Taco Zone Control Board

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  #1  
Old 10-17-19, 12:00 PM
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Taco Zone Control Board

I installed a Taco board last winter but now it seems that zone 4 on the board has failed. Both thermostat and valve lights activate but neither the boiler or the pump turn on.

I moved that zone 4 thermostat and valve to zone 3 and the board activates the boiler and the pump as it should.

Any ideas what problem I should look for?
 
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Old 10-17-19, 03:13 PM
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Did you try jumping out that zone 4 at the board
 
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Old 10-17-19, 04:56 PM
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No, but I'd like to try that. I'm assuming that could confirm a bad board, right?

Can I find instructions for that or would I just need to figure it out?
 
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Old 10-17-19, 09:06 PM
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Remove board from controller and look on bottom side for poor solder connections, broken/cracked traces, etc.

Reflow solder joints that look questionable.
 
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Old 10-17-19, 09:07 PM
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Welcome to the forums.

There are many variables to those control boards. More than likely you have a bad relay.
Please post a well lit picture of the board and we can help you further.
How-to-insert-pictures.
 
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Old 10-18-19, 07:15 AM
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New board is less than year old. Relays have a high reliability factor.

Most likely problem is manufacturing assembly defect.

Bad solder joints are major assembly quality issue.

AOI (automatic optical inspection) systems are used at end of assembly lines to look for defects. https://www.cyberoptics.com/product-...al-inspection/
 
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Old 10-18-19, 09:03 AM
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Hi, did it work before and now has failed?
Geo
 
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Old 10-18-19, 11:58 AM
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He did not say it was a new board installed. I request a picture as it helps to identify the exact model.
 
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Old 10-18-19, 04:28 PM
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The unit is a ZVC405. It was purchased new, has been in use for about a year, and zone 4 was working last year.

Picture attached. Looks like it attached upside down but I installed the board right side up.

The wires you see plugged into zone 3 now were in zone 4. I unplugged zone 3 wires because it didn't need heat atm. I even moved the little diode thing from zone 4 to zone 3 just to be sure that wasn't blown.

Next step is to remove the board and check solder points I guess. Any other ideas? Or is there a more reliable board I can purchase?

Name:  taco.jpg
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Last edited by PJmax; 10-18-19 at 06:16 PM. Reason: reoriented/resized picture
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Old 10-18-19, 06:09 PM
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Hi, if you’re not using zone 5 for priority shut the priority switch off and use that zone for zone 4.
Geo
 
  #11  
Old 10-18-19, 06:21 PM
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That is a solid state logic control board. No relays for the zone valves.
That board carries a 3+ year warranty.

You could use Z5 like Geo mentioned but I'd try to get a warranty exchange.

Taco ZVC-405 manual (pdf)
 
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Old 10-19-19, 09:47 PM
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The back side of board has soldered connections. It would be easy to visually check them and reflow any questionable ones with ordinary soldering iron.

There does not appear to be any static sensitive solid state logic devices on that board. Board is a rudimentary control system designed to be used by HVAC service types.
 

Last edited by doughess; 10-19-19 at 10:05 PM.
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