Heating the floor or no?

[canuck1]

I know how questions like the title for this thread usually go. I'm looking for realistic pros and cons, not just "of course!" or "why would you waste the money?"

My detached garage plans are for three bays (one for storage, one for my wife and one will be my workshop). My workshop portion is pretty small (16' x 30' if I don't steal from my wife's space ) but I have worked out a way to fit a 2-post lift.

I have friends who have (Propane fuelled) hydronic heat for attached garages, so I've sought local advice, I wanted the sanity check here if possible as well.

My car is a summer-time driver, so most all the time I spend in the garage is early Spring, late Fall and Winter. That rules out the need for AC. What I'm wondering about is whether or not hydronic in-floor heat is the best solution for someone like me who is not retired (yet) and only gets into the garage after work or weekends. Wouldn't it make more sense to simply have an efficient space heating option that gave me heat quickly, when I needed it? I have natural gas on my street but am also building the capability to run a heat pump (either option could heat the liquid fairly efficiently).

I like the deluxe sound of HEATED FLOORS but will I be happy I spent the money on it rather than another solution given the way I use the space?

Thanks,

Sean

 

[T45]

OP what exactly is the scope of work you plan to do in your space?.
What is the budget for this as a capital improvement project, loosely speaking?
Where do you live, regionally, at least... and what is the climate?
Also, Is this garage built yet? Where are you in the planning/lifecycle of the space?
etc.

 

[canuck1]

I like to modify/reconstruct cars (my Cobra replica mostly). I live on an island off the southwest coast of Canada, due east and a little South of Bellingham, WA. Climate zone 9a, SW facing oceanfront. The overall budget is (roughly converted to US dollar equivalent) $300,000 including new 3+ bay garage structure complete, landscaping, septic system replacement and repaving etc. We just finished an archaeolgical survey and digging foundation starts this month. This is the last house I will live in, so resale value isn't high on my list of considerations. I'm 60 now. Our latest house was a perfect match to our plan of going to single-level living. No garage means I get to build what we need.

Sean

 

[Firebrick43]

I think heated floors are the best thing about my garage. Supremely comfortable, even when air temps are in the mid 50/low 60's. If you feet are warm, you are warm usually. Bad part is I have fallen asleep sometimes on the creeper. I also have them in the 1450sqft addition on the house.

 

[larry4406]

I vote heated floors. Not my money.

There are likely thousands of posts just like this one to sway someone one way or the other.

 

[mm08822]

Forced hot air gives you heat and cooling - temp and humidity control.
Heated floors and ceiling fans may be a fair trade - some lose wrt humidity. If you are spending all of your time in there during the cold season, then toasty toes would win for me.

 

[JohnX14]

For a 3 bay garage, I'd just put in a NG/ Propane Modine Hot Dawg heater. I have that in my 2 bay detached, and another in my 2 car attached garage. I keep the detached at 45 degrees, and turn it up when i go out to work there. Anything more than 50 generally has me sweating. The unit is priced reasonable, and the installation is peanuts. I wouldn't want hydronic radiant for a few reasons. I like the quick rise of the unit heater if I turn it up. I like the dry heat, for when I'm washing, waxing or detailing vehicles, or even staining or painting a woodworking project. And despite my recent post about rarely losing power, I wouldn't want hydronic in my garage when it would freeze in an outage. Granted, the same could happen to my house, and I have a portable generator to manage that outage. It doesn't take much to run whatever is heating your garage floor.....although I do know that radiant is sometimes run from an electric water heater as a quick, easy, and cheap heat source. It doesn't need to be a more expensive fossil fuel boiler. Do you plan to have water in this garage? Just hose source? Bathroom? That and your location would be meaningful.

 

[fitter30]

Radiate heat / warm floor great to work on but can't turn it off. Cement floor has lots of mass and mass is hard to heat. Air is easy. Pull a car in and it's -12°c to bring it up to room temp going to take hours. Insulation. In subfloor helps so your not heating the ground. Might look at radiate tube heaters.

 

[jack stand]

Insulate the slab like your going with radiant, set in the pex loops.
Make your mind up later. (after your disappointment with conventional thinking)
The insulated slab will benefit any type of heating and dropping in the pex is pennies in the overall budget.

