Gas and Oil Home Heating Furnaces - propane smell

On an intermittment basis we smell propane out side the house. Our supplier found a leak and fixed it. We were assured that was the problem. We still smell propane. Our three York furnaces(two are a/c as well) and hot water heater are vented through a sloping roof. Typically we smell the propane when there is low pressure and the wind is coming from the back side of the roof. It does not happen most of the time. Once every two weeks when the equipment is running. It does not occur when the equipment is off. Since we cannot find any other leaks and we only have the odor outside the house we believe it to be propane that is not being consumed efficiently by the equipment. Any insights will be appreciated.

Call a service person as soon as you smell it again. If they give you any crap, call the propane company, if still no luck call the fire dept. They will get somebody out there.

Seems at this point a line pressure test must be made. If it hasn't already. NOW

If you only smell the oders when the equiptment is running, it is possible one or all of the heaters/water heater needs to be tuned up.

I've seen furnaces run too rich and all of the gas doesn't burn properly resulting in it being released into the atmosphere. This seem to happen more often in high efficiency equiptment.

You dont say how old is this set up . Have you all ways had all 3 furnaces and the water heaters? Could it be you get a pressure W/C drop in the line when it all comes on. The LP tank is to small for burn off of the LP for all the units?
there are a lot of good points here in the other post Id check them all.

ED ;)

There are three new York Affinity units. Two are a/c as well and the other is a furnace only. The water heater is less than three years old. The units are all high efficiency.
The low pressure I refer to is weather not the units. There is no pressure drop off. We have noticed that when their is a low pressure front we are more apt to get the odor. Again, there is no odor in the house or near the tank or equipment. It is an intermittment problem and the odor seems to run along the front of the house the length of the sloping roof line.

Your sure that with all 3 units on and the water heater that you have 11" W/C at all units?

What is 11" w/c?
The only piece of equipment that was there when Ibought the house and is still there is a water heater that is about 1 year older than the new equipment I had installed. Perhaps the problem ocurrs when more than one furnace is operating. Thanks for your help and sorry I cannot figure out the w/c abbreviation.

What Ed is referring to 11" WC is 11 inches of water column, referring to propane gas pressure. Alot of times you can experience pressure drop if more than one furnace is on at one time. Call your supplier or heating contractor to check the pressure when all the apliances are running at the same time. It should have 11" WC with all of them on.

Thank you for the clarification. Would a pressure drop result in ther propane not be being burned and therefore vented into the air?

It would sure mean it dont burn right . Also you can use a lot more gas that way if the Psi W/C is not right at the burner. Also if the lines are not the right size going to all of the units you have there.

I appreciate all the replies.
Service man arrived and started at the tank which is about 45 feet from house and below it. He showwed me that the instrument he was using indicated a faulty regualtor which could be releasing propane. He changed the regualtor and then checked the line from the tank to the regualotor in the house. No leaks. He then measuring w/c at the regualtor one unit at a me said all were operating on the button. We loaded up all the units and there was no unexpected drop or leak. He checked all the connections and said he could not see where there was any problem. We are in a low pressure front today and it is raining very hard. I will get out to see if I smell any propane. We did not detect any odors yesterday. "Call us back if you smell it again.We are resonsible for the tank, the equipment on it and the gas. Leaks are our responsibility" There was no charge and no concern expressed regarding safety. I will report out the next event. I greatly appreciate the forum and the assistance.

If you have poor mixture air to gas ration in the burner of the furnace it will not should on a leak test or on checking manifold pressure.

I've gone on my share of trouble calls where the custumer smells gas when the unit is running. I did all the usuals, check the tanks, regulator, and leak tested the system all with good results. Checked the manifold pressure at the unit, 10 inches solid. All text book results.

The problems in this case lies with in the unit. There is one unit that comes to mine, Peerless Pinicle Boiler, that you need a real time combustion analyzer to check the air to fuel mixture. With out doing that it's next to impossible to get the mixture right sometimes resulting in propane oders out the exhaust. Now mind you, in this situation, there is no "leak", just improper combustion.

Thanks for the information. If the regualtor wasn't the problem i will have the three furnaces and hot water heater checked for the mixture. I would have to run each unit seperately to determine which one or ones were the problem. At the very least I no longer fear for a leak and explosion.

When you have that many units on one supply tank. I would run down all the line size and make sure that they are the right size. Also you want all the units on when you test the W/C for one unit at a 11" W/C. This test on the units manifold. You do have a 2 stage set up there I hope. With one on the tank and another at the home.

ED ;)

Thanks to everyone that helped out. Service tech arrived and tested the tank which is about 60 feet from the house. The regulator was bad and had "wash back"( I think). We had the repair made three weeks ago and have not had any odor.He was surprised that no one else had noticed the bad regulator. He also checked every other connection under full load and found no leaks. I hope this helps someone else. Great forum. Thanks again