Radiant Slab vs. Everything Else

[Crazy68Dart]

I'm torn. I read about the great things about radiant slab heat, but also am the type to keep things simple. It is certainly a complicated install, as well as complicated system. I am not sure about the reliability long term, but that is a concern as well. More related to the system components.

I also read about condensation, etc. due to the lack of air movement. Other heat sources help to dry the air.

Any of you turned off by your radiant floor setup? I like the idea of a mini split which would also get me A/C for the humid summer months. If it does not keep up in the winter, maybe an additional natural gas fired tube heater or supplementary electric.

My space is a hobby garage. If it can be efficient enough, I would not mind leaving it heated all winter long, but with the slow recovery of slab heat, I am not sure of the reality of kicking the heat on and having a warm space in short order.

What to you guys think?

Thanks!

 

[Backlight]

Well, I prepped my building for radiant, 2" slab insulation, 5/8" pex as per the heat loss calculations. When it came time to install a proper boiler and all of the associated kit the quotes were simply not economical for a garage. I decided to go with a high efficiency unit heater (Modine Effinity93).

While it might not be quite as good as radiant at less than 1/4 of the cost I'll be fine with it. Plus with a unit heater I can run it when I want, I don't have to heat all winter.

 

[pstnbly]

Radiant good, everything else *****, LOL

 

[Backlight]

Radiant good, everything else *****, LOL

If you have the $$ do it. I'd say the only downside is slow heat recovery after you open the garage door.

 

[tdkkart]

If you have the $$ do it. I'd say the only downside is slow heat recovery after you open the garage door.

And there's always that person that has no experience spreading falsehoods.........

Actually, because the heat source, the concrete and other items in the room, don't go rolling out the door when you open it, the heat recovery is actually quite fast. When you're heating the air, every time you open the door your heat source excapes and has to be replaced, not so with radiant, pretty hard to cool off thousands of pounds of concrete in a couple minutes.

 

[Backlight]

And there's always that person that has no experience spreading falsehoods.........

Actually, because the heat source, the concrete and other items in the room, don't go rolling out the door when you open it, the heat recovery is actually quite fast. When you're heating the air, every time you open the door your heat source excapes and has to be replaced, not so with radiant, pretty hard to cool off thousands of pounds of concrete in a couple minutes.

If you are stating ambient air temperature recovery using radiant is the same or quicker than forced air I disagree. I hold to my statement. Moreover, a slab (and every other item in the room) has thermal mass regardless of the heat source (appreciating the fact the slab would clearly have more thermal mass when using a radiant heat source).

As to my level of direct or indirect experience, you are not really in a position to comment.

 

[kabinenroller]

In floor radiant is difficult to beat if your building is designed for it. A well thought out system is efficient, quite, economical, and trouble free.
I have installed it in an existing building with moderately good results, because I could not excavate and insulate the footings the system worked but was not as efficient as I would have liked.
When I relocated and built my new shop I designed the building for Hydronic heat. The differance is incredible. My building never varies more than a couple of degrees from the thermostat setting, everything in the building is as warm as the air, there is no moving air so there are no drafts. Even with the vaulted ceiling where my lift is installed the ceiling temp is only 3 or 4 degrees warmer than the temp. at workbench height. ( I checked everything with a lazer thermometer)
Being the building is very well insulated it stays cool in the summer, I do not open the overhead door unless I am moving a vehicle.
I did rough in for a through the wall air conditioner but at this point have not needed to install one.
I would not even concider a differant type of heating system.

 

[MagKarl]

You need to decide how much you want to spend. It's a much larger initial investment, and needs to be "on" to maintain temp vs. "on demand" heat sources that can be fired up only when you're out there.

There's no clear answer, everyone's climate, usage, and wallet are different.

I find it interesting how we can rationalize both in floor heat and on demand water heaters for the same idea of "efficiency", but for different reasons. Sometimes heating something that is unused is considered a waste, and heating another only at time of use is considered a waste.

