Last week our pilot light went out. When we tried to relight, the pilot would light but when I released the button it would not stay lit, so I could not start the furnace of course.
A friend replaced the Thermal Couple for us and that seemed to fix it. The pilot would stay lit in "pilot mode" then we could replace the cover and start the heater as normal. We set it to the mid-way mark (labeled "Hot"). Later that night, it went out again but we were easily able to relight it. No problems since then until today, been about 5 days.
The furnace is in an outside room off of our carport and it gets very cold in there (uninsulated) so we put some insulation in today. We used a water heater blanket, but only wrapped the top 3/4 of the heater in order to avoid touching the control box or getting anywhere near the pilot area. When doing this, the pilot went out so we turned off all the gas, just to make sure we didn't have any problems. After we were done, we relit the heater.
This time, the pilot worked fine but when I put the gas control knob into the "full" position and then used the Temp dial to get the furnace to light, rather than catching at the lower temp area (several lines under "hot"), it wouldn't catch until 1/2 way between "hot" and the max setting. Now, if we try to set it down midway to "hot", which is the recommended setting, the heater doesn't stay lit, although the pilot does. So, we took off all the insulation, checked to make sure the thermal couple wasn't loose or damaged and can't find anythign wrong, but we cannot set the furnace lower than 1/2 way between "hot" and max. This troubles me because last week when we replaced the couple, it could be set a lot lower if we wanted.
The furnace was made in 1996. We bought the house in June '02 and have had no problems, outside of the hot water not lasting as long in the winter as in the warmer months. But since we're in Arkansas, we don't have much cold weather, so it's not been a huge bother.
Any advice? Should we call out a plumber to look at it? Is it okay that it doesn't catch until this setting?