Capitaine wrote:
recommended Reiff heaters
Our P210’s Conti TSIO520 came with a Reiff XP 6-cyl system installed.
We have only used it a few times and never in temps lower than 0C. It is very effective and raises Oil temp raised by about 50F in 1h. My unit is 115V AC and I use a 220V-115V transformer (5kgs) which I have carried on occasions in our luggage compartment, together with a 25+15m extension cord + connector kit.
The system is tested regularly during annual inspection, but it is not a good idea to run it unless you are actually going to start the engine: if not starting the engine then it can cause internal corrosion due to oil drain back and temp cycle.
Antonio wrote:
it is not a good idea to run it unless you are actually going to start the engine: if not starting the engine then it can cause internal corrosion due to oil drain back and temp cycle.
Thanks Antonio: I’d never heard of this before. Is it because of condensation when the engine cools down again?
This Mike Busch AvWeb article says it’s ok to leave the engine heater on permanently if it’s a multipoint system (i.e. not oil pan only) and insulated, keeping the whole engine above dewpoint.
The ‘theory’ is that an engine heater helps reduce the initial friction and damage that can occur at extreme low temperatures on startup, partly because of different metals and coefficient of expansion, plus the nature of physical design of certain components.
In addition to this the oil is not going to flow well, can take a longer time to reach vital components, and can increase friction initially. This can be considered bad for the battery and the starter in some cases.
However most ‘artificial’ heating will largely be localised and therefore cold spots will always be present.
Any cold spot will cause condesation.
Causing this for a couple of hours prior to flying is unlikely to cause major troubles, but I certainly wouldn’t run my heater for long periods.
I have the Tanis, with individual cylinders, oil pan and crankcase but would prefer the whole engine at the same temperature if I was not flying, cold or otherwise.
Obviously the very best is a heated hangar where the whole engine is at a nice ambient temp all the time.
My ‘rule’ is 6deg or more, fine. 5deg or less, engine heater gets used.
Actually if its 6,7, or 8 and I’m not in a hurry, perhaps doing some jobs first, I’ll use the heater anyway.
We’ve the Reiff system as well. We use a GSM switch which I usually activate in the evening if we plan an early departure.
GA_Pete wrote:
However most ‘artificial’ heating will largely be localised and therefore cold spots will always be present.
I know of this, but I’ve made an interesting observation. We installed a new engine a couple of years ago and I removed the system from our old Conti and installed it on the new one. Probably I didn’t treat the clamps that go around the cylinders as good as I should have as I found out during the next annual that three didn’t work any more (they worked after installation, of course – maybe I overtightened them though I followed the IM). I couldn’t remember seeing differences in CHT after preheating so I checked the data from the engine monitor. In fact at least after a couple of hours of preheating there was no difference between the three working and the three other cylinders. I have no data of the preheating process, of course, as the engine monitor starts logging only when the master switch is turned on. Before engine start all six CHTs were always within one or two F from each other. Even oil temperature was the same.
I’d love to have mains power permanently available and would definitely use a GMS switch. I’m envious.
We’re outside, so I have to use a Petrol generator, which I only take to the field when necessary.
I think our engine set up would really benefit from 3-4 hours of pre heating, but it usually gets 1 or two, but that makes a very noticable difference.
Terbang’s experience is not at all surprising.
Heating the six pots individually is just a marketing exercise, to say “Hey we do it properly”. It is BS. The engine is a ~200kg lump, with the outside highly thermally conductive (aluminium) and there is no need to heat it in many places. As I wrote further back (I merged two identical threads) you just need to heat the sump.
Another thing is that (again, look at previous discussions on oil temperature ranges) there is no need to heat the engine to +20C or any similar “sandwich toaster” temperature 
That would also be marketing BS. You just need to warm it up to some temperature at which it is safe to start it. 0C needs no heating, but -20C does, so a system probably ought to achieve a delta T of 20C (or 20K, in engineering terms ). And I am sure you would get that with say a 100W-200W resistor screwed to the base of the sump.
