Can a new water heater cause a Aquatherm heating system to fail?
You should have four lines hooked to the heater one coming in from the water supply one that goes out to the faucets there should be two other hookups one that sends the hot water to the heating system and one that returns it if you take the heater hose that returns to the heater and disconnect it first shut off the water to the heater and sometimes they'll put stops on the return line and the main line to heater line that you can open and close. If they have these shut offs on them shut the water off to both lines also turn off the cold water supply that fills the heater then disconnect the hose that Returns the water to the heater is a good idea to open the t&amp;p which is the pressure release valve before you disconnect the hose then open the line that goes to your heater and open the water that fills the heater itself put a bucket under the line that I told you to disconnect open the valve to the water heater slowly until water comes out without any air in it this will usually release any air that's in the system once the air is out turn the line back off hook the hose back to the heater and then try and see if your heater works make sure you reopen the line that returns from the heater you do not need to open that line to drain the heater and get the air out just leave it closed if there are no valves to shut them off then just turn out the main line to the water heater open the t&amp;p valve usually has a metal lift on it that lifts up to release the pressure then you can disconnect the hose that comes back from the heater and then open the valve from the heater and that will do the same thing to release the air