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We are second owners...here about 10 yrs now--house is about 14 yrs old
Home has 3 HVAC systems...two story house...first floor has master suite and study on smaller system than rest of first floor.
Thermostats are all original...programmable Honeywell but not wi-fi compatible
We replaced main AC compressor outside this Dec due to pinhole leaks in coolant lines and have had two problems w being away from home after May and come back to find it was not cooling...still under warranty of course...
First time service guy added some coolant said it might not have taken full charge since installed in Dec when weather was cooler...last wk he found no,problem w/AC unit itself...
Said IF thermometer used only batteries, they could be too weak to power all functions...fan might come on but not compressor...
We never knew it was not wired to house's electricity...our other house's was just one HVAC and thermostat was wired to house...vacation house we have in FL has hard-wired thermostat...X
So we changed batteries in all three thermostats but want to change to newer models...w/wi-fi probably so we can monitor problems better...
How hard/expensive is it to add a "common wire" (I think is term) for a thermostat?
Do we need AC service or electrician to do that?
My husband worked for electrician all time he was in college so he has general knowledge for some issues...
Last edited by loves2read; 08-13-2017 at 09:35 AM..
Tough post to follow. If your asking about wifi stats and how they get wired, yes you'll need a common wire. Every house is different, sometimes the needed wire is already there, sometimes wires are easy to pull, other times it can't be done without opening sheetrock.
When the house is being built... right about ZERO
But I really doubt you need to do any such thing.
Yeah. A new one.
Choose one with gray hair.
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Behind each thermostat is a set of wires that goes down to the furnace.
At 14 years... there should be plenty to work with (vs older homes)
Job one is to identify what wires you have available at EACH T-stat point.
The cables sold range from 5-8 conductors LINK
We live in TX
There is no basement furnace
My husband bought 3 Honeywell thermostats yesterday and installed them
They only use batteries a seem to be working ok as far as going on/off and following time schedule
But seems like one of them cycles fairly often...maybe too quickly...
Going to watch and maybe call AC person back next week
We live in TX
There is no basement furnace
My husband bought 3 Honeywell thermostats yesterday and installed them
They only use batteries a seem to be working ok as far as going on/off and following time schedule
But seems like one of them cycles fairly often...maybe too quickly...
Going to watch and maybe call AC person back next week
We have two programmable Honeywells that I installed 10 years ago. The switch to the furnace requires four wires, IIR, power, temp sense, mode switch, and fan on. These are powered by the HVAC. It doesn't matter, really, the new one hooks up just like the old one did. The difference for me is the temperature is programmable by day of the week and time of day with four optional switch point. There is a battery in the unit for the memory and display.
What a PITA to program two, your husband must be going nuts trying to do three. If it gets to be too much, get wifi ones and program them from a central computer.
The rapid cycle on one can be a matter of a HVAC unit that has low capacity for the zone, or higher heat loads in that zone, or an issue with the sensitivity of that thermostat. There Is supposed to be delay in cycling built into the thermostat and often into the HVAC unit. Maybe that's off?
Some of the older Honeywell programmables did run on batteries only, and did not use a common wire even if there was one.
That said, the notion that the batteries were too weak to power the system is not right.. First off, those thermostats detect battery low conditions and unless seriously malfunctioned, could go some time with "battery low" displayed on the thermostat. Secondly, in a simple 1 stage situation, it is an off on switch, not some big power hungry device, and used to be run by the old mercury switch thermostats without power.
In terms of WiFi, the Ecobee3 and 4 come with Power Extender Kits, that make it pretty simple to install in with no C Wire, as long as you are comfortable getting to the connectors at the furnace.
loves2read, how many wires do you have coming out of the wall and what colors?
Quote:
Originally Posted by MrRational
Not likely. Batteries are backup.
They come with batteries because older homes had mechanical thermostats and didn't need power, you may only have two wires because the thermostat only acts as a switch. Typically there is wound spring inside that expands and contracts with the room air, it has a mercury bulb on the end that will open and close the circuit based on the contraction and expansion of the spring. This is why it's crucial these thermostats are installed level. You would expect in newer home like this there would be at least three wires....
Edit: almost forgot about this, the Nest sytem has a rechargeable battery and in two wire systems they will rob power when the thermostat is making a call for heat/air to charge the battery. There was problems with this because in some cases it was robbing too much power, I don;t know if they resolved it. Perhaps that is where they got the idea it wasn't delivering enough power. I don't know if there other brands that do that. Other than recharging a battery AFAIK the thermostat itself should have no affect on the amount of power because it's not supplying the power to the wires.
Last edited by thecoalman; 08-16-2017 at 01:58 PM..
We live in TX
There is no basement furnace
My husband bought 3 Honeywell thermostats yesterday and installed them
They only use batteries a seem to be working ok as far as going on/off and following time schedule
But seems like one of them cycles fairly often...maybe too quickly...
Going to watch and maybe call AC person back next week
Just redo the entire ac system in your home.
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