Mini experiments: 300w vs. 800w block heater warm up time

[canhonkey]

Originally Posted by Ecodriver

Any idea where to buy one of these inline circulating tank heaters for a 1990 Geo Metro? 5-speed 1.0l if it matters. thanks.

Try here, they ship to US and Canada via USPS:

http://http://www.warehouseautoparts...ank_heater.htm

There's 6.4 Qts of coolant according to my manual in a 1.0 Firefly/Metro/Swift so a 500W tank heater would do the trick. 850W is prob over kill..

Amazon also sells em. I went to Canadian tire and their cheapest Tank circulating heater was 75$ before tax. So I'm just going to order one too.

[Billyk]

I have a Ford Escape Hybrid with an engine block heater. If the vehicle is left outdoors in the dead of winter-subzero temperatures, 75 mintues will not be long enough to raise the coolant/block to normal temperatures created by use of the engine block heater. My engine block heater uses around 430 watts and...I have a connection to the hybrid battery heater. Pre-heating this item prior to your AM start is extremely important and allows one to get into electric mode like one mile into their journey even when the outside air temperature is at or below zero. One also need to consider a front grille block to preserve the heat gain in the engine block area.

[Piwoslaw]

With my 550W coolant heater installed and winter approaching I thought I'd do a test similar to MetroMPG's. I plan to test warm-up times both for the heater, and for idling (starting with cold engine) to see the difference. Yes, it's a waste of fuel (and a source of pollution), but it is in the name of scientific research. Plus I'll do it before a planned drive, so that should partially offset any bad side effects. If I install an oil pan heater, then I'll also test it with and without the coolant heater.

I would like my results to be comparable with MetroMPG's, but before I start I'd like to know if I should pay attention to anything else. Wishlist, anyone?

In his tests MetroMPG idled for 30 seconds every 15 minutes to pump the coolant throught the block, but it turned out that even that added enough energy to skew the results towards the end of the test (and maybe in the beginning too, but that's hard to quantify without an electric water pump). So, maybe I should idle for only 15 or 20 seconds to reduce the effect of combustion heat? But is that enough to thoroughly mix the coolant inside the engine?

[Piwoslaw]

I did the test today. It was around 0°C (32°F) this morning when I started, light drizzle. I idled for 30 seconds every 15 minutes, recording the coolant temperature on the ScanGauge when starting and when stopping the engine. I noticed that right after starting the engine the 'old' (when the engine was previously stopped) temperature showed for 5-10s before it was updated. I also recorded the total energy used by the heater.

During the test the grilles were blocked, but I removed my thermal insulation. I replaced it after 2:30h, so the last 30 minutes of the test were with the insulation.

time	coolant temperature - start (°C)	coolant temperature - 30s later (°C)	total energy used (kWh)
0:00	1	1	0.00
0:15	1	9	0.15
0:30	10	17	0.27
0:45	18	23	0.40
1:00	23	27	0.54
1:15	25	31	0.67
1:30	28	33	0.81
1:45	31	35	0.93
2:00	33	37	1.07
2:15	35	39	1.20
2:30	36	40	1.33
2:45	38	42	1.49
3:00	39	42	1.60

[MetroMPG]

Good experiment.

Did you discover anything that'll change how you use your coolant heater?

[Piwoslaw]

Originally Posted by MetroMPG

Did you discover anything that'll change how you use your coolant heater?

Not really anything I didn't already know from your experiments, but I do have hard numbers for my engine that I can crunch. I'll have to sit down and use my fingers and toes to count a few things once I do an idling warm-up test.

It may seem that plugging in isn't worth while past 90 minutes, but the truth may be different: Short durations of heating only warm up the coolant, but the more time that goes by, the more heat is soaked up by the engine block. So even though the coolant's temperature isn't rising as fast, there is still heat being accumulated in the engine. Of course, once the block gets warm it starts to radiate more heat, and an aluminum block is probably better at radiating than at accumulating, so for now I'll work on better thermal insulation.

I also learned that going outside to the car every 15 minutes is not compatible with doing lots of other things at home at the same time (cooking, baking, cleaning, etc.). Thankfully I'll only have to do this one more time (when I get a heating pad installed).

[MetroMPG]

car every 15 minutes is not compatible with doing lots of other things at home

Ha! I forgot about that. It was a big time-waster. (I mean, not counting the gains in the name of science!)

[slogfilet]

I'm wondering if another experiment might be needed...

When we start the car every 15 minutes to check temperature, we're likely lowering the coolant temperature in the vicinity of the heater. This will improve the thermal transfer by increasing the temperature difference between the heater and the coolant surrounding it.

How much does convection/conduction mitigate this? I have no clue.

In actual usage, I turn on my block heater and only crank the engine after 1-2 hours (when I'm ready to go to work.) In theory, would less heat have been transferred to my coolant than if I had cranked the engine every 15 minutes?

As someone mentioned earlier, the intermittent idling will also contribute some amount to heating the coolant.

To redo this experiment would require several nights with consistent outdoor temperature:

Day 1: run heater for 15 minutes, crank engine to mix coolant, check temp.
Day 2: run heater for 30 minutes, crank engine to mix coolant, check temp.
Day 3: run heater for 45 minutes, crank engine to mix coolant, check temp.
...
...
Day X: run heater for 15*X minutes, minutes, crank engine to mix coolant, check temp.

Maybe This is something I can try soon! =)

[ConnClark]

My car came with a 400 Watt true block heater from the factory. The elements are right in the block underneath the head. I find that just 15 minutes of use makes all the difference in the world as far as getting the thing started. I get no white smoke from incomplete diesel combustion and the starter spins the crank much faster. If I leave it on for 30 to 45 minutes I get heat out of my heater a lot quicker. I might mention that I have a 3.0L diesel with a cast iron block and head.

I guess this shows what putting the heat where it matters most can do.

[Piwoslaw]

Originally Posted by slogfilet

I'm wondering if another experiment might be needed...

To redo this experiment would require several nights with consistent outdoor temperature:

Day 1: run heater for 15 minutes, crank engine to mix coolant, check temp.
Day 2: run heater for 30 minutes, crank engine to mix coolant, check temp.
Day 3: run heater for 45 minutes, crank engine to mix coolant, check temp.
...
...
Day X: run heater for 15*X minutes, minutes, crank engine to mix coolant, check temp.

That's a good idea! I've been making a mental note of outdoor temperature, heating time and coolant temperature, but my mental notepad got a memory overflow error (I've got the old model with only a few bytes of memory). I should make a habit of writing it all down in my trip log.

Originally Posted by ConnClark

My car came with a 400 Watt true block heater from the factory. The elements are right in the block underneath the head. I find that just 15 minutes of use makes all the difference in the world as far as getting the thing started. I get no white smoke from incomplete diesel combustion and the starter spins the crank much faster.

Looks like you've got a big ol' AC powered glow plug. :jealous: