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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Taco ZVC406-EXP-4 Zone Control Valve Board, brand

Customer Question

I have a Taco ZVC406-EXP-4 Zone Control Valve Board, brand new replacing the old one that failed. Wired per manufacture's instructions with Zone 6 indirect hot water heater as priority. Set the DIP switch to Priority ON. The TT connections are to a Honeywell L8148E aquastat controller. There are no external pumps. Only a single circulator for all 6 zones. When I powered up the unit the DHW heater operated properly with yellow LED from unit calling for heat and the zone valve (TACO 571-2) opening producing a red LED. Unit came up to temperature and shut off. Other zones did not work. Zone 5 and 6 T STAT LED's flash rapidly at low intensity.
JA: Sometimes, Set the DIP switch to Priority ON, HVAC issues that that you think will be really complicated end up being easy to fix. The HVAC Technician I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the HVAC Technician should be aware of?
Customer: DHW maker is Amtrol with it's own control. Setpoints can be changed, differential temp can be changed and a priority switch can be set. This unit will produce an Error 3 code if priority is set and hot water can not be satisfied within some time frame. Not really sure what the time frame is. Might be one hour. Normally with priority this 40 gallon unit reaches temperature in 15 minutes.
JA: I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and connect you two.
Submitted: 1 year ago.
Category: HVAC
Expert:  Rick replied 1 year ago.

Which XX end switch terminals are you using on the ZVC406?

Customer: replied 1 year ago.
Using the "Main" End Switch for TT. Not using any end switches for pump or Zone 6 Pump as there are no additional pumps.
Expert:  Rick replied 1 year ago.

What about the other dip switches? is this unit master or slave? I'm assuming you must have another since you have 6 zones and the control only handles 4

Customer: replied 1 year ago.
The other DIP switches are at factory settings. This is a master board. There are no other slave boards. There are 5 heating zones and one DHW zone making the 6 zones. All zones are controlled with TACO 571-2 3 wire zone valves. Tried to get the phone link to work but does not appear to be working. I am not at the job site now. I have the entire system wired with two 40 VA transformers and just wire nut connections to all zones. No priority but all work. This is so the customer has heat. TACO has been no help on the flashing LED problem. I will bench test the board at the shop tonight. Just power only. If there are no flashing LED's then I will wire one zone at a time to see if there is any difference.
Expert:  Rick replied 1 year ago.

Well you haven't given me any indication of a problem except for the flashing LED's which is a new one on me(makes me wonder about a defect in the board). Let me know what your bench test determines.