Gas and Oil Home Heating Furnaces - Wacky run times, thermostat ?
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Hiskid1973
01-25-08, 12:30 AM
I have a Miller oil furnace in my mobile home..I notice the burner runs for different periods even with the same outside temp..One time(say it's 20 deg.) it will run for three minutes and the stat is satisfied and the blower will shut off a few minutes later and it repeats the cycle every 20 min...Then maybe a week later or so with the same temp the furnace will run for 6 minutes till it's satisfied and take 30 minutes till it comes back on..This is an honeywell electronic setback stat I got at Lowe's . It is only 2 years old and used to heat and cool..Thanks for the help..God Bless..K
Jay11J
01-25-08, 06:56 AM
sounds like the Cyles per Hour(CPH) needs to be changed.
Go into the set up menu of the t-stat, and change the setting from 5 to 3 (Setting my be called "System Type", or "Cycles per Hour" (CPH).
Go into the set up menu of the t-stat, and change the setting from 5 to 3 (Setting my be called "System Type", or "Cycles per Hour" (CPH).
ecman51`
01-25-08, 05:41 PM
I am quite familiar with mobile homes. Is your mobile home some older one that leaks like a sieve?, or is it a better newer one, that has the pitched roof, better insulated,. windows that resemble a regular house, etc. What thickness walls is it?
Two different 20 degree days can be very different from each other in how the cold gets into the mobile home. Wind or no wind and wind direction, depending on your doors and windows and outdoor landscaping/bushes-trees, etc., and clouds or sun can really cause a drastic change in cold infiltration rate.
To me, anyway, it seems like either you have a sporadic stat malfunction that would have to be allowing the stat to overexceed the set temp, to be able to explain how the furnace flame would remain ON longer, yet remain OFF longer as well, under similar conditions outside.
If your mobile home were getting colder inside, due to what I mentioned above, if one 20-degree day was letting more cold in than another 20-degree day, and IF the stat were behaving normal and truly shutting off at set point (as opposed to exceeeding it), - THEN, the time the furnace comes back on should actually be for a SHORTER period of time, if the trailer were getting colder inside.
The bottom-line question to my getting-lengthy, perhaps confusing post, is - WHY is the stat, under similar conditions (so you claim) varying cycle times, and NOT cycling either shorter - or longer - each and every time? But rather, changes it's mind how to do it.
You might want to use some other reliable thermometer and see that when your furnace goes off, that it is going off at the same temperature all the time. If it truly does, something doesn't make sense as to how it can RUN longer and stay OFF longer, also, - if you really think about this one. (But it CAN be explained that way IF the thermometer gets hotter - hotter than set temp - on those occasions, proving that you must be having variations going on in the stat with it's 'swing'.)
Regarding what Jay is saying about the cycle times: That still is not addressing, in my mind anyway, the ununiformity of the cycle times. Unless of course, as I stated, those 20 degree days are actually quite different from each other. identical type of 20- degree days.
Two different 20 degree days can be very different from each other in how the cold gets into the mobile home. Wind or no wind and wind direction, depending on your doors and windows and outdoor landscaping/bushes-trees, etc., and clouds or sun can really cause a drastic change in cold infiltration rate.
To me, anyway, it seems like either you have a sporadic stat malfunction that would have to be allowing the stat to overexceed the set temp, to be able to explain how the furnace flame would remain ON longer, yet remain OFF longer as well, under similar conditions outside.
If your mobile home were getting colder inside, due to what I mentioned above, if one 20-degree day was letting more cold in than another 20-degree day, and IF the stat were behaving normal and truly shutting off at set point (as opposed to exceeeding it), - THEN, the time the furnace comes back on should actually be for a SHORTER period of time, if the trailer were getting colder inside.
The bottom-line question to my getting-lengthy, perhaps confusing post, is - WHY is the stat, under similar conditions (so you claim) varying cycle times, and NOT cycling either shorter - or longer - each and every time? But rather, changes it's mind how to do it.
You might want to use some other reliable thermometer and see that when your furnace goes off, that it is going off at the same temperature all the time. If it truly does, something doesn't make sense as to how it can RUN longer and stay OFF longer, also, - if you really think about this one. (But it CAN be explained that way IF the thermometer gets hotter - hotter than set temp - on those occasions, proving that you must be having variations going on in the stat with it's 'swing'.)
Regarding what Jay is saying about the cycle times: That still is not addressing, in my mind anyway, the ununiformity of the cycle times. Unless of course, as I stated, those 20 degree days are actually quite different from each other. identical type of 20- degree days.