Water Heater Pilot Light Blowout
I have a propane water heater upstairs in my (finished) attic that supplies hot water just to my master bath. Over the last five years the pilot light has blown out on windy days maybe only twice a year. During the last couple of months, however, it has blown out every couple of days! Sure it rains a lot here (near Seattle), but it isn’t really very windy. And it doesn’t seem to be any windier than past years.
So what things can cause the sudden increased rate of blowing out? I haven’t been able to get near the exterior of the flue since that part of the roof is 40 feet above ground. The pilot light always relights, so I don’t think it’s a thermocouple problem. My other propane appliances are still functioning fine, so I don’t think it is a supply problem.
Any other ideas on how to figure this out?
Edited 3/26/2002 11:07:20 PM ET by OFFBALANCE
Edited 3/27/2002 12:08:22 AM ET by OFFBALANCE
Replies
There should be a gap between the top of the water heater and the flue bonnet; typically about 1-2". That gap is there to prevent downdrafts from blowing out the pilot light.
Fire up the water heater by turning up the temp control, and put you habd next to that gap. Feel any heat? It's not drafting properly. Test again in a minute. Better than you hand, take a small mirror and hold it at the gap; condensation on the mirror will also demonstarte flue gas spillage.
BTW, you need to check draft with different conditions in the home; all doors and windows closed, then a door or window open and bath and kitchen fans running.
Also BTW, a draft guage is the best way to check.
Also, look at the top of the tank around and under the bonnet; there shouldn't be any siginifant rust or debris.
I personally suspect the thermocouple; I haven't had (or heard or) piolt lights blowing out for years!
Thanks Bob,
I felt no heat in the gap. Also the top of the tank was fine (except for dust).
If it were a thermocouple problem, why would it work fine for a couple of days before going out?
Ken
Because thermocouples can fail like that. It's a cheap fix. Try it.
I second the motion. My first rule of troubleshooting: Go for the easy stuff first. It works nine out of ten times.
Hmm... A lot of numerical references there. Maybe I should pursue my true calling as a mathematician.
Good points. I'll try replacing the thermocouple. I usually like to be 100% sure before replacing anything because my wife is so cheap. Almost cheaper than a thermocouple. She also has a degree in theoretical mathematics.
Say, after we have warm water, we'll be a thermal couple!
Ken
Sure, blame it on the wife...
Newer house? Very well insulated and sealed? Pilot light tends to blow out if the doors aren't used for a few hours and especially if the kitchen or bathroom exhaust fan is used? Does the heating system draw its air from indoors?
All these things were true in a house in this area. The family were sickened by carbon monoxide poisoning. The problem was corrected by unblocking the make up air to the furnace and adding a vent with a heat exchanger.
Its probably the thermocouple but have a HVAC contractor look at it to be safe. Get a CO detector. IMHO the detector is a good idea for any house with gas.
Thanks, it is a newer, well-insulated house. I have a CO detector that has never once peeped. I even moved it up to the attic next to the HWH since it is separate from the other propane appliances, and there was not even a flicker.
"I have a CO detector that has never once peeped. I even moved it up to the attic next to the HWH since it is separate from the other propane appliances, and there was not even a flicker."
Does it have a digital reaout? If not, get one with a digital readout and be sure to check the readout regularly.
The digi-readout types are more sensitive.
The best, most sensitive consumer models are available at aeromedix.com (no affiliation), which will tell you soonest if there is CO.
This is outside of my area of expertise but you could ask a contractor in your area if extending your flue and/or changing flue caps might help.
I once helped install a flue pipe and was presented with quite a selection of caps. When I asked what the difference was I was told that the cheapest ones, kind of a small inverted bowl, worked fine in most cases but that the more elaborate ones looked better and could help in some cases. He didn't specify when they would help but from their designs I assume they might be more resistant to wind being directed down the flue.
I understand that there must be a minimum distance, both horizontally and vertically, from any obstruction to your flue pipe. The code specifies this minimum. Check to see if a tree or something else hasn't blocked this space and that the minimum was met. Codes enforcement might help you get the numbers you need and might force a repair from the original installation contractor if the minimum was not met.