Cost of heating a shop

[teejk]

West central Wisconsin...I'm heating 30'x40'x10' with infloor radiant tubing using a newer LP power vented gal water heater. 2" foam under slab, R19 fiberglass batts in the walls (from what I understand walls are not as big deal as the ceiling), R50 blown insulation in the ceiling. I hold at about 60-65F through the winter because I do a lot of wood work/finishing stuff and that's what it takes. From what I have read, in-floor radiant will not save much money but it is certainly comfortable. There is something in the head that says warm feet can make the entire body feel warm and 60F is not a problem. I think your garage doors are going to cost you some but radiant will help there...it forms it's own envelope within its walls I guess. But back to the question...I think I used 500 gals of LP on that tank last year and prices being what they were, it was expensive. I'm hoping last winter was a "blip" but I pre-bought LP this year at $1.74 so cost will be about $900. One thing I am going to do is insulate the outside perimeter with 2" foam...I didn't do it on the build because I purposely held the tubing 1' away from the edges and didn't think concrete would leach that much heat into the soil. Somebody told me I was wrong. Final point...do your research on spray foam...metal expands and contracts a lot and I was warned to avoid foam because it cured to a rigid mass and tiny cracks would form and allow moisture to form on the metal (i.e. rust machine). That was a few years ago though and maybe the foam is a little more flexible now.

 

[farmer2009]

Final point...do your research on spray foam...metal expands and contracts a lot and I was warned to avoid foam because it cured to a rigid mass and tiny cracks would form and allow moisture to form on the metal (i.e. rust machine). That was a few years ago though and maybe the foam is a little more flexible now.

I have heard the same thing. Was told a way to solve the problem though was to put up a double bubble type insulation between studs and metal. Then spray foam to that as it would allow the metal to move independent of the insulation.

 

[cre10]

I have heard the same thing. Was told a way to solve the problem though was to put up a double bubble type insulation between studs and metal. Then spray foam to that as it would allow the metal to move independent of the insulation.

That's what I did.

 

[90cummins]

I use a 28,000 BTU Cleanburn hot air waste oil heater.
Couldn't be happier. I chose hot air because I may not use the shop for 3 or 4 days in the winter and didn't want the long recover time with radiant heat.
It takes 20 minutes to raise the temperature of my 40x60 shop from 30 to 50 degrees which I personally find is a good temperature in the winter.
I burn my waste oil and some from friends.
Haven't bought oil since 2005.
90cummins

 

[5030tinkerer]

I use a 28,000 BTU Cleanburn hot air waste oil heater.
Couldn't be happier. I chose hot air because I may not use the shop for 3 or 4 days in the winter and didn't want the long recover time with radiant heat.
It takes 20 minutes to raise the temperature of my 40x60 shop from 30 to 50 degrees which I personally find is a good temperature in the winter.
I burn my waste oil and some from friends.
Haven't bought oil since 2005.
90cummins

I've never used a waste oil heater. What happens with the impurities in the oil - they just get burnt along with the oil itself? Any reason with one of these furnaces not to go larger in btu size to get faster recovery and/or initial warm up times? It sounds VERY cool.

 

[George2615]

I've never used a waste oil heater. What happens with the impurities in the oil - they just get burnt along with the oil itself? Any reason with one of these furnaces not to go larger in btu size to get faster recovery and/or initial warm up times? It sounds VERY cool.

I've been looking for a used waste oil burning furnace for a few years now (New ones are very expensive, $4K and up). I'd like to find one about 80,000-100,000 BTU. Most of the used ones I see for sale are 250KBTU and up which is way too big for my garage. I've never seen one as small as 90Cummins 28,000 BTU. I also produce a lot of used oil with all my vehicles plus oil changes I do for friends. I can also get oil from several other friends that change their own oil. I don't want to stockpile used oil until I get a furnace. Once I find one I plan on mixing the used oil with regular heating oil.
I currently use a mobile home furnace to heat my garage in winter. If I can't locate a waste oil burner / furnace I may look into converting mine into one.
To answer your question about impurities, they get filtered out or minute impurities get burned up.

