Larger Blower?


Robert Burditt

TVWBB Member
Hi, I'm in the process of building a HM4 and had a question about the blower. I'm planning on using on a large backwoods smoker - approx 6'w x2.5'd x 3'h and am currently using an old bbq guru. It has a 25cfm fan. My question is will the one spec'd out be enough for such a big smoker? If I wanted to upsize the fan, what would be required? I see most larger fans draw quite a bit more amps.

D Peart

If the 25cfm fan with the BBQ Guru works today, I'd stick with the same size. In fact I'd just use the same fan, just make a simple rca->dc jack converter.

Later if you find you want a larger fan order it then.

You do not want it too big. My fan is too big for my 55 gallon UDS. I have to set the max fan speed to 50%. If it goes up to 100% it will blow all the hot air out of the bbq and the temp will actually drop. Then the charcoal gets all fired up and I can't control the temperature any more.

Most smokers are designed to work with nature convection flows. I'd be surprised if the natural convection is > 25crm for low-n-slow cooking.


Robert Burditt

TVWBB Member
I definitely don't need one bigger than 25cfm but won't there be concerns about it drawing too much power from the HM? What if any modifications would I have to make?

Bryan Mayland

TVWBB Hall of Fame
It depends more on your 12V power supply than any part in the HeaterMeter. The power MOSFET is rated for around 60A, the diode for 30A (surge, which is what it is there for). I've run up to a 1A device off of it before and checked the rest of the lines with an oscilloscope and they looked fine so that's as far as I can say.