 

[canuck1]

Considering I built my current car on jackstands in an unheated, uninsulated, stucco-on-shiplap garage, any kind of heat, especially with a properly insulated building would be a huge plus. While freezing temps here are common enough, it's rarely that cold for more than a few days in a row. The wind off the water is a special kind of heat-stripping cold though. I"m hoping proper insulation will make all the difference there.

Some have you have echoed what has me asking questions. I'm not in the garage all day, every day, where hydronic heating could really pay off. I'm a part-timer at best with big ideas about making this workspace DELUXE (to me). I'm thinking going all-in for insulation and a powerful natural gas heater that could bring temps up in minutes might be the right choice for me. The always on concept along with how long it might take to get it to the temp I want on a cold winter night is what has me second-guessing my desire for hydronic heating.

Sean

 

[JohnX14]

Insulate the slab like your going with radiant, set in the pex loops.
Make your mind up later. (after your disappointment with conventional thinking)
The insulated slab will benefit any type of heating and dropping in the pex is pennies in the overall budget.

No arguments here......

 

[Rusted Nut]

Insulate the slab like your going with radiant, set in the pex loops.
Make your mind up later. (after your disappointment with conventional thinking)
The insulated slab will benefit any type of heating and dropping in the pex is pennies in the overall budget.

This gets my vote.

Heated floors are nice, but they are slow to heat. If you’re only in the shop a day or two here and there, you’ll spend a fair sum getting it to temperature. Go with jack stand’s idea, them you can add a heat source later. Also, if you’ll have a lift, then you’re not laying on the floor.

 

[Steve W.]

Just in case you DO consider in-floor heating, … are you planning on having a lift? If so, be sure to plan its location CAREFULLY, and be SURE you know where your tubing is before you bolt down the lift.

.

 

[BurtEggley]

we had radiant heating in San Mateo when I was a kid. It is nice. If there is any dampness coming thru the floors it will drive that humidity into the air. Can be good or bad depending where one is. I would think with a lift not as fun as if you have to lay on the floor to work on car. Can see myself falling asleep in a warm spot on the floor. I haven't priced one but you won't be drilling random holes to mount something in the concrete unless you plan it. And, the slab has to be stable not to break coolant lines. On the other hand, forced air is nice too. It can condition in summer and winter. Maybe risk of ignition of aerosols is higher in a garage with natural gas, propane, oil etc.. I turn off the water heater when doing anything flammable in the garage - spray paint, draining gasoline out of the tank to change a gas sender or fuel pump etc.. Sounds like a fun project.

 

[coldh2o]

How about both? I have heated floors in my shop (propane boiler) and keep it at 12 deg C all winter. If I'm out there working for a while or painting, etc. that needs higher temp, I have a 5000W electrical heater that will bump the temp a few degrees in less than an hour.

Very expensive electrical heat but it was a relatively cheap test for proof of concept. I'm going to look for a used propane hanging furnace to replace the electric heater.

 

[JohnX14]

How about both? I have heated floors in my shop (propane boiler) and keep it at 12 deg C all winter. If I'm out there working for a while or painting, etc. that needs higher temp, I have a 5000W electrical heater that will bump the temp a few degrees in less than an hour.

Very expensive electrical heat but it was a relatively cheap test for proof of concept. I'm going to look for a used propane hanging furnace to replace the electric heater.

A propane unit heater will raise the temp a degree a minute. Do it and you won't regret it. Maybe I'm exaggerating, but not by much 10 degrees in 20 minutes is normal for me. relatively small garages with insulation and plaster, fwiw. (24x24 and 24x28)

 

[Dagny]

Another option is high eff. gas furnace pvc chimney easy to add ac. drawback needs a drain.

 

[kabinenroller]

I designed my building around the hydronic heating system. 2,400 square feet, 9’ side walls, full foundation, 2x6 walls, and an insane amount of insulation. I keep my system set a 60 degrees 365/24/7, it is very comfortable to work in and I never worry about condensation on bare metal. I have a wall mounted propane boiler. I highly recommend this type of system but you have to keep the thermostat set a a constant temperature, raising or lowering the set points is not efficient.

