Another "winter is coming" thread about GF in a cold garage

Last week we had a solidly good overnight cold snap, and it occurred to me that the unheated garage where my GF lives could become a big problem as we roll into winter. Moreover, I figure it’ll only get worse since I vaguely recall seeing the lower temp spec in the manual was 40 degrees, but the outside temp will likely go negative by Jan/Feb.

First things first, I browsed the forums here to see what people have done and get some idea of what works and what doesn’t. Next, I went on Amazon to shop for electrical heaters, hot air blowers, etc, and to see if there was any obvious commercial solution. Yes, there were some things available, but I didn’t want to spend a massive amount on electricity by heating the entire volume of a poorly insulated garage all winter. And of course, it’s too late in the season (and too expensive at the moment) to properly insulate/finish the garage, so that’s off the table too.

So, I figured I’d do something a bit more… Custom. Without further ado, I present the Smart Hot Box. (Pics first, description below)…













Basically, the idea was to create a large open-top box lined with reflective mylar illuminated by a 240 watt hot lamp. The obvious problem comes from leaving the heat lamp on too long, which could damage the GF. So I leaned into my home automation setup to produce a custom temperature controller. Essentially, when the hot box is over the GF, there’s a little tempertature sensor sitting on the GF that talks to a local hub. Likewise, there’s a Smart Switch that controls the light. When the sensor gets too cold (45 deg or below), then the hot light automatically turns on. When the temperature stabalizes to the threshold 45 deg, the light automatically turns off. A few thoughts:

(1) I currently have only one redundanet method in place to turn the hot light off if it’s on too long. However, considering the nature of technology and it’s occasional failures, I’ll be setting up another emergency off switch as a second redundant regulator.

(2) The lumber used to construct the hot box’s frame is just a fe wpieces of old, warped scrap pine I had lying around held together with mismatched screws and nails.

(3) I laser cut the angle brackets that hold the frame together… Because why not?

(4) The reflective mylar is the same emergency foil blanket hilers like to carry around… Y’know… For emergencies.

(5) So far, the hot box generally works and I can monitor all temperature logs remotely as well as manually override the hot lamp from anywhere that’s connected to the internet via my phone app.

(6) The open-top concept is two-fold: first, it gives the best signal when connecting the temp sensor to the hub, and second, it allows heat to rise and circulate a bit more (useful if the automation fails… because I’m paranoid about cooking the GF). Yes, it’s inefficient with heat radiating away, but that’s a compromise I’m willing to make because the mylar walls balance this loss by reflecting some of the lamp’s heat back in.

(7) Total cost was around $30 + time spent improvising the design (made the hot box’s design up as I built it).

(8) The box easily lifts right up and over the GF. When I wanted to do some cutting today, I just picked it up, put it aside, plugged the GF back in for power, and fed the ventilation tube back outside. Putting the hot box back on was just as easy.

(9) Who knew home automation could be so useful? :slight_smile: Anyway, when some future person is wondering how to handle their GF in a cold garage, I hope this project narrative is helpful for their decision making process.


Seems like you gave it some thought.
I have seen people slag a pump with a heat lamp under a hood like your setup though. Make sure there is no way it can focus on your precious.

Just a regular incandescent lamp in that box will hold off a chill but I do not think that low a heat will help any components inside a glowforge.

Let us know how it works once the cold arrives.

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I like your diy mindset! If for any reason you decide it’s not going to work, oil based thermostat-controlled space heaters aren’t too expensive. You’d need to totally redesign the enclosure of course but it would probably be a bit more “set and forget”.

From last year:

Combined with something like this…

Granted it’s closer to $200 than $30, but you’re talking about protecting a multi thousand dollar Glowforge, I’m not sure the absolute cheapest solution should be the goal?


Interesting, Wirecutter changed their tune and recommend smaller heaters now. The type I use and swear by is a 1500 watt delinghi like this:

DeLonghi TRD40615E Full Room Radiant Heater

The key features for me are the digital thermostat and timer. I set mine up to heat the space to room temp during working hours and much lower overnight. It works well for me because my workspace is pretty small, I think you’d definitely want an enclosure in a garage.


If you’re enclosed, it should hardly take any power at all to keep the temp up – you can do the Btu/hr/degree calculations for a small space. Once the GF starts drawing air, you might have an issue, but it’s also dropping wattage into that air, so maybe not?

Hmm, I wonder if you could put a heat exchanger into the exhaust…

In cold climates I would be worried about the water jacket around the laser and cooling system freezing. I’m guessing that there is some sort of antifreeze in the coolant but I don’t know that. Mine lives in a basement that stays between 65 and 75 deg F all year around.

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Nice approach!

You may want to implement a warm-up action also for when you know you’ll want to use the Glowforge.

The storage threshold is rated at down to 40, but the operating window is from 60-75f for the basic.


Cool. I have lost one laser tube (not GF) in an unheated garage in sub-zero weather even with a pump pushing the water coolant through the tube 24x7.

My GF lives in the basement and the other gets drained for the winter.


Hi all – Thanks for the input and added discussion to the thread. I take the words of caution seriously and like the suggestions being offered.

A small update on progress so far. I’ve been closely monitoring the overnight temperature in the garage through the SmartHome system and keeping a close eye on the SmartTemperature sensor’s connectivity to the local IoT mesh. So far, I’m pleased to report the sensor’s connectivity has remained steady and the in-garage temperature is about 20-or-so degrees warmer than the outside lows. If the +20 F remains a constant offset (unlikely, but probably good to a first-approximation), then I have a few more months before we really push that lower bound of 40 F and the heat lamp is being regularly used to keep things warm at night.

In terms of operating the GF, I’ve been running cuts with ambient environment around 55 to 65 F, but given the operating specs specifically state 60 to 75 F for the Plus, I’ll be careful about warming things up in the future. In general, I think this will become an interesting challenge since the garage is a 2-car space with only fair thermal insulation. The DeLonghi might be just what I need… Thanks @evansd2 !

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