 

[5030tinkerer]

I've been looking for a used waste oil burning furnace for a few years now (New ones are very expensive, $4K and up). I'd like to find one about 80,000-100,000 BTU. Most of the used ones I see for sale are 250KBTU and up which is way too big for my garage. I've never seen one as small as 90Cummins 28,000 BTU. I also produce a lot of used oil with all my vehicles plus oil changes I do for friends. I can also get oil from several other friends that change their own oil. I don't want to stockpile used oil until I get a furnace. Once I find one I plan on mixing the used oil with regular heating oil.
I currently use a mobile home furnace to heat my garage in winter. If I can't locate a waste oil burner / furnace I may look into converting mine into one.
To answer your question about impurities, they get filtered out or minute impurities get burned up.

Is there a reason why a 250kBTU unit is too large? I mean, wouldn't it just run for much less time (or is there an efficiency benefit from longer run times)?

 

[George2615]

Is there a reason why a 250kBTU unit is too large? I mean, wouldn't it just run for much less time (or is there an efficiency benefit from longer run times)?

A 250K BTU waste oil furnace is way too big for my 1200 Sq Ft. garage. The 80K BTU MH furnace I currently use easily keeps my garage between 55-60 degrees when I'm working out there. I just want to be able to use the free fuel (used oil) I generate every year and save a few hundred in heating oil costs. I generate about 150-200 gallons of used oil a year between my own and other peoples vehicles.
A 250K BTU unit would burn about 1.4-1.8 GPH. Cost for used ones this size are about 1/2 the price of a new 140K BTU unit. If I could find a used one for under $1500 I'd consider buying one.
I can't justify spending over 4K for a new W.O. furnace or even $2500 for a used one just to save a few hundred in heating oil costs. It would take me 20 years to recoup that savings.

 

[dave1949]

Apparently waste oil furnaces will burn hydraulic oil too--more free fuel. I drop off used oil at the town recycle station where someone collects it for their furnace. I checked and he is glad to get hydraulic oil too.

 

[5030]

I heat my shop in the winter and have ac in the summer, necessary because of the precision machine tools. I did in floor PEX zoned heating and heat the entire shop (20 x 60) with a 50 gallon propane fired HWH and one feedwater pump circulating RV antifreeze through a Califfi manafold system. Costs me about a grand a winter and a grand a summer for 2 window ac units. 15 in the walls, 30 in the ceiling (between the trusses) open ceiling (has to be, I have an overhead rail/trolley crane). 15 in the floor and foam in the rat wall. The slab is 9" thick with steel mat and the PEX is stood off the mat with the pour on top leaving the piping about 4" under slab.

I run my feedwater pump with a Honeywell remote sensor T'Stat with the sensor in a thermowell in the slab about 20" from the sidewall. conviently under the HWH. I hold my floor tempature at a steady 70 degrees all winter. Ambient changes but the floor is always warm and any objects radiate the floor heat. To mitigate up time, I start the system on the heat cycle in early September to take afvantage of soil temperatures from the summer. Once the slab is at 70, the feedwater pump cycles on and off, running about 12 out of 24 hours no matter how cold it is outside. The HWH runs independent. I keep the standing fluid temperature around 140 degrees and system pressure (closed loop) at 7.5 pounds. I have a tempering circuit in the feed loop to intriduce heat stripped fluid back into the feed side to mitigate thermal shock and allow the system to run in smooth remperature gradients.

Been running the system for 5 years now without a hitch. I actually take advantage of the cool slab (compared to outside ambient) in the summer by opening the tempering circuit entirely and closing off the heated fluid feed side and allowing the PEX to circulate cooled fluid in the slab, normalizing the temperatures in the shop. I still maintain a closed system and keep the static pressure at 7.5 pounds.

Best investment in heat/cool I ever made and I put it in myself.

IMO, thats the only way to go.

One added 'benefit' I forgot to add....

I heat the aprons on the approaches to both my shop doors. The PEX in those locations extend to the edge of thr ratwall so I get excess heat in the aprons. My thoughtful wife parked the outdoor cat houses in front of the unused overhead door and all the barn cats overwinter there.