I have a Ruud Achiever 90 plus. It is about 5 yrs. old. When the furnace kicks on it keeps either blowing the flames out or it is shutting it down. Both fans will run but there is no flames. I have cleaned out what I can, I have shut it down and even shut the gas off at the shut off. I then resarted everything and it is still the same. What do I do?? How do I fix this?? No money for a repairman!!

Hi I have an older house with newer forced hot air boiler. The house is old and big and I think it will be more effiecient to run the fan all the time rather then only when heat is on. Lots of people have told me this will help keep constant temp. I at least want to try. The problem is, I switch the fan to on from Auto and nothing happens. If I leave it on On and heat comes on, so does fan, but shuts right off after temp is reached. When I first bought the house, the plumber/HVAC guy who did work on the unit had to come and fix the fan because of the opposite problem, the fan was constantly running regardless of what thermostat position was. I was not home when he came to fix, He has been nothing but uncooperative and we cannot reach him. The house was a rehab project and he was a bad contractor choice to say the least. What is the easiest way to resolve this? I thought maybe it would be a wiring thing but I have no idea?