forced hot water heating system...

[varkpilot]

..three zones.  

second floor....can't control the heat.  my voltmeter says zero when I touch the red wire/common.  shouldn't it be about 24v??  checked second floor zone valve  in basement and it's 27v.

a bad wire from zone valve to 2nd floor thermostat ??

how can I shut off the heat to second floor?  my gas bill = the national debt!!!  

first floor thermostat say 24v and controls heat very well.

[Snipe Hunter]

Ping Blackhat .............

[blackhat]

What zone valve?  They come in normally open and normally closed. Power causes them to change position. 
Be glad to help you through troubleshooting this.

[varkpilot]

What zone valve?  They come in normally open and normally closed. Power causes them to change position. 
Be glad to help you through troubleshooting this.

all three zone valves are closed.

[jteneyck]

all three zone valves are closed.

Do you mean normally closed, or physically closed at the moment?  If they are physically closed heat should not be going to the second floor, nor anywhere for that matter.  If you meant they are normally closed valves, then something is keeping the valve to the second floor open.  If the voltage to the valve is zero, or close to it, then the valve is stuck open and probably needs to be replaced.  

I think you should be able to turn the valve manually if you remove the solenoid. If so, that would allow you to shut off the heat to the second floor until you can replace the valve.

John

[blackhat]

I’ll try and put the pieces together. 

You said the valves are closed. Assuming you mean normally close, when 24 v is present, the valve is open and allowing water to the emitters. You said the valve has 27v, the upstairs is heating. The valve is working as it should. 

You said you measured 0 volts upstairs. I presume you meant at the thermostat connections. 0 volts means the thermostat switch is closed or the wires are shorted together somewhere between the t stat and the valve. I will assume there is no zone control panel between the tstat and the valve. Disconnect the wires from the 2nd floor stat and wait a half hour. The emitters on that floor should start to cool. If not, disconnect the wires from the valve and again wait to see if things cool off.

[MstrCarpenter]

The zero volt reading at the thermostat may indicate that the common wire (blue or sometimes brown, purple or black) is not connected in the basement. It's not needed there to control the heat, cool or fan functions because they're just single pole switches. A common would be necessary to provide power for thermostats with clocks, timers and/or wi-fi.

I'm most familiar with Taco zone valves. Here's some of what I've learned over the years;

It can take over a full minute for the valve to open when power is connected to #1 & #2. That's also when #3 is energised (from #2) to tell your boiler to turn on.

If the valve is fully closed, the manual lever will leave a serious indentation in your thumb when you use it to open the valve. (If it doesn't, the valve may not be fully closing.)

It is not uncommon for a new valve to smoke during the first few cycles. It is not the factory installed "magic smoke", it's just the heater cooking some wax residue left behind during manufacturing.

[varkpilot]

THANK YOU, ALL!
After hours of trouble shooting, we determined that there must be a short in the wiring.
A lot of wire from basement to second floor and we had to cut "hand-size" holes in the drywall but we found the problem.
First, we discovered mice droppings and then pulled some wire out without insulation.  Black burn  on red.
All new wire from furnace to thermostat!  Second floor heat is under control!!
Again, thanks for responding to my post and I wish you all a HAPPY THANKSGIVING!