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Insulation question

 
pollinator
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I'm getting ready to insulate my garage.  2x6 walls. I can get r-25, which is 8.5 inch thick unfaced,  or r-15 faced that is 3.5 inch thick for the same price.  I know you aren't supposed to "pack" insulation, so given those two options, which way would be better? Packing the r-25 a little, or leaving a 2" gap with the r-15? Obviously I want it as well insulated as possible.  Any thoughts?
 
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Is the garage climate controlled in any way?
 
Trace Oswald
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James Freyr wrote:Is the garage climate controlled in any way?



It's attached to the house, so it will get some minimum heat transfer from the house. Beyond that, it will only be heated occasionally by an LP torpedo heater most likely.  I guess the short answer to your question is, not really. It's also on the north end of the house, so while it will help protect the house from the cold north winds, but it won't get any solar gains.
 
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I wouldn't pack the 8.5" insulation down into 5.5" of space.  So of the two options, I'd go with the R15.

A third pain-in-the-ass option would be to get the R-25 and split it down into 2/3rds and 1/3rd.  Then you can do three bays with two bays worth of insulation.   IF it splits apart relatively evenly.  And if you don't mind making a ton of fiberglass dust as you tear it.
 
Trace Oswald
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Mike Haasl wrote:I wouldn't pack the 8.5" insulation down into 5.5" of space.  So of the two options, I'd go with the R15.

A third pain-in-the-ass option would be to get the R-25 and split it down into 2/3rds and 1/3rd.  Then you can do three bays with two bays worth of insulation.   IF it splits apart relatively evenly.  And if you don't mind making a ton of fiberglass dust as you tear it.



I very much mind 😊  I hate working with fiberglass, but I view it as a necessary evil. I was leaning in the direction of the r-15 as well, and I appreciate the input.
 
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I had always thought that fiberglass in a given space would be more effective denser rather than looser, and this article supports the idea:
https://www.jlconline.com/how-to/insulation/q-a-compressing-fiberglass-batts_o
Essentially, denser insulation is better per inch, but compressing a given batt reduces its total R-value.

On balance, I think you will be better off with the 8" batts compressed into 5 1/2" than with 3 1/2" batts swimming in 5 1/2". If R-25 drops to R-19 or R-20, that is still better than R-15.
 
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+ Glen

Well, I learned something. And here's a cheat sheet for that exact issue.

insulationinstitute.org/wp-content/uploads/2016/08/Compressed_R_values.pdf


And here's their page linking a lot of other insulation type info:

https://insulationinstitute.org/tools-resources/resource-library/


Rufus
 
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I always felt compressing was better than going with thinner insulation. I have this trouble all the time because I build with rough cut lumber, so a 2x4 or 2x6 is a full 4 inches thick, or 6 inches thick, and not 3-1/2" or 5-1/2"...

But I would not bother to insulate at all if you are not going to heat it, now or in the future. An unheated, insulated building is colder than outside temperature. And your torpedo heater will more than heat an uninsulated space when required.

But if you plan to heat it down the road, or are concerned about noise, then for sure, insulate it.

But just to be clear, just because the individual rolls cost the exact same, does not mean the rolls do not cover more or less. For instance where I live, a 15-1/2" roll of R-11, is the same price as a roll of 15-1/2" R-19...BUT the thicker fiberglass batt does not cover nearly as many square feet. I am sure you checked on that, but it is easy to overlook that small detail.
 
James Freyr
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Travis Johnson wrote:

But I would not bother to insulate at all if you are not going to heat it, now or in the future.



Insulating a structure has other benefits besides reducing heat loss that can get overlooked or sometimes aren't considered. Depending on the structure, one risk for a person to consider when choosing not to insulate a building is condensate will form on the interior ceiling and walls when they pass the dew point as the temperature changes outside, and insulation prevents this. This moisture can also form inside empty uninsulated stud cavities as well, even more so if the interior is then heated periodically during winter. Sometimes this condensate may not be visible if say the ceiling or walls are raw wood, as the wood can soak up the droplets as they form. This condensate then creates breeding ground for mold and other bacterial or fungal growths which could cause illness in people. If a structure such as a garage is not insulated, one way to slow or possibly prevent the growth of mold is to not put a garage door on it and make it more of a carport, or have other large openings so the structure can breathe and it doesn't trap air of a different temperature than the outside temperature. A structure that I personally would not insulate would be something like a tool shed or outhouse that are usually pretty drafty.
 
