I'm in Houston, average anual tempurature here is 70 deg.F. As I understand it, you want the block temperature over 165 deg.F. Even on the hotest days here, the block won't be above 110 deg.F. So it seems like if I use a block heater all year round, then I can always start the car at >165 deg.F.

Is anyone else this nuts? In the end I don't think I will do it for two reasons:

1. Don't think there is a Toyota dealer within 500 miles that knows what a block heater is or how to install it.
2. My friend lost his house in a garage fire (electric kids car), so I'm not that confident that block heater won't burn down my house (and new Prius with it).

Anyway, any thoughts or block heater use all year round, or is it not worth it above 40 deg.F., which is usually the lowest temp we see.

 

Hi Dan,

You are hitting on one of the problems I have with block heaters, the lack of thermostat control. Most folks are using a timer but that isn't the type of control I think is needed.

My plan is to configure thermostat for both my block and transaxle pan. This will ensure they are kept at a reasonable starting temperature, not the optimum nor ambient.

In the case of my NHW11 Prius, that temperature will probably be at or above 40F for the ICE and probably the same for the transaxle pan. With my thermistor hack, I can quickly switch to 'hybrid mode' during the two minutes of warm-up but not have to waste so much 'heating the outside.'

BTW, I didn't see any "Prius" in your description or signature. What'ca got?

Bob Wilson

 

Yep... You caught me.... I'd been waiting to get the mileage up before I posted. I don't trust the first tank since I think the dealer topped it off at 20mi, which is when I bought it.

Anyway, 2007 Prius with basic SmartKey/MP3 package. Added Port leather (Gulf State Toyota). Then I went back and added 6 more leather pieces (doors and by battery vents). They added the "special" homelink mirror and wood applique. I also added a decent tint job.

For those in the Gulf State region, you MUST get the leather option. With it they include "LiquiGel" seats. These completely releive the uncofortable-seat-problem. Another bonus is the sound proofing they added. Both of these options are things I wouldn't have done, so in the end I'm glad I got it off the lot.

Anyway, color is Magnetic Gray, and I'm rolling on 44f/42r PSI currently.

Only complaint are continual rattle problems I'm having with the dash. Everytime I take it to the dealer, the problem goes away.

 

Excellent! Sounds like a nice ride. I hadn't heard of the "LiquiGel" seats so I'll start looking.

GOOD LUCK!

Bob Wilson

 

Dan,
What would be your goal for using a block heater. Better mileage? Less wear on startup?

 

Better mileage. According to this there are 4 distinct phases of Prius operation. The goal is ultimately to get through the first two stages as soon as possible. Transition from S1 requires a block temp of 104F, and transition from S2 requires a block temp of 164F. So if I start the car with a block temp of 164F, then I'll hopefully spend as little time as possible in the warm-up phase.

But you raise a good point. I had heard that block heaters reduce engine wear, but I assume those studies were based on subzero (C) starting block temps, not room temperature block temps

You think I'm off track here?

Also, anyone worry about block heater fires?

References: http://priuschat.com/index.php?showtopic=13519

 

Unless you keep a lot of flammable material in your engine compartment, I wouldn't let that keep you from considering one. We have block heaters on each of our cars (2 Insights and a Prius). Even when my block heater cord developed a short, I still had no problems, and wouldn't have even thought about it somehow sparking a fire. However, I'm not sure how much a block heater would help in your case. I haven't used my block heater in the summer with the scangauge attached yet, but I doubt that even in the Prius you would get right up to the 165F threshold.

 

I have an F250 Diesel, and they come standard with block heaters. There is an occasional fire associated with it, so it is a possibility. But keep in mind the block heater on the diesel is VERY powerful. You need to plug it in a circuit by itself, and even then, when you plug it in, it can create one heck of a spark. There have been pictures of f@50s with the block heater pluged-in during a snow/ice storm where the entire truck is covered with 7+ feet of snow except the hood which is dry as a bone. That is how much heat the F250 block heater produces.

I don't expect the prius heaters to put out that volume of heat.

 

Dan,
I don't drive a Prius, I drive a Civic II. But I have a block heater and use it pretty much year round. My data shows that I definitely get better gas mileage using the block heater. But the improvement only lasts for the first few miles, after which the car would be warmed up anyway. So will you get better gas mileage? Yes. Will the improvement in gas mileage pay for the electricity you use to run the block heater? Not likely.

I mostly bought it so that I wouldn't freeze in the winter during those first few miles when the car was warming up, and it has worked well for that. But I also get better mileage (though again, it doesn't pay financially), and the car just seems to run better those first few miles.

So far as fires go, I can't add much - obviously any heating device has the potential to short circuit and cause a fire, but this is a Honda part, and I suspect they did a pretty good job of designing it. I did a quick Google search on Block Heater Fires and didn't find much, which would tend to indicate that it is not a big problem.

 

Bill (toast64) where do you live? I keep hearing how people think a Block Heater doesn't pay for itself but I still claim it does. The heater for our Civic HCH-II (yours and mine) are 400-Watt heaters so in one hour they consume just 0.4 kw or it will take 2.5 hours to burn 1.0 kW and my latest bill shows this as something around 11 cents per kW (or between 9 cents and 14 cents per kW) so for 3 hours of heating it is under 15 cents to warm the car and this is EASILY justifiable in my mind. I don't drink Starbucks but one cup of coffee at $6.50 would make for 43 mornings or don't Super Size that happy meal and save the $1.20 for 8 mornings. You get the idea.

I posted in one of the Civic-II threads that without the Block Heater I will see 42-45 mpg when I arrive at the office but with the Block Heater I see 47-50 mpg. That is a difference of about 5 mpg (on my car and my commute, YMMV) and if I do that for 10 mornings then that is a savings of 0.44 gal (20 miles @ 45 mpg * 10 days = 4.44 gal vs. 20 miles @ 50 mpg * 10 days = 4.00 gal). At our current prices that is a savings of $2.25/gal * 0.44 gal or $0.99 (and 10 days of heating costs 10 * $0.15 or $1.50). That shows as a loss but a very very minimal one. Face it, if you make the wrong turn on your way to a party and have to hit the *next* exit down the Interstate and end up driving 10 miles too far then you just wasted 1/4 or 1/5 of a gal and that ends up being $0.45-$0.55 so it isn't all about the cost savings sometimes (it is just really nice to get in a cold car, start it, have heat in about 4 seconds, and leave right away without having to wait for it to idle for 8 minutes). No more wrong turns now -- you are consuming your Block Heater budget each time you do that. =)