 

[ipgenie]

When I built my add on to the pole barn, I kept saying that I'm only out there a day or two a week.

I have floor heat in the attached garage and keep it above freezing but warm it up fast with a unit heater when I want. That is the perfect combo. Comfortable efficient floor heat and something else for quicker warm ups. The secondary heat makes a good backup if the boiler needs maintenance and if you go with a mini split you can have AC and dehumidification when desired.

Now my home office is out in the pole barn and I'm out there every day. I wish I'd put the tubes in the floor. At 60 you only use it some days, but when you retire that might change. Having the floor heat option might be more important to you in a few years. We love the floor heat in our home.

In any case, congratulations on your new space. It sounds like it will be really nice. You will love it!

 

[UserNameAttempt3]

With the heated floors in our house, you definitely have to mind the humidity levels, could get a lot of condensation in areas that aren't well insulated from the outside (like the AC vents), or run a dehumidifier as well, unlike with a furnace you won't dry out the air, just warm it up.

 

[ipgenie]

Our house drys out enough in the winter that we have to run humidifiers to get it into the 30% range. In a humid environment, that may well be an issue the OP needs to be aware of.

 

[dscheidt]

we had radiant heating in San Mateo when I was a kid. It is nice. If there is any dampness coming thru the floors it will drive that humidity into the air.

If there is dampness coming through the slab in a new building, it means the concrete contractor screwed up. The slab should be on well draining base, that doesn’t actually touch the slab, because of a substantial vapor barrier.

 

[JKinAK]

Heated slab with floor drains is ideal in an environment that sees snow/slush. Ice/snow/slush clear off of the vehicle relatively quickly (even more quickly if you run a fan blowing under the car) - you can work under a vehicle without it dripping on you hours after pulling it in (as opposed to a day or more). In our environment there are no humidity issues to contend with. I'd be interested to hear about the experience of folks in cool coastal areas who have in-floor hydronic heat garages - does the garage floor dry quickly when pulling a vehicle in during snow/slush conditions?
I agree with those that advise keeping it at a constant temperature - you aren't going to be able to increase the temp rapidly like you can with a unit heater.
My boiler isn't in the garage/shop so there's less risk when combustibles are present. If your house is close enough to your garage you can heat from your primary house boiler (assuming you're not going forced air in the house) - I appreciate not having a second boiler for the garage.
Regardless - definitely follow jack stand's advice - put in the pex etc.
Don't forget the floor drains!
It's gonna be great.

 

[stingry]

I have radiant floor heat in my shop here in Western Nebraska and highly recommend it. Yes, a unit heater will get the job done but comfort wise, there will be nothing better than going out to your shop when those cold winds are blowing off the water, opening the door and feeling the welcoming warmth of radiant heat!! There is nothing like it. You live in a fairly temperate climate so I can’t imagine that it would cost that much to maintain a constant temperature in your shop, particularly if you utilize the natural gas and insulate very well, particularly under and around the slab.
i’m in zone 5 so temps are regularly in the single digits and in the teens. My shop is 3600 sq ft and is very well insulated. I use a natural gas hwt as a heat source. My cost to maintain a 68 degree air temp is at most $150 a month.

 

[Bad Habit]

FWIW, I have a non-heated, very poorly insulted ~800sg ft shop on the east-side of the Cascades. Winter temps are typically under freezing, with high 20s to mid 30s normal in the shop. I'm out there a lot, for the most part it doesn't bother me. Hand warmers in my hoodie pocket and I'm good to go. What does get me though is the floor, a couple of hours out there and that cold concrete just soaks into my toes, doesn't matter how insulted my shoes are. A warm floor would be so nice...ymmv

 

[J Adams]

I live in the Portland OR area, similar climate to you, and have hydronic floor heat in my custom built house.
Best decision I ever made. It's fired by a standard 80% efficient natural gas water heater, 3 zones. Very low operational cost, it operates October through May/June.
Worst decision I made when building the house was installing a central, ducted air system because I needed an air handler for A/C. Central systems are inherently less efficient because of the ducting.
At the time, I didn't know about ductless mini-split systems, I WISH I would have installed those instead of the central system.
My recommendation for you is a 2 or 3 zone hydronic system with a mini-split heat pump unit. This would provide low cost floor heat with super efficient A/C and back up heat.
Higher up front cost but REALLY WORTH IT!!!

