Block heater Questions

[slowbird]

I tried searching. Not too many people have had discussions about the Block Heater.

Anyways, I bought an outdoor extension cord. I was thinking about plugging in the block heater when it starts getting real cold out.
My questions:

- Can I just plug the car in before I go to Bed or should I put it on a timer?

- Has there been any know issues with using the block heater, or any suspicions about the block heater causing problems.

- Should I even bother?

Almos tevery car I've owned has had a Block Heater...though I've never used one. This is my second winter with the Grand Am...I though maybe I'd give the car some easier starts.

[bballr4567]

As most people have said before cold starts are the death of a car. I dont see it being a problem at all.

[SE2000]

I'd only use it when it's going to be real cold overnight. You could put it on a timer to start say at midnight as long as you gave it say 8 hours to work. It's low wattage and since you will be using it when it really cold, it will need time to work.

[slowbird]

If it needs 8 hours than I can always plug it in before Bed...I never go to sleep 8 hrs before I have to get up for work.

[jcasemore]

I would only bother with plugging it in below about -10 to -15 Celsius (about 10 for you guys south of the border).

There are no bad things that can happen (as far as I know) from plugging it in. Just make sure you route the cord somewhere where it's not going to get pinched or hot. I have a different engine so I don't know how yours is routed but I snake mine kind of behind the edge of the headlight between the headlight and the rad somewhere and I ty-rap the plug to the grill where it is kind of out of sight but still accessible. Once summer comes I pull it back out and just coil it and stash it back under the hood.

A timer is definitely the way to go since you only need the block heater on for 3-4 hours to adequately warm the engine up. A timer also saves money. If it's like -40 out it wouldn't hurt to plug it in when you go to bed.

[rixGAphx]

I don't know whether or not the GA's stock block heater is thermostatically-controlled.

Even if it isn't, no timer is strictly necessary; just plug and unplug at your leisure.
Regardless of how many watts the heater draws, the ambient air temperature will prevent the oil (and block) from getting TOO hot.

Even if I used the same heater, here in Phoenix on a JUNE night, the block would only get to about 169*F (65*C) overnight; the ambient overnight low (97*F/25*C!!!) provides a 72*F (40*C) temperature differential.
The heated engine will really heat the engine bay, but will never approach the engine 'design temperature' of 195*F (90*C).

But if the heater is NOT thermostatically-controlled, use a timer if you want to save a few bucks on your power bill.
*Assume* the heater draws 250 w.
250w = 1 kilowatt-hr every 4 hours, = 3kwh per 12-hour overnight period
Say power is about 17 cents US per kwh; that would be (3 x 17) = $0.51US / nite.
= (30 x ~0.50) = $15 per month.
Using a $5 timer to reduce consumption by half, you would be $2 ahead the first month.
$7 / month beer money each additional month of power savings. :chug:

Just the opinion of a cheap old fart from Phoenix :D
-Rick

[SE2000]

Originally posted by slowbird
If it needs 8 hours than I can always plug it in before Bed...I never go to sleep 8 hrs before I have to get up for work.

The hours it needs depends on how cold it gets. Think of it like your interior. It take a lot longer to warm up the interior when it's -20 F than +20F. The timer is so if you get home at 6, you don't have to go outside before you go to bed.
The idea behind the heater is to keep the oil from getting too thick when you start your car, not to have the engine warm enough to throw heat right away. That would only happen if you live in the warm desert

[Crackers]

I also have a car starter... so when I plug in the car at night I only have to give it 0-5 minutes to defrost the windows (instead of double that with no block)..

[gt1ian]

A block heater only needs to be plugged in for 2 hours in won't make engine any warmer if you leave it plugged in for 8,10,or even12 hours. Also anything below -10 oC the vehicle should be plugged in. So I would suggest a timer.

[slowbird]

So I used the block heater...

It was failry cold out last night....I got home at 12:30am....I had everything plugged in by 12:45am.

Left for work at 7am...unplugged the cord, tucked everything back in. Started the car and the temp was a few ticks past the first marker on the temp gauge. (40C/100F)

Doesn't really seem like that big a deal....maybe on really cold days I'll do it again.


