You dont ever use a fuel burning heater or generator in the house . The Carbon Monoxide it gives off will kill you
Furnace keeps running almost non-stop?
- Thread starter Jdeere562
- Start date
It's running nonstop because it's zero degrees out
Correct.
What is the BTU rating of the unit?
How many square feet is it heating?
What is the fuel source?
Bingo! Actually folks, I was just being sarcastic and pulling your legs, on the cold weather here!
Bored and staying inside today. Hope your weather is warmer than mine, and you all stay safe!
I've timed mine in the past because I wondered the same thing. A 75% duty cycle for my furnace seems to me like a lot of on/off events. 
As a side note, I went for a walk last night after dinner before the alleged storm and my neighbours A/C unit was on 
. I stopped in my tracks wondering to myself this can't be. I took three steps back and sure enough the condenser fan was on and a block of ice was protruding through the grille it had been running so long.
As a side note, I went for a walk last night after dinner before the alleged storm
and my neighbours A/C unit was on . I stopped in my tracks wondering to myself this can't be. I took three steps back and sure enough the condenser fan was on and a block of ice was protruding through the grille it had been running so long. That's normal when it gets that cold . Is this the first winter living there ?
do you have a thermometer in the room with your thermostat? The furnace won't shut off if the thermostat doesn't tell it to. Is it cooler or warmer in the house?
I have seen our own house struggle when it's below 0F with this Iowa wind, our furnace will run every 20 - 30 minutes. Time to buckle down for a couple days. We haven't had this type of weather in a couple years so who knows what
is gonna break... Just my $0.02
we did this on our old furnace and it really helped keep the house balanced. The new furnace has a 2 stage blower which is even nicer. It blows at a lower speed all the time unless the thermostat commands heating or cooling.
Just my $0.02
If the room temperature near the thermostat is not getting up to your thermostat setting , your furnace could be undersized for the workload placed on it or you have a poorly insulated home where your heat is escaping , many air leaks and the furnace simply cannot keep up..
I always go by the coldest weather and running 90% burner time. My old oil furnace was good for -25F below and wind. Not so much the new smaller propane, at 80kbtu it would run almost all the time. It's main purpose is keeping the crawlspace above freezing during the worst of times. I use a 20k btu propane wall furnace almost all the time.
I only do this in the summer when the A/C is on. I find there's a cold draft in the house (20 YO) when the fan runs continuously in the winter.
How good is the insulation in your house. Insulation makes a big difference.Bingo! Actually folks, I was just being sarcastic and pulling your legs, on the cold weather here!
Bored and staying inside today. Hope your weather is warmer than mine, and you all stay safe!
I'm guessing it is normal, when it gets forty below with strong winds mine bearly shuts off. If it isn't size right it may not hold your perferred temperature. You may need to plug in an electric heater to assist??
Glad I have water filled radiators, no drafts, no noise, no excessive drying of the air. and with a water temperature of 35°C the system manages to keep the house comfortable down to about 20F (what we experienced this week, coldest so far this winter)
It's time to bring in the wood... And start shoveling it into the wood stove!Bingo! Actually folks, I was just being sarcastic and pulling your legs, on the cold weather here!
Bored and staying inside today. Hope your weather is warmer than mine, and you all stay safe!
Ha! You made my day by that comment!!! Stay warm and safe yourself!Bingo! Actually folks, I was just being sarcastic and pulling your legs, on the cold weather here!
Bored and staying inside today. Hope your weather is warmer than mine, and you all stay safe!
dnewton3
Staff member
A few things to know ....
As far as the thermostat goes, the power is typically taken from the 24VAC transformer in the furnace unit. If the T-stat indicates it's on (has power at face), then there's a high probability it's working right. If it has batteries, that's only for backup (unless it's a full "battery only" unit). Either way, if the display is working, the issue isn't with the t-stat most likely. T-stats either work or they don't; there's no in-between.
What most folks don't understand is that heating (and cooling) is a function of thermal transfer rates and capacity. Furnaces are rated in BTUs, but that's actually a nominal value as stated on the rating label. The house will gain or lose heat at a rate of "X" BTUs per hour, and the system has to be able to overcome that max rate of loss (or gain, when talking about cooling).
When the home is built, the HVAC guys are supposed to do a thermal load calculation (for heating and cooling, but we're only going to talk about heating for this thread). They will need to know a few things to properly size the equipment:
- the ductwork should be properly sized to serve the house (this is one of the constraints that often hinders HVAC performance)
- what is the thermal loss rate?
- what is the desired temp delta to hold? (that delta is simply the difference between the set temp inside and the temp outside)
As for the ductwork, there's not much one can do after the house is built; it's either sized properly or not. If it is undersized, it may not matter in moderate temps because the rest of the system can overcome the deficiency by simply running a bit longer. But at the extremes of temps (uber cold or stupid hot outside), then the undersized ductwork can hinder the ability of the equipment to do its job. Again; not much one can do after the fact. This is just for knowledge.
Regarding the thermal loss, this is where they calculate the loss/gain factors based on type of siding, type and number of windows, insulation value in walls and attic, etc. If the HVAC guy was good, he did a thorough calculation and didn't just wing it. This loss rate, and the info below, combine to tell you what size furnace is needed.
