I have a very old furnace, by Dowagiac Steel Furnace Co, Model # 90, Serial # 1622. In the past month my pilot light has gone out sporadically, upon relighting, it stayed lit and ran fine. However tonight, I came home after being gone 6.5 hours and the pilot light was out, house was 55 degrees and pilot light was out. As previously, I relit the pilot light, however it has now gone out 3 times in 4 hours. A friend thinks it is most likely that the thermal coupler needs replacing, and provided one the other day but did not replace it at that time as the pilot light had not gone out more than 1 time in about 5 days. The friend increased the size of the pilot light flame, thinking perhaps this was also needed. By this history, is this sounding like only the thermal coupler needs replaced or could more be wrong? I have not had a service person come out yet at this point.