 

[ericm]

When I started dating my wife she lived in a small house with heated floors. I mostly noticed it when I went to the bathroom at night barefoot. It was really nice! But I don't go barefoot in the shop.

It gets into the 20s at night here but rarely lower. I went with no insulation under the slab and mini splits for heat. This winter the floor has been cool but not cold like in an unheated garage. I normally wear boots when I'm in the shop anyhow and I'm planning on not lying on the floor much. That's what the lift is for! No more lying on the floor under a car.

For me it costs about $2-4 a day to keep the 2240 sq ft shop heated. It's nice to step in and it's already up to temp. The floor and all the stuff in the shop is up to temp as well.

With the extreme hot spells the PNW has been having, I'd plan for A/C. You can always leave it off until you need it.

 

[MN_Electrican]

I built my garage in 2023. 3 car, just under 1200sq ft. I had my general contractor put the insulation and tubing in with the intention of heating with it some day (hopefully that happens in 2026). they also dug down for the footings before they poured the slab for the 4 post lift i have picked out. I felt like this was minimum extra cost at the time even if i never used it. My $.02

 

[canuck1]

This is exactly the kind of feedback I was hoping for. Thanks to all who posted their experience (including ballpark $$). I'm installing a BendPak 10APX 2-post lift, so placement of everything around where the lift will go (in all 3 dimensions) is critical. I agree that it makes sense to install the pex, then figure out what heating options cost (gas boiler or air-water heat pump), then decide whether it's worth it. I'll continue construction process as if I'm installing hydronic floor heat (including pex and manifold so it's possible to pressure test with air before pouring concrete. The heating method decision can wait.

I'm in the aggregate business, so there will be plenty of well-compacted gravel installed before the vapor barrier and 2" WPS insulation is installed. The plan is for the slab to be insulated around the edges as well. I'm having trouble visualizing what that looks like from the outside, so share pics if you've got them. I'd hate it if I had to stare at the brightly colored insulation if it's visible!

There's no wall between my workshop and where my wife's car will park. This is all part of my evil master plan to banish her car to the elements when I need the extra working space Is it possible to keep different areas of the same slab at different temps? I don't know if it's worthwhile to leave some floor areas set at a minimum temp while my workshop is warmer? The total square footage of the slab is just under 1300 sq. ft. Maybe it's simpler/more efficient to just leave it all the same temp?

Sean

 

[65ranchero]

My boiler isn't in the garage/shop so there's less risk when combustibles are present. If your house is close enough to your garage you can heat from your primary house boiler (assuming you're not going forced air in the house) - I appreciate not having a second boiler for the garage.

This^ I wouldn't do it any other way set the thermostat in garage for 58F in the late fall and shut it off in early spring.
My UTV that I snow blow with will have the accumulated snow off in about an hour and floor dries in about 4hours (give or take).
Make repairing it much better

 

[ipgenie]

One thing none of us have mentioned is that in floor heat is quiet. Like no sound at all if the boiler is in a utility room. That may sound like a small thing in a shop but it's actually really nice to not have a blower fan running all the time. A mini split is the next most quiet heat/cooling source.

You can do zone heating like you are asking, but it doesn't make as big of a difference as you might think. We have an open kitchen/living room with a zone for each space. Even if only one zone is heating, the two spaces will be only a few degrees different. The floor will be warmer in one space than the other. In the shop you describe, I'd just treat any open spaces as a single zone so probably two, your wife's working space and yours combined with the parking bay.

 

[rust in the eye]

Insulate the slab like your going with radiant, set in the pex loops.
Make your mind up later. (after your disappointment with conventional thinking)
The insulated slab will benefit any type of heating and dropping in the pex is pennies in the overall budget.

