It's a 3-thermostat problem... (HVAC guys, need advice)

[NitroPress]

I've given up on putting a true zoned control system in the house for now - the wiring is too big a hurdle to get over without making it too big of a project. Next year, maybe.

For now, I want to put in more sophisticated thermostats. I think I have it worked out but would appreciate some feedback.

The house (basically as-built, too much 2002 builder's junk still in place, including cheap-*** Taco thermostats) has hot-water heating and three independent zones with individual thermostats. All three heating thermostats are mechanical, merc-bulb... and groooann two-wire. It's that missing third wire that's screwing up my plans to do a more sophisticated setup. And yes, the g'damn contractor ran 2-wire cable, the idiot.

The house also has central AC with a second thermostat next to the upstairs zone heat thermo.

Here's what I want to do:

• Put a basic digital 5-2 programmable 'stat on two of the zones. I have found battery-powered ones that don't need the third power wire - didn't know they existed! Any recommendations for inexpensive models appreciated.
• Put a decent 5-2 programmable thermostat on the upstairs zone for combination control of the AC and that heat zone. From looking at the hookup diagrams, it seems that the 5-wire connection allows control of two totally separate systems for heat and AC. Is that right? Can I do basic 2-wire heat control and 3-wire power/fan/cool control with one unit that supports 5-wire hookup? Will the heat want to turn the fan on? Suggestions for models here appreciated, too.
• I'd like matching units with a really simple daily interface (override and hold); a sensible programming process would be nice, too. Around $100 for all three 'stats would be nice.

And any further comment/feedback. Thanks.

 

[6t7gto]

Have you looked into wireless controls?

 

[NitroPress]

Have you looked into wireless controls?

Not seriously. Like the Man in Black, "I know too many Spaniards"... I have too much experience dicking around with wireless systems to want another such headache. I will pull new wire for a sophisticated system this summer.

Even if the wiring was in place now, I'd probably look at the same short-term solution. No time to plumb in a fancy system this winter and I want better control over the zones ASAP.

 

[Sidekick]

I've given up on putting a true zoned control system in the house for now - the wiring is too big a hurdle to get over without making it too big of a project. Next year, maybe.

For now, I want to put in more sophisticated thermostats. I think I have it worked out but would appreciate some feedback.

The house (basically as-built, too much 2002 builder's junk still in place, including cheap-*** Taco thermostats) has hot-water heating and three independent zones with individual thermostats. All three heating thermostats are mechanical, merc-bulb... and groooann two-wire. It's that missing third wire that's screwing up my plans to do a more sophisticated setup. And yes, the g'damn contractor ran 2-wire cable, the idiot.



He is not an idiot he ran what was required- if you had future plans you should have told him
Zone valves usually only require 2 wire.
from the thermostat and 4 wire from a controller at the boiler

The house also has central AC with a second thermostat next to the upstairs zone heat thermo.

Here's what I want to do:

• Put a basic digital 5-2 programmable 'stat on two of the zones. I have found battery-powered ones that don't need the third power wire - didn't know they existed! Any recommendations for inexpensive models appreciated.
• Put a decent 5-2 programmable thermostat on the upstairs zone for combination control of the AC and that heat zone. From looking at the hookup diagrams, it seems that the 5-wire connection allows control of two totally separate systems for heat and AC. Is that right? Can I do basic 2-wire heat control and 3-wire power/fan/cool control with one unit that supports 5-wire hookup? Will the heat want to turn the fan on? Suggestions for models here appreciated, too.
• I'd like matching units with a really simple daily interface (override and hold); a sensible programming process would be nice, too. Around $100 for all three 'stats would be nice.

And any further comment/feedback. Thanks.

Many programable t stats have several R terminals, what that means is you can operate the heat and A/c off of the same thermostat. there will be an rh and an rc terminal- just remove the jumper that comes with those stats and wire in your a/c to the rc
,y, and g terminals and your 2 wire heating from the rh and w terminals

 

[Sidekick]

If you need anymore info, contact me. I am an HVAC person with 44 years of experience

 

[BGibson421]

this doesnt meet your $100 limit but here is my suggestion: Use Honeywell pro6000 T-stats for the locations that you will use them as Heat only. When you program the t-stat you can chose Heat Only and the options for cooling will not be seen. It looks smarter and nice-er =) plus you can change them back to control cooling later if you want. For the Main T-stat I would us a Honeywell pro8000. This t-stat is just plain awesome plus it has options for a remote sensor if you so desire. When you decide to put in a full zone control system, the Honeywell zone control system does a great job and you already have the t-stats that will interface with the zoning system (all digital Honeywell T-stats work with Honeywell Zone Control and you keep your warranty.Using mismatched digital t-stats will usually void zone control warranty) This will cost you approx $250 but if youre serious about zoning later, this is a great way to start.

 

[BGibson421]

...... all of the t-stats I mentioned will operate on AA batteries until you can pull more wire.