Any comments about DC inverter technology?

I've been reading about this technology being used in heat pumps now. The sound levels and energy savings are impressive.
BTW, I've a bit of experience with this in automated welding where it has improved the performance/quality considerably.
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SEER donesn't really mean anything.... SEER numbers are done with virtually no load on the system. SEER testing is done with 80F inside and 82F outside. Pay attention to the EER numbers... those are the ones that count. EER is done with 95F outside. Check heat pump systems for efficiency here; http://www.ahridirectory.org/ahriDirectory/pages/hp/defaultSearch.aspx Check A/C efficiency here; http://www.ahridirectory.org/ahriDirectory/pages/ac/defaultSearch.aspx Check furnaces here; http://re.gamanet.org:8080/gama_cafs/sdpsearch/search.jsp?table=Furnace Check mini-split heat pumps here; http://www.ahridirectory.org/ahridirectory/pages/vrfhp/VRFHP2-23-09.pdf Check mini-split A/C here; http://www.ahridirectory.org/ahridirectory/pages/vrfac/VRFAC2-23-09.pdf
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Inverter technology has been around for years. Quiet enough to set the unit outside grandmas bedroom window. (you know, the grandma that can still hear you coast up the driveway with the lights & the engine off at 2:30am) Trane built some of the first & gave up on it "mis-forecasting" the future... The Nips took it on like a storm. Today variable speed & inverter drives are no longer cutting edge, products not offering them are falling off the pace. Even Trane has got to be looking a VFRZ... They've started relabling everything else...
Though your question wasn't about EER's & SEER's, here's my $.02: Where I come from EER & SEER be damned... typical residential cooling hours run between 5-650 per year. Heating Degree Days, on the other hand, are anywhere from 8500-10,000. When I look for a HP I'm looking for HSPF. Anything under 7 is out of the running, 8-9 looks good... A 2 stage unit, oversized on the cooling side has some great benefits. As always, duct size & airflow will be one of the biggest deciding factor.
goodluck geothermaljones

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Zero torque at low Hz input and how are you going to maintain windings temps ?
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I don't have to... They've built it, I just know it works...
geothermaljones

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wrote:

The motors are DC so torque can be controlled at all speeds. Here's the best URL I've found so far:
http://www.toshiba-aircon.com.au/web/toshibaweb.nsf/668d4ee488131f104a2564d5002c772f/6f5f04cfc75d1186ca25691d001dec97?OpenDocument
With PWM, the power to motor is continuously varied according to load therefore winding temps are directly controlled by the amount of coolant passing through the unit.
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In my neck of the woods, the heating and cooling hours are reversed. We have 4 seasons in south Mississippi.... December, January, February, and summer. I only posted those links and explained the difference between SEER and EER because the SEER numbers are so misleading. Yes I have sold and installed mini-splits, and the Mitsu brand costs the customer more than a conventional split system(including ductwork).
The only way anybody can figure out what they *NEED* is to do the math for correct sizing, and how many heating and cooling degree days in their particular location. Then and only then should they be concerned about the actual quality, efficiency, warranties, etc. of the equipment they want installed.
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How could you tell the difference??
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snip
So far your question has produced 14 replies including mine. What is the ratio of useful and useless.
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On Sun, 01 Mar 2009 01:48:40 -0500, The King

Looks like I'm batting zero......
In any event, it looks like this new technology is going to shake up the HVAC tech's life. He'll have to become more of an electronic instrumentation tech.
Have a look at this service manual. I'm impressed with the self diagnostics. EVERYTHING is monitored.
http://www.mrslim.com/UploadedFiles/Resource/PUY-PUZ-A12~42%20Service%20Manual%20OC367C%206-27-07.pdf
Another interesting feature is the linear expansion valve controlled by a stepper motor.
I've never seen such a complete technical manual and I think it is worth a perusal by you HVAC guys. It's the way of the future. The old heat pumps are going to go the way of tube TV's.
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Now... if they can just come down on their prices....
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wrote:

Wait'll China starts manufacturing them in a big way and selling them through Wal Mart.......
BTW, here's one that would have worked and the price is comparable.
DUAL ZONE 12+9 kBTU HEAT PUMP SYSTEM http://www.ductlessdepot.net/product_details-type-2-1-250.html
Brand: SANYO Model #: KMHS1272/KMHS0972/CMH1972 Status: in stock Your Price: $3003.60
Plus about $400 for wire/tubing
I could have done all the plumbing myself. They're flared connections. Just have to call HVAC tech for vaccum/charge.
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