Had a plumber out who said a backflow and expansion tank needs to be added to the water heater. The boiler already has an expansion tank. The cost for this is 500 and I have already spend 200 changing the feed vent.
He was pushing a Navien tankless water heater boiler combo to replace the existing units at a cost of $6k. I’ve noticed that once the boiler comes to 180 it starts to cycle very frequently so clearly its not very efficient and can expect that to become worse as the cold gets worse.
Given my options not sure what is best to do to maximize where I spend.
Just spend the 500 for expansion tank, backflow and risk the heater continues to function as a hog.
Spend 6k and install a tankless combo.
Any thoughts greatly appreciated from a confused homeowner.