Very old newbie.

Paul_L · 09-06-12, 04:35 PM

Hi everybody,

I just found this board today while doing a google search for a differential temperature controller. Google found Daox's diy design. Then I saw robaroni's introductory post from the Catskill Mountains and I figured I'd better join.

Over the last two years I've been installing a geothermal heat pump in my house. It's a 5000 sq ft ranch. I dug a 120' x 60' x 8' deep hole, watched it fill up with water and turn into mud, pumped the water out, dried out the mud, dumped in 6" of sand, thermally fused a ladder network of 6000 feet of 3/4" HDPE pipe with 300 feet of 3" HDPE header pipes, ran the headers into the basement and hooked them up to a pump and an 8 ton hydronic heat pump, installed a 120 gallon heat resorvoir tank on the output of the heat pump, jury rigged a temporary hookup to an air handler, and started it working in cooling mode in June.

Then I rested! (How's that for a run on sentence?)

Now I'm trying to devise a method of controlling this monster. I have found nothing on the market that is smart enough! Since I'm supposed to be an engineer,I decided to design one myself. Since I'm a very old engineer, I first tried to do it in using analog circuitry. That didn't work out, I couldn't make it smart enough. I am now resigned to doing it in a digital design, but I am too old. (Most engineers over 70 years old are automatically disqualified from doing digital designs.

) I'm trying to figure out how to selectively multiplex the outputs of eight temperature sensors into a microcontroller and then store the data. Then I can programmatically review the data and make logical decisions about running the heat pump.

It should be fun. I'm hoping to get some help here from Daox and robaroni, and maybe from some of the other resident geniuses.

I would be glad to post some pictures of a very big hole with a lot of mud in the bottom if someone will explain to me how to post pictures.

Paul_L

Daox · 09-06-12, 07:55 PM

Welcome to the site Paul. Sounds like you'll fit right in.

Mikesolar · 09-06-12, 09:13 PM

Hi Paul, given what you want to do with the HP, I would try to find a PLC that can have some analog inputs and a few digital ones for pressure switches. You will want to use outdoor temp to determine heating system temp (floor heat or rads) and also a couple of stages for tank temp based on outdoor temp (you will have to decide if you want the tank to supply DHW).

The floor heat (assuming this is what you are doing) should be run through a 3 way mix valve and you will have to find a way to do a 0-10v output to drive the motor.

We are using dedicated DDC controllers for all this but it is a long and involved programming procedure which is only realistic if you make many HPs. So, for most things a PLC will do, although PID algorithms can be difficult. They are not set up for them.

Good luck.

Xringer · 09-07-12, 06:38 PM

Hi Paul,

I found that there is some stuff hi-tech stuff that's not so hard to use.
(Even for a 66 year old guy that started out using electron tubes)..

http://ecorenovator.org/forum/applia...ontroller.html

___^___ network cable socket

This CAI controller is cheap and it can handle 8 temperature sensors.

Plus, it can do a lot more with the other I/O on the board..

Using the software isn't real hard. I found it was a lot simpler than most user interfaces.

09-06-12, 04:35 PM	#1
Paul_L Old Physicist-Engineer Join Date: Sep 2012 Location: Dutchess County, NY Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	Very old newbie. Hi everybody, I just found this board today while doing a google search for a differential temperature controller. Google found Daox's diy design. Then I saw robaroni's introductory post from the Catskill Mountains and I figured I'd better join. Over the last two years I've been installing a geothermal heat pump in my house. It's a 5000 sq ft ranch. I dug a 120' x 60' x 8' deep hole, watched it fill up with water and turn into mud, pumped the water out, dried out the mud, dumped in 6" of sand, thermally fused a ladder network of 6000 feet of 3/4" HDPE pipe with 300 feet of 3" HDPE header pipes, ran the headers into the basement and hooked them up to a pump and an 8 ton hydronic heat pump, installed a 120 gallon heat resorvoir tank on the output of the heat pump, jury rigged a temporary hookup to an air handler, and started it working in cooling mode in June. Then I rested! (How's that for a run on sentence?) Now I'm trying to devise a method of controlling this monster. I have found nothing on the market that is smart enough! Since I'm supposed to be an engineer,I decided to design one myself. Since I'm a very old engineer, I first tried to do it in using analog circuitry. That didn't work out, I couldn't make it smart enough. I am now resigned to doing it in a digital design, but I am too old. (Most engineers over 70 years old are automatically disqualified from doing digital designs.) I'm trying to figure out how to selectively multiplex the outputs of eight temperature sensors into a microcontroller and then store the data. Then I can programmatically review the data and make logical decisions about running the heat pump. It should be fun. I'm hoping to get some help here from Daox and robaroni, and maybe from some of the other resident geniuses. I would be glad to post some pictures of a very big hole with a lot of mud in the bottom if someone will explain to me how to post pictures. Paul_L

09-06-12, 07:55 PM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Welcome to the site Paul. Sounds like you'll fit right in. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-07-12, 06:38 PM	#4
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Welcome aboard! Hi Paul, I found that there is some stuff hi-tech stuff that's not so hard to use. (Even for a 66 year old guy that started out using electron tubes).. http://ecorenovator.org/forum/applia...ontroller.html ___^___ network cable socket This CAI controller is cheap and it can handle 8 temperature sensors. Plus, it can do a lot more with the other I/O on the board.. Using the software isn't real hard. I found it was a lot simpler than most user interfaces. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

09-06-12, 09:13 PM	#3
Mikesolar Master EcoRenovator Join Date: Aug 2012 Location: Toronto Posts: 958 Thanks: 40 Thanked 158 Times in 150 Posts	Hi Paul, given what you want to do with the HP, I would try to find a PLC that can have some analog inputs and a few digital ones for pressure switches. You will want to use outdoor temp to determine heating system temp (floor heat or rads) and also a couple of stages for tank temp based on outdoor temp (you will have to decide if you want the tank to supply DHW). The floor heat (assuming this is what you are doing) should be run through a 3 way mix valve and you will have to find a way to do a 0-10v output to drive the motor. We are using dedicated DDC controllers for all this but it is a long and involved programming procedure which is only realistic if you make many HPs. So, for most things a PLC will do, although PID algorithms can be difficult. They are not set up for them. Good luck.