Prius Heater

Shaun:

It has been my experience with every car and truck I have ever owned, that a winter front is useless in city driving. The exception being an old car/truck with a solid hub fan, in which the fan is always turning.

A conventional car or truck with a clutch fan will disengage enough to allow faster warmup, and a front wheel drive car with electric fan won't have much airflow through the rad at all when the fan is off. Certainly not at 60 km/h.

I may try blocking off part of the grille this winter to help with cold highway driving. I've been very reluctant to do this as the Prius doesn't have a coolant temp gauge. At 100 km/h after 10-15 minutes the heater does blow hot air.

If you're driving in on Bishop - say from Island Lakes - and the car can get up to 70-80 km/h, it will actually warm up at -25 C. Eventually. But if you're stuck at the tracks on Kenaston or waiting on Marion by St B's, better wear the toque and mitties.

As far as "disappointments" are you referring to the fuel economy, the bone-jarring ride over Winnipeg streets (Wellington is real nasty, especially near Halter East), or just the overall hype? All in all, I still like my Prius and if I had to replace it, would probably get another one.

Well, the bears are finally gone from Broadway. Miss them? Me neither!

jay

 

Jay,

Thanks for the tips on what it takes to get some heat out of the car. Sounds like we'll still be getting an interior heater - a 10K city drive in the morning probably won't be enough to get any meaningful heat out of it. Confusing and perhaps a little sad considering you've said the engine runs non-stop in the dead of winter. I wonder why that is; it seems a contradiction.

I assume that the car also has a thermostat in the rad (or near the engine block) as well as the rotating valve in the heating hose circuit. I'm sure someone will know this one here

As far as disapointments, it's nothing really major. Partly the hype of it all, an ever-increasing mileage (as we head into the colder temps. we've jumped just over 1/2 a litre more in average MFD consumption than when we first got the car 2 months ago (although that could be related to how it's driven)), horrible muddy sounding speakers, and some minor ergonomic things (e.g., how am I going to put my size 13 Sorel's on the deadfoot plate with that parking brake there?). Like you, all in all I do still love the car. It's the only car I've thought of getting for the last few years, so I'd buy it again in a minute if we were to do it over. If it was just gas mileage, we could've just bought a diesel and be done with it (especially with that bio-diesel plant opening up in Manitoba next year); but there's so many other reasons to want to support this technology.

Anywho . . . .

I kind of know what you mean about the bears (I mean how many Aurora Bearialis Bears were there? 10?). I can see how it brought more people downtown and all that, although perhaps I'm weary to speculate on the economic spinoffs for Broadway businesses. What I don't get is why people would want to see these bears again next year? Pigeons on Portage! Who's with me?

I think I'm going to write a letter . . . .

shaun

 

P.S. I'm also a little bothered by the fact that the Prius doesn't have a coolant readout (and to a lesser extent - oil pressure guage). I'm just so used to seeing them in our old Sunbird (and every other car out there), that it's a little odd. At least then you knew when you had enough hot coolant to get some decent air in the cabin, or when you needed to get some hot air in the cabin (if you were going to overheat).

 

Shaun:

If I'm careful I can average 4.2-4.6 l/100km city driving if I can roll along on Bishop, Pembina, St Mary's, or Portage. If I have to drive a lot of side streets with frequent stops, more like 5.5-5.8 l/100km. At -40 stuck in traffic trying to get downtown, more like 9.8 l/100km.

Compared to my 2000 GMC Sierra SLT, which never did better than 20 l/100km summer and at -40 more like 48 l/100km city driving, I'm not complaining. I just think every car is WAY overrated on fuel economy, especially city driving. Their definition of "city" and my definition of "city" are 180 degrees out of phase.

Personally I would love to see them build a giant pigeon with the head overlooking Great West Life, the butt aimed at the Legislature and pooping on the dome. But that's just me.

I actually made a point of avoidng Broadway unless for some reason I had an appointment on Vaughn, Kennedy, Hargrave, etc. Those bears really backed up traffic and a lot of idiots were walking around the bears and even stepping onto the street. Usually right in front of you.

