Design programs for HVAC sizing solutions

William & Patti Feldman review HVAC design software Rhvac 8 by Elite Software

Rhvac 8 by Elite Software,, is an HVAC design program that calculates peak heating and cooling load requirements for rooms, zones, systems and entire buildings for residential and light commercial projects. The software, which calculates in accordance with the ACCA Manual J, 8th Edition, also automates calculations for duct sizing, determines equipment selection from a database updated monthly (derived from ARI and GAMA of thousands of equipment models from more than 250 HVAC manufacturers) and creates sales proposals quickly and accurately.

Rhvac 8 also links to REM/Rate, Architectural Energy Corporation's home energy rating tool, REScheck, the Department of Energy's energy codes program, and the Energy Gauge USA home energy rating program.

The solution calculates from manually entered data or directly from floor plans created with an optional Drawing Board module. Rooms and zones can be assigned to 15 systems with up to 1,000 rooms grouped into 10 zones per system. Zoning cfm adjustments are automatically handled by the program as needed.

Rhvac can also calculate the length of tubing needed for hydronic radiant floors and can calculate duct sizes in accordance with Manual D and the static pressure loss of the duct system, showing the static pressure requirement of the system fan.

The basic version of Rhvac uses a manual entry tabular input process, with the user typing in room dimensions. Activating the optional Drawing Board and graphic Manual D Ductsize modules enables CAD-savvy users to draw any size floor plans with any number of required duct sections and have duct sections automatically placed and sized on the drawing.

Rhvac includes a Quick Sales Proposal feature that collates information from checked boxes into standard proposal text. An optional Proposal Maker module allows designers to mix graphics and text for a more professional and customized proposal.

An add-on Bill of Materials (BOM) module facilitates the creation and customization of any kind of bill of materials report, complete with material and labor cost estimates. The program, which allows for complex part assembly items, has the flexibility to work with many different supply house parts databases.

BOM has the ability to add quoted items, services and as many custom parts as you want, either as one-time parts for the current project's bill of materials or into the user's database for future use. In addition, BOM optionally shows cost per pound, cost per area, and cost per gauge for all ductwork items. A BOM grid shows the extended costs and prices for each item, sub-totals for each section, and a grand total. Users can customize layout and select which of more than 70 columns of data to show and which to “hide,” and can save the custom layout for future projects.

Some handy features that can expedite estimates include a Duct Static Pressure Loss Calculator window that calculates duct sizes and the static pressure losses of a duct system from input of an entire duct system or just enough data to calculate the fan static pressure requirement (one single route or “path”); support for new glass and window properties, including insect screen, ground reflectance and more; and allowance for hot water piping losses.

The program also can calculate winter humidification requirements and explore various exhaust options to accurately predict fresh air requirements.

Users can perform easy in-place editing or override various values for every part in the BOM list (including price, sales tax, quantity and part number) for the current project, with any new pricing then defaulted into the database.

Ductwork items can be grouped based on duct material, gauge or shape, or any combination of those. The program does an automatic takeoff of ducts, fittings and registers from ductwork drawn, using Manual D Ductsize.

If a user draws the ductwork using Manual D Ductsize, the BOM window opens with all the ducts, fittings and registers already filled in, including costs and prices defined in the Automatic Ductwork Pricing feature. The user then edits any cost and price data, as desired, for individual parts and can add any additional parts.

New iPhone apps

Here are two new sizing applications for the field that can streamline calculating tasks for iPhone-toting HVAC technicians and designers.

HVAC Pipe Sizer (Liquid) by Carmel Software,, enables quick sizing of a simple piping system for a wide variety of pipe materials and liquids, including hot and chilled water, by inputting the fluid flow in gallons/minutes, plus the velocity, head loss or pipe diameter. Additional parameters such as the type of liquid, properties of the liquid, pipe material type, total length of pipe, and quantities for up to 11 different types of pipe fittings can be specified. Slider controls facilitate quick changes in input values, though exact values can be inputted manually.

HVAC Pipe Sizer (Steam), also by Carmel Software, enables quick calculating of the properties of saturated or superheated steam given a variety of parameters.

The application also supports sizing a simple steam piping system, using results from the steam table calculations. Users can view tabulated or interpolated results by selecting from a variety of input parameters and easily altering them using the slider control.

Bill and Patti Feldman are freelance writers for magazines, trade associations, building product manufacturers and other companies on a broad range of topics. They can be reached at [email protected].

TAGS: Technology