I couldnÂt find this Polaris hot water heater problem posted anywhere  so maybe this is the right forum: LED Error Flashing 2 Times "Control is in lock-out because the pressure switch did not close." It cost me 7 minutes of service time and a $135 service bill but I finally figured out the amazingly easy and almost stupid solution to this problem. There are two clear plastic tubes that run from the purge fan to the outake pvc, so the service tech simply took the plastic tube off the outake pvc and blew into it. It turns out the Âpressure switch can get stuck. As he blew on it, I could hear the switch popping open. So simple. After 24 hours without hot water, I was annoyed and relieved at discovering this fix. IÂve spent hundreds of dollars in repairs without getting the answer so hopefully this helps someone else out there who is struggling with the same problem. If you need pictures, send me an email: debare at(@) mac dot com so you can fix it yourself.

Probably built up scale and the normal cooling of the heat exchanger and tank during the night. The heat exchanged in a gas water heater is often a metal spiral running up the middle of the tank, and held in with just a few welds at the top and bottom. As it cools and heats it shrinks and expands and rubs on the tank wall creating all sorts of odd noises. It may become stuck, and make a single larger movement that can be relatively loud. You may even hear sizzling from rain or condensation in the flue falling onto the hot heat exchanger. The scale in the bottom of the tank and on the heating column can make all sorts of pops, grinding noises, an occasional squeal, etc. as it changes size with temperature, breaks off, and then falls to the bottom.

The Plumbing Codes are very explicit on T&P drain lines. The T&P valve must be fitted with a "Full Bore" discharge line. (The diameter of the discharge line must be equal to the diameter of the T&P discharge port-(typically 3/4")) If the water heater is installed over a floor that will not be damaged by water such as an unfinished basement or garage the line may discharge onto the floor. If the water heater is installed over a floor that may be damaged by water the T&P discharge line must terminate outside the structure or into an approved indirect waste receptor. (May not be directly connected to the house DWV system). When a water heater is equipped with a drip pan the T&P drain line MAY NOT discharge into the drip pan and it MAY NOT share a common drain line with the drip pan. When it is necessary to have a horizontal run of pipe from the water heater location to the point of discharge the drain line must have a continual downward slope (Min. 1/4" per ft. pitch). When a T&P discharge line is terminated outside the structure the point of discharge must remain clearly visible. (May not be concealled behind shrubbery or landscape material.) Under the Uniform Plumbing Code the discharge end of the T&P drain line must be a minimum of 6" above finished grade but not more than 24" above grade and the discharge end of the pipe MUST point downward. Under the International Residential Code (IRC) the discharge end of the pipe must be within 6" of finished grade and must point downward.

"When you think about it 40 gallons isn't a lot of water." I disagree. That is a lot of HOT water at 140°. If you were to draw it all down at 2.5 GPM, it would take 8 minutes. ThatÂs theoretical, because the way you draw it is to push it with COLD water. But thatÂs OK, because you arenÂt going to take too many showers at 140°  one, maybe. So to make it comfortable, you mix in 40 gallons of water at say, room temperature, and now you have 16 minutes at 102°. All the time, the fire is burning in the heater. If you have not been drawing a quart of water from the bottom of your heater once a month (And I know you havenÂt.) then you may have a scale at the bottom. This fools the thermostat into thinking you have many gallons of hot water, when all you have is a thin scale of hot deposits. Pinoke