Reiff engine pre heater and Rotax CHT

[Vic]

Hey all,

Just installed the reiff heater oil band and crank pad.  From what I can tell it seems to warm up the engine BUT my CHT temp sensors says it's only 30F.  

It's cold up here in PA and OAT is around 30 today.  I ran the heater for about 7 hours and when I put my hands on the engine it definitely felt warm, not hot by any means but definitely warmer than the exhaust out on the bottom and wings.  My engine cowling was warm and I think using a blanket helped keep the heat in, but my get EFIS says the CHT was only 30 and my oil temp was 86.   

 

How can that be? Has anyone else had that happen to them with those Rotax temp sensors?  I only have one CHT sensor so everything reads 30 for me on all 4.  I am not going exactly sure what temp my heads were since I don't have a temp gun, thinking about picking one up to just check for next time.

[Tom Baker]

If it is an early generation engine the cylinder temp is as far as you can get from your heat source. I could see it being cold.

 

[Roger Lee]

Your low CHT is because Reiff does not warm the cylinders. The bottom engine pad is too far away from the top cylinders. It has a pad on the bottom of the engine and the oil tank. A good engine pre-heater is Tanis. They are kind of the gold standard. They warm each individual cylinder, the engine block and the oil tank.

[Jim Meade]

I have a Reiff on both my Rotax 912ULS and several friends use them as well.  To be honest, I've not noticed - not paid any attention to - CHT.  In nearly any Iowa weather the Reiff will warm the oil to the mid 80's.  I use an old blanket or sleeping bag over the cowling.  Perhaps the question is whether the CHT matters when it comes to starting the engine?

Does the Tanis require approval?  My understanding is it uses non-standard bolts so I'd think Rotax or at least FD would have to approve it.  Maybe someone who uses Tanis can comment on that.

[Roger Lee]

I've installed about 15 Tanis heaters and maybe 3 Reiff. Everyone I know likes their Tanis. Tanis is approved on the CT. This model Tanis pre-heater was made just for the Rotax engine where Reiff just has more of a one size fits all. Tanis targets the oil tank, the engine block and each cylinder. Rotax has done testing with the Tanis to show its effectiveness.  The Reiff crankcase pad by itself isn't enough to warm the cylinders like the Tanis does. Tanis has heated bolts that replace one bolt on each cylinder air intake flange. Tanis has been doing this for a couple of decades for the Rotax without any issues.

Plus you can use either heaters with   https://www.switchboxcontrol.com/  to turn the heater on or off when ever you want from any location. You can use this for a battery charger too.  

[Tom Baker]

9 hours ago, Jim Meade said:

Does the Tanis require approval?  My understanding is it uses non-standard bolts so I'd think Rotax or at least FD would have to approve it.  Maybe someone who uses Tanis can comment on that.

Any change to a SLSA requires approval. Of the Tanis installations I have made no critical hardware was replaced. The closest to critical was the screw holding the drip tray on a Tecnam. A CTSW drip tray would be the same. The worst engine heater I have encounter is the EZ Heat. The two pads are hard wired together, one for the crankcase and one for the tank. It makes removal of the tank for cleaning impossible without modification to the wiring.

[Madhatter]

Hate to be too simplistic but a 75 to 100 watt drop cord light bulb inside the blanket covered cowl overnight warms everything.  

[Tom Baker]

1 hour ago, Madhatter said:

Hate to be too simplistic but a 75 to 100 watt drop cord light bulb inside the blanket covered cowl overnight warms everything.  

I used to use two 100 watt bulbs for my Warrior, but the incandescent bulbs are hard to find now. I now use a small cube heater with a fan sitting on the lower cowling. I does a nice job. When I had my CT I used a $20 heater from Wal Mart ducted with one blowing air through the cylinder baffle, and the other end stuck in the oil door. I have a couple different set ups like that around that I can adapt to other airplanes.

[Towner]

Mine had a Tanis when I bought it, but I’ve never used it here. At what temperature would it be a good idea to preheat?

[Madhatter]

48 minutes ago, Tom Baker said:

I used to use two 100 watt bulbs for my Warrior, but the incandescent bulbs are hard to find now. I now use a small cube heater with a fan sitting on the lower cowling. I does a nice job. When I had my CT I used a $20 heater from Wal Mart ducted with one blowing air through the cylinder baffle, and the other end stuck in the oil door. I have a couple different set ups like that around that I can adapt to other airplanes.

When the government decided to ban incandescent bulbs I bought a supply. I suppose now it's criminal,  I guess we'll be back to using candles soon as we will eventually not have enough electricity also.