 

[Jackfre]

I can buy all the gear, boiler, tubing, controls, at wholesale or better and still did not put it into my new shop/garage. I would rather spend the money on tools and materials. As well, given that I've suggested this to others, I have to put my money where my mouth is. My new shop is 960 sq ft. I'm going to put in a Rinnai ES38 Direct Vent wall furnace. I've heated my homes, basement and garages with them for the last 25 years, have sold and cared for over 210,000 of them in New England (a cold climate) and just see it as the right bang for the buck. I roughed in a 1/2" gas line yesterday and have a 110v outlet where the heater will go. Once I start the installation in 90 minutes it will be done. The 38 is actually oversized for the space. I could get by with the 22, but given the modulating firing rates 10,500-38,000 btu on the 38 and 8,200-21,500 btu on the 22 I will have a little more oomph on "pick-up" heat, as I will not be heating this all the time. Built in programmable thermostat will allow a maintenance temp down to 40*, 2 1/2 hole through the wall for the supplied vent. Simple and done.

Don't get me wrong. Radiant is the balls for heat. That said, I'd rather have a new Miller Synchrowave 210 and to upgrade my plasma 380 to the 45. I need a new cyclone dust collector (Oneida or Grizzly), 6" Jointer and the list goes on. I (mistakenly, as it turns out) sold off a lot of big tools prior to moving west and have to replace them. The radiant saving will pay for quite a few of them and I'll wear good shoes and be perfectly comfortable with my Rinnai Energysaver.

 

[Crazy68Dart]

Thanks for the comments so far. To be clear, I realize that radiant is a very way nice way to heat a building. My build is new, so I was at least planning on getting the PEX in the slab. Maybe not doing the rest of the system until a later date.

However, still, it is (initially) expensive and somewhat complicated. I think we are all always looking for the best bang for our buck, so I think that is where I am at right now.

My old, small garage 18x24, was heated with a small electric heater. I had a good garage door and insulation in the walls, and plywood in the rafters to keep the heat "down". It was stupid simple, and worked awesome (for me...).

 

[jlckmj]

If you have the $$ do it. I'd say the only downside is slow heat recovery after you open the garage door.

NOT TRUE!

Radiant recovers faster than forced air due to the large heat sink of the floor and everything else in the room being warm. Plus, you don't have that constant blowing from the fan while it is doing it.

The only down side I see with radiant is if you do not plan to use the shop for long periods of time, you have to turn it down (can't turn it off) and it takes 5 to 6 hours for my slab to heat up from 40* to 65*

Jim

 

[mygarageone]

So how much is your comfort worth ? Your slab will never be warm with any kind of forced air system . With radiant heat you'll be warm at 68 degrees or less because your feet stay warm .
I have installed every kind of heating system out there , you'll never beat the comfort of radiant floor heat . Yes it's pricy but once your slab is down. You can't go back and change it.
But do as you want , it's your place . Just don't make your decision on price alone .and don't let the na Sayers sway you , most have never had radiant floor heat , there's is a opinon with out substance .

 

[mygarageone]

If you are stating ambient air temperature recovery using radiant is the same or quicker than forced air I disagree. I hold to my statement. Moreover, a slab (and every other item in the room) has thermal mass regardless of the heat source (appreciating the fact the slab would clearly have more thermal mass when using a radiant heat source).

As to my level of direct or indirect experience, you are not really in a position to comment.

Ok then , what experience do you have with radiant floor heat , help us understand your knowledge here.

 

[Streetbu]

I'll throw my .02 in. Radiant is the best regardless of what some say. BUT, it costs $$$$ not only to install, but also for energy to use. Personally, I may work in my garage every day for 2 weeks after work, sometimes its only for 10 minutes then not again for a week or two. The energy it takes to keep the slab heated for 2 weeks for no reason is a lot. Therefore until I can afford a larger heat bill I use a forced hot air fuel oil furnace to adjust the temp to what it needs to be at that current time. Takes about 30 minutes for my 24x34x8 garage to go from 38 to 65 in the dead of winter. I keep the thermostat set as low as it will go when I'm not working so at least everything stays above freezing. I use approximately 5 gallons of kerosene or diesel/week to do this, more if I'm working out there for longer periods of time and have the heat cranked up. I could swing the initial installation costs, but not the high fuel cost of keeping the garage at 60 all winter long and wouldn't want to wait for hours for the slab to come up to temp if I turned it down when I wasn't working in the garage. Once again, it does work and feel the best, but my budget dictates differently.

