Arrived onsite to customers complaint of cold spot in flooring. Problem area was in the upstairs guest bathroom, and potentially the downstairs. Downstairs zone thermostat was set to 65 degrees and it was 66 degrees downstairs. Turned thermostat up to downstairs, zones pump kicked on and sent 90 degree water to that zone, zone is concrete, so it may take a while to heat up with 90 degree water. Upstairs guest bedroom zone has one thermostat and two zone valves wired together. Thermostat sent signal to zone controller, than to zone valves, both valves opened and had 1gpm of flow through the zone, piping was hot on supply and return pipe. Found no issue with this zone. Replaced two failed expansion tanks. Cleaned tf1 filter cleaned condensate trap on boiler. Did routine checks on boiler, such as gas pressure, flame sensor, amp draw, found no issues. Thank you for choosing CPI Plumbing and Heating Inc.