Question Using an engine pre-heater on a piston engine

[Neal]

I have the Reiff engine pre-heater for my Lycoming IO-360. I realize it's probably not the best solution as I hear Tanis is the better option but I don't have much experience with this to offer an opinion, just what I heard, and Reiff is the only option offered by CubCrafters at my build time.

Knowing I had a cold morning launch last week, under 30F, I plugged in early in the week as I hoped to fly earlier but had to reschedule. I heard some time back that with Reiff, don't unplug it until ready to fly as there is the possibility of condensation if the engine is not run post heating. I'm curious what temps people use for when to pre-heat, can the Reiff be on too long or can it run continuous until the next flight opportunity? I have to say it worked well, when I got to the runup area there was no waiting for oil temps to rise, it was around 130 when I arrived at the runup. Otherwise it probably would have been 80-90 and had to wait 5-10 minutes for temps to go green for power over 1000 rpm.

I'd love to learn from others on what you use, when to use, how long to use, etc. regards to piston engine pre-heating.

 

[ve6yeq]

I too have the factory-installed Reiff system installed on my EX-3. In my research, this system appeared to be the best plug in system as it gave a more even complete heat to the engine and it has a separate pre-heat for the oil cooler. The only thing lacking appears to be a pre-heat for the constant speed prop as the oil pressure does not settle until I have completed a very slow cycling of the prop during the run-up. (Maybe I just need an insulated cover for the spinner / prop blades?)

Even with the cold weather, I am still running W100 + camguard so I have to make sure to pre-heat everything to the minimum oil temperature for W100 before starting. As the plane is parked on the ramp outside with thinner covers, it seems to need 6+ hours to warm up so I just call the FBO to plug in the extension cord either the night before if I plan to fly early, or when I wake up if I am flying later. If the weather forecast does not work out, I just call the FBO to unplug it. I will add a WiFi switch one of these days as there is WiFi coverage on the ramp.

 

[Neal]

Good point about the CS prop. I've noticed when cycling in the colder weather it does take longer to stabilize back to full forward. I do give it time at RPM to stabilize but does seem to be something affected by the cold weather ops.

I still run 15W-50 (Aeroshell) but that's a good point too, should oil be changed for winter ops? I'm not in the coldest of climates typically in VA but this year has been unusually cold, it's 18F as I type this and I'm launching at 0900 to fly.

 

[Tsquared]

For me I plug in my Tanis when temps start to hover around 40F or lower consistently. I keep it plugged in until temps I might fly in are over 40F. So for MN that's typically mid November until sometime in April. I'm also using an insulated cover when it gets below 25F. I'm in an uninsulated and unheated T hangar.

With the Tanis preheat (cylinder heads and engine oil) my cylinder heads are typically 80F warmer than ambient temp and oil is 35-40F warmer as well before startup. That said I still keep close eye on my oil temp after start and don't taxi or operate above 1000rpm until my oil temp is at least 120F in the winter.

As I understand it, leaving a Reiff system on and then unplugging the system without flying it can allow condensation to build up in the cylinders. If you check out Tanis website they provide a good explanation regarding the advantages of their system. Why Tanis - Tanis Aircraft Products. Doug Evick (Tanis owner before Hartzel purchased the company) used to give presentations with data and thermal images to better articulate what Tanis can do.

RE ve6yeq's comments on the constant speed prop they are spot on. I don't cycle the prop until post run up and even then it's a little slow coming back to full RPM. I looked into getting a prop cover, but was told that with the composite props on the FX3, they didn't suck heat from the engine like a metal prop does and that there weren't any advantages to using a prop cover with a composite prop. But one Canuck to another, Toronto isn't that cold compared to Minneapolis or god forbid Winnipeg, Eh?

Like Neal I run the Aeroshell 5w-50 year round. If I was in Winnipeg, North Dakota or Alaska, I'd change oil types seasonally.