 

[Randy in Maine]

I cannot imagine using anything other than my radiant floor heat. I just ran a new line to and from my boiler to the new garage and it is its own zone.

1 cubic yard of concrete = 2 tons of thermal mass. My garage floor is 21 cubic yards of concrete.

Very cost effective and very efficient. My shop is really air tight and well insulated that helps greatly. That helps no mater what kind of heating system you have.

I leave it about 50º out there and it stays right at that setting. I work out there in a long sleeve shirt very comfortably. No pilot light to cause an explosion from a leaking gas tank. No drafts. Dead quiet. Never an issue. I would guess hat if I lost power when it was 0º out it would stay above freezing for a couple of weeks at least. My cost was just the pex tubing, insulation under the slab, and the thermostat. You need the insulation for the slab anyway. Plus you don't lose any space for the heating system.

I turn it on around Thanksgiving and turn it off around April.

I would never want to another type of heat. I don't know anyone who has radiant floor heat it that would change to another.

 

[tdkkart]

NOT TRUE!

Radiant recovers faster than forced air due to the large heat sink of the floor and everything else in the room being warm. Plus, you don't have that constant blowing from the fan while it is doing it.

Ok then , what experience do you have with radiant floor heat , help us understand your knowledge here.

You're wasting your breath guys. Internet expertise trumps life experience every time.......

 

[SwampCat]

This title reads wrong , should say, RADIANT SLAB , then everything else .

 

[Crazy68Dart]

So I'm not trying to cause a thanks for the comments so far. lol

Is there anyone that has real world cost of heating with radiant versus heating with something else? Answer to this is probably a no...

I think the system can take up some wall space, at least based on the systems I have researched. What are the reliability aspects of the heating unit (boiler, on demand, etc.), circulation pump(s), etc. etc.?

I agree, I would do insulation anyway under the slab, so why not at least get the PEX in the slab... yeah... some more up front, but then it would at least let me choose which way I wanted to go.

 

[UpstateNY]

If you have the $$ do it. I'd say the only downside is slow heat recovery after you open the garage door.

You obviously don't have a radiant slab .........but that doesn't stop you from pontificating . I do and live in a cold climate, and you're wrong. Advice: stick to what you know .

 

[mygarageone]

you obviously don't have a radiant slab .........but that doesn't stop you from pontificating . I do and live in a cold climate, and you're wrong. Advice: Stick to what you know .

x. 2

 

[mygarageone]

So I'm not trying to cause a thanks for the comments so far. lol

Is there anyone that has real world cost of heating with radiant versus heating with something else? Answer to this is probably a no...

I think the system can take up some wall space, at least based on the systems I have researched. What are the reliability aspects of the heating unit (boiler, on demand, etc.), circulation pump(s), etc. etc.?

I agree, I would do insulation anyway under the slab, so why not at least get the PEX in the slab... yeah... some more up front, but then it would at least let me choose which way I wanted to go.

There are to many factors to get a true real cost for anyone's situation.
Building size , insulation , degree days , fuel type, where you set you T - Stat for comfort . But there are software programs that can give you a real cost estimate .
Do an internet search.

As far as equipment reliability It is .

 

[Heavymetalmechanic]

Take a look into solar thermal systems if you want to keep your operating costs down. Even in a cold climate they can convert a large amount of solar energy into heat, which is then stored in your slab. You use low (or none) amounts of fuel during the day, and if you have a programmable thermostat you can set the heater to kick in early enough to have the slab back up to temp for when you wake up to use it. Just an idea, the price of manufactured flat panel collectors has come down a lot over the last few years. And there is lots of information on constructing your own if you have the skills and time and wish to save some money.

