NO!
If you want the true comfort you pay for when you get a 2 stage furnace, you must use a 2 stage thermostat.
I ordered a Honeywell 2 stage t-stst to go with my new 2 stage furnace because my installer just installed their standard 1 stage t-stat likely cause that's all the existing wiring would allow for. (Too lazy to pull new wire) Now I am wondering whether I need the 2 stage as my furnace manual says it can operate on a 1 stage because
a) it works on a timer and
b) it stores a history of 1st and 2nd stage usage to determine when to switch from one stage to another.
Do these furnace abilities really negate the need for a 2 stage t-stat?
NO!
If you want the true comfort you pay for when you get a 2 stage furnace, you must use a 2 stage thermostat.
So the furnace features are a less than satisfactory solution. So what does a the 2 stage t-stat do that the furnace features can't compenstae for? Just curious.
It can't compensate as well for changing weather...ie one day weather is 50 outside... next day weather is mid 20's.
Here's the reason: With a 2 stage stat, The stat can call directly call for full High heat mode,depending on your set point, Furnace has the ability to fire on High stage first to quickly heat house (like when your coming off of night set down, it's called 'recovery mode') then when it gets to within a degree or two of your set point, it will lower furnace down to low fire stage and try to maintain a slow low warm airflow.
With a single stage stat, everytime your furnace starts up, your furnace control board will fire on low heat first for a set amount of time (like 10 minutes I believe for my Carrier) then if the demand is not met it will fire on High until the desired set point is reached and then will shut off. Kinda backwards from the way the a two stage furnace is intended to work!
Basically the Heating patterns are much more flexible with a 2 stage stat because the stat is doing all the controlling and thinking. It can adapt to changing conditions better than the control boards "fixed logic".
Listen to what most folks are saying... get a two stage thermostat. I bought a Honeywell VisionPro 8320 and am very happy. Why penny pinch on a thermostat when you've already paid more for a 2 stage furnace...that's the way I look at it.
[Edited by dro1984 on 11-13-2005 at 01:29 PM]
Thanks all! I can't believe what great and fast advice I get from this message board!!
Single stage stat operation...
Stat calls for heat, furnace fires first stage of heat “low fire” after furnace board timer "times out" the second stage of heat "high fire" comes on until the stat is satisfied. The unit then shuts off and waits for next call.
Two-stage stat operation...
Stat calls for heat, furnace fires first stage of heat “low fire” if temperature continues to drop the stat will then bring on the second stage of heat "high fire" to raise the temperature. While the furnace raises the temperature and is nearing the set temp, the stat will then backup to its first stage of heat “low fire” to continue to reach the set point slowly (then shut off). If the temps continue to drop instead of satisfying the set temp, it will bring on the high fire again and repeat the above till it does satisfy the requirements.
It will sit there and switch between the two positions to maintain temperature. While doing this the temperature range in your home is tightened to a narrower range. Providing you greater comfort.
Not only is the temperature tightened, the room temps are more even, you get better air filtration, greater humidification, greater efficiency, all due to longer run times.
Two-stage equipment DESERVES two-stage controls!
This is all great information. I have a related question, do all 2-stage t-stats work the same way?
I'm in need of a 2-stage heat (for a new 93% armstrong furnace) 1 stage cool t-stat. Is there a preferred model or brand? Or perhaps more importantly, one to avoid?
I guess I also want either a 7-day programmable or 5-2 programmable t-stat.
Thanks
Walt
A VisionPro that is professionally set-up would be my choice.
Originally posted by jultzya
Single stage stat operation...
Stat calls for heat, furnace fires first stage of heat “low fire” after furnace board timer "times out" the second stage of heat "high fire" comes on until the stat is satisfied. The unit then shuts off and waits for next call.
Two-stage stat operation...
Stat calls for heat, furnace fires first stage of heat “low fire” if temperature continues to drop the stat will then bring on the second stage of heat "high fire" to raise the temperature. While the furnace raises the temperature and is nearing the set temp, the stat will then backup to its first stage of heat “low fire” to continue to reach the set point slowly (then shut off). If the temps continue to drop instead of satisfying the set temp, it will bring on the high fire again and repeat the above till it does satisfy the requirements.
It will sit there and switch between the two positions to maintain temperature. While doing this the temperature range in your home is tightened to a narrower range. Providing you greater comfort.
Not only is the temperature tightened, the room temps are more even, you get better air filtration, greater humidification, greater efficiency, all due to longer run times.
Two-stage equipment DESERVES two-stage controls!
Thank You for this post....I have been told by many companys I have worked for that it makes no difference...but I wonder why the manufacturers put on a single stage thermostat option to begin with..uh.oh. could it be that they want to give contractors an easy out instead of running proper control wiring for a two-stage stat.
[Edited by addfreon on 11-15-2005 at 07:04 PM]
Havin'a good time is what life is all about.
Just wondering which Carrier furnace you've got... Any reason you chose the 8320 over the Infinity Control?Originally posted by dro1984
With a single stage stat, everytime your furnace starts up, your furnace control board will fire on low heat first for a set amount of time (like 10 minutes I believe for my Carrier) then if the demand is not met it will fire on High until the desired set point is reached and then will shut off.
I bought a Honeywell VisionPro 8320 and am very happy.
Am planning on getting the Infinity Control t-stat for my Infinity furnace, but people seem to rave about the VisionPro.
