Over thinking the heater fan

[bbs428]

Nice work Eric.

Here's my take on it. A new Nissan heater core and four 120mm fans I had laying around in my box of spare pc parts.

Two fans = low, 4 fans = high. .2 amp each. so 4.8w on low, 9.6watt on high. I did power them up and get decent airflow. Since they do not run very frequently should I even be concerned with that resistor?

I can replace them easily enough if it's a total fail. Lol. I know - not so scientific but total cost was under $50.00

[Eric Page]

Since they do not run very frequently should I even be concerned with that resistor?

Hard to say without knowing the voltage rating of your fans, and their history. If they're 12V fans, and if they've already had a hard life in whatever PCs they were salvaged from, then I would be inclined to replace them with whatever @Delta Whisky came up with. If those are relatively high pressure fans, you may only need two to accomplish your "high/low" setup. Or if, as you said, you don't mind replacing them, then press on!

Don't forget that once a plenum and ducting are in place, you may lose significant air as backflow through the idle fan when you only run one, and that heat will be directed under the glare shield with your avionics. It would be healthier for your screens and other gear to make your "low" setting operate all fans at half speed. This will expel all of the heat to the cabin and only offer suction behind the panel.

[avidflyer]

Well I flew my Kitfox for 1.4 hrs today, it was about 30 above F. My right foot got plenty warm. Got feeling around for drafts and there is lots of air coming under the passenger side door. Will address sealing up things next. JImChuk

[bbs428]

Hard to say without knowing the voltage rating of your fans, and their history. If they're 12V fans, and if they've already had a hard life in whatever PCs they were salvaged from, then I would be inclined to replace them with whatever @Delta Whisky came up with. If those are relatively high pressure fans, you may only need two to accomplish your "high/low" setup. Or if, as you said, you don't mind replacing them, then press on!

Don't forget that once a plenum and ducting are in place, you may lose significant air as backflow through the idle fan when you only run one, and that heat will be directed under the glare shield with your avionics. It would be healthier for your screens and other gear to make your "low" setting operate all fans at half speed. This will expel all of the heat to the cabin and only offer suction behind the panel.

They are 12v and new, just never used. They do move some air. I like your idea to operate all fans at half speed on "low". I do have an Aluminum shut off valve that can be adjusted as well. That resistor is looking like it could get more use than I initially thought. Thanks!