 

[tdkkart]

Take a look into solar thermal systems if you want to keep your operating costs down. Even in a cold climate they can convert a large amount of solar energy into heat, which is then stored in your slab. You use low (or none) amounts of fuel during the day, and if you have a programmable thermostat you can set the heater to kick in early enough to have the slab back up to temp for when you wake up to use it. Just an idea, the price of manufactured flat panel collectors has come down a lot over the last few years. And there is lots of information on constructing your own if you have the skills and time and wish to save some money.

If people won't spend the couple thousand dollars it takes for the mechanicals of a standard radiant system, or won't spend the money to operate it monthly, they sure as hell won't want to pony up the $$$ for solar.
Most of the mechanical parts for a standard gas or electric radiant system are the same as for a solar system, and are relatively affordable. It's the heat sources that cost the big dollars. Electric heaters are cheaper up front but cost more to run, gas units are cheaper to run but cost more up front. Solar systems are basically free to operate, but cost much more to buy up front.

 

[BadgerBoilerMN]

Size of garage?

Intended use and schedule?

Number of rooms, use and schedule?

Available fuels and cost?

Open flame unit heaters are cheap for a reason.

Radiant heat is unmatched for comfort, economy and longevity. Nothing matches a radiated slab for recovery when the garage door is opened since the whole slab picks up the load and only a few pounds of air are lost to the outdoors.

If you can't afford it that's OK, your next best choice for heating is a low-intensity direct vent infrared...if you are using gas.

 

[jives]

My house has a radiant hydronic slab, 2 heating zones. The main portion of the house has a bank of south facing windows that provide solar gain to the slab. Hot water provided by a Baxi Luna tankless propane water heater. Because it is propane, it is not cheap.

My observations:
--The lack of blowing dusty air is a huge benefit. No drafts, no dust. Our boiler is in a first floor mechanical room, and it does make noise.
--It can take a bit of time to warm the slab up, but since the slab stores heat, and we have a highly insulated house, and because the thermostat is never below 58 deg, we never really have to warm it up much. We may go several days in mid winter without the heat on, but that is because of the solar gain.
--Our two zones are solar south side and non-solar north side. Thermostat on the north side is set low because that is the sleeping side of the house. There is less heat transfer from the warm south side to the cold north side than you might think. Just a couple of feet away from each other the slab may be toasty on one foot and cold on the other. Point here is that if you need to get the slab from cold to warm, it will take a while.
--I reckon a single zone garage does not take much plumbing, but the piping, manifold, valves, thermostat unit, boiler, and water intake in my house is complicated (we've also got an upstairs zone). There is nothing in this system I feel capable of fixing on my own. If something does go wrong, like a leak in the slab piping, whoa.

Conclusion? We poured our garage slab last week. No radiant (simply could not afford it anyway). Garage will only be used sporadically in the winter (couple hours per week), and radiant cost is not justifiable. Our plan is electric unit heaters, which fits well with our new photovoltaic system.

At some point we may add in a solar air heater.

 

[BadgerBoilerMN]

Baxi Luna does not make a tankless water heater. If you have one of their boilers, or a combi boiler, the outdoor reset would control delivered water temperature on outdoor reset. No overshoot possible if properly programmed. Annual service and water chemistry is a must on the Baxi, more especially when burning relatively dirty propane.

There isn't enough juice in the typical PV system to heat any living space.

 

[Crazy68Dart]

I've had a few threads on radiant over the past year or so. Mainly to figure out the best way to install the slab, insulation, PEX, etc.

Garage will be roughly 38x28, 1 16x8 and 1 10x8 garage door, 1 service door, two standard-issue windows, garage height is staggered, roof peak will be 18'. single stall will be vaulted/scissor for lift, the remaining will have roughly a 10' ceiling and storage above. storage is storage only. Everything will be insulated, R-13 walls, ceiling as much as I can, at least R-19. Garage doors will be CHI doors, I think they have an R-14 rating.

I have access to electric, natural gas. We have reasonable fuel prices in this area, I would need to look at my last bills for numbers.

