I am getting conflicting advice on tube sizing for a project and am trying to understand the true theory of inslab hydronic heating as a primary souce of heat. I have a in slab Hydronic heating project being installed in the Kelowna BC area. A 1600 sq ft shop that I want to be able to maintain at about 10 degrees Celsius, an attached residence with slab on grade main floor of 1300 sq ft and a second floor above the main of 1450 sq ft. There is between 5000 and 6000 feet of tube in this whole design with zones of up to six loops up to 300 feet long. My thought and some advice I receive is to use 3/4" tube as it is the primary heat source and will reduce head pressure on the circ pumps. My designer says to use 1/2 inch ox barrier pex in this project. Can anyone give me any firm advice as the reasons one would choose one or the other. Thanks in advance. H2obody.

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Originally Posted by h2obody

I am getting conflicting advice on tube sizing for a project and am trying to understand the true theory of inslab hydronic heating as a primary souce of heat. I have a in slab Hydronic heating project being installed in the Kelowna BC area. A 1600 sq ft shop that I want to be able to maintain at about 10 degrees celcius, an attached residence with slab on grade main floor of 1300 sq ft and a second floor above the main of 1450 sq ft. There is between 5000 and 6000 feet of tube in this whole design with zones of up to six loops up to 300 feet long. My thought and some advice i receive is to use 3/4" tube as it is the primary heat source and will reduce head pressure on the circ pumps. My designer says to use 1/2 inch ox barrier pex in this project. Can anyone give me any firm advice as the the reasons one would choose one or the other. Thanks in advance. H2obody.

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My designer says to use 1/2 inch ox barrier pex in this project. Go with the designer. Oxygen barrier is a better tubing (depending on the brand) and the head pressure will not be a problem depending upon how you zone and how many loops in each zone. You might also consider like I did to run additional loops of pipe with separate zones in the same area. Future think when you develop a leak and since I did the job for a very good friend of mine the additional cost was minimal. Also if the person is a true designer/engineer he is required by law to carry some errors and omission insurance. The insurance might come in handy if there is a major foul up.