# Most efficient placement of Ceramic Heater



## madderscience (Jun 28, 2008)

Assuming the heater core is under the dash someplace as in most cars, Can you just disconnect the input side of the ducts to where the heater core went and leave them open to the car interior? You could then block off the exterior intake vent, so it will always recirculate? the ceramic core could then go in the old heater core location. 

I did something similar in my MR2. (though I used a toaster instead of a ceramic core)

It would be good to have some kind of forced/heated air directed against the windshield for defrosting.


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## Stunt Driver (May 14, 2009)

THought about that, but not possible in FIero - both core and fan are in front trunk compartment, literally outside of cabin. This makes installation a snap, but no recirculation.

I think i'll go with standard setup, it's not extremely cold here, so should be good.

I wonder what is rated power of standard core? Any one knows?


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## Woodsmith (Jun 5, 2008)

Stunt Driver said:


> I wonder what is rated power of standard core? Any one knows?


I wondered this a little while back and came to the conclusion that a few kW would be about right.

For my heater I am playing around with 1.5kW of cooker ring elements for a dry system and also considering 4.5kW of wet system. Not sure which I will go with yet. The wet has less fire risk, the cooker rings are designed to 'cook' things!


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## Stunt Driver (May 14, 2009)

why not ceramic heater?
And any thoughts on recerculation?


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## Woodsmith (Jun 5, 2008)

Stunt Driver said:


> why not ceramic heater?
> And any thoughts on recerculation?


I'd have to 'buy' a ceramic heater, the cooker rings I have plenty in stock and the water heater is old stock too.

The MR2 has recirculating heat as the ducting from the fan box to the outlets are all under the dash. There is a flap in the fan box that diverts the intake from the outside the inside.

With your set up, where does the fan draw fresh air from? Is there any point in that duct where you could install a branch that will go through the firewall into the cabin?

I am thinking of, perhaps, using large bore waste pipe or workshop dust extraction pipe, a branch or Y piece and a blast gate or two to divert the inlet from outside to inside.


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## Stunt Driver (May 14, 2009)

I didn't dig that far, but fan is almost below the intake - which is in windshield wiper area. Everything is possible, just not sure at what price of labor. SHould be able to get mine installedin a week or two, after done travel, and i'll see if it's enough.
It never really gets below freezing in my area, so it may be ok, but i'll be advising people that donor must have recirculation


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## PhantomPholly (Aug 20, 2008)

Stunt Driver said:


> Looking at ceramic heater now, convincing myself to give up amps for sake of easier use and installation.
> 
> But here is dilema - my Fiero doesn't have air recirculation, so i'd have to heat up outside air pushed to inside car.
> On the other side - I could simply install 1 heater per foot area for drive rand passenger, and use outside air only to clear the windshield when needed. Wouldn't this be more efficient?
> ...


The most efficient placement of ceramic heaters is against the skin, but this is not recommended for a variety of reasons...



Seriously, if you are looking for the least amount of energy use, then you have to consider there are really only two reasons for heat in a car:

1) Keep the windows clear
2) Keep the occupants warm

Clearly the first is solved strictly with a dashboard defroster/fan, ignoring heat to the rest of the car. These are available through trucking magazines for those who work way up north.

For the latter, it could be quite reasonable to wear electric socks connected to car power, an electric blanket or seat warmer on your backside, and warm clothes. My airplane has a truly anemic heater (an 8" muff on the exhaust, not enough to really warm a large volume of air), and I regularly employ the electric socks / warm clothes philosophy when I'm flying at 16,000' and the temperature is 50 degrees colder than on the ground.


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## vpoppv (Jul 27, 2009)

I'm not a spokesperson for Harbor Freight, I swear! But how about one or two of these? They go on sale for $9.99:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96144


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## dtbaker (Jan 5, 2008)

vpoppv said:


> I'm not a spokesperson for Harbor Freight, I swear! But how about one or two of these? They go on sale for $9.99:
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96144



15 amp fuse at 12v tells me these things can't throw much heat!

