Taco Zone Valves w/ new Thermostat


  #1  
Old 11-23-05, 07:49 AM
rfhughes
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Taco Zone Valves w/ new Thermostat

I recently purchased and installed a new Honeywell programmanble thermostat. I just came across postings in here saying you cannot use a digital thermostat with Taco Zone valves since they drwas 0.9 amps. Do any Digital thermostats work with Taco??
 
  #2  
Old 11-23-05, 03:25 PM
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If your determined to use a digital stat

Then use an RA845A relay to switch the load.
 
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Old 11-23-05, 03:34 PM
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Taco zone valves

With some thermostats Honeywell supplies a resistor which must be installed. I don't know the ratings of the resistor. Honeywell's web site may be of some help.
 
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Old 11-24-05, 11:30 AM
rfhughes
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Checked with Mfr. Taco

It is not the current draw that is the problem as most of
the thermostats handle 1.5 A. If you have purchased a current robbing
thermostat, uses the battery only for power outages, you have to put a
3000 ohm resistor across the 571 terminals # 1& 2. The reason for this
is we have an internal switch that turn a heater on and off which breaks
the circuit which the thermostat is depending on to supply power to its
memory. If the Programmable thermostat is battery operated you don't
have to do anything special except hook it up.

The above is their reply to me my thermostat has batteries for display only not for power outages. Honeywell RTH230B. I must admit the Thermostat is not working right as far as the programing does not automatically lower and raise temps as I wanted. When I installed it I removed the wire jumper between Rh and Rc as per directions, I guess I should check my Taco Zone valve to see if it works.It is a model 555-122, Do you know how to test a valve to see if its working right??
 
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Old 11-24-05, 11:40 AM
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Testing Taco Zone Valve

With the thermostat not calling for heat for at least 30 minutes, check the pipe on both sides of the valve. If the pipe is hot on both sides (aprox. 1 ft. from the valve) the valve is problably open & should not be. If hot on one side & cool on the other or both sides cool, valve is closed. Turn up the thermostat & give things a few minutes & check the pipe again. It should be hot on both sides.
 
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Old 11-24-05, 12:52 PM
rfhughes
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Can't do that........

lest see I have 5 zones w/ 5 taco zone a valves so there isn't a foot on either side. I guess I will try swapping it out with another zone head
 
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Old 11-24-05, 02:42 PM
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5 zones

It does not have to be a foot. The only reason for checking both up & downstream of the valve is to feel for temperature difference. Close to the valve on one side & a little distance on the other side is fine. No need to change parts without knowing they are bad.
 
  #8  
Old 03-23-10, 07:24 PM
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Re: Taco Zone Valves w/ new Thermostat

The Honeywell T87 non-mercury (looks like an old-fashioned round) and T8775A (non-programmable digital round) t-stats don't handle the current draw of a Taco 57X series zone valve. Although the HW t-stats are rated for 1.5 amps and the Taco zone valves draw 1.1 - 1.25 amps (measured) the t-stat contacts burn out.

I'm replacing them with Honeywell TH5110D t-stats which require batteries but work well under the load.

I'm seeing the problem with these HW digital t-stats, not the entire line of HW digital t-stats.
 
  #9  
Old 03-27-10, 02:32 PM
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resister

Those honeywell stats that require a resister have that info right on the install sheet and they say its only for the Taco zone valve and the Trane resistance heaters. The supply houses can get the resioster as an accessory out of the honeywell book but few have it in stock. I ran into one that had both the Trane resistance heater and a Taco zone valve so I had to get two...
 
 

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