Only one way to get bubbles and that is by introducing air into the stream most likely there is a leak in the plumbing this kind of leak only leaks air when there is suction. if you are losing no water then you have a suction side leak. WHich is strange because the heatr is not on the suction side.
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Only one way to get bubbles and that is by introducing air into the stream most likely there is a leak in the plumbing this kind of leak only leaks air when there is suction. if you are losing no water then you have a suction side leak. WHich is strange because the heatr is not on the suction side.