Heating a Garage

[Gregor 4,846]

 

I have compiled a spread sheet keeping track of my garage furnace for 1 week. The furnace is is on 24/7. 71 degrees. Not running mind you, just on. Not turned off or down at night.

 

Here is an explanation of the numbers on the spread sheet, of the numbers.

 

DATE…………Yeah, it’s the date

 

TIME………....12 hour period from 8AM – 7PM, 7PM – 7AM I went in 12 hour periods because it is

usually much cooler at night. I cou8d have gone from 12 to 12, but I can’t

tell you the last time I was awake at midnight. I’m not sure there still is a midnight.

 

AVG TEMP….This number was calculated by taking the actual daily temp recorded and posted by

weatherundergrund, for 12 hours and divided by 12 These temps are from the nearest

reporting station to me, which is about 30 miles north of me as the crow flies.

 

RUN TIME…...Number of minutes my furnace ran for the previous 12 hour period.

 

GAS USE……..Amount of gas my furnace used for the 12 hour period. Calculated by

multiplying the number of minutes by the amount of gas that goes through my furnace

while it’s running.

 

GAS COST……Number of minutes, X what my city charges for gas.

While this is not a constant, I took an average of 4 months. The previous Nov Dec

Jan Feb

 

ELEC USE…….Number of minutes, X the amount of electricity used

by my furnace in 1 minute.

 

ELEC COST…..Amount of electricity multiplied by my cost.

https://www.omnicalculator.com/everyday-life/electricity-cost

 

TOTAL………...Cost of gas + the cost of electricity.

 

24 HOUR TOT… Total cost for the previous 24 hour period.

 

24 HOUR TEMP..Average temp per hour for the previous 24 hour period.

 

You will see some numbers LARGER and in BOLD print. On these days, my overhead garage door

was opened. Not for long, less than 5 minutes total, but it was opened.

 

One interesting fact I did learn was, cutting the outside air temp in half does not double the run time of the furnace. It usually comes closer to tripling it, depending on the actual temp numbers. I’m sure some brainiac can figure out an equation for this, but it’s not me. I expect that number will increase as temps get colder.

 

I am compiling another spread sheet. This will show a week of setting the thermostat down to 45 degrees at night. The whole purpose of this is to compare the run time of the furnace. I can’t swear I have my cost numbers right, but I am able to read the clock connected to my furnace. Which is more than I can say for my grand kids. They are not use to looking at a dial with hands,

 

I could not save my spread sheet in a format that other members could open, so I transcribed all the numbers to a word document, and simply copied and pasted. I have a bad habit of transposing numbers. If a number looks really off from what it should be, that’s probably why.

[Gregor 4,846]

DATE	TIME	AVG TEMP	RUN TIME	GAS USE	GAS COST	ELEC USE	ELEC COST	TOTAL	24 H TOTAL	DAY TEMP
11/24/21	AM-PM	54	81	60.75	.47	2.60	.16	.63
	PM-AM	42	83	62.25	.48	2.67	.17	.65	1.28	48
11/25/21	AM-PM	30	191	143.25	1.10	6.13	.38	1.49
	PM-AM	19	242	181.5	1.40	7.77	.48	1.88	3.37	25
11/26/21	AM-PM	30	210	157.5	1.21	6.75	.42	1.63
	PM-AM	33	190	142.5	1.10	6.10	.38	1.48	3.11	31
11/27/21	AM-PM	46	145	108.75	.84	4.66	.29	1.13
	PM-AM	33	178	133.5	1.03	5.72	.36	1.38	2.51	40
11/28/21	AM-PM	34	170	127.50	.98	5.46	.34	1.32
	PM-AM	27	232	174	1.34	7.45	.46	1.80	3.13	30
11/29/21	AM-PM	47	163	122.25	.94	5.24	.33	1.27
	PM-AM	42	163	122.5	.94	5.24	.33	1.27	2.53	44
11/30/21	AM-PM	40	90	67.5	.52	2.89	.18	.70
	PM-AM	36	158	118.5	.91	5.07	.32	1.23	1.93	38

[Gregor 4,846]

If I have my numbers anywhere near right, it cost me $17.86 for the week to heat my garage. I expect that number will at the very least quadruple in colder weather. $18 X 4 = $72.

 

He!! I burn up more than $17 in cigarettes. EVERY DAY !

 

[Achto 27,609]

44 minutes ago, Gregor said:

He!! I burn up more than $17 in cigarettes. EVERY DAY !

 

One of these can help knock that cost down.

https://www.amazon.com/Prestige-Group-Powermatic-Cigarette-Injector/dp/B0195V6AY4/ref=zg_bs_10342498011_33?_encoding=UTF8&psc=1&refRID=12K7Z36TZ3K10FXJNV6F

 

After purchasing the injector my average cost is about $12 per carton.

 

 

 

[Gregor 4,846]

6 minutes ago, Achto said:

After purchasing the injector my average cost is about $12 per carton.

