Loopcad Free Download

[Kym Wash]

LoopCADmakes it easy to do the math but it is also important to know how to do the math without software which leads to today blog post. What happens when you need to quickly figure out how to size your pump without access to a computer?

How close is this to my loopcad calculation? Its about double. My radiant infloor system was designed for a 10 degree delta T with the highest head loss circuit being 4.9. When I add the head loss for my REHAU ProBalance manifold that adds an extra .01 feet of head making the total head in my system 5 feet of head.

Lets quickly break down what that all means. The BTUH is the heat required every hour to heat the space you are putting the radiant into. This number will be provided to you by your radiant designer or installer and is a critical number. Get this number wrong and all bets are off so dont even try to calculate it if you do not know how.

The DELTA T is the temperature drop in your radiant in floor system. Most residential systems are designed to work at a 10 degree delta T because it provides for an even temperature across the floor. In commercial applications or in areas we dont live in a 20 degree delta T is common.

The last number is the specific characteristics of the fluid you are using. In this case it is pure water which is 500. This represents the weight of 1 gallon of water ( 8.33 ) , times 60 minutes in an hour times the specific gravity of the water. You do the math and it equals 499.8 which we round to 500. It takes 1 btu to raise 1 pound of water 1 degree in 1 hour.

This means that for my radiant infloor system I need a pump that can do .78gallons per minute at 9.48 feet of head. Using this number we can now look up the pump curve for a Wilo or Taco pump and select our pump for the job. ( I am a big fan of Wilo and Taco Pumps )

28-35 btus per square foot is serious output at 110 degree water and far higher then anything else on the market. You can see the report yourself its linked to on my site in the various blogs on raupanel.

I do not guarantee or warranty any of the statements made on this site so do not take them to seriously. In any project you must always consult with an expert and follow local codes and regulations. Not doing so can result in very bad things.

All comments and thoughts are mine alone and do not represent the companies I work for or anyone else for that matter. I have not been paid, bribed or coerced into writing any of these posts unless otherwise noted. :)

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