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Block heater on a timer?

P

Paul Shuler

Member
I drive an 08 duramax. In the past when it gets down below about 10 degrees I will wake up around 3:00 AM and go out and plug it in so that when I go to work at 5:45 AM it is ready to go. Getting tired of going out in my boots and skivvies at 3:00AM. I have found a timer that plugs directly into the outlet I would like to use. My question is the it is labeled with a max of 15 amps. Will my block heater draw more than that or can I get away with it and stay in my warm bed?
 
If it is one of the little ones that has the round dial with the buttons you push to set the time, it will not last very long.

Here is something to think about. The electric to run you block heater for an entire month, 24/7, is around $30.

So just plug it in before you go to bed and forget it. Your truck will like it better anyway. A few hours will just get it barely warm. Most newer truck do not have a very high wattage heater on them.

There has been three barns burnt to the ground around me here with timers being found to have caused the fires.
 
We've been putting block heaters on timers for close to 30 years. We've always used the heavy-duty outdoor rated timers.

Generally speaking 110V outlets are on 15 Amp circuits, so if it draws more than 15 Amps, you should be popping the breaker/fuse.

You can get a Kill-A-Watt meter to find out for sure how many Amps it draws, but it should be well under 15 Amps. Does the owner's manual say how many Watts the block heater is rated at?
 
A thought. My high school senior son finally convinced me to installl a remote-starter on the pickup. I did not want to, thought it wsa a real waste of money, but after a year or so I did it.
I used to complain to him, warm that thing up!! Donn't just jump in and go!!
Now he does, he warms it up 5 or 10 minutes, defrosts the windshield before he even gets in, he can see good. I believe it's much safer. He's convinced me. I think it was a good thing.
 
Like JD Seller says the cost to run the heater isn't that much. I keep my service truck plugged in from the time I get home each evening until the time I leave the next morning, and honestly can't tell the difference on my power bill..........but it sure makes a difference when starting it in the cold.
 
When my diesel was a daily driver I used a timer regularly. No problems. Set two or three hours before I needed it to start. They run approximately 450 watts so a 15 amp timer should be fine.
 
I would also plug it in all the time, especially in real cold weather. We do that with one tractor on the farm so if the electricity goes out, the tractor is warm and will start to run the generator.
 
A remote starter does you no good if the truck won't start. Diesels start so much better/easier/smoother with a couple hours' of block heater time.
 
He needs the heater to warm up the engine enough to start. Diesels can be very resistant to starting in low temps.
 
Paul,
It would be very easy to use a small timer to power a relay that in turn would turn on your heater. I made one like that for my mom's electric wheel chair. It would charge for 30 minutes a day.

Or I have 2 old paragon timers that is heavy enough to do the trick.

So, if yours don't work, there are other timers you can use.
 


When I had my own truck and came home for the weekend, I'd plug it in when I got home, and unplug it before I started it to leave. I think it's a whole bunch easier on the the motor and don't raise the bill much.
 
There really should not be any reason to guess on this. The owner's manual or dealer should be able to tell you the wattage on the heater to in turn tell you the amps based on a 115 or 120 voltage. For that matter maybe they know what the outlet needs to be eliminating doing the math. Back when dad had the dairy he had the one tractor plugged in on a timer that was commercial rated. Not something flimsy such as what you would plug the living room light or porch light to scare the thieves away.
 
Like JD Seller said, plug it in when you get home and leave it plugged in.
A few dollars of power in the winter provides good piece of mind knowing you have a vehicle that will start right up when you need it.
An emergecy trip to the hospital in the middle of the night, a friend or family needing help in the wee hours of the morning etc.
A power failure ten minutes after you plugged your truck in could really mess up your day as well.
You plug it in because you know how hard it is on your truck trying to start it cold so why skimp trying to save a couple of dollars on power, consider how much better your truck starts warm vs cold and think of how much longer your pricey duramax starter will last.
 
If you want to get fancy, you could call in an electrician, have them add circuit that has a thermostat that closes on a fall in temperature. So you plug in, regardless of the winter temp, if it gets cold enough and meets the predetermined set point, the block heater comes on and stays on until you unplug it. If the temp doesn't get low enough, the heater stays off.

Heat on demand, no timer involved.

Good luck,
Bill
 
Bill, that might work in VA, but it wouldn't do much good up here on the tundra, where it doesn't get above freezing for months at a time!
 
There's no reason you can't do that, it's VERY common around here.

There's no reason to worry if a timer will handle the load, as there are all sorts of heavy-duty outdoor timers on the market.
 
I'm with the plug it in when you park it and pay the electric bill.
Harsh weather, AC power is never a given.
might be out for a minute or a week......
I do the same with my gas truck with a battery tender (I don't drive much)
park it and plug in the tender (I use a cigarette lighter adapter so I don't have to bust ice off the hood every time.)
Is it a pain? sure, but when I need my truck, I need it now..

Don't want to? ok, in your situation, I'd run a circuit with a light switch in the line next to my bed. 3am, flip the switch, go back to sleep.
 
I did the same thing with my power stroke put it on a timer to set three hours before I to use the truck,never had any problems with it but when the power went out it would throw the timer off. This is what I used. Says 10 amp on the back.
a178477.jpg
 
The few days it actually got that cold here, I never had any problems with my 08 starting. Are you plugging it in just to have heat faster, or is there something wrong with yours that requires it to be plugged in? Ive heard of guys up in really cold country not ever using a block heater to start theirs, but rather to have heat faster.
 