 

I have considered that in the past.

[ri702bill 8,345]

I do not know the "sin" tax Illinois adds to each pack - here in RI cheap offbrand butts are $10.80 per pack, name brands are even higher - 2/3rds of that is the state tax!

 

Back to the topic - are you doing anything additional, like a ceiling fan, to spread the heat in the garage??

Edited December 2, 2021 by ri702bill

[Gregor 4,846]

14 minutes ago, ri702bill said:

I do not know the "sin" tax Illinois adds to each pack - here in RI cheap offbrand butts are $10.80 per pack, name brands are even higher - 2/3rds of that is the state tax!

 

Back to the topic - are you doing anything additional, like a ceiling fan, to spread the heat in the garage??

~ $92 a carton w/tax

I have a ceiling fan, but don't run it much. My T-stat is about 4' off the floor. 24 X 26 garage. When winter really gets here, and it gets cold,  and I record the run times, I may think twice about spending my days in the garage. NO SMOKING in the house.

[ri702bill 8,345]

My new garage is about the same size - the old one was falling down - used to be a 2 bay automotive business my Father in law ran rebuilt same footprint but increased the wall height from 8' to 10 feet - added about $2 grand in materials and labor - well worth it. My town USED TO allow a partial teardown and rebuild if you were too close to a property line as long as all parties involved agreed - mid construction we get a new building inspector and had to move the left wall in by 3 and a half feet - there goes my 12 foot wide garage door!! Had to settle for a 9 foot wide door....

[Maxwell-8 4,277]

2 hours ago, Gregor said:

If I have my numbers anywhere near right, it cost me $17.86 for the week to heat my garage. I expect that number will at the very least quadruple in colder weather. $18 X 4 = $72.

 

He!! I burn up more than $17 in cigarettes. EVERY DAY !

 

That ain't bad. before we insolated ours, we could burn that $72 a day with just heating to 60°F.  Now, it's much better!

[Handy Don 12,237]

2 hours ago, ri702bill said:

partial teardown

What part did you leave? 

In our village I'd have needed a building permit for that much work. The building department reviews the plans and if a grandfathered or variant structure will need change to be compliant, you find out then. Once the permit is issued (for a fee, of course), you are good to go.

[Gregor 4,846]

2 hours ago, ri702bill said:

mid construction we get a new building inspector

I would have needed a permit BEFORE any construction. Once approved, I don't think the next Joe Blow to come along can change it.

[elcamino/wheelhorse 9,326]

Not too be off topic kinda but carton of smokes is $55.92 including sales tax here in Philip Morris (sp ) land.

[ri702bill 8,345]

Yup - we had the 25-75% rule for years - tear down the other 3 walls( not the one too close to the property line), rebuild those 3, demolish & rebuild that problem wall, put the roof on.

HAD the permit in hand AND approved - demolishing the other 3 started, enter new inspector. Ever notice when a new dog moves into the neighborhood, he lifts his leg higher than all the others to soak the fire hydrant & wash all the other scents away - same deal.

Edited December 2, 2021 by ri702bill

[Gregor 4,846]

I have described before how my garage is constructed. It has a basement. The pre-cast concrete slabs are exposed underneath. They are the ceiling of the basement. I believe this is why the garage floor is so cold. The basement, (storage shed) is not heated. I know that insulation is typically installed on the heated side of a wall, not the cold side, but that's not possible in this case. Would gluing  2" styrafoam to the underside of the slabs provide much insulating value, or am I asking for trouble with trapped moisture? 2" insulation has an R  value of 10. Is there another, better way of doing this? I should have put heat in the floor, but it's a bit late for that now. Thanks   Greg

[ri702bill 8,345]

You may wish to do that, but you would need a way to vent that area so that moisture does not collect.

[Handy Don 12,237]

Concrete is tricky. Depending on the mix and composition, its heat and moisture conductivity can vary widely. Also, it is likely that these slabs have metal reinforcement embedded and causing it to rust would be dangerous. To me, this is a case where getting advice from a knowledgeable expert might be worth the cost, probably an architect with strong experience with concrete stuctural elements (as opposed to someone who builds neat houses).

It may turn out that putting heating (via resistance wiring or circulating hot water) against the underside and then covering that with insulation would be an effective option and lower the need for space heating in the garage above. I can testify that working in spaces with heated floors is extremely comfortable!

Edited December 3, 2021 by Handy Don

[WHX?? 48,833]

You really are bored ain't you Gregor!

Nine foot doors suck Bill.... just ask my truck mirrors how I know! Who the heck built this shed he could have easily put in tens...... 

[WHX?? 48,833]

On 12/2/2021 at 7:54 AM, Achto said:

fter purchasing the injector my average cost is about $12 per carton.

Yah well you need to switch brands or I is gonna quit bumming them..... 

[Gregor 4,846]

On 12/2/2021 at 7:54 AM, Achto said:

 

One of these can help knock that cost down.

After purchasing the injector my average cost is about $12 per carton.

