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Burnham Apline with indirect DHW circulator and Taco Zone valves

I recently had an Alpine boiler installed and cannot seem to locate in the manual the proper wiring for a set up for indirect DHW in a system using zone valves instead of zone circulators. (Boiler has "system" and "boiler" circulators as stndard). My contractor has the DHW aquastat run to a Taco Zone valve controller -- Zone 4 priority on -- which operates the zone valve for the DHW zone but as far as I can tell, the boiler DHW circulator stays off. The control panel on the boiler also indicates Central Heat is on when there's a DHW call, which makes sense as the Taco zone controller cannot send a special signal to the boiler to differentiate between a heating zone call for heat and zone 4 call from the aquastat.

My question is whether the DHW indirect tank aquastat should be wired to both the DHW temp switch terminals on the Alpine boiler and to Zone 4 of the Taco zone controller. This should turn on both the boiler in DHW mode, boiler controls turn on the DHW circulator, and Taco controller opens the zone 4 zone valve. The Taco zone controller would also send a Central Heating signal to the boiler but if priority is set on the DHW by the boiler it should not matter that Central Heating is also on.

The only problem I foresee is that the DHW circulator may run before the DHW zone 4 valve is open since the Taco zone valves take about 30 seconds to fully open. The DHW circulator would be running briefly on a loop that is closed which might briefly overload the pump motor.

Any other setups with zone valves instead of zone circulators on the Alpine that have been field tested?


  • Cookhigheffhaus
    Cookhigheffhaus Member Posts: 7
    Indeed I have both a DHW circulator and zone valve for DHW. An unusual design I believe but don;t think there's much harm.

    Problem I have tho is the Burnham Alpine boiler has separate inputs for boiler and DHW. But with the Taco zone valve controller there is only a single TT boiler output so even with DHW on priority zone, the Alpine doesn't know it's a DHW call. Since I have outdoor sensor, on warm days it takes forever to satisfy the DHW since the boiler temp stays about 140 (thinking it's a central heat call on a warm day).

    I found another thread here on point "DHW Priority Question" /discussion/151793/dhw-priority-question

    But I am wondering if there is an easier solution -- take a tap off terminals 2 and 3 on the DHW loop taco zone valve (end switch) and wire it to the input for the boiler DHW terminals. Then when the DHW thermostat calls for heat, the zone valve will open then trigger a DHW call to the boiler (again because the Zone Valve controller is getting a call the boiler will also think there is also a central heat call from the signal to TT but I don't think that will matter much).

    Anyone have an idea if this will work? Or should the DHW inputs be wired to to terminals 1 and 3 on the zone valve? Or would I need a relay on 1 and 3 then wire that to the DHW inputs on the boiler to isolate the zone valve switch from the boiler DHW inputs?