Line Voltage Thermostat Wiring - Electrical - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 11-23-2009, 11:32 PM   #1
Newbie
 
Join Date: Nov 2009
Posts: 1
Rewards Points: 10
Default

Line Voltage Thermostat Wiring


I have successfully wired up 3 LinevoltPro 8000 thermostats. And then I came to the fourth one and am having no success, but then it only has 2 12gauge wires in the wall box plus the ground. Both of those wires are hot at 120v each according the the voltage tester.

The successful installations had 2 sets of 12 gauge wires, line and load. This last one though is giving me issues. I can't for the life of me figure out how to wire this LinevoltPro 8000 which has 4 wires, double pole, 2 red and 2 black to the 2 wires at the old thermostat location.

What would be the best way to install this LinevoltPro 8000 in this situation and control this 240v 10' heater, if it is even possible? Adding another 12-2 cable isn't out of the question either, but where would that go to if that is the only option, to the breaker panel or the baseboard heater?

Thanks guys for whatever assistance you might provide.

Bill

Advertisement

bswigart is offline   Reply With Quote
Old 11-24-2009, 12:23 AM   #2
Member
 
Join Date: Sep 2008
Location: Oregon
Posts: 1,497
Rewards Points: 500
Default

Line Voltage Thermostat Wiring


Generally there is a 120 volt heater and only the hot is switched.

Then there is a 240 volt heater which has two hots and both hots are switched.

Then you seem to have a 240 volt heater with only one hot switched.

This thermostat appears to run off of 240 volts. And since you have only one hot switched, the other hot wire is not there to power the thermostat!

Your options are to get a single pole thermostat which is battery powered if you want programmable.

Or an old fashioned on/off single pole thermostat which is not programmable.

Or rewire your heater so both hots go to the thermostat and there are two wires returning to the heater (like the others). Note: Before going and hiring someone to do this, verify that the heater is in fact 240 volts and not a 120 volt heater.

Advertisement

Billy_Bob is offline   Reply With Quote
Old 11-24-2009, 08:12 AM   #3
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Rewards Points: 2,000
Default

Line Voltage Thermostat Wiring


Since most double-pole line voltage thermostats only interrupt one side during normal operation, one method is to wire both poles in series.

HOWEVER, this particular model may require the full 240 Volt input across the line side of the unit, and may not function properly when configured as a single pole unit.

My best guess is you need to use a different model for your scenario.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 11-24-2009, 12:57 PM   #4
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Line Voltage Thermostat Wiring


Quote:
Originally Posted by Billy_Bob View Post
Then you seem to have a 240 volt heater with only one hot switched.

This thermostat appears to run off of 240 volts. And since you have only one hot switched, the other hot wire is not there to power the thermostat!
Unless the 'stat has the option to be powered from 120v and switches the 240v, and assuming the 240v source is at the 'stat box [which can be checked].
Anybody got a link to a manual for this?
Yoyizit is offline   Reply With Quote
Old 11-24-2009, 01:14 PM   #5
Member
 
Join Date: Sep 2008
Location: Oregon
Posts: 1,497
Rewards Points: 500
Default

Line Voltage Thermostat Wiring


As I always say... "When all else fails, read the instructions"!

I searched google.com for LinevoltPro 8000 and found this...

http://www.programmable-thermostat.c...hermostat.html

And it says (on the page)...
"Requires 240 volts - does not work for 120 volt applications"

I don't see any mention of a battery???

So I guess it works by needing both legs of the 240, then the internal resistance of the heater would leave a bit of 240 on the lines at the thermostat, thus powering it.

