Paulbm has it right: There are two separate issues here: 1. That the furnace is using all of the combustion air for combustion -meaning that it is pulling the air into the furnace and then sending it out the flue. 2. The furnace has a problem with missing air return - so it's pulling the air from the closet, heating it, and sending it out to the rooms. 3. Both things are happening All of these situations are serious and are an indication that the job wasn't done by a qualified installer. The fact that it sucks the door closed indicates that it's probably at least #2 The closet must provide combustion air intake by having vents of at least a specific size that are a combination of requirements by the furnace and water heater manufacturer. Alternately, you can provide outside air intake for the furnace through a pipe - also spec'd by the furnace manufacturer. (you would still need venting for the water heater). You may not have a disconnected air return on the furnace. That is very dangerous in that it will draw carbon monoxide from the water heater flue into the house. In a way, you are fortunate that the water heater is being blown out. Far worse would be for the water heater to stay going and kill you while you sleep. Get this problem resolved immediately. Also get a Carbon Monoxide detector. Carbon monoxide is colorless and odorless. It's possible that this problem was a legitimate error... but not likely. I would be very suspicious of the person who did the install. What was done here can kill you and your family.

A 15 year old tank heater should definately be replaced. What you choose to replace it with will depend on if you choose to keep it power vented and what size you may need. I personally wouldn't keep it power vented unless there was no other way to vent, simply because of the noise it generates as well as the expense compared to a conventionally vented water heater. If you have issues with venting locations, then I might consider replacing it with a tankless power vented model. At least then, the vent wouldn't fire up except when you were actually using hot water. The cost differential between a power vented conventional heater and a tankless would be virtually non existant, but the install price of the tankless would be quite a bit higher. With the efficiency differences, you might be able to recoup the additional install costs in the 10 years you plan to stay in the home.

Hi, Bottom panel maybe screws are stripped. You want to put some pressure under the panel by the screw and then try to take the screw out. Think like pulling and turning the screw at the same time. If you know about electricty get a meter and measure the voltage at the breaker. Don't do this if you don't have a clue. Good Luck Woodbutcher

I believed you when you said, " I replaced (the original tank), wired it as directed." Now, this new tidbit has me concerned about the whole electrical scheme. As I started to read your message, I expected that you were trying to say that there was a circuit taken off of one leg of the line. But you describe it as a line coming into the heater and powering one of the elements. That suggests that the other element is also powered by a simplex, 110-V circuit. If so, this needs rewiring as you have a seriously miswired condition. I suspect this because you said: "I tested the connections numerous times and always came up with 120, never 240" To get 240 V, you need to have two legs of the service wired into the heater. And this would put each (say, the Âblack and the ÂredÂ) on each heater, the upper and the lower. Since each of them has a second terminal, those are wired to the neutral (white) wire. If that is the case, that you have a 3- or 4-wire cable properly connected to the heater, then it means that the one element was not able to be shut down by the thermostat. Moreover, it also appears that the chance wiring has allowed the one element to be powered by 240V via the cord connection. Certainly, removing this cord is the right and the first thing to do. It appears that, for the first six hours, the new heater was being warmed by only one element. When the thermostat attempted to shut down both elements, the miswiring stopped one and started the other at doubled voltage. (Boom!) While a water heater is power with 240V, the elements operate independently at 120V, each. They should never see 240V, unlike the heating element in a clothes dryer. Now, if the unit is properly wired, you can test voltage again and get the following results. If the colors are Black, Red and White (and Green, if available,) the voltages will read as follows: B to R > 240V; B to W > 120V; R to W > 120V; W to G > zero V. For purposes of testing only, you should get the same voltages comparing a HOT wire to either neutral or ground (Green.) The White and Green will only share a terminal in the service entrance panel. (Different, though if the feed is a subpanel.) Please reply. Pinoke