I think the heater was working fine. We ran out of propane, had the tank refilled. Water in the tank is cold, thermostat set on medium hot. Pilot lights, burner ignites and burns for about 3 minutes. The high temp limit switch resets and shuts down the system. Water is still cold. I reset the switch and started over, same result. Bought a new switch, same result. I bypassed the switch and within 5 minutes the bottom outside of the tank began to smoke and put out a "burned pan" smell. I shut the system down and reconned the temp limit switch.

Observations: appears to be venting properly, heater is less than 6 months old, it's a Bradford White 50 gallon. Flame is burning orange, I'm not sure how it used to burn.

Any thoughts?

By "temperature limiting switch" I assume you mean the FVIR "anti explosion" control. IF so then you must have a venting problem keeping the flue gases from exiting the combustion chamber, and if the flame is yellow, it is not getting enough air, or the flue is blocked.

If the unit is 6 months old, then it is still under a warranty. Did you have a professional install it?

We bought the house 6 months ago and the heater was replaced as a condition of sale. I really don't know who installed it but we can probably find out.

Is it likely that something inside the heater itself is blocked? I put a smoking piece of cardboard about an inch away from the flue that vents to the outside and it seemed to suck the smoke right out.

look at the label and find the manufacturer date...if its less than 1 year you have a warranty w/o a reciept...contact BW and they will send a repair person for free

if its over 1 year then you will still get free parts, but not labor

if you have the receipt or a supply house tag that will save you too

i always sticker every water heater....maybe the plumber did too? call him

Bradford White uses their serial number as their date code. It will have two letters. Go to their website and it has a page you can go to to see when it was made. It is a 6 year warranty from the factory for parts and tank.

If you can not locate the original installer, call a plumber and have them inspect it. If there is a problem with the venting, then it can be a more serious issue, like Carbon Monoxide poisoning, if you keep running it.

the installing plumbers name will be on the plumbing and gas permit/inspection form.
get THAT plumber back to have warranty work performed.

Maybe in Mass. that would work but other areas might not require a permit even for a licensed plumber.

gas work with no permit/inspection ???
your insurance companies must love that...

Even when it is required, it is seldom done. Doing so would add a couple of hundred dollars to the installation with NO benefits to the customer.

the benefit to the customer comes when the house goes up for sale and the home inspector asks for permits.
around here they DO ask...
banks will not lend money on a home unless the home inspector gives it a passing grade. this passing grade includes permits and inspections on any recent visible improvements.
gone are the days when homeowners or handymen installed things that required permits without taking the necessary permits.
if one talks to the local inspectors, one will quickly find out what a PITA this is for them..

Gas flow is low.screen?

Here, the inspectors look at the water heater, and IF there are obvious deficencies will make a note for them to be addressed, but NOTHING about permits.

Inspectors here are the same. They just look to see that all codes are met and thats it. Nothing about permits.