Intended use -- as much as the wife and kids will allow. Reality, few times a week, at times could go weeks without being out there. Just the reality of life with a family, and demanding career. I don't mind keeping it heated (above freezing) as long as it does not cost an arm and a leg (hundreds of dollars per month). But if it takes days to get it up to temp to work, that is not ideal either.

My main concerns with the system is its complexity and many failure points. The initial up front cost hurts, but I assume this will pay off in the long run.

Additionally, A/C. Would need to add a A/C unit of some type. This is not that critical, but I think as I get older this may become pretty nice to have. Maybe a wall unit or something.

Thanks everyone again for the help.

 

[Stuart in MN]

I leave it about 50º out there and it stays right at that setting. I work out there in a long sleeve shirt very comfortably.

A friend has in floor radiant heat in his garage. The thing I noticed is you can keep the temperature pretty low and it's still quite comfortable in there; it's one of those interesting things about how radiant heat works.

 

[Mike K.]

So I'm not trying to cause a thanks for the comments so far. lol

Is there anyone that has real world cost of heating with radiant versus heating with something else? Answer to this is probably a no...

I think the system can take up some wall space, at least based on the systems I have researched. What are the reliability aspects of the heating unit (boiler, on demand, etc.), circulation pump(s), etc. etc.?

I've had slab heat since 2006. I'm in Medina so I suspect we have the same weather. In 2005 the gas budget billings was $160 / per month without the garage. Now it's at $115 / per month with the garage. (We are using more ccf, but the costs are down.) From 2010 through this month the house & garage have used 1,778 ccf. Garage is set at 65 for most of the your. I'll lower during extreme cold periods. House is 2100 s.f. built in 1999 with R13 walls.

The first year, I estimated the garage was $100 per month (we use budget $1200 total). Now it's much less.

Garage is 28 x 60 x 25 tall. Only heat is the boiler on the first floor. The second floor is usually 5 to 7 degrees colder than the first. The garage is not fully insulated yet, so I have many air leaks.

As mentioned before, quick heat recovery with everything heated when the outside door is open. No dust. Generally quiet. No maintenance.

The boiler is in a well vented closet 3' wide, by 2'. All the pumps & valves fit on a 3' x 4' panel. Above & behind the boiler.

If I want to quickly bump the heat I use an electric heater or small propane heater.

I would highly recommend in-floor setups over any other options.

Mike K.

 

[jives]

Baxi Luna does not make a tankless water heater. If you have one of their boilers, or a combi boiler, the outdoor reset would control delivered water temperature on outdoor reset. No overshoot possible if properly programmed. Annual service and water chemistry is a must on the Baxi, more especially when burning relatively dirty propane.
There isn't enough juice in the typical PV system to heat any living space.

Yes, the Baxi is a combi unit . . . domestic hot water and hydronic heat. By definition it is tankless and a water heater.

The combi unit makes things even more complex and requires maintenance. We already had a terrible "Quietside" unit replaced free of charge by the HVAC guys. The point being that radiant is about as complex as you are going to get, unless you go geo. I cannot see radiant being a good choice for part time use.

As for PV, no it won't heat the garage, nor the house. Our PV is an 8.1kW system and runs no heat or hot water. But, it can be used to help keep electric costs down, especially in 10 years after the thing is paid off.

 

[sands35]

I'll throw my .02 in. Radiant is the best regardless of what some say. BUT, it costs $$$$ not only to install, but also for energy to use. Personally, I may work in my garage every day for 2 weeks after work, sometimes its only for 10 minutes then not again for a week or two. The energy it takes to keep the slab heated for 2 weeks for no reason is a lot. Therefore until I can afford a larger heat bill I use a forced hot air fuel oil furnace to adjust the temp to what it needs to be at that current time. Takes about 30 minutes for my 24x34x8 garage to go from 38 to 65 in the dead of winter. I keep the thermostat set as low as it will go when I'm not working so at least everything stays above freezing. I use approximately 5 gallons of kerosene or diesel/week to do this, more if I'm working out there for longer periods of time and have the heat cranked up. I could swing the initial installation costs, but not the high fuel cost of keeping the garage at 60 all winter long and wouldn't want to wait for hours for the slab to come up to temp if I turned it down when I wasn't working in the garage. Once again, it does work and feel the best, but my budget dictates differently.

