Instructables
Picture of Fireplace fan
I recently installed a small gas fireplace. It's a great unit but it doesn't circulate heat very well without a fan. I wanted to improve the heat output and found this fireplace fan on the web. While the fan looked very professional, the price ($140) put me off. So I decided to build my own.

Materials:

  • Computer fans (2), $2.99 each, Newegg.com
  • Fan noise dampeners, $1.99 for a pack of two, Newegg.com
  • AC adapter / power supply, input 120V AC, output 12V 500ma, Model TEAD-41-120500U, $2.99, eBay.com
  • Panel-mount stereo 3/32" submini phone jack, $2.99, Radioshack.com
  • Steel sheet, 26 gauge, 12"*12". You can find this near the roofing and sheathing materials at Home Depot but basically any sheet that you can cut will work.

Tools:

  • Dremel
  • Soldering iron
  • Work bench
  • Drill and a drillbit slightly larger than the threaded part of the phone jack
  • Ruler and pen
 
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Step 1: Mark fan screw positions

Picture of Mark fan screw positions
Using the dampeners as a template, mark the position of the fan screws on the steel sheet. Leave about 1/4" inch between. Drill the holes. This will give you two squares.

Step 2: Draw circles

Picture of Draw circles
Find a round object such as a mug that has the same diameter as the fan blades. Use it to draw circles in the middle of the squares.

Step 3: Cut fan holes

Picture of Cut fan holes
Install a metal cutting disc in your Dremel tool. Cut along the circles. Do this step outside as metal dust and sparks will fly everywhere. Wear gloves and eye and ear protection! The cut edges will be sharp. Use a sanding stone to finish them and round any other sharp corners.

At this point you can also cut the metal sheet to the correct width. It only needs to be as wide as the two fans.

Step 4: Measure and mark bend lines

Draw a line at the bottom of the squares, below the fan holes. Measure one fan thickness (25 mm) from the first line and draw a second line. Measure one fan height (80 mm) from the second line and draw a third line. Cut the sheet to the right height along the third line (leftmost in the picture).
doo da do6 months ago

And I like the tube running through the fire.

doo da do6 months ago

Wire in the thermastateq will come on and that will keep the fans cool. Doodado

kransbox10 months ago
Will these fans automatically run at full speed this way, or could someone hook up a dial that would allow them to run faster? I made this (or something like this) and my fans aren't moving enough air. I was curious if my fans were pulling the maximum current by default.
cgfluid3 years ago
That looks great! I'd love to be able to build something like that, unfortunately I'm not that handy. We've been looking for an efficient little fireplace for a little while now and finally came across one that looks perfect. We found it at http://www.comfortsolutionsutah.com, check their fireplaces out!
yudystuff3 years ago
craft foam will work as well
I use one of those fireplace grate heat exchangers in my home as my primary heat source burning pallet wood. I got it from hastyheat.com one of the things to note is they have these die cut ceramic fiber insulators similar to the silicone gaskets used here only they can handle much higher heat, insulate the fan better and since they are die cut they have 4 little arms and a center patch that covers the fan motor protecting it from heat, I will add a pic to best describe. Something you might consider as it seems more appropriate to the application.
2010-04-25 19.38.47.jpg
bobinette4 years ago
how safe is it to use phone jack to connect the ac/dc transformer to the fan?
 Thats what i thought too when i used 2 12v PC fans (with 1 A running) but it actually works well. The only concern is the plastic melting and the 2 contacts making connection, hence a short circuit, due to the heat of the fire. For a safer channel, run a chute (or square tube) made of metal to the back and then have it point to where you want the heat.
solow755 years ago
This is not my idea, but I thought I would throw it out there. Epoxy a thermostat to a magnet and attach to the bottom of the firebox. When it gets hot it will turn the fans on and they will stay on until the fire cools.
ReCreate5 years ago
You Can Get Fans From an Old Computer, You Can Get the Metal From an Old Computer's Casing, and You Don't have To buy a New Adapter/Wall Wart/Power Source You Likely Have Around Collecting Dust, And If you Don't You Are Likely To find someone throwing one away. ~ReCreate
cool, looks very very nice.
For you electricians out there, do you see any problem with putting a dimmer switch to control the outlet in the fireplace? Would that not give better fan speed control?
energygeek5 years ago
When I first read this title of this thread it scared the crud out of me, (make your own fireplace fan = certain death by flames) but now that I see how you made it and the application....looks like a keen idea! Good job.
Great tutorial, very cleanly done (unlike some builds on here) and well thought out. Im impressed as I have actually built one of these (8 fans wide) for my wood burning fireplace that was hugely innefective at warming the entire house. Airmovement is critical if you want anything more than a body magnet like most fireplaces are. Good job!
clear aquarium silicone sealant lightly "painted" on the non showing sides of sheet metal also dampens noises and vibrations.
A little less time consuming way is to just buy the right size hole saw from your local big box home improvement center. Make sure you clamp the metal sheet to some wood with your holes and some screws. Rotating sheet metal is dangerous
or do what I do and run your marking tool around the inside of the fan case following the blade. gives you the exact cutout needed.
lithoss5 years ago
This looks awesome.. one question though, is nobody worried about the fans getting too hot and partially melting and/or causing a fire somehow? Maybe I'm just paraniod,... anyone want to put my worries to rest?
I love this fan, it's been bookmarked on my browser for over a year and this weekend is the big weekend. I'm going to build two of them. I have a question. Is there a simple way to put these fans on a remote control or even better yet, a thermostat? Anyone have any ideas? D
antarctic74 (author)  scotiadallas6 years ago
Some computer fans ship with a temperature sensor that turns the fans on when a particular threshold temperature is reached. Conversely, the sensor shuts the fans down when the temperature drops below that point. The range of the sensor is obviously intended for measuring the temperature inside a computer case, not a fireplace, so it may not turn on/off when you want it to.

