Variable Speed For Forced Hot Air Furn.: Worth It ?

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Old 05-05-05, 07:27 AM
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Variable Speed For Forced Hot Air Furn.: Worth It ?

Hello:

Have pretty much decided on a Trane/American Standard replacement gas, forced hot air, furnace for my house (New EnglanT area). Present unit is about 30 years old.

Have just started getting HVAC contractors in for quotes.

Unit will have an output probably of 100 K Btu approx, and be the Freedom 80 or Trane XL80 Two-Stage Unit.

Haven't received their formal quotes yet, but am told that the variable speed unit would add about $ 600 to the price over the basic Two-Stage models.

Is it worth it ? Why ?

Any caveats or things to be aware of if I do get the variable speed ?

BTW: Might as well also ask: their catalog sheets shows ratings in BTUH.
Shouldn't it be in BTU/H ?

Thanks,
Bob
 
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Old 05-05-05, 08:49 AM
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First of all, I see where you live in the New England area of country and I am making assumption that heating is more important than Air Conditioning. You are wasting your $$$ if you don't purchase a 90+ AFUE gas furnace whether single speed blower or 2 stage variable speed. Energy will only get more expensive. You don't say what your plans are for air conditioning but your dealer should take into consideration the addition or replacement of AC at a future date into consideration. Your ductwork should be surveyed and you should insist on a written Manual J heat/cool load calculation for properly sizing equipment along with a minimum of 3 written detailed quotes. Find a dealer that will spend the proper time answering your questions and one that you find an appropriate comfort/confidence level. Now to variable speed. A variable speed blower costs less to operate, helps smooth out even temperature from room to room, is quieter than a single speed blower, and if furnace is equipped with a high efficient media cabinet can provide improved air quality-less dusty. If a matching AC or heat pump is purchased, a variable speed unit will improve the dehumidification process while cooling. Now the downside. A variable speed furnace costs more to purchase. The big ticket item to repair or replace would be the variable speed blower motor(GE ECM). Check with dealer and find out warranty coverage both labor and part for the motor. If you plan on being in home for 10+ yrs, I would definitely consider variable speed. And if it was XV80 or XL80 vs a 90+ AFUE furnace, I would opt for the 90+ furnace for energy savings. I recently purchased an XV90 Trane and love it. You should also list any concerns with your existing system and communicate to quoting dealers so that your expectations of new system are met or exceeded. You should check with your utility on any special rates/rebates for installing HE equipment. Trane is currently offering rebates on selected equipment and I believe AS is offering either interest free financing or no payments for one year. My opinion. Good Luck!
 
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Old 05-05-05, 09:16 AM
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Reply from OP

Hello:

Thank you very much for detailed reply, and info.

Would like to go to the 90 as you suggest, but really is no practical way of getting the PVC flue out of the house from where the furnace is located now.

Will probably have to settle for the 80.

Thanks again,
Bob
 
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Old 05-05-05, 10:29 AM
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Don't rule out a 90+ AFUE furnace without first asking dealers for their help/suggestions on the best method of venting waste heat. One other idea-only purchase from authorized dealers. Good Luck!
 
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Old 05-05-05, 10:59 AM
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Might take and read this post first

http://forum.doityourself.com/showth...125#post770125

ED
 
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Old 05-05-05, 05:36 PM
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For the most part, I concur with TigerDunes. The one exception would be the variable speed motor. The new ones, I must admit have come down in price due to them now being two components, separately replaceable. Still, I personally, would not buy one for my house.
 
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Old 05-06-05, 10:26 AM
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Ok, I am going to cover much as I can here since you have way too many open threads.

~~~~~~~~~~~~
XV Systems?

I have the XV90 system in my home. I had it installed last fall since our old 1968 Chrysler Airtemp bit the dust.

I love it to death. I always grew up with forced air and I thought the are all the same no matter what. I figured I'd step up and go with the variable speed blower. Great thing about the variable speed system, they use less power, and quiet.

The two stage heating is the best part. You're getting the heat as needed... Not all of it at once. With the mild/cool weather we had last weekend, was great. When we needed the warmth, we got it.. Not a big blast of heat on a single stage system.

When we had our cold blast last Dec around Christmas, it was down to -20's at night, the system ran steady in first stage, and only went into 2nd stage as needed. (2-stage stat). With the two stage system,. the variable speed blower will kick up higher speed for heating, and higher for 2nd stage to move the heat.

I have allergey, I run the fan 24/7 to help clean the air for me. With the fan running in "ON", the blower runs slow (about 50% of total CFM) to just move the air quietly and enough to clean, and provide even temp in all rooms in the house. The room temps maybe about +/-1 from each other.

Power usage been a little less than the last system.. now note, I never ran the fan on the old system since it was loud/drafty, now I do all times. and see no incresse in power usage.

~~~~~~~~~~~~~~~~
Comfort R

Trane and A/S uses Comfort R control for cooling. It's great.. I haven't use the A/C on my system since this was all put in last Oct.. but My parents has it, mom likes it. She said she had to go down a couple of times to make sure it was running.

On start of cooling, the blower run slow to get the coil pre-cooled. after about 3 minutes the blower then runs about 80% speed (still very quiet vs a regular blower) to help remove humidity from the air. after about 15 minutes, the blower then goes into high speed. still pretty quiet.