I finally got my ceramic in-duct heater working at 96v by putting in bigger fusing... it kept popping 20amp fuses at 96v. The unit is rated for 1500 watts, and feels about the same as original regarding the heat that makes it to the windshield, but it is not 'hot'.... If you live in a really cold place I'd suggest getting two of them in somehow.

I put the one right in-line downstream of the fan rather than pull apart the dash to get to my core... I was concerned it might get too hot and melt plastic, but it is fine with the amount of air blowing thru....


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## Voltswagen (Nov 13, 2008)

Heres a budget idea -
I haven't tried this myself but I'm told it makes for an inexpensive but practical defroster. I currently have heated seats as my only creature comfort and may try this for defrosting.

Buy a 1500 watt pistol style hair dryer ( the type with the transformer on the power cord). Cut the transformer and plug off....now you have a 12v hair dryer.
Plumb the nose into your defroster hose and hard mount it with the switch in the High Position. 
Toggle switch the 12v power supply somewhere on your dashboard.
Instant heat! Not to mention it will probably defrost the windshield in 20 seconds.


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## dtbaker (Jan 5, 2008)

you probably want to run it off your HV traction pack rather thaan draw huge amps thru the 12v system. If you are doing a dc-dc converter, there is no way it will pull 1500 watts.


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## PhantomPholly (Aug 20, 2008)

I was so excited by that idea for use in my plane that I calculated the amps - and realized I cannot get 125 amps out of my 65 amp alternator...

TANSSAAFL.


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## Voltswagen (Nov 13, 2008)

DT
I use a 12v deep cycle and a DC/DC converter to power my accessories.
I think I may be able to run the Hair Dryer directly off my 12v since it will supply the needed 1500 watts. Granted, I couldn't run it for an hour since my converter only supplies 500 watts but 5 or 10 minutes should suffice to defrost the windshield. Maybe even less.
I just ran a test of my daughters 1600 watt Revlon Dryer and on HIGH it draws 11 amps......LOW it draws 3 amps. That was with the ac/dc converter still attached.


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## Voltswagen (Nov 13, 2008)

Phantom
What would you need 125 amps for?


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## PhantomPholly (Aug 20, 2008)

Voltswagen said:


> Phantom
> What would you need 125 amps for?


12v * 125amps = 1500 watt hair dryer. Won't work for me for aux heat with only a 65 amp alternator, and draining the battery in flight on purpose is a BAD idea.

16,500' altitude * -3 degrees F/1,000' = 49.5 degrees colder at cruise altitude than on the ground = damn chilly.

Tiny airplane + no room under cowl to fit a decent heat muff over the exhaust pipe (air cooled engine) = pitiful heater.

The perils of flying.


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## Voltswagen (Nov 13, 2008)

Phantom
I see. You are referring to 125amps per hour or AH. Well, yes you could not run it for a full hour so constant heat would be a massive drain.
But for short bursts of a few minutes or so....it would defrost a windshield.

Interesting, my Kill -A -Watt meter only reads 11amps draw. Wonder what their actual metric is? Must be current only not amp hours.


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## PhantomPholly (Aug 20, 2008)

Voltswagen said:


> Phantom
> I see. You are referring to 125amps per hour or AH. Well, yes you could not run it for a full hour so constant heat would be a massive drain.
> But for short bursts of a few minutes or so....it would defrost a windshield.


Windshield is absolutely not a problem. I assume it's because there is enough "dry air" leakage past the front seal to keep my steamy breath away (canopy opens by tilting up/forward; a tiny bit of air seeps through while I'm cruising at 210mph and exits along the sides - low pressure there due to Venturi effect). Air up high is desert-dry. Mostly it's my hands, a little cold air crawls up along the stick and also by the throttle quadrant. I've banged my head trying to seal it all, using boots where the pushrods go through. Do need SOME fresh air , just need some heat!

Canopy is great, though, on cold days as long as the sun is shining it's usually fine. Night, in the weather- not so much.

