I am a one man operation. I do mainly service and repair work. One of my customers called Mon. with no heat. I was out of town. So I call this technician that I have used before in a bind. This guy has 20+ years in the business and his family owned a HVAC company in Dallas. By, the way I have way less than 20 years. Anyway he goes out and calls to tell me that the circuit board is out on this Lennox system. I tell him to talk with the people and explain that I will have a replacement board the next day. I had access to a new board that day but wanted to check the system before I invested 200+ for a board. Tues. I go by the job and do what I always do, ask the cust. what the problem is. (because they always know, LOL) Then I inspect the unit. I crank the unit up and find that the induction motor activates but the igniter didn't light. So I look at the diag. code. It says pressure switch is not activated. So I ohm it out and sure enough it is bad. Everything else appears to be good. I replaced the pressure switch and now the igniter comes on and the gas valve opens. But, the igniter goes out just before the valve opens. I can light the unit with a lighter and it works perfectly. So, I inspect the igniter and see that it is cracked. So, I take it down to the supply house and get an exact replacement. It does the same thing. So, I call the tech I sent the day before and ask what he did. He says, "i replaced the tstat and found that there was no low voltage coming out of the board" So, this leaves me to believe that there is a voltage problem at the board. I check voltage a the igniter and only get 74 volts. Everywhere else I get 120. With this knowledge as well as what the other guy tells me I think I have a bad board. I replaced the board. Unit did the same thing. I'm pissed. Finally, I call the local Lennox dealer and have them run the igniter by model number. Come to find out that this specific series of heater has an 80v igniter. Of course the supply house has never heard of one and I am left to buy it for $80 bucks through the Lennox dealer. This solves the problem and unit work perfect. So now I have replace the pressure switch (actual problem), a new circuit board, igniter, and another igniter. I have about $450 in parts on a job that should have cost a service call and a pressure switch. Now I am really pissed, so I call the tech back to tell him what I found. He said "I blew into the switch and it click so I thought it was good, so I changed the igniter out(with a 120v igniter) and it still didn't work, so I assumed it was a bad board." This idiot with 20yrs experience, number one, didn't look at the diag code which was right, he replaced the igniter without telling me, he replace the flame sensor, and the thermostat, all because he was to lazy to look at the code. He just started replacing parts. I only charged the customer a service call and a pressure switch, I ate the rest. The next day I see this tech and he says that he has the old igniter if I wanted it. When I got it there is a big, well not that big, tag on it that says 80v. I could have choked him. Then he has the nerve to tell me that he will do a few "free" service calls to make up for my loss. Thanks but no thanks.