papasumms Posted December 6, 2009 Report Share Posted December 6, 2009 I have a natural gas hot water tank. The top of the tank gets so hot that it sets off the smoke alarm. The "B" vent also gets hot. It sets off the smoke alarm only when hot water is being used for a period of time, i.e. shower, doing laundry. What is causing it to get so hot? Plugged vent? Quote Link to comment Share on other sites More sharing options...
hausdok Posted December 6, 2009 Report Share Posted December 6, 2009 Sounds like it could be. 1. Put a mirror close to the draft diverter on top and see if it gets covered with condensation because it's spilling. 2. How old is it? Maybe the flue baffle is completely shot and isn't slowing down the hot air rising up through the unit. 3. What temperature have you got it set to? 4. What control valve has it got? A few years ago there was a recalled gas control valve. Look at the recalls on this site or at www.recalls.gov ONE TEAM - ONE FIGHT!!! Mike Quote Link to comment Share on other sites More sharing options...
kurt Posted December 6, 2009 Report Share Posted December 6, 2009 That isn't right. There's not anything coming out of a water heater that's good for you, except hot water. If it's setting off the smoke alarm, something's way wrong. Quote Link to comment Share on other sites More sharing options...
RobC Posted December 6, 2009 Report Share Posted December 6, 2009 Are you sure that alarm is not a CO Detector? Smoke alarms detect smoke not heat. Quote Link to comment Share on other sites More sharing options...
MMustola Posted December 6, 2009 Report Share Posted December 6, 2009 The OP said the problems seems to occur when he uses the shower or laundry. This sounds like the dryer or bathroom vent is depressurizing the house. How new or tight is the house construction. I would look at lack of make up air. Quote Link to comment Share on other sites More sharing options...
Marc Posted December 6, 2009 Report Share Posted December 6, 2009 In addition to Mike's suggestions, you might also confirm that the vertical rise of the flue measures at least 5'. Also confirm that negative pressure conditions within the area of the water heater are not excessive. The presence of other vented gas powered appliances within the same space as the water heater may cause sufficient negative pressure to result in draft issues on natural draft appliances. The presence of bath or kitchen exhaust fans, clothes dryers (electric or gas powered) will add to a negative pressure issue. Marc Quote Link to comment Share on other sites More sharing options...
Marc Posted December 6, 2009 Report Share Posted December 6, 2009 Also check that the draft hood is properly installed. It should clear the top of the water heater to allow ventilation air to enter the flue alongside the burner gases, aiding the draft within the flue while also cooling the flue gases somewhat. Marc Quote Link to comment Share on other sites More sharing options...
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