Similar one to mine here - imagine a day like this, then lower the temp 50 degrees with the wind blowing through your cabin... Brrrr!



> Interesting, my Kill -A -Watt meter only reads 11amps draw. Wonder what their actual metric is? Must be current only not amp hours.


Sounds like you're running it at 120 volts rather than 12v. 1500 = v*a, so changing volts changes amps.


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## Voltswagen (Nov 13, 2008)

Yes, you are right.....120v DUH!


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## PhantomPholly (Aug 20, 2008)

EVs and airplanes face a lot of the same problems - space, weight, power for accessories, efficiency. Still hoping someone invents a megabattery so I can lose the ICE in the plane. Who needs a turbocharger when your motor makes the same power irrespective of altitude?


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## F16bmathis (Jun 6, 2008)

Hey, you both seem to know... I bought one of those square ceramic heaters, but it has no wiring diagrams. Hows it get wired? And how many amps should I expect to pull? Guess I might have to wire it up outside truck and see...


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## PhantomPholly (Aug 20, 2008)

All I could guess would be to look for a mfgr/model and look it up on line.

Volts * Amps = Watts. Circuit Breakers protect the WIRES, not the Equipment. You can only let the smoke out ONCE. Lawn Darts 0 / Radio Free Europe 1! 

That's about the extent of my electrical know-how.


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## dtbaker (Jan 5, 2008)

what I know is that the typical 1500 watt ceramic heater core pulls something over 20amp on a 96v nominal system at start. I don't know exactly since I don't have a dc clamp meter and my hv gauge in the car has too wide a scale and is analog so I can't get a super accurate reading or spot the initial draw as the element heats up. I substituted single strands of 22ga wire for fuses, and seems to work fine until I can borrow a meter to see what it is actually pulling.

the switching is pretty elaborate as I bought the 'kit' from KTA-ev.com which includes the contactor, resistors, capacitors, and a diode so the thing can be switched from 12v power (fan switching on).


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## Stunt Driver (May 14, 2009)

for some reasons my ceramic heater pulls 2-3 amps at start, but gradually grows to 7-8 on 84 volts DC. According to killawatt it pulled 1250W on AC110v when hot, again, starting at ~700w when just started.

post pics of what you have and mighty forum should be able to advise


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## PhantomPholly (Aug 20, 2008)

Resistors sometimes change resistance with temperature. The heating element is a resistor.


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## Stunt Driver (May 14, 2009)

yes, except that resistance must grow with temperature not drop

unless it is semi-conductive material


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## elevatorguy (Jul 26, 2007)

The ceramic heaters have a positive temperature coefficient, the cooler they are the more current they draw.
They are sort of self limiting, and will reduce current draw if heat is not removed. I have not tested the self limiting part, not anxious to replace parts. Blow a lot of air and the current and heat output will go up.
That may be the extent of what I know,


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## Stunt Driver (May 14, 2009)

elevatorguy said:


> The ceramic heaters have a positive temperature coefficient, the cooler they are the more current they draw.


RE-read my post: 3A when heater is cold; 8A when full hot. 
opposite from what you just wrote.


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## elevatorguy (Jul 26, 2007)

Stunt Driver said:


> RE-read my post: 3A when heater is cold; 8A when full hot.
> opposite from what you just wrote.


http://www.dbk-usa.com/products/ptcheaters/ptcheaters.htm

I read and understood your post, yours is either not ceramic type or something else is going on. It seems to work opposite of my heater and the type in the link above.


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## F16bmathis (Jun 6, 2008)

I e-mailed evparts.com, they sent a diagram. 144V + goes on the outside and middle spade connections, 1,3 and 5, and the negative goes on the inner spades, 2 and 4. Tested it with a 12V fan, instant heat - lots of heat! Used 12 gauge wire and they didn't seem to warm up at all, but will use 10 gauge on the install. Should be pulling around 10-12 amps. Now I just have to install it! Here's the diagram... http://www.evparts.com/img/ht2511productinfo.PDF


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## Stunt Driver (May 14, 2009)

It's killing me, guys.


