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Taco zvc404 with triangle tube prestige excellence questions
First time post here and I'm sure I will probably forget something important but I will try and give as much background information as possible. I'm a big DIY'er who is fairly competent.
The system I am working on is a combination hydronic heat with DHW with Triangle tube prestige excellence. The old zone control was a Honeywell Aq250 which was replaced with a Taco zvc404. The problem we were having was that the thermostat would call for heat but the zone control was not sending that call to the boiler. It would not close the circuit at the T T terminals. This did not happen all the time but seemed to only happen with large temp swings. A simple reset at the breaker would fix the problem and heat would come on and work well until the next time. This was happening about 3-4 times a month.
I was able to replace the zone control and the heat side works. My question is about the DHW priority setting using the 4th zone. The Honeywell only had the T T wires and the 120 Hot, neutral and ground wires that were connected to the boiler. The Honeywell had a light that would come on when there was a demand for hot water and I'm assuming that it would shut off the zone circulation pump. For the life of me I can't figure out how the honeywell zone control knew when there was a demand for hot water?
Right now the boiler will move priority over to hot water when there is a demand for it but the zone circulation pump still runs. Do I need to run another wire from the boiler to the 4th zone and if so from where? Do I even need to worry about the zone circulation pump running and just let the boiler deal with it?
I apologize if some of my descriptions are not very clear and appreciate any help.