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Split the r25 down and get 3 bays out of 2 pieces.... Absolutely the way to go....
 
pollinator
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Insulation should not be packed down firm.
It insulates because of the small pockets of still air, packing it down eliminates the pockets.
 
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Trace,

I am going to offer up a potentially unpopular opinion on this subject.  My garage is open enough that insulation seems redundant.  I would certainly insulate the wall next to the house, but unless you are spending a lot of time in a climate controlled garage, I fail to see the point of insulating the garage at all so I guess I would say just go with the cheapest option.

Even if the garage is climate controlled, garage doors are poorly insulated and don’t really seal well—there are almost always gaps and air leaks here and there.  Even if you had R200 insulation, these gaps and leaks negate the insulation.  And each time you open the garage door the insulation is rendered moot.  

Normally I am all for great insulation, but in the case of a garage, this is a big question mark for me.  

I guess my suggestion—and it only a suggestion—is to go with the cheapest option.

These are just my thoughts and take or leave them as you see fit.

Eric
 
Trace Oswald
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Thanks everyone for your inputs.

Eric, I think you make great points.  There are a couple reasons I am insulating the garage.  Menards had a great sale this year, and I got 18' rolls of insulation for $5 a roll.  I bought enough to insulate several of my interior rooms in the house and to do the garage.  I don't plan on heating the garage all the time, but every year we have a number of days that are -20F, and last year we had two days that were -40F.  I haven't decided if I will use a gas heater, a pellet stove, or maybe a wood stove, but I want to be able to heat the garage to at least above 0 on truly frigid nights.  My old truck struggles to start when it's -20.  I'm not too concerned with how quickly the garage cools off again after I open the big doors to leave for work.  

Insulation will also let me heat the garage quickly with a torpedo heater when I need to do maintenance on something in the winter, and it seems like something always needs maintenance.  A good torpedo heater will warm an insulated garage up to 50F really quickly, and I much prefer touching metal at that temp :)
 
Eric Hanson
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Trace,

I don’t suppose there is any chance that you could put in a small rocket mass heater is there?

I suppose given your challenges, I can see insulating your garage.  I would still suggest going with the cheapest insulation possible as I think most of the heat loss will through those cracks and crevices and of ceiling/roof.

Eric
 
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This will be a longer 'observational' post from some metal garage/barn building on our property over the past couple of decades and will include some comparison with our house.  (I hope this is not hijacking Trace's original intent of the thread and hope it generates further discussion.)  The house is ~1915 built, so before electrical/plumbing/central heating, etc.  I suspect houses like this were built a bit 'drafty' due to the use of a central woodstove (cookstove) and the need for air exchange,.....but it should be remembered that winters here hover a lot of time around 0 degrees F.   The house has some sort of newspaper-type bits for insulation that they must have used at the time of construction.  We are even draftier than normal due to reasons I won't go into, but the house would be considered a compromise between 'tight' insulation and open; we definitely are burning more wood and fuel oil than we need to.

We have several small outbuildings that were insulated to varying degrees with the whole gamut of what's available, from that silver 'bubble wrap' type insulation to hard foam sheets to fiberglass bats.  Animal stock live in these buildings and their own heat is the main source, although we've added greenhouse attachments to the buildings which add A LOT of heat of sunny days.  The buildings cool down at night, but the immediate animal quarters provide an extra separation from the cold.

We had two steel post and beam buildings erected over time....neither of them insulated and neither have anything but the initial gravel/sand flooring upon which the structures were built.  We do have chickens that live in them and fare pretty well, but these buildings are cold.....you could not in any sustained way work out in them in the middle of winter without space heating.  Part of the reason I've not gone whole hog with insulation on these buildings is the chewing rodent factor.  Because we have the stock animals and have lots of food in various parts of these buildings.....again, for reasons I won't go into.....rodents *will* find whatever bits fall here and there and will make a home where there is food.  The damage from mice and rats has been enough on the little insulation that exists in the smaller outbuildings to have been a deterrent to insulating these steel buildings until something permanent is done about mice/rats/.....and English sparrows (aka, "rats with wings"...!)