This is exactly what I have done, nigh on ten years ago now. STILL haven't installed a boiler, not because I don't want one, long story.
With R10 foam under the slab and substantial insulation my garage remains liveable in all but the coldest weather. It is attached to my home so some heat is radiated from there.
There is ~ 1000' of PEX in the slab and a manifold waiting to be utilized. The additional cost for those items, done by me, was nominal compared to the entire build.
You can't do it later.

 

[jblnut]

Is it possible to keep different areas of the same slab at different temps? I don't know if it's worthwhile to leave some floor areas set at a minimum temp while my workshop is warmer? The total square footage of the slab is just under 1300 sq. ft. Maybe it's simpler/more efficient to just leave it all the same temp?

You can do multiple zones with numerous ways to make the water go where it's needed when it's needed. I have in floor in my farm shop, shop office, house and house garage. There is no other system that I'd install if in floor was an option. I'd leave it all as one zone and heat it all the same. I'd look at your insulation package and spend more money there as well. Leave the heat on all the time in all zones and don't look back. It'll be nice to be able to go out there and have it ready to work at all times.

One thing none of us have mentioned is that in floor heat is quiet. Like no sound at all if the boiler is in a utility room. That may sound like a small thing in a shop but it's actually really nice to not have a blower fan running all the time. A mini split is the next most quiet heat/cooling source.

The quietness of in floor heat is soooooo nice. No loud fans and blowers that kick on just as your favorite song comes on the stereo, no noise whatsoever.

I installed a minisplit in the shop last summer to provide shoulder season heat and cooling all summer. It is sooooooooo nice having a cool space with low humidity. A 2-ton unit cools my 54x72x18 shop with no issues.

 

[canuck1]

I've attached an scan of the floor plan for those who were asking about bathroom, water etc. We have a well (for irrigation only), so the pressure tank and associated plumbing (for city water connection as well) will live in the mechanical room along with the main electrical panel (it's mislabelled as 'garden'). My lift configuration will be assembled 10" narrower than depicted too.

I like the idea of having it warm and ready whenever I need it, I just don't know if I can justify the expense of the natural gas boiler or heat pump. Once I have a handle on initial investment and operating costs I'll be better prepared to make a decision. Building costs are so high right now, I need to exam all costs. I am drawn to the DELUXE aspect of always on floor heat though!



Sean

 

[Chuckster in NJ]

BEFORE you pour I suggest installing Radiant loops and a floor drain to daylight………. You don't have to hook up the loops until you are ready but if you want a comfortable heat, radiant is the best choice.
I keep my slab at 45*F during the winter and it is very comfortable working in there and if I want it warmer in the garage (at spur of the moment) I just plug in my 20KW DeWalt heater.

 

[finn]

I post this, more or less every time the op’s question comes up, which is probably three times per year:


We built a 32’x54’ garage at our then cabin, now retirement house. I planned it for a 30’x32’ unheated garage and a 24’x 32’ shop with 14’ ceilings for a lift. Plan was to wall off the shop space after we retired. The shop section has pex in the 6” insulated slab and a mason chimney with a wood stove. I also ran a propane line, and installed an overhead propane heater.

I never finished the installation of the radiant heat. I found that the wood stove kept the floor warm (remember, the slab is insulated) as long as you burn more or less regularly, and the hanging heater heats the place up rapidly, even though I never built the proposed partition.

Well, shortly after I retired, but before I ever got around to finishing the radiant system, I found another, larger building a mile away that had an office, well, bathroom, septic, 16’ eave height, an attached lean to for cold storage, a couple of 14’ tall doors, and radiant heat. I bought that as my new to me shop, converted the fuel to propane with a new boiler, and installed a hanging propane forced air heater.

I also have radiant in the house, so radiant isn’t foreign to me.

Cons of the radiant systems is, first, they don’t modulate or anticipate well in the shoulder seasons where there are wild temperature swings night to day. That’s true even though both the house and shop have outdoor reset hardware and software.

It takes a long time to raise the temperature from a low set point compared to what the hanging heater can do. That forced me into installing the hanging heater as a supplement. I’m not in the shop on a regular schedule, or for a predefined length of time.

