Terms and disclaimer
A starting point, not engineering
The tools are free to use. In return, please read what they are and what they aren't before you buy or install anything based on an answer.
What a tool's answer is
Each tool follows a published chart or method and shows its math, so you can check every step. The answer is a starting point for choosing a size. It is not a load calculation, an electrical design, an energy audit, a water test or an installation plan.
When to call a licensed pro
Have a licensed pro confirm the numbers, and do the work, for:
- whole-home heating and cooling (an HVAC pro can run ACCA Manual J for your home),
- anything that runs on gas, including water heaters, pool heaters and generators,
- anything wired into your electrical panel, a transfer switch, or a 240-volt circuit,
- structural work, and anything that needs a permit or has to meet local code.
Each tool says where its own method stops. How we size lists them all.
Safety
Where equipment can hurt someone, the tool quotes the safety advice of the agency that wrote it, such as the CPSC, the CDC or the Department of Energy. Follow it, and follow the maker's manual for your model.
Products and specs change
Product specs on the tools come from each maker's own page or spec sheet, and each tool shows the date they were checked. Makers change models and specs. Before you buy, confirm the numbers that matter to you on the maker's current spec sheet.
Mistakes
Each tool's math is checked against its source before it goes live. Mistakes can still happen, and sources change too. The tools are provided free and as they are, without any warranty. You decide what to buy and how to install it, and Foundry NW isn't responsible for those decisions or their results.
Links to other sites
The tools link makers, government agencies, code bodies and stores. Foundry NW doesn't control those sites and isn't responsible for what they say or sell. Some links are affiliate links; the affiliate disclosure explains which.
Using the tools
You're welcome to use the tools and share links to their results. Please don't copy the sites or present them as your own.
Changes
These terms may be updated. The date of the last update is at the bottom of the page.