garage furnace run time

[icefisherman]

I have a big max 45k btu heater in a 625 sq foot garage. It has 3 1/2 insulation in the walls and 6 in in the ceiling. I have a ceiling fan I run all the time on medium. When I am not out there i keep my thermostat at 42 degrees. When my furnace kicks on it only runs for a minute or two than it reaches the right temp and shuts off. Is that too short of a cycle time? How long does yours take to run a cycle time? It doesnt even seem like enough time to evaporate the condensation in the vent. I have a honeywell basic thermostat on the same wall as my heater but on the opp. end of the garage.

 

[cowboyjosh]

is your heater louvier things adjusted so the heater isn't blowing a stream of hot air directly toward the thermostat? If so your heater may be a wee bit oversized. Have you timed the cycle time? Sometimes a minute or two is really closer to 10 minutes.

 

[Mike007]

I have a big max 45k btu heater in a 625 sq foot garage. It has 3 1/2 insulation in the walls and 6 in in the ceiling. I have a ceiling fan I run all the time on medium. When I am not out there i keep my thermostat at 42 degrees. When my furnace kicks on it only runs for a minute or two than it reaches the right temp and shuts off. Is that too short of a cycle time? How long does yours take to run a cycle time? It doesnt even seem like enough time to evaporate the condensation in the vent. I have a honeywell basic thermostat on the same wall as my heater but on the opp. end of the garage.

Yes, 45K is most likely oversized. An extremely short run cycle with a room temp of 42* can ruin a heater due to condensation. You could try adjusting the heat anticipator if you have a non digital stat, or the cycle rate if it's digital. This will give you a larger temp swing, but it will make it run longer. You could set the stat at a higher temp too.

 

[icefisherman]

I do have a nondigital thermostat how do u adjust the heat anticiapator its just a plain honeywell turn dial one?

 

[Mike007]

If you pop the outer ring off, you will see a little copper arrow thingy towards the bottom with some small numbers under it. At the end of the numbers it will say "longer" with an arrow. If you slide the copper arrow thingy towards longer it will give you a longer heat on/off cycle.

 

[icefisherman]

I took the ring off and mine doesnt have an adjustment must be too cheap.

 

[Mike007]

I took the ring off and mine doesnt have an adjustment must be too cheap.

If it's the common round Honeywell, Ive never seen one without a heat anticipator.

 

[Keith_MN]

I solved my short cycle problem by installing one of these: http://www.rancoetc.com/ranco-etc112000000-p-102.html

You can adjust the differential set point up to 30 degrees.

Honeywell, White Rodgers and Johnson controls all make something very similar to the Ranco.

When working in the garage you can narrow the differential to make it more comfortable. When just trying to keep it above freezing you could stretch it out for longer run times.

-Keith

 

[bochnak]

Mine has that adjust-ability. I think I paid $15 for mine. Only gripe is lowest temp is 50.

 

[oldgoaly]

Mine has that adjust-ability. I think I paid $15 for mine. Only gripe is lowest temp is 50.

IF it has a mercury switch (glass tube) mount it crooked on the wall, it will think it is warmer/colder double check which way the glass tube moves. about an 1/8-1/4 will put you in the 40's for lows. If you have A/C on it it effect the a/c temp also.
honeywell round w/o a anticipater? haven't seen one? made in china maybe?

 

[icefisherman]

I think i may have a bad thermostat. I noticed it kicks on or off when the temp only moves by a half a degree. So that would make sense for the really short cycle time. Someone was telling me honeywell has a cheap digital thermomstat that goes down to 40 over at the depot.

 

[Chetter]

If you pop the outer ring off, you will see a little copper arrow thingy towards the bottom with some small numbers under it. At the end of the numbers it will say "longer" with an arrow. If you slide the copper arrow thingy towards longer it will give you a longer heat on/off cycle.

I came across this thread and I went out and checked my Honeywell t-stat and just as you said I found the adjustment you talked about. Mine says longer to the right side with an arrow pointing to the left and there is a copper arrow looking piece that slides and I moved mine to where it says what looks like 1.2 which is nearly to the bottom of this slide which wasn't much of an increase from where it originally was set at. I set my temp at 48* which kicks on at about 47* and turns off at 51-52*, does that seem right? Run time is just under 10 minutes, does that seem short or about right?

 

[Mike007]

I came across this thread and I went out and checked my Honeywell t-stat and just as you said I found the adjustment you talked about. Mine says longer to the right side with an arrow pointing to the left and there is a copper arrow looking piece that slides and I moved mine to where it says what looks like 1.2 which is nearly to the bottom of this slide which wasn't much of an increase from where it originally was set at. I set my temp at 48* which kicks on at about 47* and turns off at 51-52*, does that seem right? Run time is just under 10 minutes, does that seem short or about right?

The longer the cycle the better for efficiency and wear and tear on the equipment. Of coarse with a longer cycle you get a larger temp differential which at a point can be uncomfortable for some people. A good starting point for setting a heat anticipator, which is part of what determines the length of the cycle, would be to match the control circuit amp draw to the numbers on the scale under the copper arrow thingy. Some equipment will have this amp draw in its literature or on the name plate. Or it can be measure with an AC milliamp meter.

 

[icefisherman]

Well I went to the depot and scored big. I got a rite temp digital thermostat that goes down to 35* and it had a thing to control the temp swing up to 2 degrees on it. It was orginally $47.47 i got it for $11.03! It was a open box and discontinued model. I hooked it up and it works. Now I just have to wait for it to adjust to my garage temp to really mess with the temp swing setting to see how good its gonna work.