Here's a more interesting observation.  After the collapse of our 40 X 80 ft. quonset this past spring from excessive snow-load, we used the same builder who did the steel buildings to build yet another structure, this time 30 X 40.  It's built on a 4 ft high pad of gravel and fill (county code for flood zone)....the pad extends 10 to 15 ft beyond the building perimeter and at the same height as the floor of the building as part of the code.  This time, my wife wanted a warm building and we settled on the probable toxic gick selection of spray foam insulation along with a ceiling that is insulated above it.  There are many doors and windows in this building because we anticipated that moisture would be an issue.....and it has been, but not enough for us to regret the decision.  This is the first winter for this new building and we've already had many days around zero degrees F and some nights down to -20F along with unseasonably cold days.  What is striking is how warm that new building is.  In all of the other buildings, we are well into the period where water bowls freeze rather quickly and need to be chipped out and replenished once per day, sometimes more frequently.  But in this new building, the water has never yet frozen.  I will add that I installed a 5000W electric garage heater in that building and my wife said she's had it turned on for a bit when preparing food, but only on the coldest day so far....it otherwise stays turned off.

So I guess I'm pleasantly amazed at how 'self-heating', for lack of a better term, this new building is.  I can't say how much might be passive solar from the building itself just warming from the sun, but we are at the worst time of year for that to have a major effect.  I'm left wondering about the size ratio of buildings and the amount of 'pad' or ground on which they are built---Could geothermal explain some of the heat in this building even though it was not built with any deliberate attempt to capture such energy?  As it is a new building, we have not ruled out installing some sort of wood burner....RMH or other such item....although the installation of food storage bins and electrical wiring are the higher priority at the moment.  For us and maybe for others with animals to feed, the uneaten feed that falls here and there or gets left in bowls is cause for bad rodent issues.....which leads to destroyed insulation.  I'd be curious as to other's solutions to this problem and use it as a heads-up to Trace as something to consider if there will be food around garage after the new insulation.  Thoughts?
 
Trace Oswald
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Eric Hanson wrote:

I don’t suppose there is any chance that you could put in a small rocket mass heater is there?



None 😊  A rocket mass heater is pretty much the exact opposite of what I want. It takes up far too much room, takes too long to heat up, takes too much babysitting. I think rocket mass heaters excel in living areas. It gives you a nice warm place to sit or lie on. It isn't hard to keep an eye on your fuel if the fire is inside the house with you. The long time to heat up isn't a big deal if you are going to warm an area and keep it warm all winter. I would love to have one in my living room. I would hate one in my garage.
 
Mike Haasl
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John, your building could be self heating since all that gravel is giving its accumulated heat from the summer off to the building.  It may lag the outside temperatures (like a lake) and it might keep it colder for a couple months in the spring as the building tries to overcome the large mass of cold gravel.
 
Travis Johnson
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John Weiland wrote:This will be a longer 'observational' post from some metal garage/barn building on our property over the past couple of decades and will include some comparison with our house.  (I hope this is not hijacking Trace's original intent of the thread and hope it generates further discussion.)  The house is ~1915 built, so before electrical/plumbing/central heating, etc.  I suspect houses like this were built a bit 'drafty' due to the use of a central woodstove (cookstove) and the need for air exchange,.....but it should be remembered that winters here hover a lot of time around 0 degrees F.   The house has some sort of newspaper-type bits for insulation that they must have used at the time of construction.  We are even draftier than normal due to reasons I won't go into, but the house would be considered a compromise between 'tight' insulation and open; we definitely are burning more wood and fuel oil than we need to.

We have several small outbuildings that were insulated to varying degrees with the whole gamut of what's available, from that silver 'bubble wrap' type insulation to hard foam sheets to fiberglass bats.  Animal stock live in these buildings and their own heat is the main source, although we've added greenhouse attachments to the buildings which add A LOT of heat of sunny days.  The buildings cool down at night, but the immediate animal quarters provide an extra separation from the cold.

