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

[paulgato]

Great post Piwoslaw. Really impressive stats there. I guess the wide range of temperature rises must be due to wind speed?

I just recently installed a 2kw coolant heater with pump. It's fine, but I was thinking of adding a small pad heater to the oil sump pan to get a more even heat distribution, and because with just the coolant heater my coolant temperature drops immediately by 10 degrees C as soon as I start the engine. I'm assuming this is due to the cold oil hitting the oil cooler (oil/coolant heat exchanger).

But 250w or 125w? I can't decide. Which do you think would be better? I was going to go for a conservative 125w pad heater but perhaps if it is being switched on at the same time as the coolant heater for an hour or less, then a 250w heater might be better. What did you find? Do you find that a 125w heater is about right for you?

I also have a diesel - a 1.9 litre VW TDi - but perhaps you are in an area with colder winters?

[2000mc]

from the kat's heater catalog
USAGE GUIDE
Engine Oil Pan
2-5 quarts 100 WATTS
5-8 quarts 150 WATTS
8-20 quarts 250 WATTS
20-35 quarts 500 WATTS

im guessing their figures are for their protection, but for my 4qt system i played along and only got the 100w. figure i might, sometime ,want to plug in my car, when im not at home/not on a timer.

[paulgato]

Thanks 2000mc. And how do you find the 100w pad heater? Do you find it heats up OK? How long do you have to have it on for to do the job?

I have an onboard battery charger operating overnight anyway so my other option is to have a small (100w?) sump heater and leave that on all night together with the battery charger, but it would use over a kwHr overnight, whereas a 250w heater on for an hour in the morning would use only 0.25kwHr. I don't think there is much point having a pad heater on for more than 4 hours as any heat introduced before that will be gone by morning, but the battery charger needs a full ten hours to do its job, so using a mains timer is tricky unless I have two separate mains supplies into the vehicle, which I don't really want.

[2000mc]

I really couldn't say, I installed my oil pan heater at the same time I installed an oem block heater. Coolant temps pretty much seem to level off around 2hrs at 55-60 degrees F above ambient. I'd say I get about 3/4 the temp change from 1hr

[paulgato]

I really couldn't say, I installed my oil pan heater at the same time I installed an oem block heater. Coolant temps pretty much seem to level off around 2hrs at 55-60 degrees F above ambient. I'd say I get about 3/4 the temp change from 1hr

OK, so about 30 degrees C temperature rise above ambient. Sounds like you've got about the right amount of heating overall given that you (presumably) have no thermostatic control over it.

You could have a bit more heat, but it's always better to under-specify heating than to over-specify. Thermostats can (and do) fail in the always-on position. If my thermostat fails in the ON position then I've got 1.8kw of heat going on, which is going to start stuff boiling. Probably the only consequent damage would be to the heater element itself, but still... Also, if my pump fails then my 1.8kw heater element will probably burn out within minutes. With your set-up, you're never going to get massive electricity bills and never going to overheat anything or burn anything out, even if you accidentally leave it on for a whole weekend. You might be able to boost the temperature rise you can achieve there by improving the insulation of the engine bay, and by blocking the radiator grille to stop the wind getting in.

But what wattage is your block heater? You've got a 100w sump heater and a ??watt block heater?

[doviatt]

Won't AC circuit timers solve the "what if..." left connected for an entire month scenario?
Worst case, it is on only the entire time the timer is set for on a daily cycle.

[paulgato]

Originally Posted by doviatt

Won't AC circuit timers solve the "what if..." left connected for an entire month scenario?
Worst case, it is on only the entire time the timer is set for on a daily cycle.

Yes, those timers are useful, but with my 1.8kw coolant heater, if my pump fails the heater element is likely to be toast within minutes, and if the thermostat fails it is likely to be toast within a couple of hours. The company who makes these heaters sell far more 3kw units than 2kw units but I wanted a bit of a margin for error!

I'm not complaining, and I like that my more powerful heater can make a useful 40 degree C temp rise in 20 minutes, but keeping the power of these heaters below the level where thermostats and pumps are necessary is quite smart from the KISS and reliability point of view.

[oil pan 4]

Dont waste money, time and energy with small wattage heaters.
A larger heater will get the engine warmer, faster and to a higher temperature.
Smaller heaters just slowly waste energy by bleeding heat off into the surrounding environment, never getting the engine up to a more usable temperature.
If you click on my fast warm up ideas link on the last page I updated the idea with actual tests using a 3700w engine heater setup. That heater set up got the engine warmer, faster and used less energy than a single heater element setup.

[2000mc]

The block heater from saturn is a radiant element that sets against the block, so I don't think it would be near as efficient as one in coolant. I don't know for sure what the wattage is, but I was thinking I'd heard 500w

I would totally agree with oilpan4, I think 4x the heat for a 1/4 of the time would be far better.

If I ever get around to swapping to a manual steering gear, I'll remove my currently disabled power steering pump, which will allow me a great place to add a circulation heater. I don't think I want to go past about 1800w total though, so I can still use a standard 110 outlet

edit: so most ppl on the saturn forums seem to say 300w block heater. considering that, it doesnt sound as inefficient as i was thinking
edit#2: so yea, looks similar to metrompg's bolt on heater which is also 300w. post15- http://ecomodder.com/forum/showthrea....html#post7274

[oil pan 4]

Circulating heaters are nice but you dont have to have one.
I used 3700w to heat a V8 diesel and 2 turbo chargers. The 2 turbo chargers are almost as big as some 3 and 4 cylinder engines. If you put a 1000w and standard 600w heater elements in a 4 cylinder engine block I think you would be doing really well. I bet it would warm up faster than my diesel and its coolant circulating 220volt powered setup.