How many btu's would you say......

Uni R

About 20K BTUs, but it really depends. Gasoline is 114K/gallon, so at 60mph @ 20mpg, your car as a heater has about 6% efficiency if you have the heat cranked full blast. =)

Brad_6

are in my car heater? I was driving my dakota this frosty AM and i remembered my brother at one time had told me that typical A/C for a car is approx. 25,000 BTU's of cooling due to sunload, etc..... Then I started to wonder how many BTU'S of heat is produced by the heater core.
I'm thinking it has to be a relatively high amount since it heats up sometimes zero degree air and puts out some pretty hot air even at those low ambients. (long commute, empty mind...) Sorry for the odd question, but where else to ask? I figured if anybody had a ballpark figure, I would find it here. Thanks in advance, Brad

zeke

If your brother is right about the 25000 BTU/hr, then the mechanical work of the compressor is about 1/3( from estimated COP of 3) of that value or equivalent to 8000 BTU/hr and assuming overall engine efficiency is say 40%, the heat that will have to be removed by the car radiator is 60/40*8000 or about 12000BTU/hr which is only a small fraction of the heat
removed from a car moving at 60 mph with a 30 mpg fuel rating.At that speed you would have to remove the heat of 2gal/hr or about 220,000 BTU/hr.which swamps out the airconditioning load onn the radiator.

Weezbo

Your Heater core my friend doesnt produce any heat....

it is not much more than a mini heat emmiter with a blower motor behind it to cool off the water or anti freeze water solution...........in the case of a southwind from german VW's it is more along the lines of a three phase forced air heater. maybe by now there are fancy solar plate collector systems that have some type of blower motor or hydraulic heating systems that uses tranny fluid...who knows buh really i dont know of any heater cores that produce any heat. some of the best heater cores are like Bus heaters,Oldsmobile 98's from the 60's and early 70's these two are my favorite heater cores as they can drain the heat right outta the block:)) who needs a thermostat ... the heater core can work like a radiator cooling the motor,what temp do you want the motor to be and how much heat do you want outta the block? ok,may i suggest "radiant Heating?" if you know a major car manufacturer i have a great idea for Heating a vehicle:)

Brad_5

OK, I knew I should have asked

how many btu's of heat is my heater core removing from the coolant solution. you are right weezbo, and boilers don't produce heat either. they just convert various forms of stored energy into heat and so on and so on. i just thought it was cool how zero degree air could be heated so quickly.

Weezbo

Longtime ago i asked my old indian engineer buddy

the same question. and he gave me a similar answer that i gave you. then we discussed different motors and sizes of motors and carburation and exhaust temps and cooling ports in heads and automatic transmissions ,and cab sizes and insulation and like days later i knew justabout everything aguy woulda wanted to know about heater coils:))so,for my next experiment i yanked the back seat out of my 63 dodge dart,and an heater core and heater blower motor out of an Olds 98 blocked off the trunk from the car, carpeted it after running some lines back to the trunk ,lashed these lines up to the heater hoses and had like max heat in my car in a Flash:))) nothing could ramp like that POS ) it could melt snow off the entire car body )) i got great gas milage in that car:) 225 slant six with its own second radiator sorry i forgot its your question

hr

It's basically a hydronic/ air coil

you would need to know the coil size, number of passes of coil in the fins, fin spacing, fin thickness, fin shape, air movement (cfm) through the coil, and the air temperature entering the coil as well as the water temperature entering and leaving the coil. For a start! And of course all this is variable in the car, ie blower speed and coolant temperature.

Do a heat loss calc on your car and you may find the coil is sized to meet or exceed this load! I wonder if Siggys HDS allow these inputs!

Modern day cars run some real hot coolant temperatures, helps with emissions, among other things. Beyond the 212° boiling temperatures, hense the pressure cap and overflow tanks. You can get a lot of btus from a small coil with 220 plus water temperatures and a fan forced convection!

Actually if you look at HW coil performance the colder the air passing through the coil the higher the output. You are playing with the delta T just as you do in a hydronic system design.

If your car starts to overheat in the summer, kick on the heater full speed. This will sometimes dump enough heat to get you to the shop by adding some additional heat transfer surface to the coolant. You've added additional radiator surface area.

Keep the windows rolled down of course

hot rod

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jim lockard

Heat loss

Seems if your driving a service van, there is never enough heat. Perhaps Brad you could work up a heat loss cal on the way back-----Just watch were your going. Best Wishes J. Lockard

hr

Think about a heat loss on a truck or auto!

single pane glass, lots of it.

Metal siding with very little if any insulation.

Plenty of gaps and penetrations (infiltration).

Design temperature of?? Maybe 30 below.

Wind speeds of 70mph plus!

It's a wonder they can be warmed at all. Good thing that hunk of cast iron under the hood has some BTU's to give

Not uncommon in REAL cold country to see most of the radiator covered to allow enough heat from the engine to run efficiently and warm the occupants. The heater core becomes the radiator in this case

hot rod

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Brad_6

Thanks for your replies....

As i said in my original post, where else to ask? I had told my friend @ work that I was wondering about heater core output and that I had posted a query. Yes, he gave me a look like I was insane. I then went on to explain that "the internet isn't just for porn anymore Tommy"...

Yes, Hot Rod, Weezbo and all others, thats what made me think it must have been a small powerful "radiator". Please indulge me w/another question... If you can pressurize water to raise the boiling point why cant they make a small water filled, pressurized 1500W heater that would contain say 265 degree water and pump the "super heated" water thru a coil and blow the heat into the room. Wouldn't the surface temp of the sections be warmer then a regular water or oil filled one? My mind is wandering to a pressure cooker on the stove, it takes a tough piece of meat and tenderizes it due to the extra high temps of the liquid. To me it seems like synergy. I also know my logic is completly flawed.... I just can't wrap my mind around why.....and thats why I drive around unable to reconcile/understand it. I mean, why cant they heat the water w/microwaves (110 Volt) under pressure and achieve 265 degree water... Like I said, my logic is flawed and what bothers me is that i can't put it to rest in my mind why. It had to read the theory of fuel injection approx. 20 times before i could grasp that the gas pedal is really an "air" pedal and when i step on the gas, i'm really stepping on the air... I know i am dense, but curious. It is a bad combination. But I am grateful for your time and information. Thanks, Brad

jim lockard

Hot rod

Brad said it was a long drive.
It has always amazed me that A/C works in a car at all when you consider the temps under the hood in the middle of summer. Best Wishes J.Lockard

jerry scharf_2

too expensive

A bigger coil and simpler boiler/piping is a whole lot cheaper. There is also the risk factor of pressurized hot water rupturing. Cars do it because they have to not because they want to.

jerry

hr

At 15 psi

water at sea level boils at 249°F. I suspect the coolant in some automotive applications gets this hot. I think the addition of glycol (antifreeze) rises this boiling point even higher. The radiator cap on my Dodge truck, with a diesel, is 15 psi.

As far as the automotive heater core goes, they are pretty similarly sized as those found in kick space heaters. 8, 10, even 12,000 btu/hr. are possible from these. At 180 supply, fairly small gpm flow.

Actually the cores in the VRV kickspace heaters are made in England. Same factory has made the radiator and oil coolers found on Triumph motorcycles.

hot rod

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hr

Jim

and consider the load that solar gain adds to the cooling load! Throw some high humidity in the mix and you get quite a comfort challange.

Nothing an engineer can't handle! Mini vans now have zoned, multi temperature HVAC systems!

hot rod?

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