Electric Heaters & Fire Risk

[Peter Aeschliman]

All,

I've finally finished drywalling and insulating my shop. It's about 450 sq ft has 8' ceilings.

I'm trying to figure out how to heat it in the winter, and I'm limited to electricity as the energy source. I've done some searching here and the Dayton electric unit seems to be a favorite:

http://www.amazon.com/Dayton-G73-Electric-Garage-Thermostat/dp/B000TK2SWO/ref=wl_it_dp_o?ie=UTF8&coliid=I3EOGS09L3EPQP&colid=3243OCS6C0GX3

Before taking the plunge, I wanted to ask you guys about the risk of fire. I have a 3hp Grizzly dust collector that I've modified to accept two high efficiency Wynn Environmental filters. I still have to do the job, but I'm close to being ready to install 6" PVC runs to my machines. I'm going to do my best to collect dust at the source. I also have an air scrubber I plan to add a duct to so that the intake and outlet are as far away from each other as possible.

But frankly I'm sure there will still be some airborne dust particles. I don't want to start a fire, and my concern is that the heat coils in this style of heater could ignite airborne dust.

Is this a concern? I won't be doing much finishing in the winter, but if I do, it will be brush on water based finishes. So I'm more concerned about wood dust than fumes.

Thanks in advance.

[Jason Roehl]

Airborne dust won't be your problem by a long shot. It would be a stretch even using an electric heater in a shop with absolutely no dust collection. What you will need to watch out for would be dust settling on the heating elements. During the heating season, that may not be much of problem when the heater is running periodically, but at the start of the heating season, when the heater has had a chance to collect dust all throughout the non-heating season, you will need to clean the elements before you turn it on.

Don't lose any sleep over dust explosions in home shops--they just haven't happened. Not that they absolutely can't, but they are very difficult to even purposely cause, let alone happen accidentally.

Fires in settled dust are a whole 'nother ballgame...

[Lee Schierer]

Since electric is your only choice, why not use a heat pump. They give you more heat for your buck than resistance heating. A geothermal heat pump type unit would cost even less to operate.

[Peter Aeschliman]

Thanks guys.

Lee, I just took a quick look at electric heat pumps and those are a bit outside my budget. I'm in my shop for probably 30-40 hours per month. In the Seattle area, the heater will be needed for around 6 months per year, so I'm not going to be consuming a ton of energy. If this were a living space, if I were a professional or a retiree, I'd definitely consider more efficient options.

But in my current world, the extra initial cost of the heat pump would virtually never be recouped through energy savings.

Jason, you basically confirmed what I was thinking... If I get my dust collection working well and I'm careful about dust accumulation on the heating elements, It's probably unlikely that it will cause a fire.

[Rod Sheridan]

Peter, just vacuum out the heater at the start of the heating season.

We did that with the natural gas fired unit heaters that were in the woodworking plant I worked in.

Regards, Rod.

[Heather Thompson]

Peter,

I bought a Cadet Hot One a few years back, my shop is about the same size as yours and the model RCP402S does a great job, leave the heater running 24/7 all season. I tested it at -10 degrees and was able to hit 93 in the shop, :eek: bought at the end of season and got it for cheap. At the beginning of the season I blow it out with the compressor and no problems ever, here is a link to the Cadet site. http://www.cadetco.com/show_product.php?prodid=1012

Heather

[Jason Beam]

I have the Dayton heater you mention, Peter. I absolutely love it. Before that I was using a stand-alone oil-filled radiator.

Your fire risk, in my opinion, is greater with the wiring than with the dust. The research I did told me that a space heater is NOT to be EVER left unattended. Space heaters are notorious for causing electrical fires. It's not the heating element, though, like many people think. It's the plug.

Even a properly-working space heater with all of its safety gear in perfect working order gets real dang warm at the plug. Pulling its maximum current anytime it's operating means it's dragging a LOT of current across that plug/outlet connection - even the best-fitting plugs still generate heat.

