Setting back a Thermostat

[TractorJeff]

In the Shop I set the Thermostat back to 53 degrees when I am not out there. I turn it up to 62 in the morning about 2 hours prior to start of Work.
One 10 by 12 Insulated Door facing South - Warm Wind, One 10 by 10 Insulated Door facing West - Cold Wind.
Approximately 975 sqft with a continuous run Ceiling Fan, R19 Walls, R38 Ceiling.
Seems like the 50K Big Maxx Furnace runs quite a bit - 3 to 4 Heat Cycles per Hour.
Does this seem reasonable?
Propane use is slightly less than a Gallon a Day doing set back.
As I am working out there everyday would it make more sense to only Set Back 5 Degrees verse the 10 Degrees I am currently doing?
There is close to 20 tons of Tractors in there currently which would hold heat better with less Set Back in my opinion.
Many days the Overhead Doors are never opened.

 

[bmwpowere36m3]

Setbacks don't always save on fuel. Generally the longer the setback the more the savings.

Sometimes you just need to try and see... it would likely take a full season to determine. Ideally you track your usage with daily outdoor temps (heating degree days), as colder days will obviously use more fuel. So, any savings you see... are they simply because it was "warmer" overall, or did you in fact save fuel.

 

[yeldogt]

gallon a day seem reasonable ... good actually.

I'm doing twice your sf with a 38k heater ..... you are getting a bit of short cycle ... but by no measure excessive -- unless it's only running 5min.

As BMW mentioned .... it really is a test to see how the different setback work out. Just have to try and see what works. I keep mine a bit warmer and try and keep the space just above 60 all the time. I'm not all bundled up and doing physical stuff in my space

 

[TractorJeff]

Set back to 53 is 12 to 13 hours, Thanks to Covid.
Last year it was approximately the same Fuel usage but less Heating days where the Temperature was turned up above 53 degrees. (Saturday, Sunday and some evenings)

 

[yeldogt]

A simple run timer would give you an idea --

How much does the system run over a week at given set points -- with an outdoor temp.

 

[Bert_]

I had some issue with my house furnace short cycling. no matter the settings I couldn't get the digital thermostat to run less than 3 to 4 times an hour. This would not be an issue with a properly sized heater, but mine is about double the size it should be. And no I didn't put it in.

I ended up getting an old Mercury thermostat and setting the anticipator to the lowest setting. Now at cycles about once an hour but runs longer. I had done a setback with the digital thermostat to about 58* at night. Now it stays a constant 64*.

I actually use less fuel this way, and it's more comfortable.

 

[yeldogt]

I had some issue with my house furnace short cycling. no matter the settings I couldn't get the digital thermostat to run less than 3 to 4 times an hour. This would not be an issue with a properly sized heater, but mine is about double the size it should be. And no I didn't put it in.

I ended up getting an old Mercury thermostat and setting the anticipator to the lowest setting. Now at cycles about once an hour but runs longer. I had done a setback with the digital thermostat to about 58* at night. Now it stays a constant 64*.

I actually use less fuel this way, and it's more comfortable.

Unless you have a properly sized heater -- what you did is often the answer.

People don't even understand what you did ... or why they had them years ago on every thermostat. The idea today being .... I want it "X" temp -- keep it at "X".

 

[Denwood]

3-4 times cycling in an hour does not sound unreasonable. You have two larger doors in your shop which is where your heat loss is. Check your door seals. I dropped radiant run times by nearly 50% on our loading bay after the Ecobee stat warned of not keeping up with loss during a -35C (very windy) weekend. The issue was door seals. I posted data about it a year or two back if you're interested: I posted pics and data in this thread on the topic: https://www.garagejournal.com/forum/showthread.php?t=414538

Before/after from that thread. Orange bits are the radiant run time data. Click to enlarge:

 

[Denwood]

Duplicate deleted

 

[TractorJeff]

Thanks Denwood! that was the Thread I remembered seeing, just couldn't remember when?
Basically the Seals are in Good condition.
I know that there are a small spot on each door where it isn't as tight as it should be.
Plus a little constant loss through the Concrete floor and all the Tractor Iron that is absorbing Heat also.
I am going to mess with the doors some to try to tighten them up a little more.

