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Thread: Setting up my thermostat, how often does your furnace run?

  1. #1
    I race my Neon, but commute my EVO. neonglh's Avatar
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    Default Setting up my thermostat, how often does your furnace run?

    So, my house is not perfectly insulated, but it's not bad. House is wrapped in Tyvec, all new energy efficient windows and doors, and the attic has some insulation in it. My furnace is about 8 years old, and works well (forced air).

    I had an old style thermostat until last night, when I bought this guy:



    I set it up using mostly the default settings, so it does 62 degrees at night, 68 degrees when I am home, and I set it to run on a 20 minute cycle (3 times per hour). After fiddling around with it, I noticed that it did come on every 20 minutes, but it stayed within about 3 degrees of the set temperature. The house would warm up to about 69 - 70 degrees, and then within 20 minutes, it would get down to 67 or so, where it would come back on again for about 5 - 8 minutes.

    So my question, is this the best way to do this? It seems like the furnace is running quite a bit, but the temperature never drops that much. The house is very comfortable, but I don't want to get slapped with a HUGE energy bill this year. Last year, with the old thermostat (but keeping it cold as hell) my bills were between 60 and 80 a month for gas (heat and hot water).

    So my question, anything I should change on my setup to make it more efficient, and, how many times per hour / how long does your furnace run?

    Thanks!

    --mark

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    Lifetime User boardjnky4's Avatar
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    This is all a guessing game. Some people will argue different points of how to set it up, but in the end, you may just want to play with it for different months and see what your bill ends up looking like. Compare it to last year's if the weather has been similar.

    Also, I have the same thermostat. How did you set it so that it runs on 20 minute intervals?

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    In the setup, there is 5 intervals you can set (30 minutes, 20 minutes, 15 minutes, 12 minutes and 10 minutes). The 20 minute one was for furnaces 90% efficient and higher, so I selected that one.
    Last edited by neonglh; 10-05-2010 at 09:46 AM.

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    Climbin in ya window... travisn's Avatar
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    Your thermostat really wont change anything in regards to how efficient your house and furnace are. It just makes it so you dont have to think about turning it down when you leave and go to bed. Never heard about it running on 20 min cycles. All the ones I have used run the furnace until the temp is reached then stays off until it gets back to the temp i set it at.

    Have you considered moving the thermostat?

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    Quote Originally Posted by travisn View Post
    Your thermostat really wont change anything in regards to how efficient your house and furnace are. It just makes it so you dont have to think about turning it down when you leave and go to bed. Never heard about it running on 20 min cycles. All the ones I have used run the furnace until the temp is reached then stays off until it gets back to the temp i set it at.

    Have you considered moving the thermostat?
    Every thermostat runs on cycles. If after 2 minutes the temperature falls below the target, it won't run again until the next 20 minute cycle. It's to make sure you don't run it non-stop.

    I am trying to figure out how often other people's furnaces are running, so I can gauge if mine running a 3 times per hour is normal.

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    Lifetime User boardjnky4's Avatar
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    Quote Originally Posted by travisn View Post
    Your thermostat really wont change anything in regards to how efficient your house and furnace are. It just makes it so you dont have to think about turning it down when you leave and go to bed. Never heard about it running on 20 min cycles. All the ones I have used run the furnace until the temp is reached then stays off until it gets back to the temp i set it at.

    Have you considered moving the thermostat?
    By properly setting up your thermostat, you can save up to 30/month on energy.

    ---------- Post added at 09:47 AM ---------- Previous post was at 09:47 AM ----------

    Quote Originally Posted by neonglh View Post
    In the setup, there is 5 intervals you can set (30 minutes, 20 minutes, 15 minutes, 12 minutes and 10 minutes). The 20 minute one was for furnaces 90% efficient and higher, so I selected that one.
    I need to go back and look at this

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    President: Big Cat Club newman's Avatar
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    Lol, my furnace pretty much turns on in november and doesn't turn off til april.
    Icecream Paintjob

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    GIMME DA COOKIES JayS's Avatar
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    Quote Originally Posted by neonglh View Post
    The house would warm up to about 69 - 70 degrees, and then within 20 minutes, it would get down to 67 or so, where it would come back on again for about 5 - 8 minutes.
    Did you have a window open or something? 3 degrees in 20 minutes is a lot of temperature loss when it's 50 outside. On a 0 degree windy day your furnace will probably be running constantly.

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    That's what I'm trying to figure out, I have nothing to gauge it by. I believe it was in the 40's last night, but it was 3 degrees in 20 minutes. I don't have any windows open, but I may have to hunt down more drafts / add more insulation in the attic

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    Climbin in ya window... travisn's Avatar
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    Quote Originally Posted by neonglh View Post
    Every thermostat runs on cycles. If after 2 minutes the temperature falls below the target, it won't run again until the next 20 minute cycle. It's to make sure you don't run it non-stop.