We had two steel post and beam buildings erected over time....neither of them insulated and neither have anything but the initial gravel/sand flooring upon which the structures were built.  We do have chickens that live in them and fare pretty well, but these buildings are cold.....you could not in any sustained way work out in them in the middle of winter without space heating.  Part of the reason I've not gone whole hog with insulation on these buildings is the chewing rodent factor.  Because we have the stock animals and have lots of food in various parts of these buildings.....again, for reasons I won't go into.....rodents *will* find whatever bits fall here and there and will make a home where there is food.  The damage from mice and rats has been enough on the little insulation that exists in the smaller outbuildings to have been a deterrent to insulating these steel buildings until something permanent is done about mice/rats/.....and English sparrows (aka, "rats with wings"...!)

Here's a more interesting observation.  After the collapse of our 40 X 80 ft. quonset this past spring from excessive snow-load, we used the same builder who did the steel buildings to build yet another structure, this time 30 X 40.  It's built on a 4 ft high pad of gravel and fill (county code for flood zone)....the pad extends 10 to 15 ft beyond the building perimeter and at the same height as the floor of the building as part of the code.  This time, my wife wanted a warm building and we settled on the probable toxic gick selection of spray foam insulation along with a ceiling that is insulated above it.  There are many doors and windows in this building because we anticipated that moisture would be an issue.....and it has been, but not enough for us to regret the decision.  This is the first winter for this new building and we've already had many days around zero degrees F and some nights down to -20F along with unseasonably cold days.  What is striking is how warm that new building is.  In all of the other buildings, we are well into the period where water bowls freeze rather quickly and need to be chipped out and replenished once per day, sometimes more frequently.  But in this new building, the water has never yet frozen.  I will add that I installed a 5000W electric garage heater in that building and my wife said she's had it turned on for a bit when preparing food, but only on the coldest day so far....it otherwise stays turned off.

So I guess I'm pleasantly amazed at how 'self-heating', for lack of a better term, this new building is.  I can't say how much might be passive solar from the building itself just warming from the sun, but we are at the worst time of year for that to have a major effect.  I'm left wondering about the size ratio of buildings and the amount of 'pad' or ground on which they are built---Could geothermal explain some of the heat in this building even though it was not built with any deliberate attempt to capture such energy?  As it is a new building, we have not ruled out installing some sort of wood burner....RMH or other such item....although the installation of food storage bins and electrical wiring are the higher priority at the moment.  For us and maybe for others with animals to feed, the uneaten feed that falls here and there or gets left in bowls is cause for bad rodent issues.....which leads to destroyed insulation.  I'd be curious as to other's solutions to this problem and use it as a heads-up to Trace as something to consider if there will be food around garage after the new insulation.  Thoughts?



Oh it is very much self-heating!

My house does this as well. You have to remember that a concrete slab on grade is only losing heat on the outer edges of it. About four feet in from the sides it is picking up geothermal heat from the ground. It is only 57 degrees, but it is still heat.

I say that because my house is T-shaped, both slabs on grade. Last year we moved into our Tiny House and so it was vacant. No heat, no one living here, NOTHING. Yet it never got below 44 degrees. That is pretty amazing because when I checked it, it was -7 degrees below zero (f) and as I said, no heat or life in the house at all.

Now that is with the heat off. I could actually turn my radiant flooring heating system on, but shut off the boiler. That would engage my pumps that would mix the water in the middle of the floor (57 degrees) with the water on the outside of the slab (below freezing), and when I do that, the house does not get below 55 degrees. This is essentially geothermal heat at play. I am picking up the heat from the center of the floor that is 57 degrees and about 2/3 of the floor size, and mixing it with the outer 1/3 colder water. Doing that, is how the temp stays at 55 degrees.

Now 55 degrees is not warm enough for human occupancy, but taking my house from 55 degrees, to 70 degrees is much less expensive, so I have a very, very efficient home to heat.

The bigger the building, the more heat that can be gleaned though. There is a indoor sports complex near my that is about an acre in size. It is a super insulated building and when I asked the manager of the building how much it cost to heat the place, he said NOTHING. The geothermal heat brings it to 57 degrees, and then with some passive solar gain...it stays warm enough all winter without supplemental heat. Of course the price for free winter heat was, building a super insulated building an acre in size.
 
