Crown Boiler TWZ Series, Installation Instructions Manual

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XII Operation
A. General Information
This boiler uses the Hydrolevel Hydrostat® model 3250-Plus control to provide control of boiler water temperature, as well as to
manage demands for up to two circulator zones. In addition, this control also provides protection against low water conditions.
The 3250-Plus is used on both boilers equipped with tankless heaters and those without. In the latter case, the low limit is
normally turned off so that the boiler will not maintain temperature when there is no call for space heat (“cold start” operation).
Boilers not equipped with a tankless heater comply with the 2007 Energy and Independence Security Act, using an “Economy”
feature, which raises or lowers the target boiler water temperature during a call for space heat based on thermostat cycling
patterns. For additional information see Part B of this section.
FIGURE 12.0 HYDROSTAT 3250-PLUS CONTROL COMPONENT LAYOUT
IMPORTANT
This boiler is equipped with a feature that saves energy by reducing the boiler water
temperature as the heating load decreases. This feature is equipped with an override which
is provided primarily to permit the use of an external energy management system that serves
the same function. THIS OVERRIDE MUST NOT BE USED UNLESS AT LEAST ONE OF THE
FOLLOWING CONDITIONS IS TRUE:
• An external energy management system is installed that reduces the boiler water
temperature as the heating load decreases.
• This boiler is not used for any space heating.
• This boiler is part of a modular or multiple boiler system having a total input of
300,000 BTU/hr or greater.
• This boiler is equipped with a tankless coil.