into them, so at the power-up events they have to be told to close fully. This initializes their position. After that, the position must be kept track of in software somehow. During operation, the position is tightly controlled by some kind of high-precision algorithm.

The EXV-metered systems in industry are meant to be engineered and specified to the particular application. Parker and Emerson both sell the EXV's in a range of capacities. They are meant to be mated to a controller that is picked out, a sensor array that is picked out, cables that are picked out, and everything is ordered as individual components. The order is quoted, and ships as assembled as the engineer spec's out. Not cheap at all.

The OEM way this happens includes this previous step and has more options. The design team gets a few basic controller boxes and sensors to do research and development with. Licensing contracts and agreements are made, the manufacturer gets a software development toolbox, and design parameters are hammered out. While running trials, first with simulation software and then in the lab, the OEM decides how to integrate the EXV software into the microcomputer that was spec'd to run the machine.

During trials, the design team twiddles and tweaks with hardware and software while the marketing and accounting teams are projecting the future and counting costs. While prototypes are being tortured and certified to conform to safety and operating standards, everyone involved is figuring out who gets paid to do what during manufacturing. In the end, Parker or Emerson or whoever the source is gets a bulk order for raw goods, plus a cut for their intellectual property. Service and spare parts orders are contracted out the same way.

As far as we are concerned, the only useful universal controllers to be had are going to be the industrial type, as the OEM's hold on tight to their design team boxes. These industrial boxes are made to be set by sharp fridgie techs and mechanical engineers. Not quite user-friendly, but it wouldn't be a major undertaking to get the thing to do what you need it to do reliably.

The stuff inside the residential units may be able to be used by salvaging all the controls, sensors, valves, etc. from a unit that has developed a leak or some other "minor" problem and transplanting the guts (or repaired unit) into something else. Finding out where individual components came from, and what they need to run with, is nothing like robbing a cap tube or TXV from an "inferior" older unit, as the EXV drive hardware and control software is integrated, embedded, and grafted into a master control that serves a purpose larger than just EXV control. Not many people have been able to successfully command or "jinx" these OEM units.

Staying with the Emerson / Alco line, there are two basic lines:

Super Universal, expensive:
097707 - Emerson Flow Controls 097707 - EC3-X33 Stand-Alone Universal Superheat Controller
Descriptive brochure:
http://estore.rrd.com/emerson/download.ashx?did=873
Plain jane driver module:
EXD-U-00

Cheaper version: good luck finding one.

http://www.emersonclimate.com/europe..._EXD_HP1-2.pdf

Parker / Sporlan, Siemens, Danfoss, Carel, etc. all make their own takes of these controllers. They all seem to like RS485 / ModBus serial communications. Not surprising, due to the industry standard.

12-10-15, 09:29 AM	#177
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Here's the thing about electronic expansion valves: They don't all work the same way, and you are relying on an electric over mechanical control layer to regulate how your system acts. If you pony up the money for a turnkey rig, it will do what it was designed to (hopefully well). There are 2 main types of EXV's: pwm and stepper. The pwm type work like a super-fast solenoid valve, and I imagine they have some kind of damper built into them.You feed them a square wave, and they conform to the duty cycle of open / closed. Who knows whether they are normally open or normally closed? Who knows how slow or fast the damper is? Not me. The stepper type are a modified version of a brushless dc motor. They work kind of like the 3-phase compressor you bought, and require a specific motor driver like the VFD you are selecting. They have to be told to move. I don't imagine the EXV have a position sensor built into them, so at the power-up events they have to be told to close fully. This initializes their position. After that, the position must be kept track of in software somehow. During operation, the position is tightly controlled by some kind of high-precision algorithm. The EXV-metered systems in industry are meant to be engineered and specified to the particular application. Parker and Emerson both sell the EXV's in a range of capacities. They are meant to be mated to a controller that is picked out, a sensor array that is picked out, cables that are picked out, and everything is ordered as individual components. The order is quoted, and ships as assembled as the engineer spec's out. Not cheap at all. The OEM way this happens includes this previous step and has more options. The design team gets a few basic controller boxes and sensors to do research and development with. Licensing contracts and agreements are made, the manufacturer gets a software development toolbox, and design parameters are hammered out. While running trials, first with simulation software and then in the lab, the OEM decides how to integrate the EXV software into the microcomputer that was spec'd to run the machine. During trials, the design team twiddles and tweaks with hardware and software while the marketing and accounting teams are projecting the future and counting costs. While prototypes are being tortured and certified to conform to safety and operating standards, everyone involved is figuring out who gets paid to do what during manufacturing. In the end, Parker or Emerson or whoever the source is gets a bulk order for raw goods, plus a cut for their intellectual property. Service and spare parts orders are contracted out the same way. As far as we are concerned, the only useful universal controllers to be had are going to be the industrial type, as the OEM's hold on tight to their design team boxes. These industrial boxes are made to be set by sharp fridgie techs and mechanical engineers. Not quite user-friendly, but it wouldn't be a major undertaking to get the thing to do what you need it to do reliably. The stuff inside the residential units may be able to be used by salvaging all the controls, sensors, valves, etc. from a unit that has developed a leak or some other "minor" problem and transplanting the guts (or repaired unit) into something else. Finding out where individual components came from, and what they need to run with, is nothing like robbing a cap tube or TXV from an "inferior" older unit, as the EXV drive hardware and control software is integrated, embedded, and grafted into a master control that serves a purpose larger than just EXV control. Not many people have been able to successfully command or "jinx" these OEM units. Staying with the Emerson / Alco line, there are two basic lines: Super Universal, expensive: 097707 - Emerson Flow Controls 097707 - EC3-X33 Stand-Alone Universal Superheat Controller Descriptive brochure: http://estore.rrd.com/emerson/download.ashx?did=873 Plain jane driver module: EXD-U-00 Cheaper version: good luck finding one. http://www.emersonclimate.com/europe..._EXD_HP1-2.pdf Parker / Sporlan, Siemens, Danfoss, Carel, etc. all make their own takes of these controllers. They all seem to like RS485 / ModBus serial communications. Not surprising, due to the industry standard.