Proper Aqua-stat Settings

Proper Aqua-stat Settings

Storage Tank Stat ₍₁₎

Desired temperature usually 120^o to 140^o F see scalding.

Boiler High Limit (AQUASTAT WITH RED RESET BUTTON INSIDE BOILER) ₍₂₎

180^o - 210^o depending on boiler operating temperature.

Boiler Operating Stat ₍₃₎

Not all systems have this feature.

If the temperature sensing bulb for the aqua-stat is on the inlet side of the boiler, than set the stat to the desired delivery temperature (check to make sure the cold water feed is plumbed into the tank or hot side of the boiler to have the sensing bulb for this aqua-stat on the inlet side of the boiler).

If the sensing bulb is on the hot side of the boiler this aqua-stat should be set 30^o - 50^o above the desired delivery temperature and a tank stat should be utilized for correct operation. If this setting is too low it will cause the boiler to short cycle (turning on for less than 1 min than turning off repeatedly) .

Return Pump Stat ₍₄₎

If you have a return pump stat, it should be set 20^o above the desired delivery temperature to ensure pump is continuously operational.

Modulating gas valves on instantaneous boilers ₍₅₎

Adjust the tank stat or operating stat up to the point that it is 20o above the desired delivery temperature. Adjust the mod valves evenly so the flame reduces to "off" at maximum desired delivery temp i.e. 140^o -150^o max. Reset the tank and operating stat to the original desired storage tank temperature usually 120^o -140^o.

Note. if the boiler is short cycling check all stats for correct settings. Short cycling will cause the boiler to 'soot up' reducing heat transfer and could cause flame rollout and possibly a boiler fire.

If the boiler is operating with an automatic boiler pump turn off (a.k.a. economaster) when the boiler is turned off. We recommend this feature be disabled or set to continuously on. With the pump running continuously, the tank will have a more consistent and even temperature. In addition the inlet temperature to the boiler at start up will be higher reducing condensation problems at the heat-exchanger.