Block heater vs. Coolant heater

[Greybrick]

An interesting thread on immersion block heaters vs. circulating coolant heaters and some considerations for getting ecu controled engines to optimum operating temperature and thereby optimum FE quicker;

http://forums.beyond.ca/showthread/t-99149.html

http://www.zerostart.com/

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[Snax]

I actually read that entire thing before I bought my tank style heater. Unfortunately there are still a couple of misconceptions left untouched in that thread:

1) Most engine blocks are setup with a closed coolant loop that is not obstructed by the thermostat. The coolant has to circulate when the engine is running, so this is where it does it when it's cold. Tank style heaters MUST be installed inside that loop to work effectively. Installing them where the heated coolant can travel through the radiator is just a waste of energy.

2) Tank style heaters don't heat the oil directly, HOWEVER, they do heat the coolant inside the coolant loop, the block, and anything else in direct contact with it. In other words, oil still in the head, on the cams, surrounding bearings, etc. is heated as well. In addition to that, the embodied heat energy stored in the block and coolant is rapidly transferred to the cooler oil circulated from the pan. So it may not be hot when it enters the pickup, but by the time it passes the pump, it's already picking up heat and is up to full operating temperature very quickly.

[GasSavers_TomO]

Originally Posted by Snax

1) Most engine blocks are setup with a closed coolant loop that is not obstructed by the thermostat. The coolant has to circulate when the engine is running, so this is where it does it when it's cold. Tank style heaters MUST be installed inside that loop to work effectively. Installing them where the heated coolant can travel through the radiator is just a waste of energy.

This is why I couldn't use a tank style or hose type heater in my VX.

Originally Posted by Snax

2) Tank style heaters don't heat the oil directly, HOWEVER, they do heat the coolant inside the coolant loop, the block, and anything else in direct contact with it. In other words, oil still in the head, on the cams, surrounding bearings, etc. is heated as well. In addition to that, the embodied heat energy stored in the block and coolant is rapidly transferred to the cooler oil circulated from the pan. So it may not be hot when it enters the pickup, but by the time it passes the pump, it's already picking up heat and is up to full operating temperature very quickly.

And this is part of the reason that having a block heater on a VX is a good thing. All VXs have an oil warmer setup connected to the oil filter. The warmed coolant is circulated around the oil that is going into and out of the oil filter once the motor is running, thus warming the oil very quickly.

The VX motor (as well as other Honda motors) has a valley that runs the length of the cam and allows oil to pool there after engine shut down. This keeps the cams sitting in oil so that there is lubrication as soon as the cam rotates on startup. That oil is heated as a byproduct of the block heater as well.

Another benefit of the Honda block heater is the fact that the aluminum block will transfer some heat to the aluminum transaxle casing and slightly warm up the transaxle lubrication.

[Snax]

Part of the problem with the tank style is just finding where to tap into the block to complete the coolant loop. On some motors it's pretty obvious. On my Tercel, it took awhile before I found the block drain plug on the opposite side of the motor from the rest of the hoses. Fortunately the threaded fitting provided in the kit was the correct size, although I did have to go purchase 3 feet of heater hose to wrap back around the block.

Using the heater return line and the coolant drain tap, there is really only a 6" difference in height between the two. I was able to create the needed vertical rise by lowering the tank another 6" below that. Figuring out how to mount it at that height was the next challenge.

In short, I'd say block warmers are slower and less expensive. The up side is that they are dirt simple to install.

Tank heaters come in higher power ratings and can heat up the coolant and block much more quickly, but they cost more and require considerably more effort and planning to install correctly. Used on a timer, they are also more energy efficient than leaving a lower power heater plugged in all day/night.

[8307c4]

What we need is a study of the cost of Kwh used vs. fuel saved.
For this to work we have to know:

- How much are we paying per kwh.
- How long the heater stays plugged in, per day.
- How many minutes it saves in warm-up time vs. unheated.

I'll throw in the heater for free thou I am sure they don't last forever, but...

Most cars today heat up real quick, so if it saves 5 minutes of time then assume we get 35mpg vs. 26 for 5 minutes at 60mph only saves us like a mile or two on that one gallon...
Remember it only saves fuel for those few minutes it saves vs. unheated.
Ok, one could say it saves all along but it doesn't save ALL of it either.

