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Happy Pappy
join:2012-08-26
Greenville, OH

Happy Pappy

Member

Brilliant mind needed to assist bonehead with DPST 240V Stat

I have a number of Honeywell LineVoltPRO 8000 Thermostats, Programmable, 7-day, Electric Heat, 1H (TL8230A1003). They have 2 red and 2 black wires. This is for radiant ceiling heat.

The wiring diagram is shown in the top pic.

I also have the thermostat (electric) box that has ONE black, ONE white, and the copper ground. The current (old) T-stat (TWO wire) is connected like this:

Line in Black to Red on T-stat
Line in White capped to White of Load (Does NOT touch T-stat)
T-Stat Black to Black of Load
Copper to ground

I have 240V showing on two Load wires when T-stat is on HIGH. I have 0 V showing when T-stat is on LOWEST setting.

Now...the question: CAN I wire the new Honeywells into the box using the existing wiring? If so, what configurations can I use? (Which wire goes to which wire and so on). I would REALLY like to get rid of the spst configuration for the safety of the dpst configuration if possible.

nunya
LXI 483
MVM
join:2000-12-23
O Fallon, MO
·Charter

nunya

MVM

Pictures would be immensely helpful, as I'm having a real hard time following your description.

Do we know for certain the heaters are 240V? Some are 120V.

If they are 240V, then the white wires were not properly re-identified as "hot". They should be re-identified as hot, if they are not neutral.
Then it's simply a matter of adding the white to the switch (t-stat).

leibold
MVM
join:2002-07-09
Sunnyvale, CA
Netgear CG3000DCR
ZyXEL P-663HN-51

leibold to Happy Pappy

MVM

to Happy Pappy
said by Happy Pappy:

I have 240V showing on two Load wires when T-stat is on HIGH.

What two load wires ? If you have 240V showing when measuring between the black and white wires going to the load then your white wire is the 2nd hot leg.
Get red electric tape and mark both white wires (the one coming from the electric panel and the one going to the load) with the red tape (this is required to be code compliant and to let everybody know that those white wires aren't neutral).

Then follow the instructions for the new thermostat (treating the white wires with the red tape as if they are red wires).

mackey
Premium Member
join:2007-08-20

mackey to Happy Pappy

Premium Member

to Happy Pappy
said by Happy Pappy:

I also have the thermostat (electric) box that has ONE black, ONE white, and the copper ground.

Yeah, your description is really confusing. Your old thermostat is wired with 2 blacks going to it (1 line 1 load) with 2 whites just passing through the box yet the box only has a single black and single white in it??

/M
Happy Pappy
join:2012-08-26
Greenville, OH

Happy Pappy

Member

Problem solved. Case closed. Upon closer inspection, I found all the T-stats were spst. Since I had the correct electrical wiring, I pulled them all out, tossed them and simply wired the new units dpst and they work GREAT. They even SHUT OFF (after my wife lived with them as installed for 17 years.)

We are newlyweds so I am having a "field day" rebuilding this house CORRECTLY!

Thanks anyway!

tp0d
yabbazooie
Premium Member
join:2001-02-13
Bulger, PA

tp0d

Premium Member

Sooooo...

they were not shutting off prior? ie, they were warm with the tstat not calling for heat?

If they were 240v, and one leg unswitched, you could have a ground fault that is leaking current to ground, and will keep part of the element hot. This is a fire hazard. If this -was- the case, you need to do more investigation, including careful terminal to ground ohm tests. you could have some failing elements. I see 240v to ground heat issues all the time with water heaters.

-j