Travis Johnson
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I have a friend who does a lot of earthwork and logging, and his method for starting equipment when it was cold out is so simple that most people miss the obvious...

Just leave the machines running...

Granted this is Maine, so while it can get down to -30 below zero (f) or below, it seldom does so for more than 10 days at a time. So during those stretches, he just leaves his machines idling all night. The tractors he just kept running of course, but his crushers and screens he keeps idling, but cycling, meaning the conveyors are kept rotating, and the jaw on the crusher flopping back and forth.

It is great. When you get there in the morning, you jump in and go to work. Cabs are warm, everything warmed up and running, literally a minute to crank everything to full throttle, and go to work.

He figured the amount of wasted time getting things running, and the damage done getting them running at low temps, more than made up for the fuel consumed during the night, and besides, that fuel is tax deductible anyway. Loss of production, labor hours, and equipment damage is not, and is taken right off the profit side of business.

Homesteaders can do the same thing. It would take a lot of idling through the night in fuel consumption on what our vehicles and equipment uses, versus that of building garages, shops, insulating, and heating them, just to get a machine or vehicle to start when it is super cold out. But again it depends. Shops and garages serve other purposes, and if a place is cold all the time, idling stuff through the night quickly adds up. But lets say a homesteader is doing some logging, and it is really cold. Just letting his Kubota tractor idle through the night will cost a few dollar's, and in the morning they can just jump on it, and go to work. That is a big savings in time when someone only has a weekend in which to work, and they work a real job.
 
Eric Hanson
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Trace,

Yeah, ok, I get that the RMH in the garage is pretty far fetched.  My thinking was that if you could heat some mass—as opposed to air—the mass alone could provide some heat that would not simply rush out the door every time it gets opened.  

If you don’t mind me asking, where are you located?  -30 is awfully cold, but I have been there as well.  I grew up in central Illinois and we regularly got temperatures that sank to the -20 to -25 territory.  I had a beloved outdoor cat growing up and one year he was sleeping in an old pet crate (used to transport medium sized dogs in a plane in the 1960s.  Inside the crate we put a laundry basket lined with an old sleeping bag.  We put an old blanket over the whole thing to give a sort-of door to the crate.  But it was still probably -10 at the warmest inside the crate.  My solution was to add 3 1-gallon jugs of water (they were old milk jugs) filled with hot tap water.  We stuck these jugs just behind the laundry basket.  

An hour later I went out to check on my cat.  I pulled the blanket back, stuck my head in and was greeted by a blast of 90 degree air and my cat was purring loudly!  The next morning the temperatures had dropped to “only” about 60 degrees.  The hot water had more than held up all night.

My point in all of this is that a hot mass can really store heat a LOT better than air can.  This is an important component of the RMH.  I know that this is still likely far fetched, but is there any chance that you could heat a mass to leave inside the garage to slowly radiate away it’s heat?

This is really just me spitballing but I think that s heat radiating mass is great way to store heat.  Water has an amazing heat capacity so some hot water is a 5 gallon bucket with lid attached would store and slowly release a generous amount of heat.  I had neighbors (that sadly moved—I really liked them!) that had chickens outside their house in a little hutch.  They were using the deep litter method to heat the chickens on cold nights (which around here is more like 10 degrees), but this technique was not really working.  I told them about my cat and suggested the 5-gallon bucket of hot water with a lid and they were sold!  They continued to use a 5-gallon bucket with a lid until they moved.  Their chickens were happy!

Anyhow, another long winded post and take it for whatever you think it is worth.