 

[Cubonaut875]

As someone who has experience with both systems you are spot on. The Tannis is a much superior system. When I was specking out my plane I asked about a Tannis system and they said they had not done as many in the full IFR panel. Knowing how the Tannis installs and the proximity to the various sensor leads I opted to go with the Reiff. Cubcrafters functions better with things they do all the time. Problem being, you can't leave the Reiff system plugged in, you have to heat it only a few hours before flying and once you heat it you should fly it. Being a person who likes to fly early in the morning, I am not going to get up at 2:00 am to plug in the heater. I got around it by buying a remote switch SwitcheOn 4G/LTE Remote Power Switch - SwitcheOn SwitchOn power switch, I can set the time for it to start depending on the temp. It is controlled by an app on my phone. It also gives me the temp in the hangar - kinda interesting information. I'm thinking of buying a Tannis Cabin/Avionics preheater to plug into the spare outlet on the power switch, but I'm having trouble justifying the $473.00 for the Cabin heater. The Cabin heater would also keep the battery warm too however. The insulated cover is also a great idea, with the Reiff it allows the whole engine compartment to heat, not just the oil.

 

[Neal]

I'm not sure a few hours is enough for the Reiff based on my recent use. Two weeks ago I did a multi-day preheat attempting to fly waiting on winds. When I finally flew, cranking around 20F outside, the heat level was great, when getting to the runup area I was probably over 130. I typically won't do a runup until over 125. I planned to fly this past Friday so Thursday I went to the hangar to preflight and put the Reiff on at 4 PM. The next morning was in the teens, maybe 20F, and I cranked at around 9 AM. I got to the runup and was still in the yellow and had to run at 1000 rpm a few minutes to get to 125. So in that experience, personally I would want ideally a 24 hour preheat if possible.

Now let me state the obvious so no one beats me to the Darwin award of blowing up their airplane and hangar. When plugging in, or more so disconnecting the plug for the Reiff inside the oil door which is inside the engine compartment, make sure power to your extension cord is OFF. Connect the plug and then apply power. I had a nice arc when disconnecting Friday morning and it's great having an electrical arc in a fuel fumed (assumingly) engine compartment. Yeah, my setup is a little bit of a hassle to disconnect/reconnect that cord but from now on that's my procedure.

 

[Cubonaut875]

Do you have an engine cover? And yes for sure, turn it off before you unplug it. At 12F degrees a couple of weeks ago I had an 85 degree oil temp after only a few hours on the heater, I think I had it turn on at midnight.

 

[Neal]

Do you have an engine cover?

No. Temps here in VA are not normal. Rare do we have winters this cold.

 

[Cubonaut875]

Get a moving blanket from U haul or Harbor freight Moving Blankets - Harbor Freight Tools, it will make the world of difference. The Bruce's custom cover is awesome but it was pricy, it allows the whole engine compartment to heat.

 

[Neal]

Good idea, I have one in the hangar already and will use that going forward. I guess the next question is what temp is desired?

 

[Cubonaut875]

Tsquared observation on the metal prop sucking heat from the engine is spot on also. The Trailblazer is composite so it is not as good a heat conductor as the Borer metal prop. I covered my prop on my previous plane while I preheated.

 

[Cubonaut875]

The Reiff will just keep heating unlike the Tannis that will go to I think 50 or 60 degrees over ambient. I, like you, wait to do run up at 125 oil temp. It usually dosen't take that long. If you take the moving blanket and use a couple rachet straps to fully wrap it around the cowl, I'm sure it will be as good as the pricy cover.

 

[Neal]

A quick google search:

According to information available, a Reiff engine heater typically aims to raise the engine oil temperature around 80°F above ambient temperature, with a thermostat limiting the maximum oil temperature to around 150°F, effectively capping the engine's maximum heated temperature at that level.