The delta T topic boils down to this ... What temp differential can the system maintain when at full run (operates non-stop)?
Examples:
- Let's assume your system can sustain a 70degF delta (inside to outside)
- Let's also assume you set the T-stat to 70F (you want it to maintain 70 deg in the house)
1) Now say it's 30 degF outside. That is a 40 degF delta (70-30=40); well within the max capacity 70F it can sustain at full-run (non-stop run). So the furnace will "cycle" on/off to maintain the 30 deg delta.
2) as it gets colder, let's say it drops to 10F outside (still t-stat at 70F inside). Now the furnace delta (70F-10F=60F) is larger; it needs to run a lot longer to maintain that same 70F inside; it's operating nearly at max capacity and will run "most" of the time per hour (maybe 55 of the 60 minutes).
3) once it gets to be -10F outside, the max that furnace can hold would be 70F(the max capacity delta it was sized for) above the outdoor ambient; hence it could hold the house at 60F inside with the furnace running non-stop.
If it's -10F outside and you want it to be 70F inside, it would take a system capacity "X" BTUS to hold that 80F delta, and still "maintain" that 70F inside. And that would only be true if the ductwork is right (which it probably isn't).
OP - I cannot tell you why your system isn't keeping up, but I suspect it's a function of all three issues. It's not uncommon when homes are built to have the ductwork undersized (the builders cheap out to save money ...). And I can't say if the transfer rate calc's are correct. Nor do we know what the dT value is when they did the capacity calcs. Sometimes you can over-cap a system a small bit to make up for a crappy ductwork system; but only maybe by 5% or so.
But the reality is that, unless you have a well engineered and fully capacitized system, your furnace will indeed run non-stop when it's really cold outside.
As far as the thermostat goes, the power is typically taken from the 24VAC transformer in the furnace unit. If the T-stat indicates it's on (has power at face), then there's a high probability it's working right. If it has batteries, that's only for backup (unless it's a full "battery only" unit). Either way, if the display is working, the issue isn't with the t-stat most likely. T-stats either work or they don't; there's no in-between.
What most folks don't understand is that heating (and cooling) is a function of thermal transfer rates and capacity. Furnaces are rated in BTUs, but that's actually a nominal value as stated on the rating label. The house will gain or lose heat at a rate of "X" BTUs per hour, and the system has to be able to overcome that max rate of loss (or gain, when talking about cooling).
When the home is built, the HVAC guys are supposed to do a thermal load calculation (for heating and cooling, but we're only going to talk about heating for this thread). They will need to know a few things to properly size the equipment:
- the ductwork should be properly sized to serve the house (this is one of the constraints that often hinders HVAC performance)
- what is the thermal loss rate?
- what is the desired temp delta to hold? (that delta is simply the difference between the set temp inside and the temp outside)
As for the ductwork, there's not much one can do after the house is built; it's either sized properly or not. If it is undersized, it may not matter in moderate temps because the rest of the system can overcome the deficiency by simply running a bit longer. But at the extremes of temps (uber cold or stupid hot outside), then the undersized ductwork can hinder the ability of the equipment to do its job. Again; not much one can do after the fact. This is just for knowledge.
Regarding the thermal loss, this is where they calculate the loss/gain factors based on type of siding, type and number of windows, insulation value in walls and attic, etc. If the HVAC guy was good, he did a thorough calculation and didn't just wing it. This loss rate, and the info below, combine to tell you what size furnace is needed.
The delta T topic boils down to this ... What temp differential can the system maintain when at full run (operates non-stop)?
Examples:
- Let's assume your system can sustain a 70degF delta (inside to outside)
- Let's also assume you set the T-stat to 70F (you want it to maintain 70 deg in the house)
1) Now say it's 30 degF outside. That is a 40 degF delta (70-30=40); well within the max capacity 70F it can sustain at full-run (non-stop run). So the furnace will "cycle" on/off to maintain the 30 deg delta.
2) as it gets colder, let's say it drops to 10F outside (still t-stat at 70F inside). Now the furnace delta (70F-10F=60F) is larger; it needs to run a lot longer to maintain that same 70F inside; it's operating nearly at max capacity and will run "most" of the time per hour (maybe 55 of the 60 minutes).
3) once it gets to be -10F outside, the max that furnace can hold would be 70F(the max capacity delta it was sized for) above the outdoor ambient; hence it could hold the house at 60F inside with the furnace running non-stop.
If it's -10F outside and you want it to be 70F inside, it would take a system capacity "X" BTUS to hold that 80F delta, and still "maintain" that 70F inside. And that would only be true if the ductwork is right (which it probably isn't).
OP - I cannot tell you why your system isn't keeping up, but I suspect it's a function of all three issues. It's not uncommon when homes are built to have the ductwork undersized (the builders cheap out to save money ...). And I can't say if the transfer rate calc's are correct. Nor do we know what the dT value is when they did the capacity calcs. Sometimes you can over-cap a system a small bit to make up for a crappy ductwork system; but only maybe by 5% or so.
But the reality is that, unless you have a well engineered and fully capacitized system, your furnace will indeed run non-stop when it's really cold outside.
but a gas stove top won't?
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