Old Aquastats on Wood Boiler

If the aquastat is rated to switch the voltage and current involved, it could be wired in series with whatever turns the boiler on/off. (Assuming there is a control system.... There might be some variations, such as operating a damper or some kind of stoker.)

If it is domestic hot water, I think the maximum setting is 120°F (~49°C) to prevent scalding.

Its impossible to tell with out knowing what brand, model, and intended application it was designed for.

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boiler type would help some. is it an indoor or an outdoor boiler? the outdoor types usually had an aquastat controlling a damper door these where usually only 24 volt the two wires if this is correct then connect to a small voltage regulator that reduces regular house hold 110 volt down to the 24 volt required. I usually set my outdoor boiler at a temp of 180 to 220 degrees they are low pressure, and i use a normal hot water tank pressure valve that is factory set for 17 pounds.

You are a bit vague on details

-What is the boiler used for? Heating or hot water or both?

-If it is for heating, than is it, a gravity system or one with a pump?

-What voltage is the two wires?

They could go to a combustion air intake damper, a pump, a combustion air blower, an alarm or any thing else.

Follow the wires and see where they take you.

aquastat control the fan or air opening for wood boilers. when it gets hi, it stops the fan or closes the air intake. when the water temp goes down about 10 degrees, it turns the fan on or opens the damper. contact the manufacture to learn what it should be set at. most homes use 180 degree water temp. if it is base board copper, ok. if it is pex tubing in the concrete or under the food floor, that is too high. there is no answer till a professional who designs the systems can decide. heat loss will tell you how much each room needs. loss to that room and how you are heating it.

If you have infloor radiant heat with laminates or other adhesive type materials, you need to regulate your temperature accordingly to the manufacturers max. temps. For example, I run my boiler temp at about 170 deg F. to keep my floor at 80-85 deg F.

I also adjust my aquastat temp throughout the fall/winter/spring accordingly to control my burn. You will likely also want to adjust the span on the aquastat, you could start with a 10-12 deg F. span and monitor from there.