Given that there’s no practical way to use setbacks since, with the slow response, the energy costs are high. The people that will inevitably dispute this are confusing the benefits of a well insulated building with the thermodynamics of heating a structure. Keeping a structure the same temperature 24/7 will use more energy, given the same insulation, than incorporating a setbach, which a hydronic system doesn’t excel at. Remember, I have 16’ ceilings and large overhead doors, along with five large windows and four man doors.

It’s expensive to install and maintain compared to a simple ducted forced air furnace. or a relatively cheap hanging heater. Pumps, boilers, valves, manifolds, and Taco controllers are all expensive and failure prone.

Positives are: first, it’s quiet, with only pumps and no fans.

Second, it’s clean, again, with no fans.

Third, it’s even heat, but be careful of letting the floor get too warm. Hot feet are uncomfortable.

Would I do it again ? Not sure. Probably depends on the climate. If the winter temperatures are in the 20s and above, them it's a hard no. If it regularly hits sub zero (F), then a hard maybe, depending on how often I use the shop.

For me, the wood stove supplemented by the hanging heater works best, except the wood stove isn’t practical in my large shop. It’s fine in the smaller 32’x54’, and would be even better if I walled off the workspace as initially planned.

It’s all moot, though, since we winter in Az now that I’m an old fart.

 

[jblnut]

Cons of the radiant systems is, first, they don’t modulate or anticipate well in the shoulder seasons where there are wild temperature swings night to day. That’s true even though both the house and shop have outdoor reset hardware and software.

This is always brought up as a con and I have zero issues/complaints in regard to temp swings in my shop. Once I switched to running the shop off of the floor slab stat all crazy temp swings went away. The slab will be 2f warmer than air temp when it’s above 0f and 3-4f above air temp when it’s -10f or colder. The pumps run more at night than during the day but not a lot. When I was running the temp off the air temp it’d go crazy when the sun went down and would pump heat in the slab all night to get the air temp back up. Come morning the slab is a quite warm so as soon as the sun comes up the heat shuts off but the slab is now radiating all the heat out and it gets really warm in the building.

OP - install an extra piece of PEX capped at the end in the slab that runs to the center of each individual zone so you can put slab stats in. You won’t regret it.

It takes a long time to raise the temperature from a low set point compared to what the hanging heater can do. That forced me into installing the hanging heater as a supplement. I’m not in the shop on a regular schedule, or for a predefined length of time.

This was my plan as well at first but I just keep it at a set temp and pay for the heat. Now that it’s heated with an outdoor wood boiler I don’t really care if it takes extra heat. Throw a few more pieces of wood in.

Given that there’s no practical way to use setbacks since, with the slow response, the energy costs are high. The people that will inevitably dispute this are confusing the benefits of a well insulated building with the thermodynamics of heating a structure. Keeping a structure the same temperature 24/7 will use more energy, given the same insulation, than incorporating a setbach, which a hydronic system doesn’t excel at. Remember, I have 16’ ceilings and large overhead doors, along with five large windows and four man doors.

If you intend to use in floor heat to heat a structure that you plan to use daily keeping it the same temp all the time won’t use that much more heat. If it’s something one is worried about install a topper heater so you can bump it up when you go out there. This will almost require a floor state for the in floor system or it’ll get cranky and not run when the air temp goes higher from the hanging heater.

It’s expensive to install and maintain compared to a simple ducted forced air furnace. or a relatively cheap hanging heater. Pumps, boilers, valves, manifolds, and Taco controllers are all expensive and failure prone.

Positives are: first, it’s quiet, with only pumps and no fans.

Second, it’s clean, again, with no fans.

Third, it’s even heat, but be careful of letting the floor get too warm. Hot feet are uncomfortable.

There is a line of “is the juice worth the squeeze” with everything one spends money on. A building heated with In floor heat is comfortable enough to work in that I’ll happily spend the extra on the equipment and maintenance so I have warm feet when I am in the building. I’ve had my oldest in floor system running for close to 15yrs and have replaced only the pressure tank. The other three in floor systems I own have needed zero maintenance in the 3-8yrs they’ve been running.

