I have purchased a new Rheem 2 stage furnace with 3 zones for a new house that I’m building and have two questions that I am wondering about.
1) Is 90′ to far to run to the A/C condenser, would it lose effeincy and have to be upsize, any other concerns with this length of run?
2) I am told that the furnace will fire at low stage and run for 15 minutes and if the thermostat isn’t satisfied it will then fire at high stage until set point is achieved. I think this would be fine in most normal living conditions, but I will have a separate zone for a finished basement area that will be set at 60 when not in use and 70 when being used. I would like the furnace to fire at high stage immediately to achieve this faster but my installer says it won’t work this way. Any other opinions on how to make this work?
Thank you in advance for all comment and suggestions
Replies
you are in over your head. get a good pro involved. if you have to ask here you are headed for trouble. not trying to be rude. just want you to realize this. good luck!
"Is 90' to far to run to the A/C condenser, would it lose effeincy and have to be upsize, any other concerns with this length of run?"
90 feet for refrigerant lines is farther than I like to design for, but is it too far? No. If the lines are sized properly and run properly (get the manufacturuer's help on this and hire a very good contractor) the effect will be minimal, depending on the capacity of the unit. I recommend staying within 50 feet for anything 7-1/2 tons and under. If the lines are undersized, you will lose capacity (not efficiency). If they are not properly pitched and run for the installation, there could be many problems almost all of which will fry the compressor.
A residential zoning system will not do what you wish. Options include: living with its limitations or having two separate systems installed.
How did you decide/determine the size of the furnce you bought ?
Tim:
Thanks for the reply. I would think my request for the 2 Stage to operate this way makes perfect sense and am surprised that there isn't a way to do it!
I let my contractor do a load calculation via Rheems system but he did reccomend that I increase the size for best results. Says the calc gives you bare minimums?
Thanx, Ken