Thermostate problem

Usually those surge tanks do a good job of bleeding the air out themselves.
If the engine is getting warm but you still do not have enough heat, chances are you heater core is clogged. If so, you could try back flushing it to try to knock out the clog.
First though check if it is clogged. If after the engine is warm and the thermostat has opened, feel both heater hoses going into the firewall, under the hood. They should both be hot. If one is hot and the other just warm, then the heater core is clogged.