Eric
 
John Weiland
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Trace, one more consideration of a 'tweener' variety....somewhere between a proper RMH and a standard woodburner, just in case you wish to experiment down the road.  I'll bump this thread to get started (you may have to scroll to the top of the thread to see the build):

https://permies.com/t/42529/FWIW-Rocket-stove-heater-concept#333627

The design met with well-deserved criticism for lack of engineering detail, but it does function and was simple to install.  It is still working and is still sitting, as a prototype, in a drafty, uninsulated building.  I fire it up everytime I go out to do some little item in the shop there and only when the temperature outside is below 10 degrees F. (not unusual for me to be out in that building when it is -20 F).  It is, as was noted by Peter vdB, essentially a batch-box rocket heater....not a rocket *mass* heater since there is no mass that it is heating.  It is relatively compact since the horizontal exhaust portion is just long enough to get outside of the building before turning upward into the main exhaust chimney.  (The chimney is now as high as the roof lip and the system does 'pull' better than before.)  Part of the reason for reviving the thread was your comment about fast heating.  Since my building here is uninsulated, it's not a fair comparison....I can only go with what the magnetic thermometer on the barrel reads.  That said, when I fire it up with a good fire build (good dry kindling and/or cardboard scraps), the barrel will be at 800 - 900 degrees F within 10 min., often sooner than that.  If I stoke the box with additional wood and adjust the door opening 'just so', it will hover between 400 and 600 degrees pretty steadily depending on the amount and quality of the wood still in the burn box.

The convenience of your torpedo propane unit is obvious and I certainly understand your reasons for wanting to go that route.  But if you wish to dabble with the RMH concept in different forms, just thought I would add this here.

Travis and Mike, thanks for additional input on our insulated building....I will be monitoring the temperature throughout the winter.  The south face of that building is shown below and we hope to add a long, maybe 8 - 10' wide sunroom addition on this side that will encompass the far walk-in door and the large garage door---that way on sunny days, we can open those doors and capture extra passive solar heat.
Fat-sheep.jpg
Fat sheep
Fat sheep
 
Trace Oswald
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John Weiland wrote:Trace, one more consideration of a 'tweener' variety....somewhere between a proper RMH and a standard woodburner, just in case you wish to experiment down the road.  I'll bump this thread to get started (you may have to scroll to the top of the thread to see the build):

https://permies.com/t/42529/FWIW-Rocket-stove-heater-concept#333627

The design met with well-deserved criticism for lack of engineering detail, but it does function and was simple to install.  It is still working and is still sitting, as a prototype, in a drafty, uninsulated building.  I fire it up everytime I go out to do some little item in the shop there and only when the temperature outside is below 10 degrees F. (not unusual for me to be out in that building when it is -20 F).  It is, as was noted by Peter vdB, essentially a batch-box rocket heater....not a rocket *mass* heater since there is no mass that it is heating.  It is relatively compact since the horizontal exhaust portion is just long enough to get outside of the building before turning upward into the main exhaust chimney.  (The chimney is now as high as the roof lip and the system does 'pull' better than before.)  Part of the reason for reviving the thread was your comment about fast heating.  Since my building here is uninsulated, it's not a fair comparison....I can only go with what the magnetic thermometer on the barrel reads.  That said, when I fire it up with a good fire build (good dry kindling and/or cardboard scraps), the barrel will be at 800 - 900 degrees F within 10 min., often sooner than that.  If I stoke the box with additional wood and adjust the door opening 'just so', it will hover between 400 and 600 degrees pretty steadily depending on the amount and quality of the wood still in the burn box.

The convenience of your torpedo propane unit is obvious and I certainly understand your reasons for wanting to go that route.  But if you wish to dabble with the RMH concept in different forms, just thought I would add this here.

Travis and Mike, thanks for additional input on our insulated building....I will be monitoring the temperature throughout the winter.  The south face of that building is shown below and we hope to add a long, maybe 8 - 10' wide sunroom addition on this side that will encompass the far walk-in door and the large garage door---that way on sunny days, we can open those doors and capture extra passive solar heat.



John, thanks for that.  I am looking at the possibility of a batch type rocket heater.
 
Trace Oswald
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Eric Hanson wrote:Trace,

Yeah, ok, I get that the RMH in the garage is pretty far fetched.  My thinking was that if you could heat some mass—as opposed to air—the mass alone could provide some heat that would not simply rush out the door every time it gets opened.  

If you don’t mind me asking, where are you located?  -30 is awfully cold, but I have been there as well.  I grew up in central Illinois and we regularly got temperatures that sank to the -20 to -25 territory.  I had a beloved outdoor cat growing up and one year he was sleeping in an old pet crate (used to transport medium sized dogs in a plane in the 1960s.  Inside the crate we put a laundry basket lined with an old sleeping bag.  We put an old blanket over the whole thing to give a sort-of door to the crate.  But it was still probably -10 at the warmest inside the crate.  My solution was to add 3 1-gallon jugs of water (they were old milk jugs) filled with hot tap water.  We stuck these jugs just behind the laundry basket.  

