2 zone heating system problems


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Old 02-11-14, 10:47 AM
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2 zone heating system problems

I am having issues with my 2 zone baseboard heating system. It seems like only one zone will work at a time. I found a thermostat wiring diagram in one of the threads here and will be checking all of the wiring tonight when I get home. The odd thing i have noticed thus far is that the thermostat for the 1st floor (honeywell programmable) has 4 wires going into it. The thermostat on the second floor is a simple 2 pole thermo. There is no cooling system on the chain. We have window units only. Is this normal? Is there a reason for 4 wires on the programmable thermostat?
 
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Old 02-11-14, 12:20 PM
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Erik,
Generally a simple programmable t-stat for hot water only requires 2 wires.
If you have AC or warm air with a fan there can be more.
What kind of t-stat is it. Make & model and is it possible to take pics of the t-stat and wires.
Do you have zone valves or pumps to control your zones and what kind of zone valves if any.
 
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Old 02-11-14, 12:37 PM
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Many thermostats can be wired with an 'extra' wire (called a "common" wire and connected to the "C" terminal in the thermostat) in such a way that the thermostat (even if it is battery powered) can be powered from the boiler controls.

Four wires though? not usual in a 'heat only' setup.

What terminals are the four wires connected to? and the bigger part of this question, what are they connected to at the other end, by the boiler?
 
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Old 02-11-14, 03:48 PM
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Well if you have AC as well as hot water you should have a minimum of 5 wires. Rw and W for your hot water heating Rc G and Y for your cooling. You may even have an additional wire for the C terminal. But 5 is the minimum.
 
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Old 02-11-14, 03:51 PM
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Yes, but he said there is no A/C on these thermostats, heat only.

There is no cooling system on the chain. We have window units only.
 
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Old 02-11-14, 05:56 PM
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I interpreted it wrong then, I thought he meant there is no cooling on the second floor.
 
 

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