Learning about new furnace - 2nd stage

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Old 12-12-07, 01:31 PM
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Learning about new furnace - 2nd stage

I've got a new Trane XV95 & Honeywell VisionPro IAQ. This new furnace is 2 stage variable speed. Trying to figure out when it decides to kick into 2nd stange. When thermostat kicks on in morning and has to climb 10 degrees, if/when will 2nd stage get called? Hard to hear when it happens. One guy said it would stay in 1st stage unless it can't keep gaining on getting to set tempurature. Reading from others in the forum, because of the immediate temp diff, it will kick into 2nd immediately. What SHOULD happen?

Thx - Jerry
 
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Old 12-12-07, 03:58 PM
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The general idea would be to have it run on low until it no longer can keep up. How every mfg. accomplishes this I'm not sure; thermostat, timers, ?

Found this from one mfg. :

The Comfortable Way to Heat Your Home
Two-Stage Heating
Two-stage heating reduces temperature swings within your home, maintaining a consistent, comfortable and preferred temperature. Most of the time the furnace operates in the first stage or low heat for greater efficiency and comfort. On colder days, if first stage can not satisfy the heating demand, it switches to high heat or the second stage. Standard, single-stage furnaces only offer one level of heat - high.

Two-Stage Heating:

X. Two-Stage Control Board -- Control center for two-stage operation.

X. Two-Stage Gas Valve -- Adjusts amount of gas to accommodate two stages of operation.

X. Two-Speed Combustion Air Blower -- Adjusts amount of air delivered to accommodate two stages of operation.
 
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Old 12-12-07, 04:18 PM
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Thanks. I'm with that. Running as much as possible on 1st stage the better. This is probably the case all day long keeping the house at set tempurature. I just wonder what happens upon thermostat detecting a hugh gap (when it's set to come on in am). I'm assuming it jumps into 2nd pretty quick. But not spending time in the basement, I can't tell when it does.

And then another curious question is, once it gets told to run on 2nd stage, does it stay there until temp is met? or back off when gets within a degree or so.
 
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Old 12-12-07, 04:53 PM
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I'm not sure. Maybe someone else does.

But here is something you could do if you are curious enough: Go outside during some of these times and time the rotation of the fractional cu.ft.dial of the gas meter.
 
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Old 12-12-07, 06:55 PM
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2 Stage

Most furnaces, once they hit the second stage (high fire), will stay there for the duration of that particular call for heat. Jay11j is more familiar with Trane than I. Maybe he will jump in here & shed some light on the subject.
 
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Old 12-12-07, 08:08 PM
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Originally Posted by jerryjcp View Post
I've got a new Trane XV95 & Honeywell VisionPro IAQ. This new furnace is 2 stage variable speed.
Nice set up.

Trying to figure out when it decides to kick into 2nd stange. When thermostat kicks on in morning and has to climb 10 degrees, if/when will 2nd stage get called?
If the dealer wired the W2 from the EIM (control for t-stat) to W2 on the board,(No jumper on board from W1 to W2) it will kick into 2nd stage right away when the system is in Recovery Mode.

Hard to hear when it happens.
Should hear a change in the blower speed..

One guy said it would stay in 1st stage unless it can't keep gaining on getting to set tempurature.
On a normal winter day, when the furnace has recovery from set back, it will run 1st stage most of the time.. Only time you will see 2nd stage kick in if it outdoor temp is near design temp (Load Calc.), then it will cycle into 2nd stage for a bit, then back to 1st stage.. (mine starts seeing 2nd stage when it's -5˚, when it's near -10˚ my furnace will run almost non stop in 1st stage, and 2nd stage will cycle in and out).

The t-stat is a smart stat, and it will figure your home's heat lost and you won't see the changes in the room temp reading.

of the immediate temp diff, it will kick into 2nd immediately.
Yes, it will fire off to 2nd stage right away if you bump t-stat up, runs in 2nd stage for a few min, and go back to 1st stage.

If you'd like you can post your advance setting from the t-stat, and I can go over and make sure it's set up to match your system.
 
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Old 12-12-07, 08:56 PM
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Jay, Thanks for your response and help.

Not sure what advance setting from thermostat you are looking for. From the IAQ install guide, I have these partial settings that seem appropriate:
172 = 1
176 = 2
180 = 0
240 = 5
250 = 5

I don't see jumpers on either the control or EIM. I'm sure it is set up to do 2nd stage as once the installer was testing machine, he disconnected the blue wire from control which he said was 2nd stage. Turned on furnace with t-stat bumped up (after the 5 minute wait time that apparently the T-stat requires), and let it run for a bit and then while it was running, reattached the wire (door control was tapped closed for the experiment). A few moments after reattaching the wire, the furnace did indeed "kickup". I really never hear this though with door on and not knowing when to spend some time in the basement sitting by the furnace esp if it was already on 2nd by the time I got down there and I wouldn't even know. Which brings up a wish... I wish there was some indicator on either the trane or honeywell when it's running 2nd stage.

