Thanks for the information about the advantages of the variable speed over the two stage furnace.
But, what about reliability? It seems to me that the fewer the working parts, the more reliable. And so, the edge there would seem to go to the two stage furnace. Also, is one easier to service than the other?
I'm considering the Trane XV90, XL90, or Bryant Plus 90i.
I'm a Trane guy. We have intalled plenty of the 2 stage and variable speed furnaces. No problems.
As far as easy to service, any company who deals in a particular brand there service techs will be well versed in the inner workings of your system. Well, at least a ligitimate company would!
The variable speed is the best bang for the buck and has a great warranty.
trane has benn useing the v drive sinse the early 90 s
and i have installed a lot of them. the motor is by ge and like anything else as long as installed properly is very dependable and last a long time
now guys, tell us what you would charge to replace the VS motor, including service call & labor ???
Most of the features that make a modulating furnace work are electronic. My experience has been that any process that used to be mechanical and is now electronic is many times more reliable.
It stands to reason. Electronic circuits have few if any moving parts to wear and produce very little heat ( the number one enemy to reliability).
May I suggest the Ruud Mod 90. Consumer Reports rates it above both the Trane and the Bryant for owner satisfaction.
to replace the vs motor can be very costlywith out breaking the rules about pricing
in a lot of cases the controler is what has gone bad not the motor. this would cost less then replacing the intire assenbly
i have worked on and installed vs units trane and lenox since 95. in ten years i have replace 1 intire motor and two controlers. that leaves me to believe they are just as reliable as any other motor in use
just for the record 1 controler went bad because water was dripping on it from an iced up coil because the owner didnt change the filter for two years
the second was because the crawl space was very hight humidity and the owner put in a dehumidifier in the crawl
the last one the motor shorted out
so the dependability is there
I look at it this way. Cars are way more reliable now than they were 20-30 years ago (not to mention cars from before that time). And yet cars today have so many more systems and components that "could" fail. All things being equal, more components or moving parts "might" mean higher potential for failure but it doesn't guarantee higher failure rates and doesn't take into consideration higher manufacturing tolerances now compared to 2, 5, 10 years ago and more.
Besides, if you get a good parts and labor warranty from the contractor that is installing the HVAC system it really becomes moot.
(I should add that this is my opinion --in general, not just for HVAC-- and I'm not an HVAC professional, just a home owner.)
[Edited by takeflight on 04-13-2005 at 05:56 PM]
I had to replace the 'controller unit' for the VS blower on a Carrier Weathermaster 2-stage furnace about 3 weeks ago. It was 4 years old and under warranty.
It cost me nothing for the part and 1.5 hours labor for the diagnostic & replacement. If you search on my ID for my posts, you can see the process I went thru, as I posted it here.
I've had an Armstrong in my house for the past six years. No service calls, no problems. Two stage variable speed is good stuff.
First off the VS motors used today in most systems are the GE ECM motor. The motor is a DC brushless motor with permanently mounted magnetic segmants on the rotor and 18 poles on the stator and a virtually nill failure rate. Especially when compaired to a PSC motor with sleeve bearings. The modules are a seperate componanat and are considered very durable. At last check, around 40% of the modules that hae been returned have no fault found. Many are misdiagnosed. Quite a few that have failed have been from water damage, as someone previously mentioned and they have been upgraded since then to a beter dipping process to help protect them. This same damage a PSC motor will succum to.
How many guys spend extra time trying to figure out how to troubleshoot them, and just replace the whole assembly? A lot. The motor diagnosis is a simple resistance measurement yet it goes untested. The module, if ineed failed, is not overly expensive.
For the techs out there who sell systems with VS motors I suggest a good training event on ECM. If I may be so bold as to add a link to one of the best ECM classes...
I think that the guys who talk down variable speed motors,still buy cars with roll down windows,because there is less moving parts to go wrong! XV90 nice furnace!
It's NOT the BRAND,it's the company that installs it!!!!!