I have hydronic floor heat. I leave the thermostat at 45*F and it takes ~30-45 minutes to get up to 50-55 or so. Garage is 28x32. Yeah the rate of change is slow, but when it is at 50, I can work in shirt sleeves with no problem. Rolling around on the floor doing car work is much nicer than with forced air.

Having warm feet during the winter is a huge plus.

If you can afford the initial outlay, it's great.

Sooner or later I'll buy a wifi thermostat and be able to turn it up before I get out there. That would cost less than adding a small forced air gas unit.

It also recovers in minutes from an open garage door.

 

[theoldwizard1]

OP, what type of fuel do you have available ?

So how much is your comfort worth ? Your slab will never be warm with any kind of forced air system . With radiant heat you'll be warm at 68 degrees or less because your feet stay warm .
I have installed every kind of heating system out there , you'll never beat the comfort of radiant floor heat.

Unquestionably the most comfortable heat you will experience ! If you are only using the building a few hours a week, the cost to maintain the slab temperature is an issue.

I also read about condensation, etc. due to the lack of air movement. Other heat sources help to dry the air.

All heating systems remove moisture from the air. Radiant heat is slower to remove moisture than forced air.

I like the idea of a mini split which would also get me A/C for the humid summer months.

The ultimate combination for a garage in the midwest is a mini-split heat pump AND radiant in-floor heat. The heat pump can provide some auxiliary heat for big temp changes (opening a door) and take care of A/C in the summer.

The nice thing about this combination is that you can install the radiant heat first and wait a couple of year and install the mini-split !

 

[BadgerBoilerMN]

Or install the PEX tubing, no matter what, and the mini-split right away.

The expensive, but not necessarily "complex" part of any hydronic radiant system, is the heat source.

We design and install many garage heating systems but rarely use a combi-boiler. The two mentioned are the most "complicated" on the market, and perhaps the poorest supported as well. A bad combination, more especially for the DIYer.

Nearly all of our garage heating systems run with a one boiler or tank-type condensing water heater and one, and sometimes two, pumps with one thermostat. Not that complex, but not cheap if done properly.

It is all about how you use the space, how often and priorities.

This a UK webpage (where Baxi is more popular) dedicated to the Baxi "Combi-Boiler". I can't find any reference to "tank-less" water heater. If they make one, I haven't seen it in the nearly 20 years since the first one arrived in Canada...

 

[pseudorealityx]

OP, what type of fuel do you have available ?



Unquestionably the most comfortable heat you will experience ! If you are only using the building a few hours a week, the cost to maintain the slab temperature is an issue.


All heating systems remove moisture from the air. Radiant heat is slower to remove moisture than forced air.


The ultimate combination for a garage in the midwest is a mini-split heat pump AND radiant in-floor heat. The heat pump can provide some auxiliary heat for big temp changes (opening a door) and take care of A/C in the summer.

The nice thing about this combination is that you can install the radiant heat first and wait a couple of year and install the mini-split !

Heat does NOT remove moisture. It does lower relative humidity, because warmer air can hold more moisture per given volume. You're not actually removing moisture from the system.

 

[Crazy68Dart]

I am sure something like the following has been discussed ad nauseam in this forum but I was planning on something like the following (if I do radiant floor):

http://www.supplyhouse.com/Takagi-T...kagi-Tankless-Indoor-Water-Heater-Natural-Gas

 

[jonjon1]

I figure it this way, and I did A LOT of garage systems, both radiant and other...

Radiant is comfortable, in a hobby garage or toy box, is it economical? Not in my opinion..

Think of it this way for half of what radiant will cost you, you can put heat and A/c in your garage, so when someone says "my feet are always warm" I say "yah, they are, even in the summer, I can work in my garage all summer with out sweating a bit or having to leave the doors open and getting eaten by bugs..."

