DIY thermal differential controller (solar hot water pump controller) - Page 4

Xringer · 11-28-09, 09:29 AM

I wonder if the thermistor could be removed from a modern Tstat
(like the RTH221B1000)

Honeywell at Lowe's: 1-Week Basic Programmable Thermostat

And re-connected using a twisted-pair?

If you could locate the thermistor inside the warm-air collector, the Tstat
could be used in the AC mode. Coming on whenever the temperature
inside the collector got above ~75-85 deg..
I think these things have about three degrees of Hysteresis..
So the fan was moving a lot of air, it would shut down pretty quickly,
as the collector cooled off a bit.

~~
In the early evening, you could try using the heating mode. If the outdoor temp
dropped below 70, air from the house would be sucked into the collector
and cooled down a little.. (Assuming the house was still warm).

dremd · 11-28-09, 02:11 PM

Quote:

Originally Posted by AC_Hacker

I did a search for "Differential Controller Kits" and came up with this:

[CENTER]

Again, you are the MAN!
Anybody try this yet?
If nobody else does, I'll try one in Feb/March for the pool heater.

Bicycle Bob · 11-28-09, 02:26 PM

"They're fairly inexpensive, and highly reliable, and they can handle considerable current without additional electronics thingies.
Here's one that should be right in your range.
-AC_Hacker"

Thanks! "On at 40 C, off at 32 C." I thought I'd want to leave shutoff closer to my indoor temperature, but I see that their range only goes up from that model. I suppose that if the collector is active, it will usually kick on the fan, since it hits 70 C pretty easy in still air. Has anyone tried these limits, and watched a partly cloudy day get wasted?

dremd · 12-17-09, 11:46 PM

Browser Warning

Joe · 01-03-10, 01:13 PM

doax mentioned an arduino in the first post, I like that idea, they can be had for as little as $15 for a clone. They have tons of support online so getting the code right should'nt be a problem, and once we do everyone can copy and paste it. Kinda like MPGuino project. They also sell cheap lcd displays for like $20 so we can use the serial print function to display temp and pump on/off status, ect. I bought one a few months back and have been real busy with things so I haven't got past the first few little tutorials(I can blink some leds like you wouldn't believe) but it is fun to play with and I see tons of uses for us.

boardom · 01-21-10, 08:41 AM

I was looking around for the same type thing, with a bit more... Brains then just an off/on differential controller. These two links are great resources. The Arduino board seems to be the way to go.... Tons of possibilities, very low cost.

Hearth.com Wood Stove and Pellet Stove Forums....and much more! | My New Control System

arduino (woodnotoil)

Solar Mike · 05-02-10, 04:16 AM

Quote:

Originally Posted by boardom

I was looking around for the same type thing, with a bit more... Brains then just an off/on differential controller. These two links are great resources. The Arduino board seems to be the way to go.... Tons of possibilities, very low cost.

Hearth.com Wood Stove and Pellet Stove Forums....and much more! | My New Control System

arduino (woodnotoil)

Another cpu controller that is very easy to program is the PicAxe, they have a mini-basic interpreter inside the chip. Plug them into a breadboard add a couple of resisters and a capacitor and you can connect to the serial port of your PC to program them. They have inbuilt basic commands to read the DS18b20 1-wire bus temp sensors and are absolutely ideal for making solar controllers. Here is a link to the UK site that manufactures them, I believe there is someone in the USA importing them.
PICAXE

Cheers
Mike

bsmith · 07-31-10, 06:04 PM

I built a differential controller that has 4 temp inputs and temperature logging that is pretty cheap ($49). I wasn't going to pay $150 for it either. Here's the link if you are interested (just take out the spaces).

http://sites.google.com/site/mydtcstore/

AC_Hacker · 08-01-10, 01:34 PM

Quote:

Originally Posted by bsmith

I built a differential controller that has 4 temp inputs and temperature logging that is pretty cheap ($49). I wasn't going to pay $150 for it either.

Looks interesting...

What is the current draw?

In what format is the data stored?

-AC_Hacker

bsmith · 08-01-10, 01:53 PM

Here is some from a screen capture. The line under the s command upto the relay states and relay on time is what is stores off each tick.

I just noticed the picture I posted is for a depopulated version that just does the temp logging. You can get one with one or two independent differential or HEAT/COOL thermostat functions (selectable).

Current draw is about 15-20ma. When the relays are active, add about 33ma more each.

