FAN TYPES-SINGLE, MULTI,VARIABLE

[nathan9999]

I'm looking at a Trane set-up that utlizes a 2 speed fan on a 13 SEER AC unit and a 4 speed fan on a 80% 2 stage furnace. At least that's what's on the Trane website. I still have to see if these units are rated to be used together.

I've read a few posts concerning fan types. Some of the professional members have indicated that variable speed (ECM) fans are the way to go, while other inidcate that multiple speed fans (2 speed, etc.) are sometimes less reliable than a single speed fan.

So if the professional members were buying for their own home (and had to pay retail) what would you buy as far as fan types, and what are the important issues?

Thanks

[tinknocker service tech]

trane has used two speed fan motors on thier condensers for years and so have others. they are dependable
variable speed blower is the best way to go

[duc dowg]

agree

[mayguy]

If you want quiet soft air flow all times when there is no call of heat/cool, go variable speed.

If you are a person who wants even temp, and also a good air filter system like Media filter system, go variable speed.

Also with variable speed blower, it will take less power to run since it's running on DC power vs AC power. I noticed our light bill has dropped about $20 a month when I went with variable speed, and I run my fan 24/7 for even temp, and air cleaning with the media filter.

[docholiday]

Originally posted by nathan9999
Some of the professional members have indicated that variable speed (ECM) fans are the way to go, while other inidcate that multiple speed fans (2 speed, etc.) are sometimes less reliable than a single speed fan.

So if the professional members were buying for their own home (and had to pay retail) what would you buy as far as fan types, and what are the important issues?

I dont think reliability is a question, multi-speed PSC's have been the workhorse for years and have done well. ECM's offer imporvements in efficiency and the ability to provide constat airflow when the duct static changes and additional control is also often avaialbe that alows some addtional control of humidity.

Definately worth the retail difference in price.

[nathan9999]

On a related topic (I hope) how does all this relate to air handlers? I have read about air handlers but don't know how they relate to a split system, if at all. The Trane webiste speaks of variable speed air handlers. If I am looking at a split system is an air handler included or is this another component?

[docholiday]

No, you are looking at a gas furnace if I remember correctly, an air handler is used in a heat pump only or air conditioning only application.

[nathan9999]

Doc, so the Trane XL 13 SEER AC (2 speed) and the XL80 furnace (4 speed) would work independently of each other, correct?

Can a variable speed fan be put into a AC unit or furnace that originally had a 2 speed or 4 speed fan?

[dash]

Originally posted by nathan9999
Doc, so the Trane XL 13 SEER AC (2 speed) and the XL80 furnace (4 speed) would work independently of each other, correct?

Can a variable speed fan be put into a AC unit or furnace that originally had a 2 speed or 4 speed fan?

Yes, two indendent motors,one in the furnace and one in the outdoor unit.

VS can't be be added on,buy your new furnace with a VS motor.IMHO

[beenthere]

Spend the extra to get the VS blower, you won't regret it.

[mrssb]

For whatever it is worth, I could not agree more with what everybody else has posted. VS is with ou a doubt worth the money, and adds to the comfort level of the home. I would pay retail in a heart beat for VS.

[bornriding]

Nathan,

I'm going to get blasted for this...but here goes !
Having any system that uses a variable speed motor without a subseguent reducal in BTU output. In other words, a two speed system may have a two speed blower & a two speed compressor for two different levels of cooling. And this is very efficient.
But, if you just have a variable speed blower without a two or more speed compressor, then you only save the difference in energy between the variable speed motor & the single or two speed motor.
By my calculations, you would save less than $10.00 / year for that differance in blowers, and yet that variable speed blower will cost you several hundred dollars more to install it and many hundreds more to replace it. To me that is 'no payback'.
And the only benefit that you would receive, is a little lower humidity level. So, do you have a problem with humidity ?? It may be worth the var. sp. Just realize that you are spending hundreds for a small comfort difference.

