When arrived, the burner was running for 4 minutes. Checked the history of the control, there was several times when the burner as running for only 3-10 seconds then shut off for end of heating cycle. Checked the zone valves and thermostats. The zone valve for the entry was getting 24 volts for a second then dropped out then 24 volts for a second. Jumped out wires in the thermostat to check operation. When handling the thermostat, the low battery light came on. Replaced the batteries, checked for power at the zone valve and system operated properly.