Installing digital programmable thermostats

[Bostonkevino]

Hi,

This is my first post. I recently bought a new home, the builder "cheaped out" and installed non-programmable thermostats in each of the 2 zones - I want to upgrade to programmable units.

I am replacing Robert Shaw (Invensys) non-programmable thermostats with LUX model WX-500 programmable units. My problem is in the wiring - the 2 current (pardon the pun) units are wired differently, and cannot be configured the same as the replacements, as follows:

Unit 1 (first floor zone) 3 wire configuration (RC & RH jumped together, w, and Y)

Unit 2 (second floor zone) 6 wire configuration (RC & RH jumped together, W, Y, B, O, G)

Both units are the same model Robert Shaw thermostat.

As I look at the replacement thermostat, I see that this unit does not offer connections for the existing "B" or "O" marked wires in the original config - anyone know what these are for and what to do about them?

The house will eventually have central air conditioning (coil is installed in system), but I have not purchased/installed the compressors yet - probably next year sometime.

I appreciate any/all comments or suggestions

Thanks,

Kevin O
(BostonKevinO)

[chickenwing]

Double check and make sure the thermostat is compatible with your system. For instance, a multi stage heat pump with auxiliary heat requires a thermostat designed for that type of system and is not compatible with some of the less expensive thermostats commonly found at lowes or home depot. The back of the thermostat packaging should tell what type of system it works with.

Hope this helps... good luck.

[Bostonkevino]

Hi Chickenwing,

Thanks for the feedback - regarding your suggestion I belive that the replacement thermostat is correct for the system (I'll check again). This is not a heat pump, and it has nothing exotic or advanced wired into it - so seems to be right.

There was a diagram that came w/ the replacements install directions that referenced wiring when other connections besides rh, rc, w, y & g were present - it just didn't happen to include wires (actually connection posts) marked "b" and "o"...

I'll keep on researching, when I get an answer I'll post it here in case anyone needs it in the future...

Thanks again,

Kevin O'

quote:Originally posted by chickenwing

Double check and make sure the thermostat is compatible with your system. For instance, a multi stage heat pump with auxiliary heat requires a thermostat designed for that type of system and is not compatible with some of the less expensive thermostats commonly found at lowes or home depot. The back of the thermostat packaging should tell what type of system it works with.

Hope this helps... good luck.

[Bostonkevino]

Hi,

Here's the scoop - turns out the config I described (see above posts) represents a master/slave relationship between the 2 thermostats (upstairs in zone number 2 the 6 wire config is the master - downstairs in zone number 1 the 3 wire config is the slave).

SOooooooooo The company (LUX) responded to my inquiry (by phone) and told me that their model # TX1500 (about $20.00 more) is capable of the master config, but that the downstairs will remain non-programmable (a slave to upstairs zone).

I guess I can live w/ that for now, should still save on fuel costs overall (especially cooling in summer) - and I'll manually adjust zone 1 as necessary when needed...

Not a perfect solution - but a solution.

Kevin O'

[Bostonkevino]

Hi All,

Well, I installed the new thermostat (LUX model TX1500) today. It was a snap, I marked the wires as I disconnected them from the old unit, reversed the process to connect the new unit, slapped in 2 AA batterys, turned the power back on at the breaker, and ta-daa! it works perfectly...

Programmed the unit to correspond to our schedules (including seperate heating schedules for SAT & SUN

This thing is really cool - it even tracks the hours on my filter and reminds me when to change it! Also, The people at LUX are to be commended for excellent customer service - I'd buy their stuff again.

Coincidentally, unit just kicked in to begin heating up zone 2 (right on time!). It will be great to step into a nice pre-warmed bathroom tomorrow a.m.

Cheers!

Kevin O'

[Troy]

Congratulations! [^]

[pof5]

I just purchased a new digital thermostat. When I went to remove the old one and install this new one I noticed that on the old thermostat the red and white wires were used but there was a blue and black one the was unhooked. So I went ahead and setup the new thermostat for a two wire configuration, but does anyone know what these two wires are? Perhaps one is able to supply power so I don't have to use batteries? I mean the original thermostat did function without these two wires installed.

Any insight and help would be great,
Thanks!

[16x80]

pof5

Welcome to the Home Repair Forum

Your two wire system is only heating or cooling, The four wires would be for both. As long as you have it wired for two wire config you should do just fine.

16x80

[pof5]

I'm confused?
Right now my system is wired for only heating or only cooling?

And those other two wires are for the other, and by not being hooked up, then half my system wasn't hooked up?

Thanks

[16x80]

Ok. So your saying you have both heating and cooling in your home. Did they both work before? and do they both work now? The only systems I know of that run both heating and cooling on two wires are in a manufactured home, This would be where the furnace changed the polarity on the wires and makes the thermostat work backwards to allow for cooling.

Throw me a bone here. 16x80