Question about indirect tank aquastat

briandonahue1800

I have two boilers and two indirect storage tanks with aqua stats that should be closing zone valves when the water hits 120 for domestic hot. The zone valve wasn’t closing and domestic hot was getting up to 180 so I switched out the zone valve the problem is still occurring. Is it most likely the aquastat? Any good way to test that? The aquastat looks pretty new.

HVACNUT

If its just a simple mechanical aquastat like an L4006 or L4080B, you'll hear the audible click when you turn the dial and the contacts make or break.

Pictures would help. Having an electrical meter would be the simplest way to figure this out. What model aquastat and zone valve?

You can try to remove one wire from the aquastat to see if the zone valve closes. If not, trace that wire to the zone valve and disconnect the wire there. The valve itself could be bypassing.

briandonahue1800

thank you. Believe its a 4080 B breaks on close, not hearing a click when adjusting temperature. Its wired back to a zone valve which i replaced. Starting to think its wired wrong

4GenPlumber

If the tank is sitting at 180 you wont hear anything, its already over heated. "Breaks on close" is like saying "on when off". If the water is at 180, check for power from each contact in the aquastat. One lead on your multi meter to one contact, other lead from multimeter to ground. Only one contact should have power. If both have 24v then aquastat is bad. More than likely something is wired wrong at the Zone Valve. Send Pic of that.

hot_rod

breaks on close?? Sounds like an oxymoron.

A limit control usually designated by a L in the part number will open on temperature rise or at the temperature setting. So when the tank hits the set temperature the contact points open, no power crosses. Zone valve is closed.

@HVACNUT suggestion about removing one of the wires from the control when the zone valve shows open, tells if the control is open or closed.

A control with a F fan sometimes denotes a control that closes on temperature rise. Turns on a fan for example when the pipe or plenum increases in temperature.

But the model number will tell the entire story of the control, how it controls, the differential, adjustability range, etc.

An indirect will have a L limit switch that opens, or turns off the zone valve when at temperature