Deciding on new furnace, question about D/C motor

[thesober]

Newbie alert...this is a very simple question simple question.

The contractor told me that the d/c motor uses less electricity. Does this motor run in the summer time when the AC is on? or does it only run during heating season?

Im trying to decide between Hi effiency Carrier Comfort and Infinity furnace. Does two stage play a significant part compared to single stage?

[BaldLoonie]

That is your blower motor they are talking about and it uses less juice year round.

2 stage gas valves provide more comfort by letting the furnace run on low fire in mild weather, which is most of the time. You can have this feature with & without a variable speed blower motor.

[Freezeking2000]

If i were installing a new system i would absolutely get the DC motor, it will save $$$ over the life of the motor.

[nextwave]

Unless you ever have to replace the motor, in which case you will be putting down a huge chuck o'change on a replacement DC. My experience is that a DC is more likely to fail with age...but not 100% familiar with the Carrier Infinity specs.

2-Stage is definitely worth it (IMO) but be careful with the variable unless there is a reason to pursue it...

[amickracing]

From what I've heard DC motors hardly ever fail, it's almost always the control module. The control module is way cheaper than the motor too. Unfortuntely a lot of guys either don't know how to test the motors or just plain don't and replace the motor and control making for the huge bill.

[ryan_the_furnace_guy]

I see many more AC motors failing than their DC counterparts. In my opinion the DC motors are much more reliable. And given that, if you run your fan continuously, they can save you "conservatively" $200 per year at today's electrical rates. I would say it is worth it.

[bob hubbard]

The only time the vari-speed motor saves you money is when you run the blower on 24/7 . Otherwise its a comfort thing . Leaving the fan in the auto position wouldnt have much savings at all over the standard motor . The best thing about running the blower all the time is air filteration & on low speed it alot less noisey . This system will leave you in awwwwww when it does need a service call for a repair . Bh

[mark beiser]

A varriable speed blower will maintain the set airflow as the filter loads, weter or drier coil, slightly less than ideal duct system, etc.
It also helps with overall comfort and humidity control if set up properly.

The current VS motors, and thier control modules, are very reliable. One of the 2 main things that kill VS motor modules are electrical spikes/surges, wich can be prevented with a good whole house surge supressor, or just one for the furnace.
The other is the blower having to operate against an ESP of >.9" WC. There is a perception that VS motors can be used to compensate for badly undersized, or poorly designed duct systems. That perception is absolutely wrong.
Proper duct sizing and design is just as important with a VS blower as with a standard blower.

With a 10 year P&L warranty, you won't have to worry about the replacement cost for 10 years. The blower will have saved you enough in energy costs over that period to more than pay for its up front cost and its replacement cost if it fails out of warranty.

[mayguy]

Originally posted by mark beiser
. One of the 2 main things that kill VS motor modules are electrical spikes/surges, wich can be prevented with a good whole house surge supressor, or just one for the furnace.

My parents are out in the country, I kept telling mom that she better get the surge supressor for the house or furnace.. Well, last week, the moduler on the motor was out.. it has to be replaced..

Now she called to get a surge protector added onto the house.

[markwolf]

Originally posted by bob hubbard
The only time the vari-speed motor saves you money is when you run the blower on 24/7 . Otherwise its a comfort thing . Leaving the fan in the auto position wouldnt have much savings at all over the standard motor . The best thing about running the blower all the time is air filteration & on low speed it alot less noisey . This system will leave you in awwwwww when it does need a service call for a repair . Bh

I just cannot believe that even for a second.If you do a startup on a new standard furnace & a new variable with dc motor the amp draw is ALWAYS less than half.Are you saying that using less than half the power will not save money?

[markwolf]

Originally posted by nextwave


Unless you ever have to replace the motor, in which case you will be putting down a huge chuck o'change on a replacement DC. My experience is that a DC is more likely to fail with age...but not 100% familiar with the Carrier Infinity specs.

2-Stage is definitely worth it (IMO) but be careful with the variable unless there is a reason to pursue it...

I work for a large carrier dealer &last year I replaced one dc motor & one module versus the fifty or so ac motors I replaced.we are a high end dealer most of our resi equipment is variable speed alot of them 16+ years old with no problems.

[Edited by markwolf on 10-31-2005 at 01:10 AM]