New Garage + heated driveway build - indoor wood boiler

[Hessian_]

Hi,
I am planning a new large garage. Likely two normal bays + an RV bay. I am also looking to install a hydronic heated driveway. Driveway is fairly short - probably 200ft total from road to house to where the garage will be.

I'd like to install a radiant tubing floor at the new garage and have an indoor wood boiler in the corner to supply energy to the driveway and the garage in the winter time. There's over 30 acres of forest so I have no concerns about supplying enough wood.

What are some things I need to consider? There are times that we will not be able to keep the fire going - i.e. we may be on vacation over some winter periods. As long as the pump keeps moving the glycol mix around, there shouldn't be a freezing risk would there ? Do I need backup heat?

 

[peakbagger]

I have run into these commercially on occasion and one thing to consider is that a glycol mix does have a lower freezing temp, but it gets quite viscous. If you anticipate having to not run the system full time then you need to calculate the pressure rating of the tubing and the pump pressure (head) requirements for the worst case which is the viscosity of the fuild at the lowest ground temperature. Its likely you will need a variable speed pump or a booster pump to get the "jello" that may form in the line moving. In most cases the commercial setups just assumed 24/7 and when we needed to mess with them we had to put in temporary means of heating the fluid.

 

[maple1]

The first thing to check out is whether you're allowed to have a boiler in your garage or not.

 

[salecker]

Wow
You must really love making firewood
Heating an outside driveway will definitely keep you busy cutting wood.
Chose your boiler carefully, and storage must be a part of your system.
Plus lots of insulation,everywhere.Under you slab,under your driveway, and super insulate the shop walls and roof system.

 

[Hessian_]

maple1 is correct that an inside boiler will not be insurable, so that's out, so an OWB is back in consideration for this purpose.

I have no issues cutting firewood. I'll be cutting a lot of firewood either way. My idea that I can have a heated garage and a heated driveway just from wood, but if I go away for a few weeks in the winter time then it's no big loss. I'm not home, so snow on the driveway isn't an issue. And it's no big deal if the garage gets cold. I would likely need a small propane/electric boiler to keep the glycol lines from freezing if it gets really cold.

Last year I gave up on the idea of an OWB for house heat, I don't want to be married to it. This way, I don't have to tend it daily if I don't want to. Admittedly, I have a lot of research ahead of me. The house already uses a heat pump anyway so I see little benefit to use OWB for the home.

 

[salecker]

If i was you i would go with an outdoor gasser,put the storage in the shop.
Forget about heating the driveway,that's a crazy way to work yourself to death processing wood to heat the outside world.
Run good underground lines to the house and shop
With storage you are not a slave to the firebox.You can decide when it`s convenient to fire the boiler.

 

[brenndatomu]

Wow
You must really love making firewood
Heating an outside driveway will definitely keep you busy cutting wood.

No doubt...15 minutes with a snow blower is equal to about 12 hours of making firewood!

Chose your boiler carefully, and storage must be a part of your system.

Yes. A good gasser will work fine, but with plenty of well insulated storage, next level stuff right there!
And may I suggest giving these a good look...

HeatMasterSS Efficient and Easy-to-Operate Outdoor Wood Boilers

Outdoor Wood Boilers and wood furnaces for rural home heating designed and manufactured for real world conditions. Easy to Use, Built to Last

heatmasterss.com

 

[hobbyheater]

This boiler burned 22 cords in one year , A Jetstream gasification boiler with storage burned only 4 cords a year. Over 40 years burn 880 cords or 160 cords !

 

[salecker]

Hobbyheater has years of experience heating with wood via hydronics
He has had first hand knowledge of the amount of wood various levels of boilers in the same buildings in the same area use comparably
I have only one boiler to go by in a very cold climate.
Where he resides will be a lot closer to the climate you have

 

[Hessian_]

No doubt...15 minutes with a snow blower is equal to about 12 hours of making firewood!

Yes. A good gasser will work fine, but with plenty of well insulated storage, next level stuff right there!
And may I suggest giving these a good look...

HeatMasterSS Efficient and Easy-to-Operate Outdoor Wood Boilers

Outdoor Wood Boilers and wood furnaces for rural home heating designed and manufactured for real world conditions. Easy to Use, Built to Last

heatmasterss.com

the difference is I'm planning to be chopping the wood anyway to heat the shop and my house has three fireplaces.

The heated drive way is 50% flex, 50% a fun project, 50% a desire to have a fancy brick paver stone driveway.

 

[brenndatomu]

50% flex, 50% a fun project, 50% a desire to have a fancy brick paver stone driveway.

Uh...math, n stuffs...
Hey, whatever trips your trigger man! 👍

 

[salecker]

the difference is I'm planning to be chopping the wood anyway to heat the shop and my house has three fireplaces.

The heated drive way is 50% flex, 50% a fun project, 50% a desire to have a fancy brick paver stone driveway.

You must love making firewood...
Myself i tried to cut down the amount i have to processes each year, by building a well insulated home.
I really have better things to do then make firewood,i do enjoy processing the 8 cords a year for my house. And feel that i can continue to do that as long as i am healthy.
Next year i will be starting to sell unmillable wood as firewood. I will be using mechanical equipment to log and process firewood.Even then i would not consider heating the outside world.
Any more firewood processed than 8 cords a year will be for sale.In 10 years or so when my existing boiler might be near it's end of life i will be looking for a more efficant boiler if i can find one that is built like a tank.

