In floor heating vs. radiant vs. forced air in shop??

[PILOON]

Regardless of how you end up heating, I'd suggest you pour your floor over a foam board base to prevent the cold floor syndrome.

At minimum do about 2-4 feet around the perimiter.
Sure wish I had done mine that way as the shop is comfortable to work in but my feet freeze.

You could even use recycled foam boards and maybe the lumber yards would dicount the broken ones that they always have laying about.
You can 'mix and match' brands/thicknesses as the concrete pour will even everthing out once floated.

With foam you are then heating only the concrete slab, without you are heating the ground as well to who knows how deep.

 

[jgrreed]

I think part of the problem with heating these spaces is that the slab provides radiant cooling
even when your heating the space. You have to overcome the fact that you have many tons of thermal mass radiating cold into your space.

I think you should look into radiant in the floor and solar pannels on the roof to
heat the floor.. I've seen this done before and it works very nicely...

Alberta may be on the cold side for this so research will be the key...

Regards,
Chris

That's a really good thought. In the back of my mind I'm considering going geothermal/solar for the whole place. The acreage is on the south side of a valley, so the sun is REALLY low in the winter and the roof of the shop won't get much sun. If I was in a different location, it'd likely work better.

-Jer.

 

[Redneck in training]

Hi All,

I'm looking to pour a slab, insulate, and finish my 35x40 shop this summer. It's wooden framed, and metal cladded, with 10' ceiling, and a sliding door. I think I'm going to change the sliding to an overhead door.

I've heard many different opinions on how to heat it, and I'm looking for some experienced opinions to sway me.

I'd love to hear your opinions on cost of install, cost to run, comfort, and any things you'd change with yours.

Thanks!

-Jer.

It all depends how you are going to use the space. Floor heating has long time constant in the sense that it takes about 2 hours to change the temperature by 1 deg. For constantly inhabited space it is most efficient heating especially coupled with ground source heat pump. For occasionally inhabited space such as a shop you might need something that provides heat quickly. Another issue with floor heating is cost and complexity. The liquid used to heat the floor shouldn't be warmer than 115F or 45C. Therefore the system requires (beside room temperature and boiler or heat pump control) additional control system such as temperature controller operating a mixing valve, pump(s) etc.
We have floor heating with a heat pump installed in our house. If you would like more info send me a message.

 

[jgrreed]

It all depends how you are going to use the space. Floor heating has long time constant in the sense that it takes about 2 hours to change the temperature by 1 deg. For constantly inhabited space it is most efficient heating especially coupled with ground source heat pump. For occasionally inhabited space such as a shop you might need something that provides heat quickly. Another issue with floor heating is cost and complexity. The liquid used to heat the floor shouldn't be warmer than 115F or 45C. Therefore the system requires (beside room temperature and boiler or heat pump control) additional control system such as temperature controller operating a mixing valve, pump(s) etc.
We have floor heating with a heat pump installed in our house. If you would like more info send me a message.

I was thinking of a combined system as mentioned above. In floor to keep the temp at a constant 'warm' level, and a radiant or forced air to heat it up fast to work.

I'm 100% on board with the insulation underneath the slab. We own a house elsewhere that didn't have this done, and it really sucks!!!

If you can walk naked out of your house and p@e from your front steps then you can claim you live in the country.

Yaaa!!! It's not just an acreage, I do live in the country!!!!!

-Jer.

 

[Redneck in training]

I was thinking of a combined system as mentioned above. In floor to keep the temp at a constant 'warm' level, and a radiant or forced air to heat it up fast to work.

I'm 100% on board with the insulation underneath the slab. We own a house elsewhere that didn't have this done, and it really sucks!!!



Yaaa!!! It's not just an acreage, I do live in the country!!!!!

-Jer.

I just realized that the complexity of the temperature control could be overcome by combination of floor and wall radiator system as it is done commonly in Europe. Water (or glycol coolant) from the boiler enters the wall radiators first and then enters (at lower temperature) the floor tubing. If you use high temperature system such as described above the PEX tubing has to have an oxygen barrier to prevent corrosion. Also propylene glycol water mix (as the heat carrying media) is preferred due to its low toxicity and better lubricity.

 

[PILOON]

How about 'poor man's' floor heating.

i.e.: Gas fired 60gal hot water tank (cheap alberta natural gas) PEX in the floor element network and a $100. circulation pump?
For expansion chamber the guys use old well pump tanks.
Naturally antifreeze solution (one time expense) in case of failures.

I know of a few guys around here that do it that way (Quebec electricity, however), some even use wood stoves with heating coils inside.

That will keep the shop 'bearable' and a hot air furnace or construction heater to 'top up' the temps when needed.

 

[kenstrac]

I built this 36x40 x16 w 14x14 door 2x6 construction alaskan slab and heated it oil fha unit heater had 2 ceiling fans to bring heat back down ran rebar all along outside and welded it all together had some mylar I got for free put that down first then insulated with foam lifted wire up with bricks and poured floor.

BTW as you can see there is a large exhaust fan in the pictures used it in summer to circulate air in shop and to remove smoke in winter while running equipment leaving the small door open I had to hook up switch so that either the fan would run or furnace but not both as it would suck the flame backward through the burner,

 

[Redneck in training]

How about 'poor man's' floor heating.

i.e.: Gas fired 60gal hot water tank (cheap alberta natural gas) PEX in the floor element network and a $100. circulation pump?
For expansion chamber the guys use old well pump tanks.
Naturally antifreeze solution (one time expense) in case of failures.

I know of a few guys around here that do it that way (Quebec electricity, however), some even use wood stoves with heating coils inside.

That will keep the shop 'bearable' and a hot air furnace or construction heater to 'top up' the temps when needed.

It can be done but still it will need temeperature control of water entering the floor. Too quick temperature rise and it will crack you floor. In the same time boilers are very hard to operate at low temperatures. The main issue is condensation and consequent corrosion of the boiler as well as the chimney. Therefore some kind of temperature, either by design or control equipment, is necessary.

I remember a case many years ago. I was working for a process control company. We supplied, among other things, temperature control for "Crittal" heating which was a predecessor of today's floor heating. The heating was installed in a second floor of a convention centre. One day the mixing three-way valve got stuck overheating the floor to about 70-80 C. The floor expanded enough that it buckled and cracked the walls and the building almost collapsed.

 

[Blagadan]

If you do have an airtight workshop.... Lucky you!! The thing I dont like about heating the air in a workshop is that it takes a lot of time and effort to warm up all that air, and once you open the door, whooooosh, its all gone!

I have tried a few different types of heater in the past but electric IR heating has proven to be the most versatile so far. I'm going to recommend an electric Infrared heater with clear quartz lamps.

If you have a decent power supply to your shop, this would be a good way to heat it. Mine is a 3kv 240v unit which is perfect for my 20" X 30" shop. I used to have mine fixed in the centre of the workshop over my main workbench, but after a while I decided to mount it on a tripod stand so i could move it around. I use it outside in the late summer when the evenings turn cooler. Real handy for barbecues and such. I like the portability of it. The instant and direct heat is nice too.

I dont have an exact photo but here's a few ideas... I mounted it on an old "site light" tripod having removed the 500w lamps for another project...

 

[BungeeII]

Hi All,

I'd love to hear your opinions on cost of install, cost to run, comfort, and any things you'd change with yours.

Thanks!

-Jer.

Sorry, I overlooked that part in my initial response...
The overhead system I installed myself and purchased the hardware wholesale for less than $1400 in 2002. I don't know what current prices are.

An insulated slab will be wonderful, whether you go with a boiler or overhead radiant.

Happy shopping!