Air to Air Heat Exchanger

MEMPHIS91 · 06-30-16, 09:43 PM

Hey guys so here is the story, good ole Mississippi loves to throw you a curve ball, right now it is 82F 42% RH in my house. Outside it is 76F 55% RH. And will get down to about 68-72F tonight/morning. I WANT THAT BASICALLY FREE AC!!!

I want the temp without the moisture. Here are my thoughts, during the summer months I install a homemade air to air exchanger that runs anytime that the outside temp drops 2F lower than the inside temp. I can install these in the windows? Stealing the temp while leaving the moisture outside, if I just opened the windows my house would turn into a mop..... mold..... mildew.... death......

I know I am going to have to move A LOT of air to make any real difference.

Just an idea, 6 inch piece of foam board wedged at the bottom of window, 2 4" holes leading to X length of Everbilt 4 in. x 6 ft. Semi-Rigid Aluminum Duct with Collars-AM46HD - The Home Depot and then back into the house all powered with a LOW power fan.

Ideas? Thoughts? Does this all ready exist? I know about HRVs and stuff but this is different. All I want is the temp NOT the outside air.

Thanks guys, Shalom

AC_Hacker · 07-01-16, 12:33 PM

Quote:

Originally Posted by MEMPHIS91

Hey guys so here is the story, good ole Mississippi loves to throw you a curve ball, right now it is 82F 42% RH in my house. Outside it is 76F 55% RH. And will get down to about 68-72F tonight/morning. I WANT THAT BASICALLY FREE AC!!!

I want the temp without the moisture. Here are my thoughts, during the summer months I install a homemade air to air exchanger that runs anytime that the outside temp drops 2F lower than the inside temp. I can install these in the windows? Stealing the temp while leaving the moisture outside, if I just opened the windows my house would turn into a mop..... mold..... mildew.... death......

I know I am going to have to move A LOT of air to make any real difference.

Just an idea, 6 inch piece of foam board wedged at the bottom of window, 2 4" holes leading to X length of Everbilt 4 in. x 6 ft. Semi-Rigid Aluminum Duct with Collars-AM46HD - The Home Depot and then back into the house all powered with a LOW power fan.

Ideas? Thoughts? Does this all ready exist? I know about HRVs and stuff but this is different. All I want is the temp NOT the outside air.

Thanks guys, Shalom

If you ran water through a ground loop and through an air heat exchanger, you will drop temp, but you will have water condensing on the fins of your HX (because you will have raised the RH), so you will have gotten rid of some of the water. If you then run this air through an A/C you will drop the temp and more water, but it will not have to do as much work as before.

Cheapest way out is to move to Maine for the summer.

Best,

-AC

MEMPHIS91 · 07-01-16, 10:01 PM

I guess I'm not following you there AC, maybe a rough diagram would help.

jeff5may · 07-01-16, 11:22 PM

A few degree temperature difference would take a ton of surface area and even more airflow to make much difference at all. Think big solar thermal collector on the shady side of the house. A differential controller could start and stop airflow.

Randen did what AC is talking about in his garage/shop some time ago. He rigged an air handler in the building to his ground loop, using the existing water coil and pump. What he ended up with was lots of drain water and a clammy/muggy shop. His ground loop was cooler than yours by some degree, since he lives in Canada. I know he messed around with multiple heat exchangers, pretreating return air with the straight water hx, then running that air through another colder hx before it was vented from the air handler. I can't remember how effectively it worked. It's all in one of his threads in the heat pump forum somewhere.

DEnd · 07-04-16, 03:46 AM

Removable insulation maybe? I'm thinking single pane exterior storm windows. When conditions like this exist you can then open your regular windows effectively removing insulation and allowing more heat loss to the exterior. Installed well, these would also increase the r value of the lowest performing part of your house, and increase the air tightness of your home. I'm not sure how many BTUs you could actually move with this method, but you don't need to power anything for it to work either...

*Edit: Just did some math based on what I could find and it looks like with a 5°F temp difference you can move about 5.5 BTU/h per sqft.

