For years I regularly used the Tanis system on a couple of airplanes. Then I worked a couple planes with the Reiff systems installed. I really liked both systems for reliable, safe pre heat. I installed a Reiff system on my personal plane. these engines were regularly started outside at temps regularly below -20 F, and often as low as -40F after proper pre heat.
Ive also pre heated with a half dozen other "tools", none of which were as good, safe and reliable as the Reiff or Tanis systems in my opinion.
A couple of points:
As Stewart discovered, Reiff and Tanis each sell two different temperature rated systems. In cold temps, I want SERIOUS heat.....be sure to order the "high heat" version, whether dealing with Tanis or Reiff. The lower rated systems aren't worth the trouble.
If you have or ever plan to install a graphic engine monitor, buy a Reiff system, not a Tanis system. The Tanis probes occupy the cylinder head bayonet receptacles. If you have a multi probe CHT, the CHT probes will have to be exchanged for spark plug gasket sensors, which are NOT accurate, and generally a PITA.
As Dave posted earlier, the cylinder bands on the Reiff system works better than the Tanis probes, in my opinion.
If you're thinking about installing just a silicone heat pad, install one that's designed to be installed on an aircraft engine, and that is thermostatically controlled. E Z Heat is a good one. Understand that it'll take a bit longer to heat your engine than a full system but.....
A good, close fitted engine cover is really helpful in heating. And if you're parked somewhere and want the motor to stay warm. Sleeping bag, moving blankets, etc all help as well, but a good engine cover is the ticket.
Take your time heating......it's a slow process, and remember, it's the CORE of that engine you want nice and warm, not just the parts you can touch.
MTV