    I am trying to figure out how often other people's furnaces are running, so I can gauge if mine running a 3 times per hour is normal.
    Seems like you answered your own question. 60/20 = 3 cycles per hour. Of course it could be less if your house had any sort of thermal efficiency. Did you ever have anyone do one of those "home energy assessments" that can show where you are losing energy?
    Last edited by travisn; 10-05-2010 at 10:10 AM.

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    BoaterFry Fry's Avatar
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    #1 - Jay's right that's a lot of heat to lose in just 20 minutes.

    #2 - Take that thermostat back and buy a model that works properly. It should work off a temperature deadband not a time interval. That's retarded. That 3 degree drop in 20 minutes when it's 50* out is going to be a 10* drop when it's cold out. Your house is going to be cycling from 60-70 all winter, or else running the furnace when it doesn't need to.

    They're supposed to run the furnace until you hit X temperature and then automatically restart the furnace when the temperature drops to X-Y, thereby maintaining a temperature of (for example) 66-68* when your setpoint is 68*.

    "PS - Dear Fry, We miss you. Drinkers anonymous"

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    Lifetime User boardjnky4's Avatar
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    Quote Originally Posted by Fry View Post
    #1 - Jay's right that's a lot of heat to lose in just 20 minutes.

    #2 - Take that thermostat back and buy a model that works properly. It should work off a temperature deadband not a time interval. That's retarded. That 3 degree drop in 20 minutes when it's 50* out is going to be a 10* drop when it's cold out. Your house is going to be cycling from 60-70 all winter, or else running the furnace when it doesn't need to.

    They're supposed to run the furnace until you hit X temperature and then automatically restart the furnace when the temperature drops to X-Y, thereby maintaining a temperature of (for example) 66-68* when your setpoint is 68*.
    That is what I thought as well. I have the same thermostat, and you set it by time of day and target temperature. I never saw an interval option when setting it up.

    I've had several different types of programmable thermostats and never have seen any interval for how long it's supposed to run for.

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    Focus people The question was how often does your furnace run, and it seems like for most it's less than 3x per hour. Is that true? That will give me the advice I need to go forward with my home energy audit.

    It seems like my heat is leaking out too quickly, but I still want to compare the furnace heat cycles to you all, so that I can compare.

    --mark

    ---------- Post added at 10:17 AM ---------- Previous post was at 10:16 AM ----------

    Quote Originally Posted by boardjnky4 View Post
    That is what I thought as well. I have the same thermostat, and you set it by time of day and target temperature. I never saw an interval option when setting it up.

    I've had several different types of programmable thermostats and never have seen any interval for how long it's supposed to run for.
    It's now how long it runs for, it's the minimal interval between heat cycles. It's on like page 2 of the instructions!

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    Climbin in ya window... travisn's Avatar
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    Quote Originally Posted by Fry View Post
    They're supposed to run the furnace until you hit X temperature and then automatically restart the furnace when the temperature drops to X-Y, thereby maintaining a temperature of (for example) 66-68* when your setpoint is 68*.
    thats what I thought

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    That is how all thermostats work! The heat cycles thing is the minimal time between cycles. It's 2 variables that must be present in order to have the heat come on. 1. the heat must be below the threshold 2. the heat cycle time must be past due. It's a feature built into modern thermostats.

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    Lifetime User boardjnky4's Avatar
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    Quote Originally Posted by neonglh View Post
    That is how all thermostats work! The heat cycles thing is the minimal time between cycles. It's 2 variables that must be present in order to have the heat come on. 1. the heat must be below the threshold 2. the heat cycle time must be past due. It's a feature built into modern thermostats.
    Please point out this interval setting in the manual linked http://customer.honeywell.com/techli.../69-2326ES.pdf

    What page?

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    BoaterFry Fry's Avatar
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    No that's not how all thermostats work.

    "PS - Dear Fry, We miss you. Drinkers anonymous"

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    GIMME DA COOKIES JayS's Avatar
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    Quote Originally Posted by neonglh View Post
    Focus people The question was how often does your furnace run, and it seems like for most it's less than 3x per hour. Is that true? That will give me the advice I need to go forward with my home energy audit.
    Mine varies depending on the weather. Right now with the upper 40's and lower 50's with light winds I'd say less than once per hour. And I haven't even taken the screen out of my storm door yet.

    On a really cold and windy winter night it's kicking on a lot. Every 20 minutes or so sounds about right but I've never really timed it. As Fry said though, my programmable thermostat works on temp, not time. This one specifically:
    http://www.lowes.com/pd_39501-74493-...quantity_sold|

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    Quote Originally Posted by boardjnky4 View Post
    Please point out this interval setting in the manual linked http://customer.honeywell.com/techli.../69-2326ES.pdf

    What page?
    It's in the quick-setup guide, not the operating manual. What is the page where you found that, I can point it out in the other one.