MEMPHIS91 · 07-04-16, 11:06 AM

DEnd, good ideas, in the beginning I was thinking the same thing, but more along the lines of opening the window and inserting a frame into the window that had a layer of thin aluminum foil.
With the forced air setup I believe I can remove a lot more btus. My pipe will have 5 square feet per 5 foot section, I was planning on 2 sections so 10 feet so 50 btus without without air flow, the material is not smooth so I should have good turbulence. I am going to do a rough setup and measure temp drop on a data logger.

What I really need is a material that allows air in and keeps moisture out!

AC_Hacker · 07-08-16, 12:53 PM

Quote:

Originally Posted by MEMPHIS91

I guess I'm not following you there AC, maybe a rough diagram would help.

This is a "swamp cooler" ahead of the condenser coils.

http://www.builditsolar.com/Projects...ING%20G1-1.pdf

With all your DIY creds, you could build a GSHP air conditioner. Not so different from your DX water heater.

-AC

06-30-16, 09:43 PM	#1
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	Air to Air Heat Exchanger Hey guys so here is the story, good ole Mississippi loves to throw you a curve ball, right now it is 82F 42% RH in my house. Outside it is 76F 55% RH. And will get down to about 68-72F tonight/morning. I WANT THAT BASICALLY FREE AC!!! I want the temp without the moisture. Here are my thoughts, during the summer months I install a homemade air to air exchanger that runs anytime that the outside temp drops 2F lower than the inside temp. I can install these in the windows? Stealing the temp while leaving the moisture outside, if I just opened the windows my house would turn into a mop..... mold..... mildew.... death...... I know I am going to have to move A LOT of air to make any real difference. Just an idea, 6 inch piece of foam board wedged at the bottom of window, 2 4" holes leading to X length of Everbilt 4 in. x 6 ft. Semi-Rigid Aluminum Duct with Collars-AM46HD - The Home Depot and then back into the house all powered with a LOW power fan. Ideas? Thoughts? Does this all ready exist? I know about HRVs and stuff but this is different. All I want is the temp NOT the outside air. Thanks guys, Shalom __________________ שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד

07-01-16, 10:01 PM	#3
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	I guess I'm not following you there AC, maybe a rough diagram would help. __________________ שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד

07-04-16, 11:06 AM	#6
MEMPHIS91 Journeyman EcoRenovator Join Date: Apr 2015 Location: Oxford, MS USA Posts: 496 Thanks: 69 Thanked 87 Times in 61 Posts	DEnd, good ideas, in the beginning I was thinking the same thing, but more along the lines of opening the window and inserting a frame into the window that had a layer of thin aluminum foil. With the forced air setup I believe I can remove a lot more btus. My pipe will have 5 square feet per 5 foot section, I was planning on 2 sections so 10 feet so 50 btus without without air flow, the material is not smooth so I should have good turbulence. I am going to do a rough setup and measure temp drop on a data logger. What I really need is a material that allows air in and keeps moisture out! __________________ שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד

07-01-16, 11:22 PM	#4
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	A few degree temperature difference would take a ton of surface area and even more airflow to make much difference at all. Think big solar thermal collector on the shady side of the house. A differential controller could start and stop airflow. Randen did what AC is talking about in his garage/shop some time ago. He rigged an air handler in the building to his ground loop, using the existing water coil and pump. What he ended up with was lots of drain water and a clammy/muggy shop. His ground loop was cooler than yours by some degree, since he lives in Canada. I know he messed around with multiple heat exchangers, pretreating return air with the straight water hx, then running that air through another colder hx before it was vented from the air handler. I can't remember how effectively it worked. It's all in one of his threads in the heat pump forum somewhere.

07-04-16, 03:46 AM	#5
DEnd Apprentice EcoRenovator Join Date: Nov 2011 Location: NC Posts: 117 Thanks: 6 Thanked 27 Times in 25 Posts	Removable insulation maybe? I'm thinking single pane exterior storm windows. When conditions like this exist you can then open your regular windows effectively removing insulation and allowing more heat loss to the exterior. Installed well, these would also increase the r value of the lowest performing part of your house, and increase the air tightness of your home. I'm not sure how many BTUs you could actually move with this method, but you don't need to power anything for it to work either... *Edit: Just did some math based on what I could find and it looks like with a 5°F temp difference you can move about 5.5 BTU/h per sqft.