# [EVDL] How much heat does a car heater put out ?



## EVDL List (Jul 27, 2007)

Please search the archives, this topic has been discussed quite a bit
and mostly in relation to ceramic heater element experiments in (very)
cold weather, so I think you can find a lot of data there instead of
re-inventing it.

If you still have questions after digging the archive, please do get
back with the additions, then we can supplement what is already out
there instead of doing it again. When you provide references to what you
found, you even add a lot of value to others searching for the same
data.

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Altenguy
Sent: Wednesday, November 05, 2008 10:08 AM
To: Electric Vehicle Discussion List
Subject: [EVDL] How much heat does a car heater put out ?

How much heat does a car heater put out ? 

(I am speaking about the cabin heater that uses engine coolant via the
heater core.)

In 40 below weather, how large must an electrical heating element be to
keep the cabin warm ?

Thanks

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## EVDL List (Jul 27, 2007)

> Cor van de Water wrote:
> > Please search the archives, this topic has been discussed quite a bit
> > and mostly in relation to ceramic heater element experiments in (very)
> > cold weather, so I think you can find a lot of data there instead of
> ...


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## EVDL List (Jul 27, 2007)

> Cor van de Water wrote:
> > Please search the archives, this topic has been discussed quite a bit
> > and mostly in relation to ceramic heater element experiments in (very)
> > cold weather, so I think you can find a lot of data there instead of
> ...


----------



## EVDL List (Jul 27, 2007)

I searched on the words
" ceramic heater john wayland" and the first post it found
was very relevant, including the reference
http://www.evdl.org/archive/index.html#nabble-to12848664|a12852670

Which points us to the original article from 1997:
http://www.evsource.com/articles/heater_compare.php

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Altenguy
Sent: Wednesday, November 05, 2008 11:10 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] How much heat does a car heater put out ?




> Cor van de Water wrote:
> > Please search the archives, this topic has been discussed quite a bit
> > and mostly in relation to ceramic heater element experiments in (very)
> 
> ...


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## EVDL List (Jul 27, 2007)

A electric heater is rate at 3412 btus of heat per 1000 watts. If your cab 
R-factor is low which could be rated at one R-factor for one single pane of 
glass and one layer of 20 gage metal.

Lets say your cabin size has the area of a 5 foot cube, then 5 x 5 x 5 = 125 
square foot (SF) of external wall space and the outside temperature is -40 
degrees and you want to maintain 70 degree cab temperature which is a 110 
degrees temperature difference (TD)

Therefore: Btus = SF x ((1 R factor)/1) x TD
125 x 1 u factor x 110
13,750 Btus

Watts = 13,740 Btus / 3412 btu per 1000 watts
Watts = 4029 watts or 4.029 kw

The coldest it even got for my EV was when it was setting outside at work at 
a elevation of 3600 feet was 39 below which peak this temperature for about 
a hour.

I use one 640 watt cab heater on the driver side and one 840 cab heater on 
the passenger side. A 1000 watt electric water heater is use to heat the 
existing hot water core.

On some vehicles you may have to make a adjustment in the outside air damper 
doors that bring in some cold outside air to temper hot engine water that 
could be over 240 degrees. You can close these outside damper air inlets so 
your electric heating systems does not have to be as hot.

I find I can defrost my windshield with 50 degree water heat if I close 
these air inlet doors.

Roland


----- Original Message ----- 
From: "Altenguy" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, November 04, 2008 9:37 PM
Subject: [EVDL] How much heat does a car heater put out ?


> How much heat does a car heater put out ?
>
> (I am speaking about the cabin heater that uses engine coolant via the
> heater core.)
>
> In 40 below weather, how large must an electrical heating element be to
> keep the cabin warm ?
>
> Thanks
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
> 

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## EVDL List (Jul 27, 2007)

> On 5 Nov 2008 at 11:05, Altenguy wrote:
> 
> > Could you give me a link to the archives that allows searching all of
> > them at once ?
> ...


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## EVDL List (Jul 27, 2007)

> EVDL Administrator wrote:
> > On 5 Nov 2008 at 11:05, Altenguy wrote:
> >
> > > Could you give me a link to the archives that allows searching all of
> ...


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## EVDL List (Jul 27, 2007)

The numbers I have heard about and I have done a little design with are:

20,000Btu for a modern big car air conditioner, I think Solectria Forces had
about half this. But I am not sure.

My gut tells me that you want at least 10,000BTU for heat (defrost, really)
~3kW, or 20 A on a traction pack of 144-156V?. But if others have gotten
away with less, then use their data. If you scrape well *before* driving
then your needs may very well be less.

This is going from memory on 5 year old EV projects so beware...

Seth
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## EVDL List (Jul 27, 2007)

Best answer to these questions is "it depends." There are way too many 
factors to make a judgement. You're best off with empirical and 
anecdotal information.

How well insulated is the cabin against heat radiation? Are there any 
air leaks?
Is the air recirculated or from outside, or somewhere in between?
How big is the cabin?

Empirically speaking, I have a 1500W electric heater that can heat a 
fair-sized room in my home.



> Altenguy wrote:
> > How much heat does a car heater put out ?
> >
> > (I am speaking about the cabin heater that uses engine coolant via the
> ...


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