Thread: brand new direct vent gas water heater wont stay lit?

the pilot light on our old direct vent gas water heater kept going out. we had a plumber come look at it and he installed a new thermocouple and that didn't fix the problem. sometimes it would stay lit for a day after being lit sometimes it was hard to get it to stay lit. so we bought a new water heater had it installed and that one wont stay lit at all...what could be the problem?

the plumber that installed the water heater yesterday told my husband that the gas line might not have enough pressure and to call the gas company...could that be the problem or should i have another plumber come look at it?

Gordon is right for the most part. But with direct vent appliances they receive all combustion air from outside at the vent termination point. The most important issue with DV appliances (especially h20 heaters) is insuring there is no combustion air entering the chamber other than where it is supposed to. What happens is a suction will occur causing a draft strong enough to extinguish the pilot. it is very important that when the unit is serviced and the chamber door removed it is replaced correctly insuring an Air tight seal. Not doing so is a very common mistake by plenty service people. the gas pressure problem that your plumber is stating is a very very uncommon cause of this. If the pressure was low it would represent itself very quickly as a low main burner flame or total drop off as soon as the thermostat cycles on. the other uncommon cause might be a bad valve itself or plugged regulator vent to the main burner valve. But I'd bet is is the combustion chamber sucking air through a bad seal.

Check your room ventilation.

Does you thermocouple get a good steady blue flame put to it? without any breeze or draft deflecting heat away? There are not to many possibilities for this type of problem. The thermocouple generates a small current that holds open a main valve but it depends on a adequate amount of heat to do so and since you have the same problem with two new thermocouples I doubt that is the problem

most likely you dont have enough ventilation for the unit; you might want to get someone else to come look at it.