Extra Auxiliary Heater in Prius for climate demand?

Look at this, it could be the ceramic heater in a c


2017 Toyota Prius c Hvac heater core heater element. Quick heater. Air, conditioning, heating - 8771052090 - Genuine Toyota Part

 

I saw it in an ebay ad for another part, then tried to read the microscopic print with old eyes. The part number took me to 2017, but I doubt it changed.

 

This any good?

 

Yours is cheaper than mine!

 

I couldn't find any technical specs for what is called the "Quick heater".
It provides some instant heat to the heater/defroster air stream after a cold start in cold climates.

There may be more conditions than the ones that I have listed but as near as I can tell, it operates on the following logic:

Heater disabled above 50 deg F ambient or in ECO mode or the blower is not on.

Heater enabled below 50 deg F ambient, while not in ECO mode, with the blower on and coolant temperature of less than 150 deg F.

 

The funny thing about aftermarket sales of this electric heater is, how many would they sell? It's functionality is so slight that people would have no way of knowing that it failed. Actually most people don't know that it even exists.

I didn't know until I did some serious digging and since my Prius is always in ECO it would never be energized on our car anyway.

 

Capitalism is so out of control it requires [checks notes] wearing only one layer of clothing year-round.

 

I'd venture a guess that it is most economical to take heat from the gas engine only and put up with a few temperature swings that are normally handled by the electric element. Energy used by that element has to go from the fuel tank to the engine to the HSD to be made into electricity to pass through the DC/DC converter before it gets to that heater. That is a long and inefficient trip. The less energy you put through there, the better. The heat from the engine coolant is free; it is a waste product of all the work you are paying for. It just isn't available full-time due to the hybrid run pattern.

So really your choices are high efficiency heater that runs when it runs [eco mode] or part-time high efficiency heater + rest-the-time low efficiency heater [default; non-eco mode]

 

I don't get the impression that it was added so much to routinely fill in during temperature swings in stop-start operation (though maybe it does, if the coolant temperature drops below its threshold), but just to get you a little more quick heat off the bat when you get into the cold car. And no, 700 watts really isn't enough to feel (it's what, half of a typical blow dryer? but blowing out several vents instead of a nozzle straight at your head), but does have a noticeable effect on the windshield; I'll turn ECO mode off for that when needed.

 

With the Gen 3's, we have another heat source. The heat from the exhaust gasses that pass through the EGR cooler heats the coolant when the ICE is running. The cooler may be capable of transferring more heat than the "Quick heater" but the spec for btu's the cooler is capable of transferring to the coolant is not stated.

The logic for the typical EGR solenoid is closed at idle and open when the throttle is not at idle. There may be more conditions with the Prius.

 

Not just the EGR cooler; IIRC there's a second Gen 3 exhaust-to-coolant heat exchanger further down the exhaust pipe (which is where those extra hoses go).

The EGR cooler is primarily there to keep the recirculated gases cool, while the lower heat exchanger there is primarily to warm up cold coolant faster.

 

Correction on how EGR works. The EGR valve is shut off when the engine is cold, at idle or at full throttle. That precludes the EGR helping during warm-up.

 

Technically that is the EGR helping warm things up. More EGR = less power & associated waste heat.

 

And today's Hairsplitting Award goes to....