Hi,I was told by tech that the expansion tank on my oil burner might be gone or needs relief valve installed.Question burner is 5years old model RS111 all new piping and wiring why would the expansion tank be bad or need relief valve and is there anyway of knowing or testing to determine if this is bad or not.Thanks Bill

An expansion tank absorbs or allows the excess water pressure/expansion cause by heating the water to have a place to expand to. Without a expansion tank or if the expansion tank is defective the relief valve will spill water out of the system since there will be to much pressure and the relief being a safety device will open allowing the excess pressure to escape.

If a standard type tank (not in use much anymore) you could shut off the fill line and drain the tank to make sure it was empty. On the new style bladder tanks that have a air fitting on the bottom and if installed in a vertical position you can press the bicycle style air fill valve to see if water comes out. CAUTION!!! if you do this and no water comes out the tank will have to be repressurized to the proper poundage needed for system operation. If water comes out replacement of the tank is the usual conclusion.