They allow the installer to set the dip swich to what size of cooling you're using, 3 setting for air flow (Hot dry arera, Avg, and Humid areas)

~~~~~~~
Air Filter.

In my young days, I thought electrostaic filters were the best! Well, they are not. yes, it may do it's job. but over time the filter will get plugged up with dust over time.. Yes, you do wash them. but some time you get the dust that don't want to move. So it get embedded,. when they build up, it cuts down on the air flow. so it's harder on your system to try pull air across the filter.

Electronic Air Cleaner (EAC) are great system. but has too many downfalls that I don't suggest them.

What are the down falls?

-You have to keep it clean once a month. If you don't, the system is not going to clean the air.

-Snapping/Arching noise. System has not been cleaned well, or to much dust.

-Takes power.

-Produce Ozone, when you have ozone in the home, it smells funny.

I would go with the media filter. I have the Honeywell Elite F200 Media system. You only need to change the filter once or twice a year. I change mine end of heating season. since I run the fan 24/7, and have two pets. so I know I will have to do mine about twice a year. The filter runs about $25 to replace.

Aprilair, or Air Bear are good as well. Aprilair is a little more work to change otu the filter since it's not one big media.

If you choce to go with the regular one inch filter, stay away from the 88cents fiberglass.. They don't do much.. Step into the pleted filter, but they can build up fast with dust, and harder on the system.

~~~~~~~~~~~~~~

Thermostat

I have the Honeywell VisionPro. LOVE IT. it's really easy to control.. You can even set it up in your lazy boy! It has a back lit screen to make it easy to see/read in dark hallways. Really easy to set up as well. I can't find the website that has a demo of it.

Don't settle for other Vision out there.. The VisionPro has lot more option to set up for your home/needs.

I am going to link you to a write up I've done on it.. Too lazy to retype it all. hehe

http://www.epinions.com/content_176876260996

There are other 2-stage system that is non-programable if you don't want the hassle of it.. I think the VisionPro been the easiest one I've ever done.

Do NOT settle with the dealer talking you out of the two stage t-stat.. using the timer on the system is not getting the best results out of your system.

Here in my opinon about using the timer.
-System will not cycle back and forth on 1st or 2nd stage. it will only one in 1st stage for X amount of minutes before going into 2nd stage.. So if you use set back it will take so long before it will go into 2nd stage.. Also if your front door been left open, will take while to recover.

-System may cycle on and off shorter vs the 2-stage with longer run time.. Way I look at it.. Say you're driving down the highway, Where are you going to get getter gas milage?

-cruse set on?
-stop and go all the time?

~~~~~~~~~~~~~~~

Warranty.

I never been big on these. but I broke down and got it for my system. I got the 10 years parts AND labor warranty from Trane. The price really wasn't that bad compair to a service call if you do get one. I will know I will be at peace for the next 10 years from Trane with out writing a check out if something did go wrong.

I know the motor and control are not cheap on these variable speed system.

~~~~~~~~~~~~~~~

Sizing?

Do NOT go with a dealer who does a rule of thumb.. Every home is diffrent.

Make sure they do a heat lost/gain on the home.

Just for kicks, I got one dealer in who did a rule of thumb, he was going to put in a 100,000 system in.. My old one was 115,000.

The next one (Home Depot) did a heat lost/gain, and suggest the 80,000.. I did a figure from http://www.hvaccomputer.com/main.asp and I came up just about 88,000 for the house.

I'd rather be a little undersized than over sized.

~~~~~~~~~~

Hope I was able to answer most of your questions here.
 
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Old 05-06-05, 02:28 PM
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From OP: Much Thanks

Hi,

Just want to say thank you very much for taking all the time
for such a detailed and informative response.

Have really learned a lot from it, and appreciate it very much.

Best regards,
Bob
 
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Old 05-06-05, 11:35 PM
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I am glad to help you out..

Here is the link I was looking for.. You can even "Program" the t-stat. I'd say it lets you do about 70% on the demo than the real thing.

Please keep us posted on what you end up doing.


Again, glad to help.
 
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Old 05-07-05, 05:25 AM
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2 Stage Thermostat Terminology Clarification ?

Hi,

A bit confused over the terminology on thermostats.
Embarassed to ask, but really want to be sure I have it right.

Does a 2 stage furnace require a 2 stage thermostat ?

I guess what's confusing me is the "2 stage thermostat" part.

By 2 stage on the stat, do they, perhaps, just mean a programmable setback temp., or is it really that you need this type to control (properly) a 2 stage furnace such as the Trane one I will be geting (with the var. speed blower).

Thanks,
Bob
 
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Old 05-07-05, 07:52 AM
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Does a 2 stage furnace require a 2 stage thermostat ?
No it does not. They would have to use a jumper, and there is a timer on it. But like I said earlier, the system will only run in first stage (lower btu) for maybe 10-15 min before it will go into 2nd stage (full btu).

But best to use a 2 stage thermostat to put the furnace into 2nd stage right away if needed like in the morning when it's recovering from set back.


Say in the morning, the house is 64 degree, the t-stat just turns on to 68 from 60 degree setback. the 2nd stage is turned on right away (full btu) recover. As the temp gets closer to 67 degree, the t-stat will turn off 2nd stage heating, and go into first stage heating (Lower BTU) and slowly come to temp.

So yes the 2-stage t-stat controls the furnace's 2-stage heating.
 
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Old 05-07-05, 04:30 PM
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Definately get the two stage burner and multi stage fan, but stay away from variable speed technology. Unless you are willing to wait for the technology to improve...
 
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Old 05-08-05, 08:22 PM
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LBC,

The variable speed been around for about 12+ years now. They are not new.
 
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