I don’t normally think of manual mixing valves in terms of being accurate? Manual mixing valves don’t compensate for changes in either temp or flow rate and are often called “dumb” mixing valves. So how well a manual mixing valve will work for your design will largely depend on the supply/return temp and flow rate variances that your design will experience during actual operation.
It should also be noted that a supply/return differential temp of less than 15F and a maximum floor surface temp of 85F is recommended for barefoot friendly residential HR floors. Consequently, we always do our best to avoid using mixing valves in our HR floor designs. This can be accomplished by determining the appropriate PEX diameter, PEX spacing, zoning, and balance valve flow coefficient settings (Cv) that will allow all the different zones to be supplied at the same temp while still providing the required upward heat gain (BTU/Hour) to each different zone. This is the difference between a true HR system design and the typical free CAD tube layout supplied by a HR product retailer. |