Assuming we do this every day for 30 days straight.
At 60mph it takes 30 minutes to cover 30 miles...
So in 5 minutes we cover 5 miles at 35mpg vs. 26, uhm...
1/5th of a gallon one way, 1/7th the other, what this mean...
Consumes 128 / 5 = 25.6 ounces unheated vs. 128 / 7 = 18.3 ounces heated.
25.6 - 18.3 = 7.3
Geez, 7.3 ounces a day hardly adds up to 220 ounces a month, ok, saved 2 gallons.

I don't doubt that this might increase the figure on the gauge but dang if we do this every day for a month then figured out a different way we save 30 days x 2 miles = 60 miles again 2 gallons x $3 = 6 dollars saved.
But if the heater consumes 500 watts (it's per hour) that comes out to 1/2 kwh and say one kwh costs 11 cents and we leave it plugged in 8 hours a day then (8 x 1/2 x .11) we are also paying 44 cents a day for the electric x 30 days = $13.20...

Maybe, just maybe it saves 10 minutes, at which point in time it evens out but I question if 500 watts is enough for that, and I know it ain't nowhere near enough to cut warm up time completely, not even close.

Oh, and you have to leave it plugged in overnight, soon as you get home before the engine even cools off you plug it in, because I also know for a fact if you don't do this it never warms up anything.

So it just doesn't add up in my book.

[GasSavers_TomO]

Originally Posted by 8307c4

What we need is a study of the cost of Kwh used vs. fuel saved.
For this to work we have to know:

- How much are we paying per kwh.
- How long the heater stays plugged in, per day.
- How many minutes it saves in warm-up time vs. unheated.

I'll throw in the heater for free thou I am sure they don't last forever, but...

Oh, and you have to leave it plugged in overnight, soon as you get home before the engine even cools off you plug it in, because I also know for a fact if you don't do this it never warms up anything.

So it just doesn't add up in my book.

Checkout my post on the block heater installation HERE

It pays for itself in 13 weeks for me as well as giving me the creature comfort of heat in one minute by only having the heater on for two hours before the morning start and the afternoon start.

[Greybrick]

Originally Posted by TomO

Checkout my post on the block heater installation HERE

It pays for itself in 13 weeks for me as well as giving me the creature comfort of heat in one minute by only having the heater on for two hours before the morning start and the afternoon start.

Aside from the obvious immediate FE improvement there would be some additional unaccountable benefits as well I think, ie: the engine starting warmer should make for less fuel byproduct contamination of the oil leading to less engine wear, optimum oil circulation and pressure is achieved quicker thereby minimizing engine wear, less amps needed to start a warm engine thereby the alternator not having to work as long to recharge the battery after engine start, and probably a few others.

[brucepick]

Thanks Snax, for the idea re. the drain fitting as a connection point. I've been contemplating a tank or block heater and access is a concern. The block drain might help in my case.

[Snax]

Originally Posted by 8307c4

What we need is a study of the cost of Kwh used vs. fuel saved.
For this to work we have to know:

- How much are we paying per kwh.
- How long the heater stays plugged in, per day.
- How many minutes it saves in warm-up time vs. unheated.

I'll throw in the heater for free thou I am sure they don't last forever, but...

Most cars today heat up real quick, so if it saves 5 minutes of time then assume we get 35mpg vs. 26 for 5 minutes at 60mph only saves us like a mile or two on that one gallon...
Remember it only saves fuel for those few minutes it saves vs. unheated.
Ok, one could say it saves all along but it doesn't save ALL of it either.

I think that's a very valid point, however those who make shorter trips stand to benefit more by it on a percentage basis. My commute is about 8 minutes, which isn't enough to get useable heat until I am at least 3/4 the way there - if the guage even moves at all.

. . . So it just doesn't add up in my book.

I agree that a lower power heater makes less sense from a money standpoint.

[GasSavers_bobski]

Originally Posted by Snax

1) Most engine blocks are setup with a closed coolant loop that is not obstructed by the thermostat. The coolant has to circulate when the engine is running, so this is where it does it when it's cold. Tank style heaters MUST be installed inside that loop to work effectively. Installing them where the heated coolant can travel through the radiator is just a waste of energy.

Originally Posted by TomO

This is why I couldn't use a tank style or hose type heater in my VX.

TomO... On the back of the block, there's a large U shaped bypass hose that goes from the intake manifold flange down to the thermostat housing. It allows coolant to run from the head down to the engine side of the thermostat (the water pump intake). A tank or hose type heater could be installed there and only circulate coolant through the block.