12v water heater to speed warm up?

[BRoth]

Has any one ever seen a heater that fits on the 5/8 heater hose that uses the trucks 12v system to heat the water up? I know of the 120v systems but the cords aren't long enough when I drive off.

 

[CPFF]

Yer usin der rong kord !! You need the one like the trollys' use - they connect over-head and follow you down the road. #ad
#ad
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CUMMINS POWERED FAST FORD

 

[Bob Wagner]

I sell industrial heaters, if you want I can have one made for you. If its for a BD project I might be able to get you free samples.

 

[ramman]

I would think the current draw and lenght of time to heat the engine would be to much for the batteries,the grid heaters and starter motor will need a large reserve for themselves. JMO

 

[illflem]

I was thinking the same thing,in order to get much heat out of a 12 volt heater it would take everything the alternator could put out.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[HC]

I think the alternator is about 135 amps; X 12 volts (+/-), lets say you keep thirty-five for charging your batteries + other accessories and only let 100 amps go to you "fast heat" circuit. That would give 1200 watts, or about 4100 BTU, about 1/3 of what an Espar heater puts out. It would help some, but, could only be used after you had started the vehicle and only when you knew you were going to run it long enough after the warm-up to recharge the batteries from the grid heater and other drains at start-up. This system might be just what some are looking for, but, it would be considerably less versatile than an Espar or Webasto, which can preheat before you even start the engine.

 

[BRoth]

How fast does a Espar or Webasto heat up the water? If either one was hooked up directly in the heater line with the coolant flowing could you get defrosting heat from the truck heater?

 

[Lug-nut]

The Espar has a small pump which circulates the engine coolant. It also ties into the trucks heater blower to heat up the cab. I usually set mine to come on about an hour before I am going to leave (it comes with a timer) and the windows are always defrosted and the cab is warm. The Espar is pricy, but it is one of the best additions I have made to my truck. Never have to worry about finding a place to plug in, the oil is warm, and the grid heater doesn't even cycle prior to startup.

 

[HC]

How fast does a Espar or Webasto heat up the water? If either one was hooked up directly in the heater line with the coolant flowing could you get defrosting heat from the truck heater?

Yes, they are hooked up so that you get the defrost going even before the truck is started. I don't know exactly how fast they heat, but, I can make an educated guess: Since the Espar is ~15,000 BTU/hr input, If I assume 65% efficiency then it should be able to raise the temperature of 6 gallons of water/coolant by ~3. 4 degrees per minute when first started. However, the rate of rise would slow considerably as heat goes out of the water and into the block and your cab, so a more realistic number is probably 2 degrees per minute.
That doesn't sound like much, until you consider that the block heater is only 700 watts or so, which translates to less than 2400 BTU/hr. This is why in really cold weather, the block heater is probably best plugged in all night, but you could start up the Espar 1 hour before planned departure and you'd be in great shape by the time you were ready to leave.

 

[BRoth]

Humm, ok couple of questions, the rough cost of a Espar and what about calculating the effect of a 4000 btu heater after the truck has been running for about 1/2 min.

 

[HC]

Humm, ok couple of questions, the rough cost of a Espar and what about calculating the effect of a 4000 btu heater after the truck has been running for about 1/2 min.

Short answer: A 4000 Btu heater will only help the warming process by ~1 degree per minute. You probably won't be able to tell the difference in warmup time with or without a heater of this size.

Warning: LONG ANSWER FOLLOWS!

OK, it's snowing here, so I've had some fun playing around with the numbers and researching this. There are several big unknowns built in to the calculations, so don't take the exact numbers as gospel. And go grab yourself a cup of coffee before reading on. #ad


A 4000 BTU heater would raise the temperature of 6 gallons of water by about 1. 4 degrees per minute. But don't forget, we're also trying to raise the engine temperature, so that is ~930 pounds of cast iron that also needs to be heated up. Practically speaking, I don't think you would be able to tell the difference in heat-up times with or without the 12 volt "booster" in the water system. The booster would help some in maintaining temperature, at idle, once you were warmed up, I just don't think it would shorten the warm-up time by much.
Basically, we're trying to heat up three things here: the coolant in the system, the iron in the engine block, and the air in the cab. The net output of the Espar is about 10,000 Btu/hour. Here's how much 10,000 Btu would heat up each of these items, if all of the heat could be transferred to just one of the three (technically not possible):
6 gallons water, ~48 pounds, 208 degrees
4200 cubic feet of air, ~336 pounds, 124 deg.
1 engine block, ~932 pounds, 97 degrees
I chose 4200 cf air because that is my guess as to what the blower puts out in an hour, if it runs at 70 cfm on the low setting.

