Intermittent Gas Smell

KM1DAS

Hi All,

We just had a new NTI TFT installed in our basement to replace our old grossly oversized oil fired boiler. After about a 2 weeks of being online, we started getting a smell of propane in the living room which is above the boiler. I checked the room the boiler’s in and there was no smell of gas. The IPEX System 1738 flue pipe runs up to the roof through the living room closet. I have noticed the smell seems to be coming from the closet so it definitely could be a flue gas leak. When the smell is present, it definitely gets stronger when the boiler modulates to a higher fire setting. We had the installing contractor come out with his gas sniffer but all of a sudden the smell had gone away. They used the UV light to inspect all the IPEX joints and verified the fittings are glued all the way around and they sniffed all the flue piping and gas piping in the house (which is only a single 30 foot run from the regulator to the boiler). The contractor then had the propane company come out who pressure tested the gas line from the tank to the boiler gas valve and found no leaks. 

In talking to the propane company, they indicated that flue gasses shouldn’t smell of propane unless there’s unburned propane in the flue gas which there shouldn’t be. I personally watched the installing contractor tune the gas valve with a Testo 310 while on the phone with NTI in both high and low fire, and he double checked that the readings were the same when he came back. 

The gas smell in the living room comes and goes if the unit is running but there’s never been a smell in the basement where the boiler is. I’m left believing there are 2 separate issues: 1. A leak of some kind in the flue piping and 2. Some type of problem with the boiler causing intermittent fueling issues. The installing contractor has not been able to find any leaks in the flue pipe and the combustion analysis is good. 

I’m hoping someone may have insight on potential causes of the intermittent fueling issue that seems to exist and also what methods could be used to verify the integrity/find the leak in the flue piping. 

Thanks for the help!
-Paul

Mad Dog_2

Timmie Mc Elwain knows his combustible games  better than anyone.  Oh Timmie...where art thou??  Mad Dog

Mad Dog_2

I know its a pain, but can you put a water head test on the chimney flue ?  Can you post pictures?  Maybe even dye the water so u can easily see a leak.  One of the burners could be fluttering or failing to light with the others.  The installing contractor seems like he's trying to do the right thing?   Mad Dog

Jamie Hall

And your propane contractor is exactly right -- the smell of combustion exhaust gas is totally different from the smell of propane. If you can learn the difference, it will help a lot in pinpointing the trouble.

Tim McElwain

Do you have any other propane appliances. If so the smell could possibly be coming from them. How close to the house is your propane tank.

EBEBRATT-Ed

Do you have a propane water heater, range or propane fireplaces?

PRR

I was smelling gas. Or maybe part-burned gas? At the time the only propane was the water heater. And the supply was a fairly small (20 gallon?) tank. In the end, the tank was getting low (I was new to the house and to propane). When low and cold it would not deliver gas as fast as the high-BTU on-demand water heater burned it. Somehow this led to gas "dribble", raw cold gas at the ends of the burners, so it stayed in house rather than rising up the chimney.

Yes, fresh propane, well-burned propane, and part-burned propane all smell(*) different, and is good clue.

(*) Pure propane is "odorless". All heating propane has "rotten-egg" stink added to it, which burns off. My 94%eff furnace's exhaust smells "fresh", not rotten. Straight propane is like freshly rotten eggs(?). The under-fed water heater smelled like bad sewer (a related smell, the partial combustion makes intermediate stinks).