OK guys, I can take it !!! LOL

[nathan9999]

bornriding, no humidity problems. The only reason I was thinking about anything other than a single speed system was comfort. Docholiday indicated a variable (or multi-speed) fan would be helpful for heating comfort but a variable (or multi-speed) for AC would not bring as much comfort benefit.

Doc, correct me if my understanding is incorrect.

[tuccillo]

Originally posted by bornriding
Nathan,

I'm going to get blasted for this...but here goes !
Having any system that uses a variable speed motor without a subseguent reducal in BTU output. In other words, a two speed system may have a two speed blower & a two speed compressor for two different levels of cooling. And this is very efficient.
But, if you just have a variable speed blower without a two or more speed compressor, then you only save the difference in energy between the variable speed motor & the single or two speed motor.
By my calculations, you would save less than $10.00 / year for that differance in blowers, and yet that variable speed blower will cost you several hundred dollars more to install it and many hundreds more to replace it. To me that is 'no payback'.
And the only benefit that you would receive, is a little lower humidity level. So, do you have a problem with humidity ?? It may be worth the var. sp. Just realize that you are spending hundreds for a small comfort difference.

OK guys, I can take it !!! LOL

I was under the impression that the VS airhandlers had ECM motors which could be programmed to deliver a set amount of CFMs regardless (to a point) of the ESP. In other words, an ECM motor can compensate for duct issues (to a point). Isnt this the real reason to get a VS airhandler? Thoughts?

[beenthere]

Bad duct isn the real reason to get a VS blower.

It can over come slightly under sized duct, but it has limitations.


Slightly lower humidity will allow you to raise you t stat setting higher, and even if only 1 degree, it will save you on you cooling bill.


Comfort is the main, and best reason to get a VS blower.

What is your definition of slightly lower humidity, we see 5 to 10% on most systems.

[nathan9999]

So it appears that most professional members would opt for the variable speed fans. The Trane website seems to show that variable speed is reserved for the higher efficiency units, although Trane does show an 80% furnace with variable speed. I had decided to go for a 12 or 13 SEER AC unit and a 2-stage 80% furnace.

So is it the case that usually manufacturers will not put a variable speed fan on a 12 or 13 SEER AC unit? Can you recommend another manufacturer that would offer the VS on a lower efficiency unit?

Thanks

[beenthere]

York.
Carrier.

All of them, some times a contractor doesn't push them on lower eff. equipment, ask your contractor.

[mrssb]

Nathan
Currently GE is the only manufactuer of ecm motors so no matter who you buy Carrier, Trane York it is virtually the same motor, the only difference in my understanding is the controller might be set up different by manufacturers. It is still a better option than a two speed psc motor. These ecm motors are a three phase dc motor in other words they are built really tough. I do not know about anybody else but I have never seen a motor failure yet, but have seen some of the controllers go out. Have seen more than my share of psc motors failures. Take the advice of many of the pros and buy a VS motor. As for the argument about savings, I am not sure that I believe what he said about it only being a marginal amount. I see the cost cut in about 1/10, Trane has some numbers some where. I can dig them out if you are interested.

[nathan9999]

Not to be repetitive, but it still seems as though I have to buy a unit, whatever the brand, that comes with a VS, or ECM, already installed. Apparently you can't, or shouldn't install an ECM on a unit that was not designed for it.

For example, the Trane XL13i AC unit has a 2 speed fan, and the Trane XL 80% has a 4 speed fan. While Trane does offer an XL 80% furnace with a variable speed fan, apparently you have to buy a 15 SEER AC unit to get a variable speed fan.

I would like the VS fan but I would prefer not to have to spend the money on a higher SEER unit.

[beenthere]

VS is not an add on for any brand.

You don't need to buy a 15 seer a/c, to get a VS blower on a gas furnace.
If your contractor is telling you that, then its time to get another contractor.