Installation of furnace in a basement with a sub-floor
Thanks to the help of this forum, I have decided to install a high-efficiency furnace (2-stage 60000 btu with multi-speed motor) this weekend. I can foresee potential risks of water leaking from the pump and the furnace based on the questions discussed in this forum and my research. In order to reduce future headaches, may I ask for your advice on proper installation.
My basement has a sub-floor . Existing furnace, water heater tank and the filter rack are sitting 2.5″ below the sub-floor; making it a little bit inconvenient to change the filter. (have to twist the new filter before putting into the rack). An one-inch filter rack will be installed and the return duct will be changed from 8″ x 24″ to 10 ” x 24″ x 7′.
1. Do you see any advantages or disadvantages in the long-run if I raise the new furnace up by 2″? e.g. I need to use a condensing pump and there may be risks of water leaking from the furnace. would it be a good idea to separate the furnace from the ground?
2. should I use 8″ x 8″ x 2.3″ interlocking bricks or a big patio stone underneath?
3. the sub-floor was created by the previous owner? Could someone tell me what might be the reasons that a sub-floor was put in for the basement? keep the space warmer?
4. The acidic solution will go to the laundry drain and I saw posts about the need to neutralize the solution that would certainly “eat” metal pipes over time if not neutralized. could I put limestone on a soap dispenser to filter the acidic water before it goes to the laundry drain?
5. could you tell me what I should do to neutralize the acidic water? how often should I do it?
6. If the existing conventional furnace and the old gas water heater tank are using B vent, there is no need to worry about installing a liner in the B vent. Is that right? FYI, I will do a retrofit to replace my steel-framed basement windows. there will be less fresh air going to the basement. please advise if new risks will be created.
7. do you think it is beneficial to change the old gas turnoff valve near the furnace? some contractors offered it but the one coming said it is not necessary.
I really hope that the HE furnace will not create new risks to the safety and structure of the house.
Thank you very much.