 

[Neal]

From Aircraft Spruce but not sure if it's the same Reiff product:

OPERATING INSTRUCTIONS​

To use the heater, just plug it in! The recommended procedure is to place a blanket over the engine cowling and prop blades, and foam rubber plugs in the front air inlets to minimize heat loss, and plug the heater in several hours before engine start, overnight for maximum heating. Without covering, just the oil will be heated and very little heat will transfer to the rest of the engine, just like if you try to bake something with the oven door open. The thermostat will limit the engine oil temperature to 150o F. The heater is built for continuous use, but leaving it on continuously may create condensation inside the engine which may cause internal corrosion. You may use a timer, thermostat, or remote telephone or beeper activated switch to turn it on in your absence. These items are available from Reiff Preheat Systems or others. In remote areas without electricity a DC/AC inverter can power the heater from a car or truck, or a portable generator can be used. Some generators are small and light enough to be carried in most aircraft. Always use a grounded outlet for safety. For the best protection against shock, use a ground fault type outlet or extension cord. During each annual or 100 hr. inspection the heater system should be checked to make sure it is secure, undamaged, and functioning. With the engine compartment sealed, typical maximum under cowl temperatures will be about 35o - 45o above ambient (no wind), depending on the heater’s wattage. For faster and warmer preheats, the Reiff HotBand Cylinder Heater System may be added to your engine at any time. When this system is used along with the oil heater, under cowl temperatures will be about 70o to 90o above ambient, and the preheat time will be significantly reduced. It also heats the engine more uniformly, reducing the risk of condensation.

 

[Neal]

Last one for Reiff:

Aircraft preheat FAQ's

 

[Neal]

1. Does your system have a thermostat?

There are two reasons to use a thermostat. One is to turn on the preheat system if the ambient temperature falls below a certain level. Our system does not include such a thermostat but they are available from various sources.

The other reason is to prevent overheating while the engine heater is operating. Our cylinder heaters do not have a thermostat control, but some of the oil heaters do. While the engine is running the cylinder normally runs about 300-350oF. Our cylinder heater heats it about 70-90o over ambient, so there is no danger of overheating anything and, therefore, no need for a thermostat.
Our oil heaters are sized to raise the temperature of the oil up to 100o above ambient, and a thermostat on some systems further limits the oil to about 190o actual. This means in normal winter use the thermostat never cycles - it just stays closed (on). This design approach gives you the benefit of a thermostat controlled maximum oil temperature, without the disadvantage of limited thermostat life due to constantly cycling on and off.
One brand does not use a thermostat and criticizes them because they have a finite life expectancy (100,000 cycles for ours) and when they fail they can fail closed (although this is rare - they almost always fail open) and allow the heater to run continuously and overheat the oil. This is a valid concern with some other brands of oil heaters. It is not a concern with ours because our thermostat does not cycle, and because our oil heaters are sized so that they will not overheat the oil even if the thermostat fails closed and the heater runs continuously. In fact, we had to demonstrate this to the FAA to get PMA approval.
The other brand's approach with their multi-point system is to use a low wattage oil heater with no thermostat, which heats the oil 30-50o above ambient. We feel this is not enough heat in cold weather. More heat thins the oil for better circulation and lubrication on start-up and reduces your engine warm up time. A higher wattage oil heater will also give much faster preheating. We believe more heat is better, as long as the oil temp remains at a safe level.
Another thing to be aware of with the other brand's approach to oil heating is that on many engines they use a submersible probe heater in an oil drain hole. We considered using this type but decided against it. Even though it's only 50 watts, the watt density (watts per square inch) is very high due to the small surface area of the heating element. We are concerned about the possibility of the surface temperature exceeding 300o, which would overheat and damage the oil. Our 4" x 1.5" element has more wattage but much lower watt density, so gives more gentle heating of the oil without risk of scorching.

 

[Cubonaut875]

You are a wizard and my best resource! Usually when I turn on the IBBS when I start it at 2:00 am with 20F OAT the oil temp is up to 80, which I think is good since when it's summer and I don't preheat, it usually starts at 70 to 80F. I just want the engine to think it's summer.

 

[Cubonaut875]

That is an interesting read from Reiff. It reminds me of reading a study paid for by a drug company on their drug. I think I'll read it a little more carefully

 

[Cubonaut875]

I think I'm going to Infrared the temp in the engine compartment next time I preheat, check how warm it actually is.

 

[Tsquared]

I still use an old quilted movers blanket when temps are between 40 and 25. Just add some engine inlet plugs and the combo works well in warmer “winter” climates. You’re going to lose a fair amount of heat out of those big openings otherwise.