 

[Mainiac Mat]

It may be helpful to evaluate where your thermostat is located. If it's in the line of fire of the heater, it may be shutting the heater off before the rest of the room air is up to temp.

 

[Denwood]

Jeff, you're welcome All of the systematic research I've seen so far points to set backs for winter heating as large as you can manage. This is regardless of recovery mass, etc. The smaller you keep the temp delta between outside vs inside, the less BTUs you need to add over a longer period. The research on cooling shows different results where you will likely see better savings just setting a higher cooling set point and leaving it there.

That graphic I posted shows you the outside temps as well as thermostat set point (our loading bay was set to 8C) and you can see just how low the runtimes were after the door was tuned up with new seals, even with temps dropping below -25C. The insulated loading bay was surrounded on two sides by inside space that was heated to 20C, leaving two outside walls. It's about 16x32, with 20ft ceilings.

 

[Bert_]

Unless you have a properly sized heater -- what you did is often the answer.

People don't even understand what you did ... or why they had them years ago on every thermostat. The idea today being .... I want it "X" temp -- keep it at "X".

Most modern thermostats hold a ridiculously tight temperature range in my opinion. Seems like most don't even have the option to adjust it. It should be really simple to give this option in the programming. Most of the honeywell's have a cycles per hour setting but they still seem to do whatever they want.

Most garage heaters would really benefit from being able to set a larger temp swing. From what I have seen a lot of garage heaters are about twice the size, or more, they need to be anyway. Having a two or three degree temperature swing would really help these heaters run more efficiently.

The leakier the building is the more you'll benefit from a large setback.

 

[JoeMash]

Tractor- All the above responses seem spot on. I’ve had four different garages over the years, two two-car, one four-car and now 44x56x14 pole building. All have been insulated and heated with forced air, either NG or LPG, I leave the T-stat at 58 all winter long based on my desire of comfort and readiness for use versus the cost savings of managing a setback for fuel cost. I live where it’s colder than a well drillers **** six months of the year and found my time in shop is MUCH more enjoyable when tools and equipment are at least a moderate temp.
This being said, I’m out there everyday after day job for at least three hours and pretty much all day on weekends, mostly automotive and tractor work. I try to plan equipment movements in and out as to reduce the heat recovery required when doors are open. In summary..IMHO setbacks not worth it if you work in your shop frequently, find a comfortable median temp, set it and forget it.

 

[ripperd]

Setbacks don't always save on fuel. Generally the longer the setback the more the savings.

Sometimes you just need to try and see... it would likely take a full season to determine. Ideally you track your usage with daily outdoor temps (heating degree days), as colder days will obviously use more fuel. So, any savings you see... are they simply because it was "warmer" overall, or did you in fact save fuel.

$ wise, setback will always save money, its the laws of thermodynamics at play.

However, with so much cold equipment (and you working on it), you might be better off from a comfort perspective without increasing cost by performing less setback, but with a lower temperature while you are there.

Basically instead of having your equipment start at 53 degrees for the day and have it slowly warm up (probably never reaching 63), perhaps have your setback to 57 or none at all, and have the steady state temperature be 60.

 

[65ranchero]

A little different situation I have a 26 x26 2 bay , 2 single doors insulated garage off my other garage.
I use it as a work ,shop with a lift.
I originally was going to use a propane https://gas-space-heater.com/modine-hot-dawg.html heater but got talked out of it for several reasons.
Since the floor wasn't poured yet with the help of a plumber we installed radiant floor heat .I never looked back.
Getting to the point, I set the thermostat to 58F and most of the time ambient temp is at 60/61 F. and it keeps tools and winter equipment dry and not a burden on the oil fired furnace off the house.