I'm getting estimates to retrofit my 1919 house, converting from 3 floor furnaces to central gas heat. I have one lowball estimate, one high estimate, and one mid-range estimate (with two more that are supposed to send me their quotes by the end of the week). The high-end quote is twice the low end!
All of the companies have good reputations in the area and have been in business upwards of 40 years. The biggest difference seems to be that the expensive company actually took measurements and did a load calculation (although he came up with a size that is in line with the others by rule-of-thumb), and he emphasizes that his company ONLY uses alumaflex, not the plastic flex coil for ducting.
Question: How big of a deal is plastic vs aluminum supply ducts? He told me the ductwork accounts for 1/3 of the price he quoted me, and roughly equal to the difference between his quote and the next one lower. Is the plastic ductwork satisfactory, or will I be sorry if I go with it?
Thanks for any advice.