There is a link on the page to a pdf, but it says 8161, so I don't know if that is the correct instructions?
Billy_Bob is offline   Reply With Quote
Old 11-24-2009, 01:19 PM   #6
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Line Voltage Thermostat Wiring


Quote:
Originally Posted by Billy_Bob View Post
So I guess it works by needing both legs of the 240, then the internal resistance of the heater would leave a bit of 240 on the lines at the thermostat, thus powering it.
Like these two-wire light timers, where the timer uses about 1v and so the light gets 119v?
I couldn't tell from the link.
Yoyizit is offline   Reply With Quote
Old 11-24-2009, 01:42 PM   #7
Member
 
Join Date: Sep 2008
Location: Oregon
Posts: 1,497
Rewards Points: 500
Default

Line Voltage Thermostat Wiring


Quote:
Originally Posted by Yoyizit View Post
Like these two-wire light timers, where the timer uses about 1v and so the light gets 119v?
I couldn't tell from the link.
Actually thinking about my statement, I am wrong... It would be 240 volts if measured with a voltmeter at the two line connections (4 wire).

(I was thinking about the connections between the line and load, but no need for that if you have the 4 wire line/load set-up!)
Billy_Bob is offline   Reply With Quote
Old 11-24-2009, 01:49 PM   #8
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Line Voltage Thermostat Wiring


Quote:
Originally Posted by Yoyizit View Post
and assuming the 240v source is at the 'stat box
It's a 240v source in series with a 240v load in series with two terminals from the 'stat.
I don't think ground/neutral enters into it, whatever 'stat is used has to take a volt or so to power itself, and with no battery, programming will be lost on power fail or if the heater fails by opening.
Yoyizit is offline   Reply With Quote
Old 11-24-2009, 02:04 PM   #9
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,976
Rewards Points: 2,048
Default

Line Voltage Thermostat Wiring


deleted j
__________________
Forget super sized fries. The Washington Redskins could promote healthy eating with First Lady Obama by choosing a (red skinned) turnip for a mascot.

Last edited by AllanJ; 11-24-2009 at 02:18 PM.
AllanJ is offline   Reply With Quote
Old 11-24-2009, 02:32 PM   #10
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,976
Rewards Points: 2,048
Default

Line Voltage Thermostat Wiring


The thermostat needs the 240 volts to keep its innards going. The normal 4 wires coming into the box feed the thermostat innards with the two hot wires.

If the thermostat has rechargeable battery backup, the two wire box would work like this:

Connect one wire entering the box to one line terminal of the thermostat. Connect the other wire entering the box to the matching load terminal and also to the other line terminal of the thermostat. Nothing is connected to the remaining load terminal of the thermostat.

When the thermostat clicks off, there will be 240 volts* across the two wires entering the box and that will power and recharge the thermostat innards.

WHen the thermostat clicks on, the two thermostat innards leads are shorted to each other and the innards get zero volts and have to rely on battery backup.

Both of the wires were hot with 120 volts to ground because one came directly from the panel and the other got voltage from the other side of the line coming through the panel and passing through the heater element. At the tiny current draw (in microamps) of the voltmeter, the voltage dropped across the cold heating element is nearly zero so you measured nearly 120 volts to ground.

* More likely 239 since about a volt would be dissipated, or dropped in the heating element which is in series, given that the thermostat innards probably draw 10 milliamps or so.
__________________
Forget super sized fries. The Washington Redskins could promote healthy eating with First Lady Obama by choosing a (red skinned) turnip for a mascot.

Last edited by AllanJ; 11-24-2009 at 02:41 PM.
AllanJ is offline   Reply With Quote
Old 11-24-2009, 08:10 PM   #11
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Rewards Points: 2,000
Default

Line Voltage Thermostat Wiring


Paperwork from that thermostat's description indicates no battery is used. It needs 240 Volt input to power its function -- and as such -- won't work as a single pole unit.

The OP needs a different model for this room, or rewire it with the 240 Volt line/input.

Advertisement

__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Remote sensor for line voltage thermostat? hbridge HVAC 7 07-06-2012 04:42 PM
thermostat wiring sourmash HVAC 1 07-18-2009 11:17 PM
wiring Dual voltage motors tiquilagold Electrical 12 07-13-2009 11:24 PM
Which diagram to use on Lenox Thermostat wiring setup? Heat Pump Lenox techs needed twilightcall HVAC 1 08-13-2008 12:49 PM
Thermostat Wiring Problem crazy woman HVAC 2 08-15-2006 10:22 AM




Top of Page | View New Posts