Indiana Pook, and the quest for heat

[Pookapotamus]

The Heater in Mort did not seem to get very warm this last winter, even with a brand new heater core, so with recently removing my a/c I figured I would pull my spare heater box from the attic and take a look to see if removing the a/c core would give better air flow. Hooked the blower up to a spare battery and did a test with the a/c core and without. Yes I got better air flow, I would say double with my crude test of a sheet of cardboard over the outlet and measuring the difference. But then I got an idea.......

First of all the XJ heater box is like a maze they put lab mice in to see if they can make it through without going insane. it is quite a convoluted path the air has to take.http://i264.photobucket.com/albums/ii191/pookapotamus/Oldheatpath_zps65241ed7.jpg (http://s264.photobucket.com/user/pookapotamus/media/Oldheatpath_zps65241ed7.jpg.html)

Then looking at the design of the heater core to the design of the a/c core got me thinking why not use the a/c core for a heater core, more volume, better fins, better more direct path for the air flow and if it ever develops a leak the design of the heater box lets the coolant leak into the engine bay instead of into the floor pan of the jeep.
http://i264.photobucket.com/albums/ii191/pookapotamus/photo1_zps39a73332.jpg (http://s264.photobucket.com/user/pookapotamus/media/photo1_zps39a73332.jpg.html)

Now, will the aluminum in the a/c core react with regular coolant?
The a/c core should easily be able to handle the pressure of the coolant system, the lines are a little smaller 1/2" vs 9/16" but there are more of them so that also should not be a problem.
The valve under the hood that controls coolant going to the heater core will still be used so that you are not pumping heat into the cab at all times, so that also is not a problem.

It would be very easy to block off air flow to where the old heater core was to help provide great air flow. so far the only drawback that I am seeing is if the aluminum and glycol react and corrode, witch would be easily fixed because I am seriously contemplating evens waterless coolant.

Even bleeding the system will be fine as there are no "tanks" on the ends of the a/c core.

There would be no modifications to the vacuum lines on the heater box other than blocking the line that controls the heater door.

here would be the path of the air flow after this mod.
http://i264.photobucket.com/albums/ii191/pookapotamus/NewHeatpath_zps5df9f496.jpg (http://s264.photobucket.com/user/pookapotamus/media/NewHeatpath_zps5df9f496.jpg.html)

So what does everyone think? Good idea? Or should I go back to my cage?

[4.3LXJ]

Nice idea for the north. Should get plenty of heat out of it. It is commonly done in apartment size heating systems now.

[Pookapotamus]

OK, so... I might have created a monster...

here is air flow with full fan power and everything stock,

http://i264.photobucket.com/albums/ii191/pookapotamus/photo22_zpsde7a6e62.jpg (http://s264.photobucket.com/user/pookapotamus/media/photo22_zpsde7a6e62.jpg.html)

And here is air flow with the a/c core removed,

http://i264.photobucket.com/albums/ii191/pookapotamus/photo32_zps93ba2d7b.jpg (http://s264.photobucket.com/user/pookapotamus/media/photo32_zps93ba2d7b.jpg.html)

And here is air flow with a/c core only and all the unnecessary crap removed from the Heater box,

http://i264.photobucket.com/albums/ii191/pookapotamus/photo12_zps72bb2324.jpg (http://s264.photobucket.com/user/pookapotamus/media/photo12_zps72bb2324.jpg.html)

Now if no one can come up with a reason that the a/c core cant be used as a heater core, I will continue and see how this works installed in Mort.

[Pookapotamus]

Nice idea for the north. Should get plenty of heat out of it. It is commonly done in apartment size heating systems now.

Not just for the north Steve, think of the benefits of overheating in the desert and being able to blast that much more air through a better heat ex-changer to help cool down the engine, plus the added coolant volume.

[Pookapotamus]

Here is what I removed from the heater box, the yellow lines are walls, and as you can see I removed all of them. the red arrow shows the door that I removed, which I believe is cable controlled so no issues for vacuum lines. its now a straight shot through the heater box.

http://i264.photobucket.com/albums/ii191/pookapotamus/Partsremoved_zpsb8fb5708.jpg (http://s264.photobucket.com/user/pookapotamus/media/Partsremoved_zpsb8fb5708.jpg.html)

[XJ Wheeler]

That is some mighty fine engineering Pook! If a/c wasn't the only thing keeping us alive down here I think this would be on my list to do. But with no need for it the extra flow sounds awesome! As many know XJs don't exactly blow your hair, or for follicly challenged... collar back.

[Pookapotamus]

Thanks, still worried that I'm missing something, it can't be this easy!

[4.3LXJ]

You might want to check on this. I think the most restrictive part of my system is the ductwork. That is the housing and vents. If those are opened up, then there would be much more air flow. I don't know about yours being a later model, but the floor heater vents in mine were tiny

[Pookapotamus]

I will post a pick of the factory heat vent, it is small and tiny out let holes, I added this a while back Steve. http://tapatalk.imageshack.com/v2/14/08/24/46b9d5f453d9a11a11cfc340d5cba04e.jpg

[Pookapotamus]

Factory onehttp://tapatalk.imageshack.com/v2/14/08/24/ffef0dc6da55dc457ba6514bd5440a07.jpg

[4.3LXJ]

Ok, I am waiting. Sounds like poor Mortis is in a lot of pieces

[Pookapotamus]

Ok, I am waiting. Sounds like poor Mortis is in a lot of pieces


Not yet but he will be!