 

For those interested. I bought an injector also, and the supplies necessary to make my own cigarettes. I can pump out a carton in a little less than an hour. Cost,  $12.36 including tax, as opposed to $92

P.S. I know I should quit. EVERYBODY  should. But please. While I do appreciate your concern for my health, I really don't need to hear another lecture. I hear it almost daily from my wife. Thanks   Greg

 

And it keeps my hands busy so I am not smoking so much.

Edited December 4, 2021 by Gregor

[WHX?? 48,833]

Yah I should too Greg ...and will when I can retire or croak whichever comes first. Most likely the latter.

Folks give me the business about smoking I remind them WWII might not have been won or I may have not made seven patrols on a submarine without them.   Dan's wife really reads him the riot act for puffing mine is getting just as bad. 

[Gregor 4,846]

Yeah I am still keeping track. This time I shut the furnace off for a period each night. Except I forgot once. On line 8, in bold, I forgot. I did not post the dollar numbers as it means nothing to anyone but me, unless you are pay exactly what I am paying for utilities. The whole purpose of this experiment was to compare run times. Leaving the furnace on, against shutting it down at night.

 

The wind seems to have a much bigger effect on run times than I would have imagined. I checked some of the seeming off kilter temp to run time colorations, (line 11, temp of 25, run time 281. Line 13, temp of 23, run time 227) against the recorded winds for that period, and it was windier than normal, on the 6^th. 25 mph winds with 45 mph gusts.

 

As I said before, cutting the temp in half more than doubles the run time. Line 1, temp 51, run time 65. Line 13, temp 23, run time 227. 3 ½ times as long. I expect that number to increase dramatically as temps get colder.

 

In the end, I would have to say, It DOES save money to turn your furnace off, or down at night.

 

In the first chart I posted there is a

temp of 34,

with a run time of 170 minutes.

In this chart,

line 4, temp 34,

off time 340 minutes,

run time 118 minutes.

170 – 118 is 52 minutes less run time.

 

First chart,

temp of 27,

run time 232 minutes.

This chart,

line 14, temp 26,

off time 390 minutes,

run time 172 minutes.

232 – 172 is 60 minutes less run time.

 

But again, I believe wind plays a major factor, along with sunshine, rain, etc………...etc………..

 

In the end though, the less time your furnace runs, the less it will cost you.

I am curious to see what happens to the numbers in Jan and Feb, when winter weather really gets here. The predicted high temp for Wednesday, a week from today, 70. We shall see.

[Gregor 4,846]

	DATE	TIME	AVG TEMP	RUN TIME	OFF TIME
1	12/01/21	AM-PM	51	65
2		PM-AM	50	67	310
3	12/02/21	AM-PM	52	65
4		PM-AM	34	118	340
5	12/03/21	AM-PM	49	155
6		PM-AM	36	155	480
7	12/04/21	AM-PM	41	141
8		PM-AM	37	176	0
9	12/05/21	AM-PM	40	138
10		PM-AM	34	158	330
11	12/06/21	AM-PM	25	281
12		PM-AM	14	190	420
13	12/07/21	AM-PM	23	227
14		PM-AM	26	172	390

[Gregor 4,846]

When I owned and operated my own business, I attended seminars, and conventions pertaining  to the operation of that business. One of the subjects often discussed was the storage of food and drink, in coolers, refrigerators, and freezers. I learned that it was easier (and therefore cheaper) to cool and maintain product, than it was air. In other words, the fuller your freezer was, the cheaper it would run. Maybe this same theory applies to heat as well. It could be that the fuller my garage was, the easier it would be to heat. There hasn't been any vehicles in my garage for months. That will change of course when winter really gets here.Will that make it cheaper. I'm guessing no, not in the long run. The car will be very cold, possibly covered in snow and ice, and it will have to be brought up to temp. The overhead door will be opened, possibly 3 - 4 daily. It will be interesting to see the run times when the average daily temp is 0.  I may have to re-think the idea of keeping my garage at 71.

[Handy Don 12,237]

2 hours ago, Gregor said:

the fuller your freezer was, the cheaper it would run

Your assessment rings true for me. It's the thermal equivalent of momentum. Add mass at a different temperature and heat has to transfer one way or the other.

Heating a 4,000 lb mass of automobile (its warm interior and engine parts notwithstanding) requires a LOT of BTUs. 

 

[squonk 41,156]

Your refrigeration analogy works because a walk in freezer for example; Once it's at temp and the product inside is frozen hard, The product itself will maintain the box temp for quite a while providing the door isn't opened and closed a bunch. Walk in coolers run more because the product temp isn't as "dense" so it doesn't help maintain as well. Plus they are usually opened and closed more often. 

 

With a garage, if there is more stuff in it to act like a heat sink the heat it will maintain longer. but if you're opening that overhead door and inserting a 2500 lb. block of ice that goes out the window. That block of ice will absorb all the heat it can out of the air and anything around it that's warmer