If I had to get from St Mary's to Portage, or if I was visiting my Aunt on Roslyn, I'd just swing off onto River and either take Wellington then past Misercordia, or turn off on Osborne. Longer but easier, even dealing with The Village.

jay

 

Shaun:

Me too. For that reason alone I'm extremely reluctant to put a winter front on my Prius. A winter front won't help in city driving, but it DOES help on the highway.

My 2000 GMC Sierra SLT was ordered with the towing package, as I had a camper at the time. It was my experience the truck struggled to reach normal operating temps at -20 C or colder on the highway, unless I put on a winter front. The truck had a fairly good factory temp gauge so I didn't mind running the winter front.

I'm not willing to wait for the Triangle of Doom to light up on my dash to let me know I've overheated and ruined my motor.

Only half of the cars and trucks I've owned over the years had an oil pressure gauge. I think they're a good idea, but most folks ignore them anyway. Some factory gauges have a calibrated "deadband" so they always claim a certain reading, even when not true.

jay

 

The heater works the same as on a conventional car, with a couple of exceptions:
1. There is a supplemental electric heater (2 actually) mainly to provide heat until the coolant is sufficiently hot.\
2. Since the ICE is not always running, thus the engine mechanical water pump is not always running, there is a separate electric coolant water pump to circulate coolant through the heater core.

The AC compressor is only for AC. It is not a heatpump that can reverse and provide heat to the cabin.

The ICE does not have to continually run to provide heat to the cabin. If the coolant temp is too low, then ICE will run. But if coolant temp is high enough, then ICE can be off for a time and the cabin can still be warmed by the heater core that gets its heat from the coolant being circulated by the electric pump. If the coolant temp gets below a threshold, then ICE will be started even if only to warm the coolant. When not heating, the HV will keep ICE off indefinitely at stops, even if the coolant gets cold, unless the SOC gets too low. This is why you can sometimes stop and start the ICE on demand with the HVAC controls.

 

A proper temperature gauge for coolant is a necessity in a Prius for winter.

You need it both to see if your winter front is letting it overheat but also to see when to turn on more heat for yourself and when to save it for the engine.

I block my radiator currently about 80% with most of the open part at the bottom for the inverter cooler.
Driving 55 mph in this weather which is like 45 degrees I might normally get up to 170 degrees.

With the winter front I get to 182 degrees on the same commute.

Drive slower and the car still cools off too much to stay in stage 4. I've seen it drop to 150.

And this isn't really cold weather yet.

FYI I've measured my coolant at 196 in warmer weather with the radiator unblocked. I only block it when temps get under 50 degrees or so.

I use the temperature gauge to watch the warm up:

I start with heater all off. (assuming windows stay clear)
When car gets to 130 I put on some heat on one of the 3 lowest speeds.
I also use recirc when humidity permits.

Then when car warms over 170 degrees I use more heat as needed. If I go slow I revert to less heat as needed to try to keep the car at least over 160 degrees.

This makes a huge difference along with the EV switch in my economy. On my 10 mile commute I can get close to 50 mpg instead of getting a typical 40 mpg.

 

Tom:

I have a 2004 Prius. Were you able to add a mechanical gauge or do you use a scantool to read the coolant temp?

jay

 

I actually bought an electronic temperature gauge from JC Whitney to use but never mounted it. Last winter I used an Auto Xray scanner which worked pretty good except it hung up every so often and I kept having to remove the battery to reset.

Now I have a scan gauge scanner. The scan gauge works great, and gives me RPM too so I can see when the engne is on. So I just use that now. It is powered by the car and so far has worked reliably with no hangs.

 

If the heater is the culprit, it has taken a 10-12 mpg hit at my "normal" mpg. Very disappointed given that it isn't even cold yet. I have the the temp set at 60 but it didn't help the mpg at all. At least it makes my truck look better for winter driving. Between the much lower mpg and almost impossible to read dash display as soon as I turn on the lights, this is not a winter car. Since the AC had virtually no effect on the mpg, I was taken by surprise on this one.

 

Thanks Tom.

 

Wow that IS extreme. At -40 C my fuel economy was 9.8 l/100km or 28 MPG. About half what it usually is in summer.

Still way better than the 2000 GMC Sierra SLT I used to own.

 

Frank, you sound like you know this system REALLY well. Could you answer a question for me? My heater works just fine until I'm at idle. At idle I'm assuming the ICE should come on or stay on to provide Heat, however it doesn't appear to be doing that.