Combustion Gas Tester False Positives

Bob Rueter · 12-07-2009, 12:48 PM

I do Home Energy Audits, (BPI Cert), and recently audited a house with an Weil-MacLean Gold lp gas boiler. My Bacharach Leakerator Jr, new this summer, gave me alarms of leaks at a T-pipe right at the boiler, and out at the 1000g tank. They called their gas company and the gas company couldn't find any leaks. I have tested some 40 joints with this tester, multiple times each, and it has alarmed 3 times. When I do the test, I repeat it 3-5 times to make sure it is legit before I show the customer.

I spoke with the service manager of the gas company, and he said that they use Gasoila pipe dope for sealing joints, and in the past, they had combustion gas detectors register false positive leaks due to the presence of this pipe joint sealant. I am not sure that is what I saw there; I have some memory of white teflon tape, but am not sure.

Does anyone have any experience with false positives such as this? Has anyone had trouble with this brand of tester? Afterwards, I was advised to do a soapy water test as a follow-up, before telling the customer. Any other suggestions for follow-up tests?

Bob

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Bob Rueter · 12-07-2009, 02:18 PM

After posting this, I spoke again with the gas provider service manager, and he let me come down to test my leakerator on his can of Gasoila. It alarmed as i put the nozzle toward the opening of the can. They had had this same problem previously with this type of detector, not necessarily the same model, but ones that sniff for general hydrocarbons like this one. They had to switch over to propane-specific sniffers that would not alarm on their sealing dope.

Perhaps its time to get a different sniffer.

Bob

**Bob Elliott** · 12-07-2009, 02:45 PM

Originally Posted by Bob Rueter

After posting this, I spoke again with the gas provider service manager, and he let me come down to test my leakerator on his can of Gasoila. It alarmed as i put the nozzle toward the opening of the can. They had had this same problem previously with this type of detector, not necessarily the same model, but ones that sniff for general hydrocarbons like this one. They had to switch over to propane-specific sniffers that would not alarm on their sealing dope.

Perhaps its time to get a different sniffer.

Bob

Nah your fine.
You just need to realize that you can get a false positive.
I only use my Tiff to narrow down the location of what I smell.

Next time use a bubble solution if you suspect a false positive.
I use 9 parts water to 1 part Joy or Dove dish soap.

In the old days working for Sears I found many leaks that way.(dare not mention the lighter trick).

**Scott Patterson** · 12-07-2009, 02:49 PM

Originally Posted by Bob Rueter

I do Home Energy Audits, (BPI Cert), and recently audited a house with an Weil-MacLean Gold lp gas boiler. My Bacharach Leakerator Jr, new this summer, gave me alarms of leaks at a T-pipe right at the boiler, and out at the 1000g tank. They called their gas company and the gas company couldn't find any leaks. I have tested some 40 joints with this tester, multiple times each, and it has alarmed 3 times. When I do the test, I repeat it 3-5 times to make sure it is legit before I show the customer.

I spoke with the service manager of the gas company, and he said that they use Gasoila pipe dope for sealing joints, and in the past, they had combustion gas detectors register false positive leaks due to the presence of this pipe joint sealant. I am not sure that is what I saw there; I have some memory of white teflon tape, but am not sure.

Does anyone have any experience with false positives such as this? Has anyone had trouble with this brand of tester? Afterwards, I was advised to do a soapy water test as a follow-up, before telling the customer. Any other suggestions for follow-up tests?

Bob

Pipe dope will set them off. Heck a trip to Taco Bell will have it alarming in about an hour or so!

I have not used a gas detector in about seven or so years. Just another gadget sitting on the shelf.

**Markus Keller** · 12-07-2009, 04:37 PM

I use a Tiff detector, as Bob, I generally use it mostly to pinpoint once I have smelled gas. Don't know about where you are but whatever peoples gas puts in the gas around here, it is pretty hard not to smell if there is a leak.

Bob Rueter · 12-08-2009, 11:17 AM

There was definitely a smell in the CAZ.

I am adding a soapy water kit to my procedure!

**Scott Patterson** · 12-08-2009, 01:28 PM

Originally Posted by Bob Rueter

There was definitely a smell in the CAZ.

I am adding a soapy water kit to my procedure!

Go to a plumbing supply store and buy a bottle of the soap suds that is made for gas detection. It will not harm anything and it also has a dye in it to make the bubbles easier to see. Last one I bought cost around $3 and came in a nifty little container with a little brush.