    But, that doesn't really help answer my question at all. Can you guys please let me know how many times per hour your furnace kicks on. That is all that I want to know

    ---------- Post added at 10:51 AM ---------- Previous post was at 10:50 AM ----------

    Quote Originally Posted by JayS View Post
    Mine varies depending on the weather. Right now with the upper 40's and lower 50's with light winds I'd say less than once per hour. And I haven't even taken the screen out of my storm door yet.
    Thanks, this is what I was looking for

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    GIMME DA COOKIES JayS's Avatar
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    I'll pay more attention tonight when I get home. I think it's set to go from 65 to 70 at 4pm so once it's got past that initial warmup I'll keep track of how often it cycles.

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    I appreciate it! I am hoping that I can get this all dialed in, and fix any leaks / drafts before the winter hits, so I can stay cozy all winter

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    Is your house empty?lol Sounds like you need more mass to stabilize the temps. You know kind of like if you keep a case of beer in your fridge it runs less often. lol
    Last edited by Blue Eyed Devil; 10-05-2010 at 11:52 AM.
    "When governments fear the people, there is liberty. When the people fear the government, there is tyranny."

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    I race my Neon, but commute my EVO. neonglh's Avatar
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    Quote Originally Posted by Blue Eyed Devil View Post
    Is your house empty?lol Sounds like you need more mass to stabilize the temps. You kind of like if you keep a case of beer in your fridge it runs less often. lol
    Hah, I can fill my house with beer

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    Lifetime User LUKE_L's Avatar
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    I put the heat shrink plastic on all my windows and door seal on my non-used winter doors. Brick house with insulated crawl space. My house stays a comfortable 68-70F when I am up and about and a mild 64-66F when I am gone. Dropping your temp more than 5 during the winter season, IMO, is pointless. Let me rephrase; It is pointless if your house sucks really hard and you have shitty insulation, single pane windows, and the bitch can't close the fucking front door all the way when she gets her skank ass out the door in the morning so you wake up to frosted nuts or snow all over your floor upon your return.

    Instead of trying to save money on how many times your furnace kicks on you should survey all exterior openings and properly seal them.

    The year before last I played the thermostat game and my heat kicked on about 3 times an hour when I wanted to be toasty. I sealed up my shit and my heat kicks on maybe once every 1.5 hours.

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    Lifetime User boardjnky4's Avatar
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    Quote Originally Posted by neonglh View Post
    It's in the quick-setup guide, not the operating manual. What is the page where you found that, I can point it out in the other one.

    But, that doesn't really help answer my question at all. Can you guys please let me know how many times per hour your furnace kicks on. That is all that I want to know

    ---------- Post added at 10:51 AM ---------- Previous post was at 10:50 AM ----------



    Thanks, this is what I was looking for
    OK, I see that now. Looks like for a Gas unit, there are really only 2 options.

    http://customer.honeywell.com/techli.../69-2327ES.pdf

    ---------- Post added at 12:53 PM ---------- Previous post was at 12:27 PM ----------

    Hey man, check out this thread on hvac-talk...seems like some really good info if you read between the lines on the specific issue

    http://hvac-talk.com/vbb/showthread.php?t=115656&page=2

    example:

    A 90%+ furnace should always be 3, as the warm up time makes it inefficient to run at 5. An 80% furnace can operate at either setting...5 will give you slightly less temperature variation in your house, 3 will provide you with slightly more efficiency (and slightly longer equipment life).

    For most 80% applications, a setting of 3 will be OK, but I would recommend talking with your contractor and make sure there isn't any warranty issues with the manufacturer. Getting into installer setup can lead to issues for DIY'ers, as changing other settings can quickly lead to problems that could turn out costly.

    ---------- Post added at 12:54 PM ---------- Previous post was at 12:53 PM ----------

    Quote Originally Posted by Fry View Post
    No that's not how all thermostats work.
    Info from hvac-talk (from link I posted)

    ---
    In the stat world, there are a few different ways to control temperature.

    1. "Droop" control - this is where the thermostat will turn on the equipment after the room temperature has "drooped" a certain amount. For instance, if the set point is 70 degrees, the stat will switch on the equipment when the temperature gets to 69.5 degrees or something...

    2. "Droopless" control - this is how the Honeywell stat you have works. It takes into consideration the CPH setting, the P+I algorithm (essentially an integral that takes into consideration the time and temperature away from the set point) and the 'thermal characteristics' of your house. The thermal characteristics of your house are "learned" in the stat and used to develop 'heat ramps' that tells the stat when to turn the equipment on and off.

    When you add multiple stages into the mix, the Honeywell stat will create multiple heat ramps and essentially calculate when the equipment is running at 90% (a somewhat simple explanation of a very complex process). As soon as this condition is met, the stat will upstage to the next heat or cool stage. This is where you are truly losing the efficiency of your system, as the single stage stat has no concept of upstaging, the equipment simply upstages after a certain amount of time, even if the first stage would have gotten you to your setpoint (and saved you money). A multi-stage stat solves both the "upstage" issue you have and the excessive cycling you now have...

    ---

    Some work that way, some don't

    gosh, another good post on heat cycle http://hvac-talk.com/vbb/showpost.ph...1&postcount=28
    Last edited by boardjnky4; 10-05-2010 at 01:04 PM.

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