Checked Buderus hot water boiler with five zones, living room and rear bedroom Are on the same loop attempted to purge air Out of system To diagnose, we have a frozen pipe in the walls no water flow also kitchen radiant Floor heat is inoperable at this time due to air in system. Highly recommend to replace purge valves on radiators. We will need three 3/8 air purge valves. Also recommend to replace air vent located at boiler on the air scoop. Discussed with homeowner about a timeframe and he Will call to make an appointment for the installation of the air purge valves will have to extend the valve stem with 3/8 one inch nipples and three couplings