 

[chew72]

Well I've actually put some thought into this already. Before I bought my house we were thinking of building and I had seriously considered putting snow melt in the driveway for the purposes of de-icing, or if I'm lazy and have too much hot water. I suppose it would also make a good dump zone

There are a couple of things to consider. Do you plan on running it all the time? or just turning it on when there's a big snow? or like my case only to de-ice once there's build up?

What is the total load that that would add to the boiler. It could very well be you don't have enough boiler capacity to heat the whole driveway. My plan was to do the zones so I could stage it in 3 separate sections so it would only heat zone 1 and switch to zone 2, then switch to zone 3. Again this was just for de-icing.

Generally you also need thermal shock protection for the driveway. If memory serves me you only want to send out water that's plus 20 or 30° f compared to the return temperature from the driveway. That way it's a gentler rise and allows everything time to expand so you won't get cracking.

Edit: oh yes! See I forgot just like a lot of people who have done this. Drains need somewhere for the water to go other than off the heated driveway and freezing into an iceberg.

 

[Hessian_]

It's a short driveway. I'm guessing that it'll be 120ft x 20ft. Call it about 2500 sqft including the walk to front door. Research tells me that it's recommended to get 100btu per sq ft so 250,000 BTUs needed for snowmelt. That means I'd need a g10000 boiler. I was just quoted 20kCAD for the heatmaster g10000 boiler alone, which certainly has me second guessing this strategy. I have to look up tax rebates in ontario - I've seen some claims of 30% rebate.

Where I am, I haven't even yet to have to shovel snow, which is kind of wild considering it's December 4th. I would probably run the boiler just to keep the garage warm, and only run the snowmelt when it's very cold or snow is expected.

 

[all night moe]

My old neighbor has a heated driveway. In the 5 yrs I lived next door, he used it once in a big ice storm.
Save your money on the plumbing a nd controls for other needs.

 

[brenndatomu]

Research tells me that it's recommended to get 100btu per sq ft so 250,000 BTUs needed for snowmelt.

I was gonna say, the heat load for a sidewalk/driveway is huge! That will use more wood than heating the building(s)
Spend all that money and then a few years later the concrete cracks/shifts and the PEX leaks, whole thing is junk...just a bad investment IMO, especially when you consider that you can buy a pretty nice snowblower for $300 during the summer! That and a $5 bag of salt takes care of the driveway quite nicely.

 

[chew72]

I tend to agree it's cool but in general a bad idea lol. I've only really seen them installed commercially for ambulance stations, hospitals, heli pads and a single residential property. The property was a multi million dollar home by the way. When I was looking into it it was for a 20' walk way and 40' of driveway done with pavers.

lol My thinking at the time was, I enjoy cutting wood more than I enjoy moving snow.

 

[peakbagger]

The local city next to me has a large wood fired power plant and they have gotten a bunch of money to heat all the sidewalks with waste heat from the power plant. Its really a way of completely rebuilding all the sidewalks with someone else's money. Its a 73 MW plant so it has lots of warm water to get rid of that could either heat sidewalks or go up a cooling tower.

 

[brenndatomu]

Our local city hall has heated steps and sidewalks...powered by ELECTRIC! It has a whole bank of 200A breakers powering this money pit!

 

[sloeffle]

That means I'd need a g10000 boiler.

Since you'll have an oversized boiler most of time you'll end up with tons of creosote and hate the boiler. I have a G4000 tied into a 2200 sq ft house. When it's 40 - 50° out and there are very few calls for heat and it starts to creosote up some. I'm probably not even going to start burning until temperatures are in the 40's or below consistently. If you do get a Heatmaster boiler, I'd get a G7000 and run the dog piss out of it vs slumbering along a much larger boiler most of the time. Mine does much better when it comes to creosote when it's 20 out vs 40. Gasification boilers do much better being ran vs sitting there idling a bunch. A G100000 is made to heat three or four large buildings.

 

[brenndatomu]

Since you'll have an oversized boiler most of time you'll end up with tons of creosote and hate the boiler. I have a G4000 tied into a 2200 sq ft house. When it's 40 - 50° out and there are very few calls for heat and it starts to creosote up some. I'm probably not even going to start burning until temperatures are in the 40's or below consistently. If you do get a Heatmaster boiler, I'd get a G7000 and run the dog piss out of it vs slumbering along a much larger boiler most of the time. Mine does much better when it comes to creosote when it's 20 out vs 40. A G100000 is made to heat three or four large buildings.

Yup, my folks have one heating 2 farmhouses and (1) 30x40' shop, and another larger shop...it just loafs along 98% of the time...a 7000 would have been a better fit IMO. So yeah, if it is sized to run a heated driveway, then its not used most of the time, it (and any brand/model) will be a slobbery mess inside...unless heat storage was used maybe...

 

[hobbyheater]

Yup, my folks have one heating 2 farmhouses and (1) 30x40' shop, and another larger shop...it just loafs along 98% of the time...a 7000 would have been a better fit IMO. So yeah, if it is sized to run a heated driveway, then its not used most of the time, it (and any brand/model) will be a slobbery mess inside...unless heat storage was used maybe...

Boiler protection is necessary whether you have storage or not !