No it starts just fine. The batteries are the original so I know I am on borrowed time on those. It just seems to start and run so much better when it’s been plugged in. I replaced all my glow plugs this fall. Had three that had gone bad. To be honest back around Christmas time someone here on the board posted a video done in Canada I think showing how different oils flowed on cold start ups. It was kind of an eye opener. The truck other than my house is the most expensive thing I have ever purchased. Maybe I am babying it but I may never be able to purchase another one like it in my life time. Want this one to last.
 
I bought a heavy duty timer for the heater on my 97 F350 7.3 diesel several years ago. Its set to come on 4 hrs before I need to leave for work. Have the timer and outlet wrapped in plastic for extra safety from moisture. Never had any problems. You do have to reset the timer if the power goes off.

While it doesn't get bitterly cold in Dallas,it still makes a big difference in how the truck starts.

You are flat out of your mind if you think I'm getting up at 3 or any time at night in cold weather to plug in the block heater on my truck!!
 
I used one just like this also if power did go off for a few minutes was just that much behind. I just set it for 2 hrs also. Timer Over 10 yes old. Vic
 
Forgot to mention - timer is plugged into the outlet, then heavy duty outdoor ext cord into the timer. Timer, outlet and where ext cord is plugged in to the timer are sealed with plastic to protect from moisture.

Since the truck sits outside, if its going to be wet, I tuck the heater plug where it plugs into the extension cord into the grill to make sure it doesn't get wet.
 
I know exactly what you mean! Mine had everything you could get, except the power adjusting mirrors and factory DVD system. One heck of a truck. Long story, but I ended up getting it for 23000. Original sticker was 54000 and change I think. Wish I still had it, got better mileage than this 2013 gasser, not by much, but it was better.
 
The block heater on GM trucks has an internal temp sensor that does not turn it on until about 0 degrees F. They have to do that because of minimum cool down required between shut down and start up based on time and ambient temp in order to run coolant temp sensor monitor for OBDII. Pesky un-intended consequences of emission laws. I know this because I went 3 rounds at the dealer with a Duramax setting false temp sensor codes.
 
I used to heat my powerstroke when I drove it in the winter with a regular timer for a light. Block heater was to pull 1100 watts. Used a regular timer like you would use in your living room that was rated for 1500 watts and never had any issues whatsoever. I would give it 4 hours everynite and what a difference that made. Could not tell any difference between 4 hours or plugging in all night.
 
Keep in mind that most household outlets are fused at 15 amps, also 15 amps x 120 volts = 1800 watts, therefore should not be an issue.

Rich
 
as stated. cord has thermostatic switch for operation below 0F. But its a good idea to have the timer. Get the heavy duty one. you be ok.
 
I have no idea what wattage a Duramax heater is. The GM gasser block heaters draw 400W on the Terrain, Astro and 1500gasser.
Thermostat on the end of the block heater cord was cut off and tossed then replaced with a quality HD U-Ground plug.
I hear people complain about fuel costs then they pickup the remote and start thier vehicle and let it idle 20minutes until it shuts it's self off.
We plug ours in before going to bed. Start them in the morning And by the time the windows have the ice and snow scraped off. The defroster is blowing warm air.
 
I don't have a block heater, remote starter, even an ice scraper. I park in an attached garage, which never gets below 45, push the garage opener and drive out. Usually feel the engine heat in 2 miles.
 
Be kind to your engine and leave the heater plugged in overnight. What you might save in electricity by using a timer will be minor compared to the excess wear to the engine from not being fully heated when you start it.
 
I went through 3 timers like in the picture before just giving up and heating all night. Ran a Val 6 heater on a similar one and it lasted a little over a month. The motors all quit spinning the dial.
Couple hours plugged in and the duramax will be up on the gauge when you start it if it's parked out of the wind.
 
I cut the thermostat off one of mine and one morning
when it was above 0 I got a computer fault. Message
board said engine was overheating. I shut it off and it
wouldn't restart. I had to disconnect the battery to
get the fault reset. I found out what happened on this
site, and I put the thermostat back on the cord.
 

I use a digital timer cord for my 7.3, it has both temperature (turns on at certain time IF too cold) fixed time program and manual override to use as a normal extension cord.

I had mine set to turn on at 3:30 this morning, it's -2 F right now and truck will be good to go when I start it.

I've heard about the duramax having the thermostat in the block heater cord, so with that type of set up, plugging it in before bedtime is likely fine since it won't run unless it wants to.
 
Local school here doesn't have heat in the bus barn. They plug in them into heavy duty timers set for 4 hours before the drivers are supposed to show up.

Bus Mechanic is a friend.

Rick
 
Never had much luck with the cheaper timers. They last a while, but quit. Had a couple on livestock wells (run a while every hour or so, kept mostly ice free in winter where I didn't have an actual waterer or windmill for a while). I use them for the tractors now. The heavy outdoor rated I have seem to last for several years.
 
Do a search for a Dayton timer, metal box and if I remember right it will handle 30 amps. We melted down a few plastic Intermatic's like pictured below. We use this Dayton on a 1500 watt heater on our 4020, close to 10 years and no problems. Farmers used to use these in chicken houses for light timers, had one in our old chicken house. chris
 
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