Block Heater and Exhaust question

basically the cat reacts with the hydrocarbons in the exhaust and that process makes heat. The first few minutes of running are enough to heat the cat and the ICE still isn't fully warmed up. Even with the thremos the ICE still has to run for 3-5 minutes before it'll go into stealth, slightly less time required with the addition of a block heater.

 

Actually, I've been wondering the same thing. I've had the block heater for about one week and we still get 25mpg in our first 5 minutes. One time I coaxed 28mpg in that time. Yesterday, I had the Prius and had the block heater on for 4 hours prior to driving. Same thing, 25mpg. Granted, it's only been about 34'F here the past week, maybe when it's colder, I'll notice the difference more. I've noticed a bigger difference in the block heater in our Sienna, warm air comes out of the vents after 3 minutes.

It's 0230 in the hospital now and I'm heading to the parking lot to plug in the car.

 

In Norway where I live block heaters are quite common, and have been so for years - due to our quite long winter.

The effect of the heater is among other things based on the effect (output/heat) it "passes on" to the ICE. A powerfull heater will be able to rise the block temp. more and faster than a weaker one.

Also many people plug the car in when they park (if an outlet is available), and has an integrated timer in the car that will turn on the heater at the desired time - often also combined with a electric cabin heater, to have the interior pre heated before driving.

 

My wife is from Finland and she really wanted to have them installed. Unfortunately there aren't as many plugs in parking lots here as there are in Finland. She used to pay extra for a parking spot with a plug.

As for a timer, we just use an outdoor timer.

 

I also think Evan is on to a potential problem here. I for the most part get mid to high 30 for the first 5 minute block of time. The first 5 minute block will vary with the type of traffic and route but if your only getting 25 that would almost mimic what the wife's 2k4 gets without a block heater.

 

I often get 25 mpg for first five minutes with or without block heater. For me it all depends on the traffic lights. My total avg mpg for the trip to work over 10 miles, remains about 5 mpg min better with the block heater.

I have over 3 lights to possibly stop at from my house to the highway.
They can easily eat up most of the first 5 minutes.

 

Yes, it works. I check every morning and can feel heat coming from behind the engine.

A little update though...I had plugged in my car at 4am at the hospital today. At 7am I went out and checked under the hood, stone cold. I guess the outlets are off. Anyway, I only got about 12mpg the first 5 minutes. Overall I'm not worried about mileage, just ran some errands after filling the tank and I'm getting 47mpg. So maybe the block heater made a difference.

 

Yes, they have the "GCFI" circuits, I didn't think of hitting reset until after I felt how cold the car is.

As for our morning drive, we have a lot of stops and lights until we get to the highway.

 

OK two of you have plugs where you park and my hospital laughs at me? We have at lest 10 Prii in the lot and there are no plugs. Am I chopped liver? Is my blood not red? What is the problem? My car sits all day and is cold at 5 or 6 or what ever. Is this fair? I need names and numbers!

 

Get a long extension cord!

Another update. I set my timer so that the EBH turns on at 3am instead of 5am, I leave for work at 8am. Today I got about 33mpg in the first 5 minutes. I guess I just have to keep it on longer.

 

Evan:

Don't get me wrong, I firmly believe GFCI's save lives, but they can also be a giant PITA. Especially the cheap ones built into the receptacle will nuisance-trip quite often.

The worst is a damp night, if the outdoor receptacles are run with steel conduit, a lot of moisture can bead up and create just enough of a current path to nuisance-trip the receptacle. In Canada folks ran into that problem around 15 years ago.

I prefer a GFCI breaker in the panelboard but those are way more expensive than the receptacle ones. The incidence of nuisance-tripping is much lower. The best solution is to use a non-metallic conduit, like this one from Anamet.

http://www.anametcanada.com/downloads/NMUA-EF.pdf

It’s liquid-tight and all fittings have built in o-rings. I rarely specify or recommend iron or aluminum conduit anymore, unless in a severe industrial application with high risk of crush or abrasion. I was chasing too many condensation-related issues with iron conduit, even when purging was used.

Another popular option here, and I use it extensively at my hobby farm, is Teck Cable. It’s a jacketed flexible conduit, usually aluminum, with a watertight sleeve.

http://www.crouse- hinds.com/CrouseHinds/InstallationDocs/IF%201417%20Revision%203.pdf

I bet you like that power cord that indicates live plug! Nothing worse than plugging in a car only to discover next morning at -40 the damn receptacle was dead all along and the car now won’t start. Yep, been there and done that.

jay

 

I went without a radiator blocker for 2 tanks then replaced it with a new one (see this post: http://priuschat.com/Radiator-Blocker-Revisited-t14875.html ). All just to convince my self about the difference they make in our mild climate. Shot answer is about 3 mpg improvement, but I have also noted that the car is hotter after the thermos dump. I am talking about the first 2 Min of operation. The temp dips ends up higher then as expected rises higher. I pop the hood to plug in and don't have the plug coming out the grill. I am also putting an old windshield reflective sun shade on top of the engine. I think that both the radiator blocker and the space blanket is interfering with the chimney effect of having the hood slightly open. Something one might wish to consider when deciding where to have you plug.