I tried to research the VW system TowPro mentioned, but found only information about 120 volt block heaters. His wife’s Jetta may just warm up faster because it is so much smaller, thus much less mass to heat. But since it warms in only 0. 2 miles, let’s assume for the sake of argument that there really is a 12 volt aux heater. If the system used a grid heater in the car's HVAC system that warms the air going through the heater core, but not the water, then the heat would come up much quicker. Next, assume the vent control is set to "recirc". Now, instead of trying to heat a massive block of iron + the coolant + 4200 cubic feet of air, we're only trying to heat ~87 cubic feet of air, the amount of air in a jetta. With 50 amps (the Jetta alternator puts out 70 total), we could get about 2050 Btu/hr, which would heat the air at about 20 degrees per minute. Doesn't sound like much, but from a 20 degree start it means in 3 minutes your heater is blowing 80 degree air, which would feel warm in comparison to the 20 degrees. This is all pure speculation on my part; we need to get TowPro to find a wiring diagram for that Jetta and see what's really going on. My best guess is that the Internet talk was just some folks who don't know much about cars confusing the 120V block heater with something else. The 120 volt heater looks like what TowPro heard described; see http://www.vwofnewport.com/accessories/jetta/blockheater.htm

The bottom line is that there is a lot of energy (BTU's) in a gallon of diesel fuel; that's why a gallon of the stuff can move a big truck 15 to 20 miles down the road. 50 Hp, a light load, is equivalent to 127,000 Btu/hr, and remember that more than 50% of the diesel burned goes out as “waste heat”, so you can figure at light load your engine is putting out well over 150,000 Btu/hr of waste heat, and this is why it can heat up in “only” 5 minutes once you start driving it. So, there are two keys to why the ESPAR and Webasto work so well:
1) They burn diesel, releasing lots of BTU's
2) We give them a "head start" on the warm up by starting the heater an hour or more before our planned departure. Even if they only heat up at ~2 degrees per minute, an hour of that makes a huge difference. Heck, if it is not but 32 degrees outside, even 15 to 20 minutes would make a difference.

So, what's your goal? If you want to warm your block faster to reduce engine strain, plus defrost your cab, then you need to go with the diesel heater. Get the remote so you can start it from inside your house. If you are just trying to get some in-cab comfort sooner, you might get there with a 12 volt heater, provided you can find one that recirculates the cabin air. I think the performance is going to leave you wanting more, but the cost is only $100 so you could try it without breaking the bank. One I found was: http://www.skingco.com/convenience/other/2heater.htm#featuresco3000c This shows a 12 volt, 25 amp “back seat heater”, for $100. They claim 1100 Btu/hr; if it works you could install 2 and use 50 amps.

Bear in mind that a 75 watt light bulb puts out ~250 Btu/hr, so that 1100 Btu/hr heater is like having four 75 watt bulbs in your cab. Its heat, but not that much heat. Even with two of these I think you are going to be disappointed. But, if you get bored some cold afternoon, find a cheap hair dryer that only puts out 750 watts, or a space heater that has a "low" setting in that range, and see if the rate of heat-up makes you happy or not. You could do this experiment almost for free, just don't electrocute yourself in the process with three or four extension cords all plugged in to each other! #ad


Cost of the Espar is ~1200 if you install it yourself, although there was a group purchase previously at ~900 so we might see that number again sometime. The Webasto group purchase price is well under 1000. The Webasto has more power (17,200 input vs. 13,700 for Espar D4) but the kit is "generic" versus set up specifically for the Dodge, so you'll need to be a slightly better shade-tree mechanic if doing it yourself. Most people have reported the better part of a day spent installing these kits.

I don't have one of these heaters yet, but I think it is going to be one of those things that once you have it, you don't know how you ever lived without it.

 

[BRoth]

HC That was great reading, well done! I am glad it is snowing in your area. We have rain here with a 5c temp.

Knowledge is a great thing indeed.

As you mentioned one can't appreciate the comfort of instant heat untill you have it.

Have a great 2001 may it be full of questions and answers, health and happiness.

signing off for the year.

Brian@bd-power

 

[illflem]

HC,how many btus does the 700w block heater put out?Reason I ask is that I've been toying with the idea of building 110 volt version of the Espar,but using the block heater for the heat source. If the block heater isn't enough I have a source for a 1500w canister type block heater for $49. My shop is heated by hot water circulated though hose running though the concrete,the circulator pump went out after 25 years this fall,the 5gpm 1/25 hp replacement pump was $70. Couple these together with a cheap 12 volt battery charger to keep your batteries from going dead while running the blower motor and I think I guy could make 110 volt block/cab heater that would cost around $150,and be about the size of a shoebox. I think it would really heat the cab,maybe even too much,if that's possible when it's zero out. It may even be possible to do it without a pump,since the block heat is low in the water jacket the hot water probably circulates through the heater core by convection and would do so even more with the blower motor running.