Would I do it again ? Not sure. Probably depends on the climate. If the winter temperatures are in the 20s and above, them it's a hard no. If it regularly hits sub zero (F), then a hard maybe, depending on how often I use the shop.

Everyone has a different way to justify the expense of anything they do. I don’t want to have a loud forced air heater yelling at me when I’m in my zen place getting stuff done nor do I want to wait to use the space until it warms up and have cold hands, feet, tools and supplies while I’m out there.

If the heated space is generating revenue you can argue it’s okay to keep it warm 24/7 and the revenue generated helps pay for the heat. If it’s a hobby space you can argue that hobbies are expensive but bring a level of mental calm that is worth far more than heating the space 24/7.

For me, the wood stove supplemented by the hanging heater works best, except the wood stove isn’t practical in my large shop. It’s fine in the smaller 32’x54’, and would be even better if I walled off the workspace as initially planned.

Very few insurance companies are okay with a wood stove in a detached structure these days. If they say they are I’d check closely as you may have an uninsured space.

It’s all moot, though, since we winter in Az now that I’m an old fart.

You’re bringing an element of looking back on the expense of all your cold weather things to your replies. It doesn’t sound like the OP intends to relocate any time soon so I say we help spend his money so he can live out his days in as comfortable a space as possible !!

 

[Jackfre]

I’ve installed a lot of radiant systems over the years. When I built my 30x34 shop with the ability to buy everything at wholesale or better pricing and lead/lag issues with radiant I chose to skip the radiant heat. I was out there all the time but simply could not deal with having to keep the system running. I wanted comfort on my schedule. Build the space to a proper spec to minimize heat loss and you don’t need a lot of heat.
IN today’s world mini-splits are the hot set-up giving you Heat/Air/Dehu. If you orient the building correctly you can install solar sufficient to run your whole property. I did that on mine and it paid for itself in less than 5 years, but I did the install myself, so savings there. My intention was to install the MS but family life changed and we left our “forever“ home 3 yrs ago.
I installed a Rinnai EX38 which heated the place perfectly. You can control them wirelessly if you choose. I left it as a straight on/off system. It took only a short time to warm the place. In you floor plan I would rough-in gas lines in the two sections and put an EX22 in each. These are splendid products and are good companions in the space, meaning they are quiet and cool to the touch and a simple install. The vent which is supplied requires only a 3” hole through the wall.
Radiant heat is terrific and if you have the resources then have a ball, but the solar/MS is the best way to go. Oh, one thing on that. You said you are ocean front. Check with the manufacturer of the MS to see how they warranty salt spray. Don’t install the condensing units on the water side of the building.

 

[dan1554]

Thought I'd post my situation in case its helpful. I put pex in my slab but have yet to connect it to anything. I have an office that I've been using for the last month or so off the side of my detached shop. I wear multiple wool socks and mucklucks to isolate my feet from the floor. Even with the wood stove hot enough to make the space uncomfortable, my feet can still be chilly. Its good to know I have the option to heat the slab, even if the upfront costs are out of my budget now.

I don't want to pay a fortune to heat the space, so the plan is to purchase an air-water heat pump and wire it directly to solar. During the day it will heat the concrete, and at night I'll rely on the thermal mass to continue radiating heat. If that's not enough, I can always add chemical batteries. But the concept is to limit costs and expand from there if necessary.

 

[canuck1]

Good stuff. I'm reading all the replies and taking in as much as I can.

Solar is certainly something I've considered, but I never thought that would provide adequate power for a mini-split unit? I'm not nearly educated enough to even know the power demand of a mini-split yet, nevermind the Solar infrastructure required to power it. I do know my garage roofline is oriented East/West with the the largest roof area exposure sloping unobstructed towards the southwest facing the longest sun exposure. it's almost tropically warm in the summer, but I'm not sure if the cloud and rain that's typical from late Fall to early Spring would make solar take a lot more time to pay off!? In any case, I tried to narrow down my own question to sort out the usefulness of hydronic floor heat. I'll try to take the time to consider ALL power source options when I've settled on actually heating the PEX I'll place in the slab or going forward with other heating types.

Sean