To further convince myself to replace the space heater I'd been using (1500w and plenty for my 20x24 space), I decided to do a test one day. I plugged it in like always and cranked it up like always. It was a good long saturday of about 6 hours of shop time. I toiled away while it churned out the heat. First, I felt the plug after I'd reached "working" temperature - it'd been on solid for only about 20 minutes before the thermostat kicked it off. That plug was WARM - it wasn't hot enough to burn, but the plug was plenty warm.

By the end of the day, the cord on it had warmed the concrete slab it was laying on for those 20 minutes - as tested with a non-contact thermometer (checking adjacent areas for relative temperature differences) - by about 10 degrees.

About 2 years prior, in my old shop which was wired with 15a outlets and 14ga wire, I pulled the wire out for another project on the plug that heater happened to be using and found charred Romex right where it connected to the outlet. - I must not have gotten the screws tight enough or they vibrated loose. Nothing makes me sicker than to find charred wire in a wall.

That was enough for me. I bought the dayton and hard-wired it making sure every connection was good and solid to ensure no heat buildup.

I've sworn off of space heaters unless I'm sure the wiring is in fantastic shape and that the heater won't be used for very long without ever being left unattended.

[Andrew Joiner]

Hi Peter,

I use heat lamps for both light and heat. Simple and efficient.

The 250 watt bulbs last a long time. I have 4 years on the pair I use the most! You get light and heat for the same cost. I have the same climate as you and it works fine.

You can put them were you need heat and light. I have the most over my bench. I turn off half of them after an hour or so.

Fire risk seems low, but I wipe the dust off the bulbs yearly for better light. The tops have polished aluminum reflectors so they don't get hot enough to ignite dust. Look up brooder lamps.


In the summer I use sun and fluorescents.

[Bob Borzelleri]

I have the Dayton heater you mention, Peter. I absolutely love it. Before that I was using a stand-alone oil-filled radiator.

Your fire risk, in my opinion, is greater with the wiring than with the dust. The research I did told me that a space heater is NOT to be EVER left unattended. Space heaters are notorious for causing electrical fires. It's not the heating element, though, like many people think. It's the plug.

Even a properly-working space heater with all of its safety gear in perfect working order gets real dang warm at the plug. Pulling its maximum current anytime it's operating means it's dragging a LOT of current across that plug/outlet connection - even the best-fitting plugs still generate heat.

To further convince myself to replace the space heater I'd been using (1500w and plenty for my 20x24 space), I decided to do a test one day. I plugged it in like always and cranked it up like always. It was a good long saturday of about 6 hours of shop time. I toiled away while it churned out the heat. First, I felt the plug after I'd reached "working" temperature - it'd been on solid for only about 20 minutes before the thermostat kicked it off. That plug was WARM - it wasn't hot enough to burn, but the plug was plenty warm.

By the end of the day, the cord on it had warmed the concrete slab it was laying on for those 20 minutes - as tested with a non-contact thermometer (checking adjacent areas for relative temperature differences) - by about 10 degrees.

About 2 years prior, in my old shop which was wired with 15a outlets and 14ga wire, I pulled the wire out for another project on the plug that heater happened to be using and found charred Romex right where it connected to the outlet. - I must not have gotten the screws tight enough or they vibrated loose. Nothing makes me sicker than to find charred wire in a wall.

That was enough for me. I bought the dayton and hard-wired it making sure every connection was good and solid to ensure no heat buildup.

I've sworn off of space heaters unless I'm sure the wiring is in fantastic shape and that the heater won't be used for very long without ever being left unattended.

What Jason said.

I hav the same heater, although the Amazon link shows a heater with a cord and a 220 plug. Mine came with no plug and the instructions said to hard wire it which I did.

This morning, it was 38 outside and 42 in the shop when I turned the heater on. When I went out there 1.5 hours later, the shop temp was 60. It's a great heater and a whole lot safer than most of the other options I considered. I did a low pressure blast from the compressor on the elements before turning it on this season, not even sure that was necessary, but I was there and I had a hose in my hand.