I put the Vision Pro 8000 on at my house & absolutely love it. Thats the stat that I'm recomending to everyone now.Originally posted by jultzya
A VisionPro that is professionally set-up would be my choice.
Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.
Not sure what brand of furnace you have but with Rheems 2 stage furnace their second stage is on a timer. Their second stage consists of 2 phases. Stage 2 phase 1 is 65% firing rate for 5 minutes. Stage 2 phase 2 is 100%. So using a single stage stat is kinda making the furnace a 2 phase furnace instead of 2 stage. I was guilty of doing that with my furnace when I installed it. But after hearing some comments on the forum I went ahead & put the 2 stage stat on.Originally posted by androidus
So the furnace features are a less than satisfactory solution. So what does a the 2 stage t-stat do that the furnace features can't compenstae for? Just curious.
Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.
Tend to agree but with my system I have dual fuel/ furnace/hpump. Variable speed 2 stage furnace/ single stage heatpump. Vision Pro is set up with outdoor sensor and no fossil fuel kit. Can't find a way to run true 2 stage on back up heat with this setup so I have to rely on the furnace board timing in Aux heat. Seems to work fine for me.
"Go big or Go Home"
Two stage furnaces typicly perform just as well with a single stage stat as a two stage stat in my opinion. For the better part of the year, the furnace will run on low fire most of the time. If, the load changes enough to require 12 minute run times, the furnace will then go into high fire to satisfy the thermostat. ~80% of the time, regardless of thermostat configuration the unit will remain in low fire anyway. On a two stage stat, the temperature in the house must fall away fom set point by almost 2 degrees to bring on the added capcity. Frankly, I dont see this as much of a benifit. Beyond that only the mod will give you the exact output at virtually any condition.
This may ruffle a few feathers here, sorry about that. Cooling, I'm all about a two stage stat though.
Zoning, is another beast, then, I would prefer the unit to be controlled by something other than the control boards timed function.
You're not ruffin any feathers. But in my climate the two-stage stat will allow the unit to run for LONG intervals before ever going into second stage. The stat can be programmed to operate the second stage sooner if needed (for comfort issues).
The real advantage is that the stat will allow the unit to step back to the lower stage to allow continued operation. No single stage stat will do this!
The new Robertshaw stats will show up an error message if the unit operates longer than an hour and doesn't change the structures temperature. I have received a few calls on this as the client will call and say that the unit has been running constantly and the stat says error. All it means is that it's cold enough outside that the first stage isn't enough to satisfy the requirements. And the unit is switching between low-high-low back and forth to maintain a constant temperature.
A single stage stat CAN NOT do this, PERIOD!
I have a Carrier Performance 80, not an Infinity. 8320 is Honeywell's high end Vision Pro without Humidity control. They have one above mine that has Humidity Control like the Infinity Control that Carrier and some others offer.Originally posted by krxman
Just wondering which Carrier furnace you've got... Any reason you chose the 8320 over the Infinity Control?Originally posted by dro1984
With a single stage stat, everytime your furnace starts up, your furnace control board will fire on low heat first for a set amount of time (like 10 minutes I believe for my Carrier) then if the demand is not met it will fire on High until the desired set point is reached and then will shut off.
I bought a Honeywell VisionPro 8320 and am very happy.
Am planning on getting the Infinity Control t-stat for my Infinity furnace, but people seem to rave about the VisionPro.
To go with the Infinity control would have ment shelling out a lot more cash for something that offers options I don't need. Besides, $XXX for the Honeywell was high enough.
>>>edit...
(No pricing, due to site rules )
[Edited by jultzya on 11-16-2005 at 11:24 PM]
I have an Infinity 96 furnace and a single stage Ameristar condensing unit (and NO, I wasn't trying to save money on the outside unit - it's a long story).
With this set up, anybody know how much difference I'd see between the top of the line Vision Pro (w/ humidity control) and the Infinity Control t-stat? I primarily want to control the noise level in the living areas serviced by this system.
Not all two-stage furnaces (or variable speed for that matter) are created equal. Some brands I would agree that a two-stage stat is necessary, whereas with others logic controls are incorporated into the furnace that practically make a two-stage stat a repeatative measure. As far as reasons why contractors might not advise or include: (1) they don't understand the equipment any better than you! (2) they are being lazy / cheap (3) at some point they sensed that adding an extra nickle of price might relieve them of the opportunity to install your new system (to be fair, most consumers do not research the different products/companies and show off price alone - anyone on this site that invests the time to learn more about their system is likely not one of those folks!) or (4) they are installing a brand that operates well even without the 2 stg stat.
Infinity Control vs. VisionPro: The infinity control was specifically designed to work with your furnace whereas the Visionpro stat was designed by Honeywell to fit in as a high-end product in the line-up. As a contractor, my cost to acquire the Infinity/Evolution control is approximately twice that of a VisionPro. My opinion: stick with your existing stat or go for the gold with the Infinity Control.
Eager to learn, willing to teach, reluctant to admit defeat.
The inffinity can control your blower speed, the vision pro can't.Originally posted by krxman
I have an Infinity 96 furnace and a single stage Ameristar condensing unit (and NO, I wasn't trying to save money on the outside unit - it's a long story).
With this set up, anybody know how much difference I'd see between the top of the line Vision Pro (w/ humidity control) and the Infinity Control t-stat? I primarily want to control the noise level in the living areas serviced by this system.
Well that difference is decisive - at least for my purposes. Gotta have the VS control to keep the furnace operating at a low hum in the background. Infinity it is.