An hour later I went out to check on my cat.  I pulled the blanket back, stuck my head in and was greeted by a blast of 90 degree air and my cat was purring loudly!  The next morning the temperatures had dropped to “only” about 60 degrees.  The hot water had more than held up all night.

My point in all of this is that a hot mass can really store heat a LOT better than air can.  This is an important component of the RMH.  I know that this is still likely far fetched, but is there any chance that you could heat a mass to leave inside the garage to slowly radiate away it’s heat?

This is really just me spitballing but I think that s heat radiating mass is great way to store heat.  Water has an amazing heat capacity so some hot water is a 5 gallon bucket with lid attached would store and slowly release a generous amount of heat.  I had neighbors (that sadly moved—I really liked them!) that had chickens outside their house in a little hutch.  They were using the deep litter method to heat the chickens on cold nights (which around here is more like 10 degrees), but this technique was not really working.  I told them about my cat and suggested the 5-gallon bucket of hot water with a lid and they were sold!  They continued to use a 5-gallon bucket with a lid until they moved.  Their chickens were happy!

Anyhow, another long winded post and take it for whatever you think it is worth.

Eric



Eric, I'm in WI.  Last year we had days that were -40 F when I went to work.  I don't remember a winter without days that were colder than -20.  

As far as using water for thermal mass, someone may be able to figure out the exact numbers for this, but I don't see how it would be feasible in practice.  Maybe someone knows how to do the math on this?  The garage is 1000 sq ft, with a 10 ft ceiling.  For all intents and purposes, the garage is going to go to outside temps every weekday morning when we have to open two of the big garage doors to get our vehicles out.  In practice, I see it working like this.  We get home at say, 6 in the evening.  Let's say it's 0 F at that time.  Some days will be much colder by 6 PM, possibly 40 degrees colder.  I would have to fill a number of 55 gal drums with water.  I have no idea how many.  For sake of discussion, I fill 10 55 gal drums with water that is 100 F.  Assuming they give off heat until morning, and I have no idea if they can last that long, what happens next?  I don't know how to calculate what temp the garage would be or how cold the water in the barrels would be by morning.  I am certain that it won't be long before the water in the barrels will approach 32 F, at which time, I have to empty them somehow before they freeze, and re-fill them with hot water.  That is 1100 gal of water I have to move every time the water cools off.  As I said, I don't know how to do the math on this, but at some point, I'm going to be busy, or not home, or the water froze before morning, and now I have 550 gals of water that I have to heat back up to above freezing just to get rid of it.  There may be ways around all this, but at some point, doing things in a more conventional manner just makes more sense.
 
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Trace,

Actually I kinda like the hot water idea.  Off hand I don’t know how to calculate the heat stored vs heat released.  

In my imagination, the place where my ideas work best, I would have a series of 55 gallon drums—let’s say 10–that would be heated to right up to boiling.  Let’s call that 210 degrees Fahrenheit.  I would stack them one on top of the other.  You would have a row of 5 double high.  The purpose would be to have as much points of contact between the barrels to conserve heat.  I would stack them on some type of wooden shelf—just to prevent the cement floor from sucking out the heat.  Further I would heavily insulate behind and maybe even beside the barrels so that the outside wall does not suck out heat.  I would put some reflective barrier on the insulation facing the barrels to direct heat away from the wall.

At this point it would be a matter of calculating the heat dissipation.  Of course, preventing freezing would be paramount. Maybe you could add some anti-freeze, but unfortunately that will lower the specific heat capacity,  maybe not enough to matter and if it prevents freezing and bursting its worth it.

Anyhow these are just my thoughts.  Let me know what you think!

Eric
 
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I guess I don't see how putting 1,328,994 BTUs* of heat into barrels each day and then letting it bleed out into the garage and out the door when it's open, would be a viable solution.  You'd basically be heating the garage daily in case you need heat.  And dealing with freezing and pumping and a lot of complication.

