have a 3 zone heating high efficiency gas. lately furnace will turn off and won't turn on again until temperature in house reaches 60 degrees. also, all 3 zones will not work at once. have tried rotating thermostats and no differences. have had furnace worked on numerous times and with no success. could it be an electrical problem?

Is it forced air or hot water? How are the zones controlled? Do the thermostats actuate the furnace, of just open the zone valves which then actuate the furnace? When the thermostat calls for heat, it switches power from the red wire to the white wire. The white wire then must both actuate the zone valve or damper and the furnace. You need to pick a zone, and trace the wiring and see where the heat signal is getting lost.

It Is Hot Water Heat. Thanks

See if the zone valves open as soon as the thermostat calls for heat, and if they signal the boiler to come on.

what kind of zone valve and how many wires go to them?

No, the zone valves don't open as soon as the thermostat is turned up. most times have to turn on furnace manually. furnace will start when temperature reaches 60 degrees. the zone valves are Honeywell and are 2 wires.

Sorry I have never seen a 2 wire boiler zone valve. Most have at least 4 wires, 2 go to the thermostat and 2 are for an end switch that turns the boiler on when the valve is open.