Hi Fred,   I wanted to let you know the radiant floor heat you designed for the Rock House at Denali National Park is performing just as you said it would. We endured extreme temperature of minus 40 degree below zero for a period of days here and the building functioned perfectly.
   Now that the sun is making its way back to Alaska and spring is on the way the boiler system and floor heat have a much easier time keeping the buildings environment comfortable as the thermostat is set to 70 degrees. Your tubing layout was exactly what the building needed to keep all rooms to a balanced and controlled 68/70 degrees. The photos attached will show the work completed on this historic building.   
Johnnie Powell    Special Projects Supervisor    Denali National Park   Denali, Alaska

Peerless/Munchkin 96% efficient boiler, 1/2" Pex, 18" spacing throughout.

  Hi Fred  I got a system design from you a few years ago - it is working fine. I am reviewing the design and notice that there is no expansion tank and your website page talks about how people overlook the need for a tank. When is an expansion tank required? I have a radiant heat system with open domestic. I use a Takagi TH1 and it heats 3500 sf just fine.
  I am doing a smaller system for my shop and using a Takagi jr. I have 2 loops of 450 ft. Any changes in designs in the last few years?           Thanks  Greg           Verona Wisconsin