Thanks to everyone that put their imput in on this thread. :D

[mattcow]

'gt1ian' is right, you only need about 2 hours to get the oil as warm as it is going to get....after that you are just wasting electricity.
The block heater does make a big difference. Put a little motor oil in a glass jar outside tonight and take a look at it tomorrow morning (if its going to get cold out). Now think of that thick oil trying to pump through a 1/4 inch line in your engine.

[slowbird]

Originally posted by mattcow
'gt1ian' is right, you only need about 2 hours to get the oil as warm as it is going to get....after that you are just wasting electricity.
The block heater does make a big difference. Put a little motor oil in a glass jar outside tonight and take a look at it tomorrow morning (if its going to get cold out). Now think of that thick oil trying to pump through a 1/4 inch line in your engine.

Good advice.

3 Things:

1- Doesn't the block heater on our cars warm up the coolant.
2- Electricity bill is of zero concern to me...as long as leaving the car plugged in won't hurt the car.
3- I use full synthetic oil....it doesn't thicken up as much as regular oil.

[mattcow]

The block heater does warm the coolant which warms the oil....cheaper for GM that way.

The heater will not hurt your car but I've had have the block heater burn out on older cars. Not sure how many hours the heater should usually last.

Synthetic may help but either way your engine will be starved of oil on initial start up. In the first second of start up you engine has rotated at least 20 times with little oil so the sooner the oil gets to the bearings the better.

A lot of drag cars have electric oil pumps which pressurise the system before the engine starts to avoid this.

[slowbird]

Originally posted by mattcow

A lot of drag cars have electric oil pumps which pressurise the system before the engine starts to avoid this.

Yea I've seen those.

Well...I guess it helps on cold nights...as soon as we get more around here I'll start pluggin' her in again.

[SE2000]

The time the heater needs to do the job is dependant on temp. How long the car has been off, if the car is outside and its windy.
If you got home at 5pm and it was -30 with the wind chill, then there would have been a bigger difference at 8am.
I may only see 1 or 2 days a year like that but since I live in the south, your condidtions are more severe. Use it as often as you feel it's worth it.

[rixGAphx]

Global warming is here to stay.

Soon the Canadians will not need block heaters, they'll need summer windshield visors like us Arizonans.

[pokesmot]

just wanted to add;

block heaters draw quite a bit of power. I'm sure there are variations of them, but the one that comes stock with my car draws in and around 5 amps last time a measured it with a clamp meter on a special test cord (your only supposed to clamp the meter around the hot (black or red) wire.

so... 5 amps x 120 volts AC = 600 watts.

my service manual states the block heater is "supposed" to draw 400 watts at 110 volts, but my plugs output 120 VAC.

In a nutshell im guessing the excess current draw is a result of using an extension cord; which almost everyone will have to use combined with their blockheater.

the majority of all circuit breakers in your house are single pole 15 amp circuit breakers... so thats 1/3 of a breakers maximum load rating before it trips.

[jcasemore]

Originally posted by pokesmot

In a nutshell im guessing the excess current draw is a result of using an extension cord; which almost everyone will have to use combined with their blockheater.


The extra current is because of the extra voltage.
Since it is a static load (Not an electric motor) a long extension cord will actually draw less current than a short cord.

On the note of extension cords, make sure to use a good outdoor cord that will not become stiff in the cold. A cheap cord will become stiff and the insulation will crack when you try to bend it.

[mattcow]

Originally posted by jcasemore
The extra current is because of the extra voltage.
Since it is a static load (Not an electric motor) a long extension cord will actually draw less current than a short cord.


I don't know about that one, I'm sure that the same amount of current is going through the heater and the cord. Now as for load (i.e resistance), the length of the cord will definitely increase the load.

[SE2000]

Wattage is current x voltage. One goes up, the other goes down. Extension cords play a roll as resistance and heat up using power. Connectors are another source of resistance. Less connectors and larger wire mean less loss.
If you're measuring 5 amps at the source plug and 4 amps at the load, you are having a big loss along the way.

[jcasemore]

Load and resistance are opposite. As you increase resistance, it decreases load. So, as you increase the length of cord, use a smaller gauge of cord, or have more connections, the resistance will go up which will decrease load and decrease current. (Also decreases heat output of the block heater).

In a series circuit like a block heater, the current must be the same through the entire circuit. What pokesmot was saying is that according to the manual it should draw about 4 amps but is actually drawing 5 amps because he has more voltage than the manual states.