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  1. #1
    Join Date
    Apr 2005
    Southern New Jersey
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    oil furnace anticipator setting (long)

    hope i'm not violating any board policy posting this here sorry for rambling.

    i have an 1200 sq ft workshop out back. it's block construction, 12' ceiling, two 10' x 10' insulated doors (read energy hog). the ceiling is insulated with the foil backed foam (1" iirc). aside from the lo R value of this stuff there was a LOT of gaps and leakage through the ceiling. in an effort to reduce oil consumption this year i got the ambition to tape all the joints and completely seal everything it definitely made a difference. years ago for heat i installed a basic rheem upflow oil furnace (model-112) which was originally shipped with a 1.0 nozzle. even with the leakage the furnace short cycled so i tried .75 & .85 nozzles. i ended up getting a box of .85s (change them every year). i have some ductwork around the top of the walls leaving the plenum to try to balance the heat some. now that i tightened up the building it seems it's short cycling somewhat again which i know is bad all way around. i decided to check the anticipator and found it set around .4 amps which i was surprised because the furnace manual calls for .1 and i'm pretty anal about stuff so i don't know why it was set there. the thermostat is a plain jane honeywell CT87A.

    so the furnace manual calls for .1 amp, the controller in the furnace has .2 amp printed on it and the thermostat instructions say if you set it too low it will burn it out. the low current draw end has "longer" stamped but there's an arrow pointing towards the higher current end giving the impression that moving it in that direction would increase run time. i understand that the anticipator artificially heats the thermostat and in my mind increasing current draw would shorten the run time. it also says you can do a current draw test which i will but why would you want to set it to a specific point when that might not be best for a given installation?

    now that i've embarrassed myself and you guys that do this for a living are ROFLYAO what am i missing here? am i just stupid?


  2. #2
    Join Date
    Jun 2005
    SW Wisconsin
    Post Likes
    Forget using that worthless t-stat.

    Get a good programmable stat, one that you can set the swing or cycles per hour or actual temp on/off differential.

    I really like the low cost LUXPRO PSP511LCa t-stat with a 1 to 9 swing setting.

    With a propane furnace, with a 9-setting I can get 19 to 20 minute runtimes with a 4-F swing; at 3-F below t-stat setting it kicks on & runs to 1-F above t-stat setting of 66-F. I feel too warm at the end of the 67-F; it is very temp-precise & consistent even at fairly variable outdoor temps.

    In single digit weather it cycles around once an hour; with my 57,500-BTUH Output furnace. I have a two story farm house with a lot of windows & several doors with glass in them, & a basement in cold SW WI.

    I dress warm & am very comfortable at this low temp setting both day & night.

    These programmable t-stats greatly increase energy use efficiency especially with the long runtimes many Oil furnaces have before the blower even kicks on!
    Last edited by udarrell; 12-13-2011 at 08:32 AM. Reason: programmable t-stats greatly increase energy use efficiency

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