When I leave house and heater is hot (just unplugged from AC) - it dwaws 9 amps, giving me ~700w on 84V battery pack. But today it was -10C outside, and since I have no recirculation - outside air quickly cooled heater to very low temperatures - it came down to ~4A draw!! And so almost no heat! So I would be better off shutting air intake. 
Looks like w/o recirculation - not much you can get out of low voltage heater like mine when it is _FREEZING_ outside.

Luckly, it not often that cold here, and I park at charging station, where car stays warm from AC


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## dtbaker (Jan 5, 2008)

Stunt Driver said:


> When I leave house and heater is hot (just unplugged from AC) - it dwaws 9 amps, giving me ~700w on 84V battery pack. But today it was -10C outside, and since I have no recirculation - outside air quickly cooled heater to very low temperatures - it came down to ~4A draw!! And so almost no heat!


this sounds totally backward from the way I thought ceramic heaters work. perhaps your 84v DC leads are backward? the heaters ARE sensitive to polarity to work right I think.


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## Stunt Driver (May 14, 2009)

that would be surprising if they are, but i'll check.

However, AC starts at 500w now, slowwwwly ramping up to 1200w (heater was outside in -5c)

Am I the only one luckly like that here?


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## TheSGC (Nov 15, 2007)

I have started working on my heater for this winter, but found I cannot get to the original heater core without draining my AC, so that will have to wait until next year.

So my idea is to use the ceramic core to make something like those useless 12 volt Defrosters, except run off the traction pack. I only need it to defrost the windows when driving as I have an AC ceramic heater to defrost and warm up the car before driving.

I tested the AC heater, and on Low it will defrost the whole EV in 8 minutes. I am betting High will really defrost quickly and heat up the cabin quite a bit.


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## dtbaker (Jan 5, 2008)

TheSGC said:


> So my idea is to use the ceramic core to make something like those useless 12 volt Defrosters, except run off the traction pack.


this is pretty much what is the recommended 'kit'.... the relay is pretty affordable at around $60 at kta-ev.com, but I am not sure why they want $100+ for the core at many places.

I m pretty happy with my setup... just stuck the core in the middle of the duct downstream of the fan. details and pix are at
http://www.envirokarma.org/ev/03.Interior.shtml


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## electricrevolt (Aug 28, 2009)

Not to be contentious, but I feel the most efficient place for the ceramic heater in back on the shelf.

Folks have a difficult time getting it into the dash, then worry about fire hazard. And even then, the ceramic heater doesn't fully heat the EV and you're still cold in the winter. My friend had to hold his ceramic heater up to the windshield to defrost it. 

We got sick of it and developed our own model Inline Water Heater (for sale) that uses the vehicles existing liquid heating hoses and climate controls. For $335, it's simple to install and natural to use. You'll find the EV heats up as warm as an ICE vehicle. Check it out on our website: http://www.evequipmentsupply.com/page32.html


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## Stunt Driver (May 14, 2009)

Not a bad idea, agree. Just alot heavier and costly. 
Do you have thermostat in that assembly, for safety in case water pump is stuck?


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## electricrevolt (Aug 28, 2009)

It is more costly. But it's more natural and more effective too. Yes, there is a thermostat built in.


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## Stunt Driver (May 14, 2009)

I don't see a single argument for it being more efficient, can you help?


ps My ceramic core does increase resistance at higher temperatures - i.e. if it's warm outside, and fan is set to low - I can see amps go up to 1300 and then start to decrease, as core reached it's temperature. But still, at start and at cold temperatures it draws very low amps.


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## electricrevolt (Aug 28, 2009)

Between the element/s and water pump, our heater will certainly draw higher amps that a ceramic heater.

In reference to efficiency, I feel it is easier to install this water based heater into a vehicles existing system. But in addition to being more efficient to install, this type heater heats the whole vehicle quickly and naturally.

But then again I'm biased because I believe that in order for EVs to gain in popularity among average consumers, they need to function similiar to what folks are already used to driving.


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