I originally ordered a pair of Thermaltake A1357 fans fans that have a temperature sensor. I intended to build the fireplace fan using them. Unfortunately they both arrived defective - the temperature sensors did not work - so I gave up on that idea. Take a look at the threshold temperatures quoted on the site and see if they work for you.
Thanks for the input! I haven't ordered my fans yet so I'm going to look into this. Surely the temperature below the firebox will trigger these temperature sensitive fans! Another question. While gathering parts I realized that there is a harness wrapped up in the middle of your intro image. Does this harness come with the fans or is this an extra item? My original though was that I would cut the white end cap on the fan and just solder those but looking closely it seems the harness is a larger gauge wire? Any input would be appreciated.
antarctic74 (author)  scotiadallas6 years ago
True, the temperature in the firebox will set the fans going for sure. But it may not drop low enough to shut them off, or even slow them down, until the fire has gone out long since.

The wires in the middle of the intro image are leads for connecting fans to a computer power supply. They shipped with the fans and I think the number of pins (3 or 4) differs to accommodate different power supplies. You won't be needing them in this project but I didn't realize that out until way after I had taken the picture. They are same gauge wire as the leads attached to the fans.
cubeberg6 years ago
How did you decide what adapter to use? Would the adapter you purchased be capable of running 3 fans?
antarctic74 (author)  cubeberg6 years ago
I sized the adapter to fit the fans. You can usually find fan specs on the manufacturer's or seller's website.

The fans I bought are rated for 12V DC (almost all are) and consume 0.13A current. So I looked for a power supply that supplies 12V DC and around 0.26A (2 fans * 0.13A = 0.26A). The power supply I bought supplies 0.5A current which is on the high side. 0.5A is adequate to start the fans but not too much to cause damage. It would be adequate to run three fans.
In you items list, you suggest using an AC adapter. And here, you suggest DC. I'm not very sure what the difference between AC and DC is, but what should I use for this setup? I also have two 12v 0.16A fans. THanks!
antarctic74 (author)  liquidsense6 years ago
The adapter converts from AC to DC. The type current you will get from your wall outlet is alternating current (AC) while the fans require direct current (DC). I revised the parts list to clarify this. Thanks for your comment!
LinuxH4x0r6 years ago
Nice Job! Instead I would reccomend having the fans blowing air into the bottom thingie. This way it is blowing cold air in, instead of hot air out, minimizing the chance of melting.
antarctic74 (author)  LinuxH4x0r6 years ago
Good idea, haxor. I'll test some different locations. Cool air goes in from the bottom, moves up behind the firebox, and hot air exits at the top of the fireplace. I placed the fans in the back because the fireplace manual recommended that location. When I reach my hand to where the fans are, it feels warm but not hot. I'm really happy how the system turned out. As an enhancement, I might add a resistor to slow the fans down a bit. They are running at full speed now and I can hear them.
This sounds great. I'm going to try one for a masonry fireplace channel heat exchanger. Just one question, what resistor would you use (including maybe a variable Rheostat.
If you are using low voltage dc computer fans just use a transformer with a lower voltage (try maybe a nine volt or maybe even 7.5)
Thats what I am doing. Running two of them off of a couple 9V batteries. My fireplace does not have a power plug as the one shown. I have wired the fans to 3 9v batteries and they are switched on/off by the switch controlling the fire (remote control switch) . So when the fire is on, the fan is on. The batteries last about a month, and then I just recharge them.
urbanhg6 years ago
very good idea i work as a chimney sweep and buying a blower for your stove can be expensive so way to save some $$
Haymaker0076 years ago
Nice job, especially the use of the Workmate as a brake for metal bending (I have to try that). I use a similar setup with a wood stove, fans are 12v DC, connected to a battery for the night and a small solar charging array for daytime, the 200CFM projects a nice heat. I cannot hear them so I wonder if yours are vibrating the base in spite of the furniture pads, or perhaps the front is laying against the back wall of the stove case (just ideas)? For information make sure of the airflow direction of the fans and the volume of air is not overly cool for the firebox (although I do not know the science re firebox temperatures/exhaust for gas stoves).Pulling cold from the bottom up and/or pushing over the firebox is the way to go. ultimately it is the distribution of btus into the room.
cubeberg6 years ago
Absolutely awesome! I just moved into a new house with a gas fireplace and was looking for something like this. I'll have to build my own!
Brennn106 years ago
This is really good. It looks really sweet. Nice job!