You open a garage door with any type of heat short of something grossly oversized and your going to be cold for a minute, I have both, furnace and radiant driven garages, and the recovery is about the same, sure with radiant the floor is still warm, thats great for the dogs, they ******* love it, but I like that warm air too... I like being able to come in from the cold and hearing that furnace running, I can run over to it and let it blow the snow off of me for a few minutes...


get quotes, figure out what is best for you, maybe bury the tubing and insulate the floor, do it yourself and then cap it off for a later date incase things change...

I personally would go with a package heatpump unit then a gas burner insert, so it will be dual fuel with a/c... Total cost for materials under $3000, install is a gas line, a 220 electrical line, and a thermostat wire, with some duct work through the wall.... I can install one in 3 hours with no issues, and they blow across the floor which is nice...

heres 3 ton 90K btu
http://www.amazon.com/dp/B006X1B5SG/?tag=atomicindus08-20

another option is just going with the heat pump ac unit and a separate 95% furnace, the cost is about the same the work is a bit more since you have to vent them and run more gas line etc...

http://www.amazon.com/dp/B00Q5LDBWW/?tag=atomicindus08-20

with
http://www.amazon.com/dp/B000ZPSX40/?tag=atomicindus08-20

so either way you will get a/c plus heat, but your heat will be 2 stages, so in the shoulder months when its not super cold {say down to 35} you run the heatpump for heat, then when its too cold for the heat pump you run the gas..

i personally like the separate gas furnace because they are 95%, plus if there is a problem with either unit you have a bit of back up...

 

[BadgerBoilerMN]

90 btuh should do it...about 17 times for the OP's garage.

A mini-split, with or without radiant.

Forget about house-size scorched air ducted units, they are usually over-sized for house with lots of windows and traffic. If you want dumb old garage heaters save your money and buy the gas-fired Hot Dawgs and blow the snow, the hat and your wife's clothes off, vroom-vroom! Gear heads, what can you do with 'em?

 

[jonjon1]

90 btuh should do it...about 17 times for the OP's garage.

A mini-split, with or without radiant.

Forget about house-size scorched air ducted units, they are usually over-sized for house with lots of windows and traffic. If you want dumb old garage heaters save your money and buy the gas-fired Hot Dawgs and blow the snow, the hat and your wife's clothes off, vroom-vroom! Gear heads, what can you do with 'em?

Obviously the op will have to do a heat loss, I was just linking the first units that came up on amazon, you can get 95% furnaces in about any btu output...

PS oversizing furnaces isnt the same as oversizing hydronic systems, where on a design day you would want your circ to run all day, having a non variable speed conventional blower fan running 24 hours a day would be counter productive, on top of that I like oversized fwa systems in a garage...

PSS mini splits are junk

 

[BadgerBoilerMN]

Over-sizing any space heating or cooling equipment is in fact counter-productive if the goal is comfort or efficiency.

The perfectly comfortable and efficient heating system has pump and boiler or fan and burner running full time during design conditions. If you have the best equipment perfectly sized the the load, the heat source will operate from between high fire and low 100% of the heating season.

You may correctly have a second stage, as with an low-intensity infrared or a backup infrared over radiant floor when quick pickup over a deep setback is required e.g. bumping up from 50 to 65F for weekend warrior work, but over-sizing most space heating or cooling equipment most often results in lower comfort and higher operating and maintenance cost.

I own three pieces of "junk" by two manufacturers and with COPs above three can't beat them with my beloved condensing boilers on natural gas...and they keep me cool, which isn't easy .

 

[mygarageone]

Not to create an argument but I keep hearing how expensive R floor heat is if your only going to use it a couple of weeks a yr ?
Yet many of these same people own either boats , snow machines or a cabin in the north and they all cost one heck of a lot more than R heating. But we humans can always justify anything we real want based on our lustfull desires . Our wants get meet and our needs get axed to satisfy our wants . It's an observation not a critizisum .
Most recreational equipment , cabins included get used only a few weeks out of the yr and they ultimately cost way more than our R heat systems.