It is known that the thermal resistance to ambient of a 30×30cm 1.5mm thick aluminium plate, natural finish, vertical, heated centrally, is 1K/W. Use a bit of intuition to scale this up to an IO540 size engine and I reckon it is about 10×. So a 200W heater on the sump ought to deliver a delta T of 20K. Exactly what you need for an OAT of -20C Even better if you plug the cowling upper holes.
Also, those cylinder heating loops are trying to heat steel which is a poor conductor. And the heat transfer from such narrow strips will be awful.
GSM switching is easy; lots of products which do that (I have one at work). You just need a power socket, which takes us back to, ahem, airport politics 
Heating the six pots individually is just a marketing exercise, to say “Hey we do it properly”. It is BS.
? I give up.
GA_Pete wrote:
I think our engine set up would really benefit from 3-4 hours of pre heating, but it usually gets 1 or two, but that makes a very noticable difference.
It all depends on the temperature, of course. My club has a setup with a heater controller that turns the heater on at a time depending on the temperature.
Peter wrote:
The engine is a ~200kg lump, with the outside highly thermally conductive (aluminium) and there is no need to heat it in many places. As I wrote further back (I merged two identical threads) you just need to heat the sump.
You could do that, but it’s often more practical to have small heaters installed at several places to achieve a good heat distribution. We usually use Tanis. I have installed two of these sets on Rotaxes. One set consists of a patch for the oil tank, small bolts (M4 r M5) on each cylinder head, and one bolt on the engine casing. This works well, and the entire engine gets heated up with even temperature.
With only one patch in the sump, the cylinders, which are the important parts to heat up for starting purposes, will not get heated much. Not unless covering the cowl with blankets. Heaters on cars usually works by heating up the coolant, which is the best method.
Airborne_Again wrote:
My club has a setup with a heater controller that turns the heater on at a time depending on the temperature.
We usually just leave the heaters on, but a temperature controller sounds like a good idea. Much better than any sort of timing or remote control.
This thread seems to waiver a bit between heating an engine for cold start and heating to avoid the formation of condensation within the engine when left.
If you heat an engine the liquids inside will gradually release water vapour through evaporation. There is plenty to be released in an oil dump or even the coating on the walls of cylinders. This water vapour hangs around in the air inside the engine and as it cools it is released as water droplets onto the engine walls and/or into the oil. It does not go away.
The water that goes back into the oil is not a problem for corrosion. That which sits on the engine walls can be if the water can combine with oxygen on the metal surfaces. If the engine is run and the aircraft flown often there will be less water in the oil to begin with. Also if cylinder walls remain coated with oil, oxygen will be kept away and no corrosion.
Using a petrol or gas heater in a hangar is a bad idea. Burning gas or oil in a confined area such as a hangar releases a great deal of water vapour into the air. This will settle as water droplets onto any cold surface such as your aircraft. You can see this on the wallpaper of people whose houses are heated by gas or oil heaters (not talking central heating here).
So as @Raven pointed out, heating an engine for 2 or 3 hours then going flying is not a problem. Heating the engine and then walking away for 12 hours or even days, is a problem for corrosion.
If the problem is warming the oil to make starting easier again that is not a problem provided you start soon after the oil is warmed. It cools quite quickly once heat is taken away.
As @Peter pointed out it doesn’t take much energy to heat an engine. 200w to 300w would do the trick.
My suggestion is a simple one. That is to use old fashioned light bulbs or failing that or not considered safe use builders lights or film/tv lights with safety guards attached. They can all be bought quite cheaply these days on Ebay or even in junk shops.
They of course all rely on a supply of electricity. If your hangar does not have you may need a small generator or we used to use a tractor battery. It was enough for a couple of hours. Of course for a bit more money you can buy some much better batteries.🙂
