A theoretical question.

With multizone systems, it would make a perfect sense to have a really variable speed fan and compressor, however, it doesn't seem that they exist.

Making a variable speed fan is not a problem from a technical standpoint.

I don't know if it is possible to make a really variable output compressor, and I'd guess it would be somewhat challenging to balance the compressor output with the airflow to keep the system within optimal working range, but to the best of my limited understanding, it's not impossible.

So why aren't they out there?

Just a crazy thought...

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--vt

I do remember a heatpump with a variable speed compressor, cant remember the brand.
The good ting of smating like that was that you can over sice the A/C
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M O N E Y! Price a replacement variable speed blower vs. a standard multi speed blower. Then price a replacement compressor and think about what a replacement variable speed compressor would cost. I worked on a variable speed type compressor in the lab for a while. It was a great concept in how they made it work, but it just didnt hold up well.

[Edited by ApplicationTech on 03-07-2002 at 08:21 PM]
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Your village just called. Their idiot is missing.

Trane made a variable speed condensor in the late 80's,early 90's called the XV1500. It was awesome. The operation is controlled by a "system controller" which picks up signals from the zone sensor and determines how fast the compressor and fan motors should operate. The compressor was directly controlled by the compressor drive, which using 3 phase DC power, could regulate the RPM's from 0 to 6250. Carrier was sued by AS because they illegaly purchased the drive schematics from the designer. I was also told that it was invented in the guy's garage. If you ever run into one you'll know it when you open up the control panel. The best thing to do is not touch it if you're not trained to.

[Edited by duckman373 on 03-07-2002 at 08:20 PM]

back in the early 80s, unfortunatly they were manufactured by General Electric. They had a lot of problems with the control module that coverted single phase power to three phase power for the variable speed compressor.
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One way to outthink people is to make them think you think. They'll think you're not really thinking what you're trying to get them to think you think...........

Carrier had the HydroTech heat pump with desuperheater and variable speed blower. But York had both Trane & Carrier beat with the ENMOD in the 70s.
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My dream is to one day own the Trane variable speed unit. The answer to your question, and the bane of my existence, is that Trane discontinued the Variable speed line for "Lack of consumer interest."

The real problem? Salesmen didn't sell it. Why not? Because they could not compete on price, and the payback was out beyond the expected equipment life. But that unit was a dream. At one time, I had sold more XV1500 than any other company in the USA. I put three in one house. The owner of that house and I are still friends to this day. His reference about my knowledge and dedication helped get me my current job at the cat food plant.

I own a variable speed compressor, and a drive assembly. I also have a controller. I'm hopeing that when I get ready to build it, the tstat and other misc parts are still available.

I have asjked Trane repeatedly when they plan to revisit the variable speed program, and they tell me never.
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There are no stupid questions. . .just a lot of inquisitive idiots.

quote:

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Originally posted by BamaCracker
My dream is to one day own the Trane variable speed unit.

I have asjked Trane repeatedly when they plan to revisit the variable speed program, and they tell me never.

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I think Carrier came out with a sixteen speed heat pump around the same time as the xv1500. Don't remember hearing much about it after the introductory press.

OK, so it boils down to two things: reliability and complexity of the control system (obvious). As soon as both get into the reasonable range, the price drops, and it may start making sense again.

I can just hope that with a massive increase in the embedded computing power and reliability, and massive drop in price, at least the control systems will get reasonable soon.

Until then, I'll just keep crossing my fingers and waiting.

I'll be the first to buy

PS: BamaCracker, when you get ready to build it, drop me a note. I'm currently working together with a really cool embedded hardware guru who can just do things on a whim, incuding the production releases, and it may be closer than you think As for the thermostat, I've got it covered
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--vt

york had the triathalon a reliability nightmare. oil return is a big problem with varaible speed also. think heat will be more likely to see true modulating output become more common long befor A/C. besides better than 2/3 of the companies out there cant put in a normal system right can ya imaging what they would do to a varaible speed system ?

look under the hood of your car, if it has air conditioning thats variable speed

VT:

Sometime ago when I was looking for a service manual on a Toshiba mini split, I was able to down load one from the following site. I also noticed that some of their units have a variable capacity compressor. The one that I glanced at used a brushless DC motor and had a variable RPM range of about 10:1. The drawings I looked at were on a multi-split unit and they contained the block diagrams of the unit. If you are interested in looking at what Toshiba's philosophy on variable capacity is go to the following site and down load a service manual on one of their units.

Sorry I don't remember the Model number of the one I looked at.



http://www.toshiba-aircon.co.uk/technical/index.html