[Peter Aeschliman]

Thanks everyone. I have room in my panel, so I think I'm going to go with the Dayton unit, hardwired as recommended.

I'll be careful about letting dust accumulate and I think I'll be okay. I'm looking forward to working in my shop comfortably!

Thanks for the advice.

[Joe Lasch]

I'm another with the same unit in my shop. About the same square footage as yours, and it does a great job through the Wisconsin winters. I set it to keep the shop only at about 50 degrees and have a wood burning stove to heat things up more when I'm out there. I had originally been planning to go with propane until I found the Dayton unit, and am glad I went this direction.

[Augusto Orosco]

I just installed mine a few weeks ago. Money very well spent!

My shop is about the same size as yours; also drywalled, but without insulation. It takes the temperature from 45F to 65F in 30 min or less.

I also followed the advice here and hardwired it. I only turn it on when I am in the shop (just a couple of hours a week), so I am not too concerned about the electricity bill.

Look for the unit new on E-Bay. A fellow Creeker gave me that advice and it was spot on. There is a seller there that has the unit cheaper than everywhere else I looked; and it was delivered to my door just 2 days after I ordered it.

[Peter Aeschliman]

I just installed mine a few weeks ago. Money very well spent!

My shop is about the same size as yours; also drywalled, but withouth insulation. It takes the temperature from 45F to 65F in 30 min or less.

I also followed the advice here and hardwired it. I only turn it on when I am in the shop (just a couple of hours a week), so I am not too concerned about the electricity bill.

Look for the unit new on E-Bay. A fellow Creeker gave me that advice and it was spot on. There is a seller there that has the unit cheaper than everywhere else I looked; and it was delivered to my door just 2 days after I ordered it.

great tip! thanks!

[Tony Latham]

How noisy are those NewAir heaters?

Tony

[tom lucas]

My shop is about the same size, uninsulated. It's colder here in the winter than in Washington. I use a 40K BTU propane, wall mount unit to get my shop warm quickly. Then I turn it off and just use a couple of space heaters to keep it warm. One is 220V and I put a twist lock connector on it so it uses the same power source as my big power tools. My shop would easily be 60+ on 30 degree days, but my feet would be cold (shop has an uninsulated basement under it). So, I bought one of those under-rug room heaters and a cheap shop rug. Placed it around my workbench where I spend most of my time. Does a great job on the feet.

The heaters the OP reference look pretty good. But I would install 2 of them, and have at least one down low. This way you heat the shop quickly and heating the floor from a ceiling-mounted heat source may be problematic. I put my 220V heater under my tablesaw. It heats the big steel mass and keeps the heat on the floor better.

As far as fire from dust - not likely. I do cover my propane heater in the warmer months to keep the dust out of the jets.

A heat pump would be good if you need AC too. but, yeah, pricey. I've thought about a minisplit. That would be ideal if the shop were better insulated.

[Tony Leonard]

I have a slide-in ac unit with electric strip for heat. I have been using one (on #3) for almost 20 years in my 16x20 shop. I keep the stock filter clean and I also built a box over the face that houses a pleated filter that I clean and change often. So far, so good. I will note that the first time I use it each season, I do get a faint whiff of burnt wood smell. Oh, I also clean the unit at least once a year inside and out. I also blow the vac the coils that are behind the filter now and then. Anyway, that has worked for me.

Tony - almost time to take the unit out and give it a bath in time for the warm weather...if it ever gets here!

[Marc Jeske]

As said above, always, on any multi hour plugged in high load device, typically often heaters, FEEL the plug and outlet AFTER a few hours running.

Monitor it occasionally... and always again a few hours if plugged into a different outlet.

They will be always SLIGHTLY warm... normal... but should NEVER be HOT, or even close to Hot.

Any imperfect connection such as not fully TIGHT screw terminals, plug prongs in the female slots,etc, will have some resistance, so with current flow, will have a voltage drop, hence wattage at that point.

Of course, wire needs to be sized appropriately.

Marc