Thoughts of varying tempertures

[bobj49f2]

I have a 30'x50' pole building with 15' ceiling. Walls and overhead doors are fulling insulated. Just started my 30' tube fired ceiling heater run on LP. I had the same basic set up in my previous building I had in an industrial park but the unit was run on natural gas. I can only get LP in my new location.

In my other building I had running water in the shop so during the winter I kept the shop at a minimum of 45° during off times and during the night. I used a multi-stage thermostat with a "wake", "leave", "home" and "night" setting. All of them were set at 45° except the "wake" which I set to 65° 15 before I would normally arrive at my shop and then the "leave" setting went back down to 45°. I did this because sometimes I would bypass the shop for a day or more if I had to go to a job site and wasn't going to be in the shop.

With my new shop I do not have running water. The shop is 25' from my house where all of the conveniences are. I do have some cleaning supplies in the shop and I do have a paint storage cabinet with oil based enamels stored. I am wondering if I can turn the shop temperatures down to 35°. I don't want to heat the building during the night for 10+ hours if no one is going to be in there. I could set the thermostat to 45° during the day and if I'm going to be working in it I would just manually goose the temp up like I did in my other building.

My concerns are; Is it more efficient just to keep the temp the same all the time? Would it take more energy to take it from 35° to 45° every morning than if I just keep it at 45° steady? Would this variation in temperature cause condensation which could cause internal corrosion in the heater? While I don't have running water I do have the oil based enamel. Over the last 3 years I've had the paint out there with no heat and it didn't seem to affect the paint but maybe it did and I just didn't notice it. Sometimes it was below zero in the shed.

 

[greenskeeper]

heat only when you are in the building for highest efficiency

 

[yeldogt]

There is aways going to be some savings with lower temps .. the question is always -- how much. Comfort is another moving target .. what's comfortable for one is often not for another.

It's been my experience over many years with all types of fuel .... the savings with low temps is directly related to insulation and air sealing ... the savings with setbacks has much to do with "what's in the building".

An empty building .... is air -- and air is easy to heat. It's why radiant tube heaters work so well in big open auto shops ... mostly air. Turn them on and all the heat is directed to one spot -- where the person is working and the tools. They don't heat the whole space

I have two large shop studios -- 1500 and 1700sf ...with supplies and equipment. It takes many hours for the "stuff" in the buildings to recover when I do a large set back. It's only worth it when I'm not going to be there for a couple weeks ... it's no different vs how it works in a house. Greater setback have diminishings returns ... even greater when there is much to heat. I think you will see little savings with 10 degree daily setbacks ..

Comfort is another factor .... some have no problem working with cold tools or a lot of clothes. I'm not one of them. So I go in with the idea of good insulation and air ceiling when I'm building.

My one building is NG ... I don't even track it. My large building on propane -- I saved 150g trying to maximize years ago ... and was uncomfortable.

Another thing is outside temp ... in cold temps .. the delta will work against you. Example -- it's going to be very cold in my area for a few days. I'm away for at least a week .... I actually dropped the temp in the building. There is no point in trying to fight the extreme cold when it will warm up by the time I return ... I still have to work with a slightly colder building when I get there.

I never drop them lower than about 55 .. that's what I put it at this week.

 

[bobj49f2]

Yeldogt, I loved the tube heater in my old shop. Like you said, objects were heated along with the concrete floor, almost as good IMO as an in floor heat system.

My question was is there a loss in saving fuel if the system has to go up 30° every day or is it best to keep it a little closer to my daily work time temperature of around 65°? Does it take more fuel to ramp it up from the 30° or is more fuel efficient to keep it at 45° all night and then have it have to make a less steep ramp up?

 

[yeldogt]

Yeldogt, I loved the tube heater in my old shop. Like you said, objects were heated along with the concrete floor, almost as good IMO as an in floor heat system.

My question was is there a loss in saving fuel if the system has to go up 30° every day or is it best to keep it a little closer to my daily work time temperature of around 65°? Does it take more fuel to ramp it up from the 30° or is more fuel efficient to keep it at 45° all night and then have it have to make a less steep ramp up?

There is aways going to be some fuel savings with a colder building .... unless you are working with a heat pump. BTU's in are BTU's in ... it's a question of how much and is it worth being cold (if you are).

I remember a study years ago when they played with set backs in a house and when the setback got over 6 the savings basically ended .. the reason was that for "comfort" the air temp had to exceed what would have occurred to overcome the colder contents.

My brother lived in an old sea captain's house -- off the coast of MA. I could not visit him in the winter ... he got used to the cold. It's what you can stand and works for you.

With an old leaky building -- or a poorly built one .. turndowns work -- because you are really heating outside.