 

[Sandmann]

For those interested.
amps x volts = watts
1 kilowatt( 1000 watts)= 3412 btu's


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Ordered on 2/7 in my driveway on 3/24 2001 2500 SLT+ 4X4 Auto Cummins, 3. 54,Quad cab,Short Bed,Camel Leather, White Exterior, Sliding rear window, Camper Special Group, Towing Group,A. R. E cap with rear door, 25'Dutchman camper

 

[HC]

HC,how many btus does the 700w block heater put out?
If the block heater isn't enough I have a source for a 1500w canister type block heater for $49.

illflem,
I think you could make something like that work pretty well. The 700 watts is about 2400 Btu/hr equivalent, 1500 watts would give you 5100 Btu/hr equivalent. True, an Espar has ~10,000 Btu/hr output, but, it is capable of heating the truck from "dead cold" in only an hour, or two at most. Your system could be turned on sooner, thus doesn't have to put out as many peak Btu's. If you ran at 1500 watts for 4 hours, and if electricity costs $0. 10 per kw-hr in your area, then your system would cost only $0. 60 per day to run.
My guess is that the circulating pump you describe would make it work much better; you wouldn't end up overheating a hose close to the heater or locally boiling the coolant.

The beauty of the Espar is that it frees you from the need for a 120 volt power source, but if you always have power [no icestorms #ad
], then your system would work great!

 

[HC]

Sandmann,

Stop it! You're giving away my secrets! #ad

 

[HC]

HC... I am glad it is snowing in your area. We have rain here with a 5c temp.

This ain't right! Our Canadian friend has +5c and rain, I'm in the Southern U. S. and I get -5c and snow! [the good news is, now I don't feel so guilty for wanting an Espar #ad
]

Until next year... [of course, that's only a couple of hours away]

 

[TowPro]

From what I understand, My Wifes VW Jetta Diesel (98 TDI) has a system where there is a unit that looks like a glow plug in the water jacket. After starting the car, if you put the heater onto full hot, this water heater comes on and assists the engine in a faster heatup. I know she can have heat out the ducts in about 2 tenths miles where my Cummins takes about 5 miles. I have never had to look under the VW hood for anything other then oil changes so I am not sure how the setup works (or if its even there, I read this info on the internet, and we all know how truthfull things can be there)
TowPro

Originally posted by BRoth:
Has any one ever seen a heater that fits on the 5/8 heater hose that uses the trucks 12v system to heat the water up? I know of the 120v systems but the cords aren't long enough when I drive off.

 

[TowPro]

HC: I checked into the TDI and the Glow Plugs in the Cooling system. Its true. There are 3. The ECU can turn on 1, 2 or all 3 at the same time. It uses coolant temp, as well as the air temp setting on the dash to decide how many to use. They don't work above 43 deg, and will shut off over 2400 RPM. There are 2 reasons for this. Faster warmup for Emissions, and faster Heat in the cab. VW has done many thing to this diesel to make it more "amercian" frendly. (they know amercians hate diesels). Things like when you get in the car and close the door, the glow plug cycle starts, and is over by the time you put the key in the ignition (in most cases, still don't think I have had to wait more then 5 sec. ) http://forums. tdiclub.com/NonCGI/Forum3/HTML/000447.html

Everyone Else. Why not just put a electric space heater in the cab. Tractor Supply sells one they call a "stock heater" or something like that that has a fan and thermostat on it. You could even wire it so when you plug in the block heater, the electric space heater comes on. Even one of those little block "catalist" electic heaters would work. the only problem would be staying warm from the time you unplug the heater, until your truck heated up.

[This message has been edited by TowPro (edited 01-01-2001). ]

 

[HC]

TowPro,
Good Link! It led me to two others, which in turn gave me more data to play with. http://forums. tdiclub.com/NonCGI/Forum3/HTML/003856.html gives a good discussion about this electrical heat “booster” system, and http://root.moose.ca/~zukinugen/FAQ17.html
has a good discussion on “Why are diesels so slow to warm up?”

All of this of course has me scratching my head, trying to figure why VW can make this work when I’m still skeptical that it could be very effective on our Cummins. So, I ran through my calculations again, to see what I would find with a “VW sized” engine. I believe the smaller the engine, the better a system like this would work. Assuming the 3 plugs are 15 amps, slightly bigger than the VW “fast glow” starting glowplugs, would give 540 watts (1840 Btu/hr) when all three plugs were on. The VW probably has a 2 gallon cooling capacity (vs our 6), and probably one gallon of that is in the radiator and does not have to be heated. These plugs could heat one gallon of water by 10 degrees in only 4 minutes.
The VW block weighs about 300# (vs. our 930#), that much heat would raise the block temperature only 1 degree per minute. One of the links runs through a sample calculation for the amount of waste heat produced by the VW engine in typical city driving, and comes up with 9000 watts (30,700 Btu/hr).

This means that if you drive the vehicle to warm it, 6% of the heat would come from these plugs, the other 94% is still coming from engine waste heat. The percentage would go up, if we figure that that 6% worth of energy has to be created by making the engine work harder via the alternator load, probably doubling the effect to be the same as having ~4000 Btu of heat - this would be almost the size of a typical room space heater.

I still think this system could only speed up the warm up by about 10%, but you have convinced me that it would be very effective at preventing the engine from cooling off during idle, the way diesels like to do. The next time I’m stuck in traffic, I’m going to tun on every electrical accessory I have, just to load the engine that little bit. TowPro, thanks for expanding my knowledge base!




[This message has been edited by HC (edited 01-01-2001). ]