I got a little confused with your post, between "Recovery Mode" and "recovery from set back". Same thing?

So, basically you think that when the furnace kicks on in morning and t-stat is all of the sudden is 10 degrees behind, due to time setting, 2nd should kick in right away. Correct?

I haven't experimented yet with the adaptive recovery mode.

Another question then, if t-stat is set at say 69 and I push it up to 70, shall I assume it should handle this degree increase entirely with 1st stage? At what point with me pushing it up at one time (meaning 2, 3, etc all at once) should it decide that 2nd is required?

Thanks for all the education on this. Wish the contractors would talk as clear.

Jerry
 
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Old 12-12-07, 09:24 PM
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Originally Posted by jerryjcp View Post
Not sure what advance setting from thermostat you are looking for. From the IAQ install guide, I have these partial settings that seem appropriate:
240 = 5
250 = 5
The two settings, 240/50 should be at 3.

I don't see jumpers on either the control or EIM. I'm sure it is set up to do 2nd stage as once the installer was testing machine, he disconnected the blue wire from control which he said was 2nd stage.
Is the blue wire on W2?
I got a little confused with your post, between "Recovery Mode" and "recovery from set back". Same thing?
Yes, in the morning, you'll the word recovery on the screen.

So, basically you think that when the furnace kicks on in morning and t-stat is all of the sudden is 10 degrees behind, due to time setting, 2nd should kick in right away. Correct?
Yes, it should if it's wired right.

I haven't experimented yet with the adaptive recovery mode.
Give it a few days to learn your home. May start an hour or so earlier to heat your home to the set point time.
Another question then, if t-stat is set at say 69 and I push it up to 70, shall I assume it should handle this degree increase entirely with 1st stage?
It may go into 2nd stage for a short time, and then goes back into 1st.

At what point with me pushing it up at one time (meaning 2, 3, etc all at once) should it decide that 2nd is required?
1˚ will fire into 2nd stage for a few sec/min.
2˚and up will stay in 2nd stage as it get near set point.

One way you can test your 1st and 2nd stage.. Go into advance settings, and at the end, screen will show "test". change the test value to 3. then far left up/down button 0 will show.

0=off
1=1st stage
2=2nd stage (may take a few sec, the inducer speed will increase, then the blower speed will speed up. You should hear the change in speed.)
 
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Old 12-13-07, 09:19 AM
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Originally Posted by jerryjcp View Post
Which brings up a wish... I wish there was some indicator on either the trane or honeywell when it's running 2nd stage.


Jerry
Like I suggested; look at your gas meter dial. I think it is the 1/2 cubic foot dial that turns pretty fast when the furnace runs. Time the revolution during different situations like when you are 1 degree off from set point and when you are 10 degrees below set point.

I realize this suggestion is not doctorial with numbers and theories and all that, but this test should not lie. You will have the answer you are looking for, one would think.

Jay,

If furnaces so easily go into 2nd stage, then under what situation are they in 1st stage for any length of time? I would have presumed they would be in 1st stage unless they can't advance the thermostat.

And do you happen to know how much efficiency of the furnace is lost by having it in 2nd stage? In 2nd stage the furnace would consume more gas, but in therory the furnace would not need to run as long, so I'm not sure what kind of trade off we have going here.

_I_ am very interested myself in these answers as I maintain a big building with giant handling units (gas furnaces/outside units) that are 2 stage and am looking for the most economical way to run the building. Like, I am wondering if it is a folly to have been setting the stats back to 50 at night (unoccupied) if this causes wasteful 2nd stage to come on and run this way up until set point, let's say.
 
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Old 12-13-07, 10:10 AM
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Jay,

I don't really understand what the IAQ 240 & 250 settings do, but I'll change to 3.

Yes, the blue is on W2 on the control.

I never see 'recovery' on the t-stat. I'm assuming cause I'm not in adaptive recovery setting??

I agree with ecman51, I didn't realize it would go into 2nd stage so easily. I assumed it would run 1st almost exclusively and then on extreme conditions, would kick into 2nd.

I thought even during morning startup, it would be cheaper to have stage 1 handle this even though it would take longer than utilizing 2nd.
 
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Old 12-13-07, 11:53 AM
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The building I take care of has many Honeywell programmable stats in it and they will say "in recovery" on the screen, during a time frame prior to the occupied set time each day, so that by occupied time, the building has reached set temp.
 
