2-3 weeks ago I had installed a 75 gallon A.O. SMITH powervent water heater. The question is --- isn’t there supposed to be a post purge on the tank after it shuts off. It has a pre purge of 30 seconds before the tank goes on. But after the tank shuts off , the powervent only runs for 3-4 seconds. Then I get a constant back draft and all the fumes end up dumping back into the house. Currently I operate the tank manually, then go out and tape a bag around the vent cap. Otherwise everyone in the house including the animals have health problems.
The house doesn’t have a chimney or smokestack effect – but it does end up having negative pressure due to stove fan, bath fans, dryer, and especially the powervent. I’ve contacted A.O. SMITH, and after almost 3 weeks of emails to them – they cant tell me a thing. They don’t know how long it is supposed to run for or even if it is even supposed to have a post purge. It’s like asking a politician a question – you get all sorts of answers, but not the answer to the question. I looked at other companies, such as Bradford White. They have a 15 second pre-purge, and a 15 second post purge. The contractor who did an excellent job installing a new furnace, is clueless about the water tank, that it is even supposed to have a purge system. The house was checked for CO, but none was found anywhere in the house. Which leads me to my final question – if CO doesn’t come out of the tank then what gases do. I have talked to at least 5 different contactors in the past 6 months and not one can tell me what gases come out of the tank or a furnace for that matter. The mind set seems to be that if there isn’t any CO , then you don’t have a thing to worry about. So is the tank defective? And what in fact does come out of the tank other than CO? thanks.