So no one can come up with any drawbacks for doing this?

I will do a test with this vs stock actually installed in the jeep.

[KMW-NWXJ]

I wonder if the faster air flow would reduce the amount of heat the air picks up on its way through? I don't know, just an thought that piped into my head.

Where will your heat come out? Any vent, or just the ac vents?

[Pookapotamus]

The faster air flow definitely will change the heat transfer rates I'm hoping the larger more efficient a/c core will make up for it.

Really nothing in the heater system is changing, everything will work as normal.

[4.3LXJ]

You gonna be able to keep a blend door?

[Pookapotamus]

Do you mean blend as in outside air and inside air? Yes that is still in place, the door I cut out was for heat vs cold, but since the valve in the engine compartment stops the flow of coolant to the core it should not be a problem.

[4.3LXJ]

That is the one I was talking about. How are you going to adjust temp? I think that AC core will put out a lot of heat

[Pookapotamus]

Was planning on running the cable that used to control the heat out to the valve for coolant flow.

[4.3LXJ]

OK, that would work. You will need to change that valve though. I suggest a valve for a 73 Dodge Polara wagon for that

[Pookapotamus]

Thanks steve

[Pookapotamus]

http://tapatalk.imageshack.com/v2/14/08/30/463de1b951795ed74f85a334c10b90ee.jpg

Sure can't say I do things half assed! Looks like I need to clean up some wiring while I'm in this far

[Pookapotamus]

New modified heater box is installed, I sure hope this works cause it's a holy pain in the rump to swap out!

Will be cleaning wiring up tomorrow, and then cutting the gauge cluster apart to replace the gauges with the ones that were below the glove box.

[4.3LXJ]

It will work

[Pookapotamus]

Well, now that Mort is running again I finally got to test this.

And... Well.... FAIL!

Super hot coolant going into the a/c core and super hot coolant coming out!

Does not transfer heat fast enough, basically warmish air coming out.

So I guess I go back to a standard heater core, modified to fit in a more direct air flow of course. Kinda wondering about having 2 heater cores in it, but I think with better air flow, the stock one will be fine. Maybe change up hoses and valve to provide more coolant to the core.

[4.3LXJ]

Pook, if you go to two cores, do you know about counter current flow?

[Pookapotamus]

I'm picking up what you're putting down Steve, any idea where to find heater cores by size? Space I have to work with is 3.5x11x10

[Pookapotamus]

http://tapatalk.imageshack.com/v2/14/10/07/855c402e848ab951b1c988ce4ab03589.jpg

Also trying to find a napa part number for this

[4.3LXJ]

Not really sure on that Dana. The best I can do is tell you how to use countercurrent flow to get maximum efficiency out of two cores

[Pookapotamus]

Looks like summit has generic cores

[Pookapotamus]

http://tapatalk.imageshack.com/v2/14/10/08/7ade5446daeec56dbb62b86a43d7874e.jpg

About the same size, but twice as thick

[4.3LXJ]

Gonna need to get the knife out for that one :D

[Pookapotamus]

Knife, sawzall, plasma cutter! It will fit!

[4.3LXJ]

Don't forget the big shoe horn

[Pookapotamus]

Ye of little faith Steve, when have you known me to fail??

Besides this thread....my first wife.... Alright I'm shutting up now 😢

[4.3LXJ]

Discretion is the better part of valor here Dana :D

[Pookapotamus]

Pfft! I have none of that valor stuff!

[Pookapotamus]

http://tapatalk.imageshack.com/v2/14/10/11/6675f5548f299cc9501a32302e6167ad.jpg

http://tapatalk.imageshack.com/v2/14/10/11/d1043effabe0bf91f589b3a4234740f5.jpg

http://tapatalk.imageshack.com/v2/14/10/11/7db6eef46ddd5a12a3dbdc5278273300.jpg

Slight modification to make it fit but boy does it pump out the heat! Around 180 deg!

[4.3LXJ]

Oh man, that sounds good. My core needs replacing and I was going to gloat that the early XJs had a three piece HVAC so you can replace the core without removing the dash. Buuuuttt, I might rethink that

[Pookapotamus]

I got a slightly used core you can have!

[4.3LXJ]

Really? it will match the one I already have

[Pookapotamus]

http://tapatalk.imageshack.com/v2/14/10/11/ad000db52785f033c2f2d54747c3c984.jpg

Top one in this pic, it's what I was using before, think it was too small, did not get too warm, the whole reason I went on this quest.

[4.3LXJ]

What core did you use?

[Pookapotamus]

The one on the bottom is from the rear heater on a 81 suburban, I think, part number 94556.

[4.3LXJ]

Interesting. I take it you had to get rid of the blend door?

[Pookapotamus]

Yup it's gone

[4.3LXJ]

Unfortunately, I need that living here where it is hot in the summer and cold in the mountains in the winter. I think I will replace the core with OEM and add a special little trick. I have a 750W electric heater coil I will add that I can run off my inverter. Instant heat when wanted and very hot heat when the engine is warm. I don't know about you, but my heater broke even at 2°F

[Pookapotamus]

Well I ran all over the city today and almost cooked myself! I haven't hooked the heater controls to the heater bypass valve under the hood yet so I could not turn my heat off. Even with everything off the heater still pumped out the heat! Should be good for winter! 😄

[4.3LXJ]

Very nice. You are now prepared for global cooling :D

[Pookapotamus]

Bring it on!