Plant Equipment and Water Loops

Section 2 covers the following rather broad range of models for various plant equipment and water loops:

 

ApacheHVAC offers three principal types of heat sources:

The Heat sources dialog provides for defining the first two of these. Air-to-air heat pump types are separately defined.

Hot water loops are used to configure, sequence, and model heat sources involving hot water. A hot water loop has a heating equipment set comprising any number (up to 99) of pieces of equipment. The hot-water heating equipment may be of different types (hot water boiler, part load curve heating plant) and can be sequenced according to a user-specified sequencing scheme.

 

Generic heat sources are used to model heating equipment that either does not involve hot water or for which the water loop modeling will be simplified. Examples include generic boilers, electrical resistance heat, furnaces, steam sources, water- or ground-source heat pumps with fixed thermal lift, or other non-conventional types of heating plant. A generic heat source is associated with a part load curve heating plant, without equipment sequencing.

Both Hot water loops and Generic heat sources can serve domestic hot water loads (passed to ApacheHVAC from ApacheThermal). Both also have options for incorporating recovered condenser heat from chiller sets, air-to-water or air-source heat pumps, and combined heat & power systems (separately defined in ApacheThermal). When associated with Generic heat source, these simply address the load ahead of the primary heat source. In the case of hot water loops, these provide pre-heating as specifically located on the hot-water return pipe. Hot water loops also have the option for pre-heating with a solar hot-water system defined in ApacheHVAC.

Except in the case of Air-to-air heat pumps (described elsewhere in this User Guide),  components that present a heating load, such as heating coils and radiators, are assigned a heat source rather than an individual piece of heating plant equipment. Individual pieces of heating and pre-heating plant equipment coupled to or sequenced as part of a Heat source are separately defined—i.e., they are not defined as types. Each item of heating plant is defined in the context of a heat source (generic or hot-water loop). Thus no individual item of heating plant equipment is permitted to serve or be an element of more than one heat source. Heating plant equipment can, however, be duplicated using the Copy button within a heating equipment set (in a hot water loop). An Import facility is provided for copying a defined heating plant items from one heat source to another (for both hot water loops and generic heat sources).

 

Heat sources described in this section are accessed through the Heat sources toolbar button below.

      

Toolbar button for heat sources list.

 

This toolbar button opens the Heat sources dialog ( Figure 3-2 ). This provides access to all Hot water loop and Generic heat sources defined within the current ApacheHVAC file. It also indicates which of the listed Heat sources has been designated to serve domestic hot water (DHW) loads when passed to ApacheHVAC from Apache Systems. A heat source may be added, edited, removed or copied through the corresponding buttons in this dialog. The Heat sources list in Figure 3-2 shows the default Type to Add as Hot water loop.

Double clicking on an existing heat source (or clicking the Edit button after selection) opens the corresponding heat source dialog (either a Generic heat source dialog as shown in Figure 3-3 or a Hot water loop dialog as shown in Figure 3-10 ) for editing equipment, configurations, options, operational settings, sequencing, and other parameters.