I am building a log cabin and plan on installing radiant heat. I have been reading where most recommend that the circuits do not exceed 300 ft for ½ inch PEX. The problem is that the house is a long ranch (64 ft.) and for the 1st 4-5 circuits and you eat up any where from 125-150 feet just getting to and from the mechanical room. Some sites talk of a remote (or forward manifold) or even a “long” manifold very simply my question is: "Wouldn’t the PEX between the forward manifold or the long manifold and mechanical room become part of each circuit coming off of that manifold anyway? Therefore in effect you really would not be shortening any circuit. Or is the fact that you would use 3/4 pex or copper for the manifold create more volume and so less heat loss and the length in the manifold would not be a factor for the circuit lengths. Did that make sense??