PegTN

I have a 20 yr old Heil gas heater that is part of a split system vented to a Tjernlund HSUL power vent in my basement. The power vent has been making more noise for about a year and has become very annoying. Depending on where the straps are holding it, it can cause noise all thru the vent and the heater cabinet. Now it sounds like an airplane. Anyway, now my heating unit won't stay on and makes a popping noise. The hvac repairman says it is the gas valve. He has quoted me $585 to replace the power vent and the gas valve. He says that the new power vent will have a control board which I don't even use so that is why the price is high.
Do you know if the HSUL which is no longer made can be oiled or repaired in any way to stop making so much noise?
And is it best to just pay for a new heating unit rather than repair one that is 20 yrs old? If so, then what brand and efficiency do you recommend for Tenn which isn't very cold. My repairman gets the best prices on Rheem and installs them the most often. Are there any particular features you would select on a new heating unit or avoid? The two that are in stock now are Rheem RGRA and RGRL. A neighbor thought Trane was the best and that is what she bought. Consumer Reports says they are all about the same as far as reliability.
Thanks in advance for your opinion.

yuri

I really like Rheem and even though I deal mostly high end Lennox units the Rheem is a good basic furnace. Not many problems with circuit boards and the model with the spark ignition is very reliable. At 20 yrs old the heat exchanger may fail soon and Heils are bad for that issue. I would invest in a new furnace and check about the government incentives for high efficiency units. Trane parts are silly expensive in my experience.