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Old 12-13-07, 01:03 PM
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Sounds like they are set to use the adaptive recovery mode and the particular t-stat is capable of displaying this info.
 
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Old 12-13-07, 07:05 PM
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Originally Posted by ecman51` View Post
Jay,

If furnaces so easily go into 2nd stage, then under what situation are they in 1st stage for any length of time? I would have presumed they would be in 1st stage unless they can't advance the thermostat.
After the temp been moved up a degree, it will go back into 1st stage after a min or two once the t-stat sees that the temp is steady. Once the temp is steady, it will run in 1st stage all time untill the stat "math" figures that it's cold out, and we are going to run 2nd stage to help the set point temp on the nose.

And do you happen to know how much efficiency of the furnace is lost by having it in 2nd stage? In 2nd stage the furnace would consume more gas, but in therory the furnace would not need to run as long, so I'm not sure what kind of trade off we have going here.
Two stage is for COMFORT. You are going to use the same amount of gas if it's running say, 30 min in 1st stage vs 15 min in 2nd stage. Longer run time provides an even temp since the air is being "changed" more in the living space.
 
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Old 12-13-07, 07:12 PM
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Originally Posted by jerryjcp View Post
Jay,

I don't really understand what the IAQ 240 & 250 settings do, but I'll change to 3.
Those two settings is CPH (Cycles per hour) on an avg, when the t-stat sees that the furnace is running 50% load, it will cycle avg 3 times an hour.... as the load increase on colder days, the run time will be longer, less cycling.
Yes, the blue is on W2 on the control.
Then 2nd stage should fire off as needed.. Make sure there is no jumper wire on the furnace's board between W1 and W2, otherwise, it going on a timer if it's wired that way.

I never see 'recovery' on the t-stat. I'm assuming cause I'm not in adaptive recovery setting??
In advance setting #530, 1=On, 0=Off. Recovery will show before your set time.. Say "Awake at 6am" furnace will come on early, the screen will show this untill 6am..
I didn't realize it would go into 2nd stage so easily. I assumed it would run 1st almost exclusively and then on extreme conditions, would kick into 2nd.
1st stage will run 90% of the time, only see 2nd stage in recovery mode, temp being bumped up at the t-stat, or extrem temp outside.

I thought even during morning startup, it would be cheaper to have stage 1 handle this even though it would take longer than utilizing 2nd.
You are going to use the same about of gas.. See my reply on the last post.
 
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Old 12-14-07, 08:07 AM
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Originally Posted by Jay11J View Post

Two stage is for COMFORT. You are going to use the same amount of gas if it's running say, 30 min in 1st stage vs 15 min in 2nd stage. Longer run time provides an even temp since the air is being "changed" more in the living space.
And this 2nd stage with the burners blasting away harder will not cause more wasted heat up the chimney? So you are certain then that in 2nd stage there absolutely is no more waste than when in 1st stage?
 
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Old 12-14-07, 11:18 AM
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Nope, as long the blower speed is set up with the spec's temp rise, you should be good either way..

Blower run slower in first stage, and faster in 2nd stage.
 
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Old 12-14-07, 11:47 AM
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Now that I've really paid attention, I can tell that 2nd stage kicks on pretty quick when the t-stat gets the wake up call in the morning. I'm not using recovery mode but might try it. Then then the temp rise gets to 2 degrees of set temp, I can tell that 2nd backs off. Rather than running it right up to set temp. I'm assuming this is so the set temp is not overrun.
Then while it is running 1st stage still 2 degrees short of set, I heard today 2nd kick back in. I guess cause the t-stat decided that it wasn't going to get there in 1st.

I suspect all day long though, while maintaining set temp it rarely it ever calls for 2nd. I'm amazed that I when I walk by the t-stat I NEVER see the actual temp below or above set.
 
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Old 12-14-07, 11:56 AM
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Yeah, the Honeywell are good stats, they are smart and it advoids the temp swing. so that's why you never see the changes unless the furnace it undersized.
 
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Old 12-14-07, 12:10 PM
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Love the new Honeywell thermostat. I have the backlight on, and I never have to squint at the display to see the current time/temp!

The one thing that the old Honeywell (1 stage only however) had that I'm going to miss, is it tracked usage for current day and previous day. Nice in summer to just see how long the A/C had to work for yesterday.
 
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Old 12-14-07, 01:06 PM
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Originally Posted by Jay11J View Post
Nope, as long the blower speed is set up with the spec's temp rise, you should be good either way..

Blower run slower in first stage, and faster in 2nd stage.
Thanks. Good. Now I can shed any guilt that building was being run inefficiently due to lack of knowledge.
 
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