[Tom Baker]

27 minutes ago, Towner said:

Mine had a Tanis when I bought it, but I’ve never used it here. At what temperature would it be a good idea to preheat?

Below 40°f for sure, it will make starting easier. While it may not be needed, you can use it anytime. If you find yourself waiting for the engine to warm up before you do your run up, you could have saved some if not all of that time by using the Tanis. 

[Towner]

48 minutes ago, Tom Baker said:

Below 40°f for sure, it will make starting easier. While it may not be needed, you can use it anytime. If you find yourself waiting for the engine to warm up before you do your run up, you could have saved some if not all of that time by using the Tanis. 

Thanks. I really don’t see myself flying below 40 here, but saving warm up time could be a plus.

[Philip Welsch]

This morning my Reiff heater had oil to 69 and cylinders to 78 and 81. Outside air was 27. Inside hanger was 32. Heater went on 5 hours prior with timer. No blanket.

[Roger Lee]

If you look under the LOA approval list here on the forum you will find both Reiff and Tanis approved a long time ago.

[Vic]

Thanks everyone for the input,  heres where im in doubt.

I am wondering if my CHT sensor is not reading correctly hearing from these other guys.  Id like to confirm my CHT sensor or ground wire on the sensor is good before I get to far gone down the heater hole.  30 is cold, but to the touch even the clutch was warm, I believe it's doing at least something warming up the whole engine,  the clutch is so far from the crank.  My engine was put on in 2004, so it's the old tbo 1500 style. 

 

If I pull the CHT sensor will I introduce any air into the coolant channels or is this just port in direct connect with aluminum?  I'm wondering if I could shoot my thermal temp gun in the CHT hole and confirm and check the reading on the end of the CHT sensor itself.   I might even try swapping the oil sensor wire with the CHT ground wire to see if that wire is bad and see if I get a cold reading still in my oil temp parameter.

Roger.  Thanks for the quick response, I'm stuck with the reiff for now. I would like to confirm that temp first before I head over to Tanis or see if I can get the cylinder bands for the reiff,  it really is surprising how warm the entire engine is and how hot the oil temp was. 

 

[Roger Lee]

Hi Vic,

Your CHT probe is in metal only and not into the actual coolant. So no loss of coolant.

[procharger]

Light bulb works for me to for years.

[Anticept]

Heat lamps are still a thing. What you can do is get 150 watt heat lamp and put it in a shielded enclosure, or buy 2 that are a little more powerful and wire them in series and see how hot they get (doubles resistance, halves total power and they will share the voltage drop, making each one output a quarter of their rated power).

I also suggest any such circuit have an AFCI added (ground fault + arc fault detection). There are in line plugs that can do this these days.

[Vic]

Hi guys,

Reviving this thread because I found my problem.  My engine was nice and toasty after letting the Reiff heat up the engine after I added some blankets to the cowling.  My issue was my CHT temps were never accurate and reading lower than they should.  I pulled the CHT sensor out and it was warm, hit it with the temp gun and yep, it reads 80+ degrees while the sensor said 15 on my EIS, they were not the correct sensors and wiring for the Rotax and the GRT system.
I found out that GRT EIS( Grand Rapids Tech) systems do NOT use the standard CHT temp probes that come on the 912. They released an addendum 100 years ago stating this and that the CHT readings will not be accurate.  They use a ring style CHT with 2 wires that look like a thermocoupler.  The addendum tells you to remove the probe and just use a normal 10mm Threaded bolt.

 

Below is what is supposed to be installed with the GRT EIS.  Right now my CHTs all have just a single wire that I'm assuming is how they look for every other EIS other than GRT.

 

I dont know why they did it this way, maybe the software version they needed to use for the VDO oil pressure sender and Oil Temp sensors caused issues with single wire CHT probes.. who knows,  the previous owner didn't know either since that's how they setup this new EIS years ago.

Does anyone else use a GRT and notice this? 

 

 

[Anticept]

Ring type CHTs were the first on the market forever ago. Bayonet style came later when manufacturers started drilling the holes for them in the cylinder heads, but there's still a lot of ring types out there. A LOT. You can even get a ring style that goes under the spark plug.

Since grand rapids tech makes units compatible for a wide range of engines, the ring type is more likely to be widely compatible with everything with minimal manufacturing differences internally. Rotax's CHT might actually be the "oddball" here in the grand scheme of things.

Two wire CHTs are also far less likely to be affected by erroneous electrical fluctuations. They are likely bi-metallic junction k or j type thermocouples. It's possible to make them thermistor as well.

Single wire CHTs are thermistor type only, and are at the mercy of electrical noise in the system if grounds aren't pristine.