I'm thinking it's much better to just come up with a space heater that will quickly heat the space for those times when you need it.  And maybe a bit of mass, or insulation, or an easy way to keep it burning through the night on -40 nights.  Is your garage open to the roof decking?  And do you have soffit vents that are open to the interior of the garage?  If so, you have a continuous leak of air so the insulation may not do as much as it would in a "tight" building.

*made up number
 
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Let's assume I don't care about the amount of room taken up by the barrels in my garage.  My first thought is, how am I going to heat the water to 210 F?  How are you going to safely stack the next row on top of a row of boiling hot metal 55 gal drums?  We agree that the barrels will cool down at some point.  Then what?  I can imagine it takes an enormous amount of energy to heat 880 gals of water from near frozen to 210 F again.  If they do freeze, the barrels will rupture.  If I use anti-freeze, the problem is worse, because the barrels will be much colder than 32 F, and so it will take that much more energy to heat them back up.
 
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Mike Haasl wrote:I guess I don't see how putting 1,328,994 BTUs* of heat into barrels each day and then letting it bleed out into the garage and out the door when it's open, would be a viable solution.  You'd basically be heating the garage daily in case you need heat.  And dealing with freezing and pumping and a lot of complication.

I'm thinking it's much better to just come up with a space heater that will quickly heat the space for those times when you need it.  And maybe a bit of mass, or insulation, or an easy way to keep it burning through the night on -40 nights.  Is your garage open to the roof decking?  And do you have soffit vents that are open to the interior of the garage?  If so, you have a continuous leak of air so the insulation may not do as much as it would in a "tight" building.

*made up number



I cross-posted with you and didn't see your response until now.  I agree with your assessment, I just don't see how it is feasible to use water.  The garage will not be open to the decking, it will have a ceiling and I've decided to heavily insulate the entire garage.  
 
Eric Hanson
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Trace,

First off, you are absolutely correct and bring up very important points.  880 gallons is a lot of water, and in this particular case that is both highly important and critical.  What I was trying to demonstrate is that bulk water is a great way to store a very large amount of heat, especially if all you wish to do is let it warm a room (as opposed to turning that heat into electricity or some other form of energy).  Bulk water will not by itself heat anything.  This is where some water heating device would necessarily play a role.

The advantage this would have over forced air heating (like your torpedo heater) is that even when you raise up the door on a -30 degree day, the water in the barrels would only slowly cool.  All the warm air will go right out the open door, but 880 gallons of 200+ degree water will only slowly cool.  And the moment the door closes, that passive radiant heat will warm the air steadily up.

If it were me and I had no barriers to my imagination, I would operate a little RMH that would be connected to the water wall.  I would plumb all those barrels together such that I would take out the water from the bottom and get it to near boiling and pump it up to the top.  If I were really crazy (and since I am pretty much operation in my own imagination, why not?) the RMH itself would be a water jacket around a combustion chamber.

Again, you are absolutely correct that something is going to have to heat that water—a lot.  You have already ruled out a RMH, so we can take that part right out of the equation.  Perhaps some type of water heater could be plumbed in.  

Ultimately, the water wall would exist in order to buffer dramatic temperature changes.  Maybe this is not the system for you.  I realize that in many ways that little torpedo heater is pretty quick and simple.  But every time the door opens, or air leaks in/out that heat dramatically flows right out whereas with a water wall or a RMH, most of the heat is still retained in the mass itself.

Trace, I am only trying to point out possibilities, but if this is not for you, then it is simply not for you.

Eric
 
Eric Hanson
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Trace,

I should have put this in my last post but I got sidetracked.

Going back to your original question, regarding insulation, I guess that I would simply go with the cheapest option available.  From the sounds of things, air is going to move in and out no matter what.  After all, that is the nature of garages.

The water wall is a possible way to buffer these temperature extremes.  But it is complicated.  It is a potentially excellent way to store heat (similar to the way that a RMH stores heat), but it would require some work and a separate apparatus to heat that water in the first place.  Insulation is vastly easier, and if this were a house I would be more inclined to use fantastic insulation.  But as this is your garage, do what is appropriate for you.

Eric
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