radiant heat from old boiler

jeremy_15

I have dug up my basement floor as part of a basement reno and am planning on running infloor heat off my existing boiler which is approximately 70 yrs old. The current system has one pump feeding a forced air heat exchanger to heat the top 2 floors and the 1" return line coming from the exchanger tee's off (before returning to the boiler)to a 5/8" line going to a 2nd pump that feeds a baseboard heat loop and a rad heat loop. A hot water supply coming from the boiler also ties into these loops just past the pump and is controlled by an actuator. I had a boiler guy design a system for me but it just doesn't seem right. He wants to install a seperate glycol heat exchanger to feed 3 loops for 450 sq ft of loops. This involves a whole lot of extra equipment but he says I can't "cheap out" on radiant heat because I won't be happy with the results. I know that the system was originally designed for infloor/Radiator heat because One 1/2 of the basement was a wood sub-floor and under that was 1" steel water lines siting on a base of burnt up coal from when the boiler ran on coal. it never worked because it wasn't insulated well enough by the coal. IT appears they then installed a rad at the end of the first loop which was later also abandoned for baseboard heat. Is there any reason why I can't just do a 2 loop system (225 ft/loop) and tie them into the existing system? I know you're not supposed to have the water temp any higher than 150 F in a concrete pad but what damage could occur from the occasional slightly higher temp (max. 165 F). Would it be uncomfortable on the feet? The 2nd pump has its own thermostat in the basement so I would assume that the pad would never get anywhere near that hot before the air temp would cut the pump out. Also is there any special drying procedures for the concrete and should the water be circulating before/during and after the pour to accelerate drying? What is the best type of insulation/vapor barrier to use (about 5.5 ft below grade in central Canada). should the heat tubes be about 1" from the top of a 4.5" pad tied to rebar? I know this is a lot of questions to ask but I want to get it right and not waste my money or wreck the old boiler. Thank you for your help, Jeremy