Shop heating advice?

[John_Mc]

Does anyone have experience heating a woodworking shop with a Rinnai type direct vent propane heater? I'm a bit concerned with how well it would tolerate all of the saw dust in the shop. Seems as though the filter would clog up quickly. I suppose if we mounted it in an easy to access location, we might be able to live with the frequent filter cleanings (assuming she remembers to do it). We have one in a room above our garage that works well, but that is a much clener environment than the workshop.

It's a 24'x26' woodworking shop with 10 ft ceilings. As shops go, it's very well insulated & sealed: 6" sprayed in foam in the walls, 8" in the ceiling, 6" in the floor (a drive-out basement underneath is my shop), double pane windows. We've been heating it "temporarily" for over 8 years now with a couple of space heaters (a 1500 watt "Milkhouse" heater and a 1500 watt oil filled radiator, a little over 5000 BTUs each.) They are a little undersized for the room, It takes forever to warm the place up if we let it get cold, but once up to temperature, those two little heaters can keep it comfortable, even when it's 0˚F out. Maybe a little cool, but good enough for working in. In a pinch, I bring in "Big Buddy" portable propane heater to warm thing up quickly. The Big Buddy has no thermostat nd puts a lot of moisture into the room, so is not a good longer-term solution). These heaters have thermostats, but no scale on them, and the settings are not repeatable (A setting that gets us 55˚ one time is significantly off the next time.)

Judging by the fact that the 10-11,000 BTUs we have now from the space heater is undersized but tolerable, I don't think we need a very large capacity heater.

We're looking for a good long term solution. Some of what we are looking for:

• Tolerates sawdust without needing to be constantly cleaning filters (occasionally is fine, but if she has to do it every day, thatprobably won't happen)
• If a combustion type heater, must be vented outside.
• A thermostat that actually works
• The ability to set a temperature below 50˚F. We generally leave it in the high 40s when not in use. We could live with a bit higher if we had to, but we really want to keep our energy use down
• Electric or propane fueled (No kerosene or fuel oil, since nothing else we have runs on that.)
• Will run unattended for extended periods (we may not be in it for a week or more).
• Ability to run when electric power is down is a plus, though not mandatory. We can fire up a generator or bring in the portable propane heater if needed for an extended outage.

We considered a heat pump, since they are so efficient, would also provide AC in the summer, and there would be no need to site another fuel tank. A few concerns with that: (1) I have yet to find one that will allow a heating setpoint below about 55˚F. Not sure we really want to keep it that warm all winter long. (2) They do not seem at all tolerant of dirty/high sawdust environments, though I'm not sure about this. (3) The heavy electrical draw would make it tough to keep things above freezing during an extended power outage (though we could fire up the Big Buddy, if we have to.)

I've seen inexpensive ceiling mount propane heaters in some people's garages and shops. Wondering how well they do in a dusty environment. Do they make designs if these that the combustion air and by products are vented outside?

 

[2manyrocks]

My concern would be the amount of sawdust in the air. Do you have a sawdust collection and filtration system in your shop?

 

[newbury]

Concerning the heat pump - you can get an external thermostat like this and I' sure there are others for any temp.

 

[Mtsoxfan]

Heat pumps would require frequent cleaning in a well used shop. We have Fujitzu for our home, and while normal heat only goes down to 64*, there is a setting for when you are away and don't want freezing pipes. It goes to 50*. Sawdust will be an issue for most heaters. Especially "live" fire ones. The dust can create an explosive environment.

 

[dstig1]

• Tolerates sawdust without needing to be constantly cleaning filters (occasionally is fine, but if she has to do it every day, thatprobably won't happen)
• If a combustion type heater, must be vented outside.

I've seen inexpensive ceiling mount propane heaters in some people's garages and shops. Wondering how well they do in a dusty environment. Do they make designs if these that the combustion air and by products are vented outside?

Just get one that is sealed combustion and properly vent and supply outside air and you are good to go. These are quite common now. No heat source will be totally immune to sawdust, but you won't have a direct open flame to start a fire. Blow out the dust from time to time.

As for your temp setting, that will be up to whatever thermostat you get. These units should work with any standard Tstat, and might even come with a basic unit.

Modine Hot Dawg® Heater - Model HDS

Modine Hot Dawg Heaters are a great option for your garage or shop. The HDS Separated Combustion Model works where there is dirt, dust, fumes and humidity.

www.qcsupply.com

 

[ultrarunner]

My godfather had a small cabinet shop where he lived in snow country and it was always warm and dry through radiant floor heat… and fired with wood scraps.

He was very particular about heat and deemed forced air to be the worst choice for a wood shop for a number of reasons including the dust collectors pulling the warm air out.

 

[dstig1]

While I agree, Ultra (...which is why I put in-floor radiant in my shop), it is almost never something that is reasonable to retrofit to an existing space.

 

[John_Mc]

My concern would be the amount of sawdust in the air. Do you have a sawdust collection and filtration system in your shop?