>m
myDTC Deluxe v1.2
s)Status c)Config t)Set LogTick f)Freeze Mode
0)Set SI Units 1)Mode_R1 2)Mode_R2 3)SP_R1
4)SP_R2 5)Bump Minutes 6)Bump Hours
7)DeltaT 8)LowT 9)HighT m)Menu r)Rules
>s
DAY:HH:MM TICK T1 T2 T3 T4 R1 R2 R1TIME R2TIME
000:01:12 012 59 59 58 58 OFF OFF 000.0 000.0
>c
DTMP LTMP HTMP MODE1 MODE2 LOGTICK SP_R1 SP_R2 FRZMODE
04 F 05 F 60 F DTC_R1 DTC_R2 5 MIN 25 F 25 F ALLOFF

11-28-09, 09:29 AM	#31
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	remote thermistor? I wonder if the thermistor could be removed from a modern Tstat (like the RTH221B1000) Honeywell at Lowe's: 1-Week Basic Programmable Thermostat And re-connected using a twisted-pair? If you could locate the thermistor inside the warm-air collector, the Tstat could be used in the AC mode. Coming on whenever the temperature inside the collector got above ~75-85 deg.. I think these things have about three degrees of Hysteresis.. So the fan was moving a lot of air, it would shut down pretty quickly, as the collector cooled off a bit. ~~ In the early evening, you could try using the heating mode. If the outdoor temp dropped below 70, air from the house would be sucked into the collector and cooled down a little.. (Assuming the house was still warm).

01-21-10, 08:41 AM	#36
boardom Lurking Renovator Join Date: Dec 2009 Posts: 3 Thanks: 0 Thanked 1 Time in 1 Post	Arduino Based Controllers I was looking around for the same type thing, with a bit more... Brains then just an off/on differential controller. These two links are great resources. The Arduino board seems to be the way to go.... Tons of possibilities, very low cost. Hearth.com Wood Stove and Pellet Stove Forums....and much more! \| My New Control System arduino (woodnotoil)

07-31-10, 06:04 PM	#38
bsmith Cheap DIY'r Join Date: Jul 2010 Location: Madison, AL Posts: 7 Thanks: 2 Thanked 0 Times in 0 Posts	I built a differential controller that has 4 temp inputs and temperature logging that is pretty cheap ($49). I wasn't going to pay $150 for it either. Here's the link if you are interested (just take out the spaces). http://sites.google.com/site/mydtcstore/ Last edited by Daox; 08-02-10 at 06:26 AM..

08-01-10, 01:53 PM	#40
bsmith Cheap DIY'r Join Date: Jul 2010 Location: Madison, AL Posts: 7 Thanks: 2 Thanked 0 Times in 0 Posts	Here is some from a screen capture. The line under the s command upto the relay states and relay on time is what is stores off each tick. I just noticed the picture I posted is for a depopulated version that just does the temp logging. You can get one with one or two independent differential or HEAT/COOL thermostat functions (selectable). Current draw is about 15-20ma. When the relays are active, add about 33ma more each. >m myDTC Deluxe v1.2 s)Status c)Config t)Set LogTick f)Freeze Mode 0)Set SI Units 1)Mode_R1 2)Mode_R2 3)SP_R1 4)SP_R2 5)Bump Minutes 6)Bump Hours 7)DeltaT 8)LowT 9)HighT m)Menu r)Rules >s DAY:HH:MM TICK T1 T2 T3 T4 R1 R2 R1TIME R2TIME 000:01:12 012 59 59 58 58 OFF OFF 000.0 000.0 >c DTMP LTMP HTMP MODE1 MODE2 LOGTICK SP_R1 SP_R2 FRZMODE 04 F 05 F 60 F DTC_R1 DTC_R2 5 MIN 25 F 25 F ALLOFF Last edited by bsmith; 08-01-10 at 01:56 PM..

11-28-09, 02:26 PM	#33
Bicycle Bob Suncatcher Join Date: Sep 2008 Location: Spiritwood, Northern Saskatchewan Posts: 42 Thanks: 0 Thanked 1 Time in 1 Post	"They're fairly inexpensive, and highly reliable, and they can handle considerable current without additional electronics thingies. Here's one that should be right in your range. -AC_Hacker" Thanks! "On at 40 C, off at 32 C." I thought I'd want to leave shutoff closer to my indoor temperature, but I see that their range only goes up from that model. I suppose that if the collector is active, it will usually kick on the fan, since it hits 70 C pretty easy in still air. Has anyone tried these limits, and watched a partly cloudy day get wasted?

12-17-09, 11:46 PM	#34
dremd Need More Eco Join Date: Sep 2008 Location: Scott, La Posts: 172 Thanks: 2 Thanked 6 Times in 6 Posts	Browser Warning

01-03-10, 01:13 PM	#35
Joe Lurking Renovator Join Date: Jan 2010 Posts: 21 Thanks: 0 Thanked 0 Times in 0 Posts	doax mentioned an arduino in the first post, I like that idea, they can be had for as little as $15 for a clone. They have tons of support online so getting the code right should'nt be a problem, and once we do everyone can copy and paste it. Kinda like MPGuino project. They also sell cheap lcd displays for like $20 so we can use the serial print function to display temp and pump on/off status, ect. I bought one a few months back and have been real busy with things so I haven't got past the first few little tutorials(I can blink some leds like you wouldn't believe) but it is fun to play with and I see tons of uses for us.