www.hvactechgroup.com - forums

I just wanted to update everyone who read my last post. Before I do that I would also like to thank those of you who took the time to help me out as much as possible. I still haven't been able to figure out why my furnace seems to emit a short, albeit obvious smell of gas at the end of every burn cycle. I had the valve replaced as recommended by two techs. This changed nothing. I posted my problem here and based on your responses I did some further checks. There seemed to be no real reason why this was happening. I then decided to ask two of my friends who live in the same subdivision as I do whether or not they had the same problem (I also wanted to make sure they had the same furnace..which they did). The first said that he did smell a small amount of gas just like I described. I then decided to go over to the other guy's house and check for myself if he had the same problem. Well much to my surprise he did too! So what's going on here??? Is this normal?? Many of you have said that you should never smell any gas at any time. Is it possible that there is a defect in the make of these furnaces or is  a defect in the valves (honeywell SV9451 or SV9451..I can't remember now for sure). I am so confused right now. I've tried contacting Tempstar but have yet to receive a response. Does anyone have any other recommendations?

It's hard to say for sure over the internet, and of course we would never want to see anything dangerous happen to a client.  The fact that your neighbours furnace operates the same way would suggest you have nothing to worry about.

Also if there was an immediate hazard, the previous tech who replaced the valve would have caught it.  There have been many issues with the smart valves over the years, but as far as I know never regarding leaking gas.

When the thermostat calls for heat, the ventor motor starts up, then the burners fire.  Once the thermostat is satisfied, the gas valve is de-energized.  Any gas left over would have no choice but to be burned by the flame that is present at the burners.  Once the burners shut off, the ventor continues to run to exhaust all the flue gases outside.  In some cases you can smell the mercaptan (odorant) that is added to the gas.  I suspect you're just smelling some residual mercaptan.

You can buy a gas leak detector,  much like a smoke or carbon monoxide detector.  For piece of mind this detector will let you know if you have any serious problems.

KIDDE Nighthawk makes a good detector that will monitor for both carbon monoxide and gas leaks.  Visit the manufacturer's webpage - Here

i got a couple of suggestions, and i never read any of the prior posts, sorry, im lazy and fast sometimes.

check the fitting elbows, they crack sometimes , especially the china ones when over tightened and cant see the leak to easily

another thing to look for is if the smell is intermittent,,, think of what is happening and going on and when it comes on and is noticed  and in realtion to what parts  and at what part of the cycle or sequence of operation...
is it always at the certain time and function of the  furnace?

check the draft, and the combustion and the drains around the furnace as well.. any un burned gases trapped or lingering or sinking caus ethey are heavier than air perhaps in a area where the  cold air forces the gas downward that is  non combusted???