Not a good one. It's a cyclonic separator on a 5 gallon bucket installed before a 15 gallon 5 HP Rigid shop vac. She's got hoses to the chop saw and tabletop belt sander which she plugs in to the system when she's using them. Nothing to the table saw, she just hits that with the vacuum hose occasionally when she is done using it. (Does not get done regularly enough.) It's a portable system. A step up from the shop vac alone: I was happy to see how well the cyclonic separator worked. Not much sawdust ever makes it to the shop vac, so we don;t need to dump that and clean the filter as often. The 5 gallon bucket needs to be emptied, but that is easier.

One thing I do like about this set up: since the collection cannister is in the shop, we don't have to deal with the negative pressure and pumping the heat out of the shop that we would if a permanently installed system had its canister somewhere outside the shop (most likely in the basement - my section of the shop, though I would not want the noise in that area with its mostly cement walls.)

 

[John_Mc]

My godfather had a small cabinet shop where he lived in snow country and it was always warm and dry through radiant floor heat… and fired with wood scraps.

He was very particular about heat and deemed forced air to be the worst choice for a wood shop for a number of reasons including the dust collectors pulling the warm air out.

If we were starting from scratch, I would put radiant floor heating in the shop. We have it in the house and love it (I like to heat with the wood stove most of the time, but my wife and daughter are always turning up the floor heat. I'll admit is is comfortable and keeps your feet warm.

Unfortunately, the ceiling of the basement already has the spray foam insulation installed. I'm not about to dig all of that out so we can put in radiant heat. It would definitely have been a great way to go.

 

[John_Mc]

Just get one that is sealed combustion and properly vent and supply outside air and you are good to go. These are quite common now. No heat source will be totally immune to sawdust, but you won't have a direct open flame to start a fire. Blow out the dust from time to time.

As for your temp setting, that will be up to whatever thermostat you get. These units should work with any standard Tstat, and might even come with a basic unit.

Modine Hot Dawg® Heater - Model HDS

Modine Hot Dawg Heaters are a great option for your garage or shop. The HDS Separated Combustion Model works where there is dirt, dust, fumes and humidity.

www.qcsupply.com

Thanks, Dave. The Modine sealed combustion units look like a good way to go - especially if cleaning them just involves blowing them out with some compressed air occasionally. I suspect that at 30,000 BTU the smallest one they show at that link is overkill for what we need.

I'm guessing something half that size would be fine for our needs. I've not yet found something in that size range.

 

[ericm979]

Ventless heaters put the water vapor generated by burning into the air. That may not be what you want.

Some folks with mini splits in wood shops have made a case holds furnace filters to filter the intake air on the mini split head. If you use enough filters it doesn't make the fan work too hard.

 

[John_Mc]

Ventless heaters put the water vapor generated by burning into the air. That may not be what you want.

Exactly why I am not considering ventless combustion heaters.

 

[4570Man]

I have one of these in my wood shop. I’ve never cleaned the dust out of it. I don’t remember the size but I think it’s 75,000 btu. It’s oversized for my insulated garage but I like the fact that it can warm it up in just a few minutes. It’s not oversized when I turn on my dust collector. I got tired of emptying it and vented it outside. That part of the plan worked great but it sucks the heat out. I’m a builder and I usually put one of these electric heaters in the garages. They work surprisingly well and I don’t insulate the garages unless the owner pays extra. The electric heat cost more than natural gas but the cost of entry is low. I can install the electric heater for $200 and the forced air natural gas probably cost $2000.

 

[John_Mc]

I was looking at some of those electric heaters online, since they are closer to the size I think we need. Have you found any brands in particular that you like?

 

[KennyG]

If you have adequate electrical service, electric resistance heat would be the cheapest to install, although not necessarily to run. You can get line voltage thermostats that will control down to 40 degrees or less. You can just wire them into a circuit to control outlets for the plug in heaters or install baseboard heat hard wired in. (Baseboards are usually 240 volt.) I think DeLonghi is the best portable heater, but the baseboards are pretty generic.

 

[John_Mc]

Probably not doing baseboard. To much stuff at floor level already. Probably have to go with a wall or ceiling mount

 

[4570Man]

I was looking at some of those electric heaters online, since they are closer to the size I think we need. Have you found any brands in particular that you like?

I buy the $100 ones. I’m sure there’s better options but I’ve never had a callback for the cheap ones.

 

[David in KY]

I had one of these little electric wall heaters (240V) in a 20'x40' insulated shop in Boise, ID. I left it on the lowest setting, which kept the shop at an even 50 degrees all winter long. I primarily wanted to keep paints from freezing, but I found it very comfortable to work in. Also, I could turn it up if needed to make it warmer, but rarely did.

 

[Sodo]

Probably too late for in-floor radiant heating. Which would be almost immune to dust.

I have a friend with radiant floor heating in his shop. He says it's a pleasure to take a nap on the cement floor under his truck.
He says cardboard boxes of raw steel parts on the floor do NOT rust at all, for YEARS.

I wonder if you could get a heatpump-water-heater that could collect its heat from outside the shop. And put coolant in the system, and tank. The ones I've seen are expected to operate inside living-spaces and may be unable to collect any heat when it's real cold outdoors.

 

[dadster4]

Would it be possible to run lines from your existing boiler to your shop? You can hang a hot water coil fan unit in the shop with no worries associated with combustion type heaters.