New furnace - what to do next
I have a two story colonial approx 2250 sq ft. The second floor is much colder than the first floor (seems to be a popular problem). Had a 180,000 BTU furnace from 1965. (Re insulated the attic last year.) All the ductwork is covered with drywall except for the main trunk. No dampers in the system.
I had four contractors out for quote. All four quoted 100,000 BTU high efficiency furnaces with variable speed blowers (each one stated the variable speed blower would help with the cooler second floor). None of them did a manual J calc. They just asked for the square footage and how many windows in the home. Being on the cautious side, I did a manual J calc and verified the need for a 100,000 BTU furnace.
I went with a two stage - 100,000 BTU furnace with a variable speed motor.
Now: The temps in the Cleveland area have fallen quickly this year.
I have a new furnace with a cold second floor. The two stage sounded like a great money saver but isn't working out too well. When running on low fire the second floor barely gets any heat. Even when on high fire, second floor isn't getting enough heat.
What to have quoted next:
I cant have all the duct work replaced.
I have gotten many opinions:
Install electric baseboard heaters in each bedroom.
Install duct booster fans.
Put a furnace in the attic.
Just live with it - the original owner did.
Any other suggestions or opinions?
Have balancing dampers installed in the supply branches at the main trunk.
Is your supply duct loud now with the VS blower.
I haven't notice a louder supply duct. The 180,000 BTU furnace had a huge blower. You can definitely tell when the furnace goes to high fire
Very hard to say without seeing the place.
Some things come to mind:
Balance dampers can only help, as beenthere mentioned.
Perhaps it would be a good idea to run additional duct to the second floor, maybe through a chase or chases built into a first floor closet, etc. Both supply and return.
I would suggest avoiding putting a furnace in the attic - the inherent heat loss stinks.
Speaking of which - what's going on in your attic?? Do you have sufficient insulation? This problem lies in one of two places - either insufficient airflow, or excessive heat loss on the second floor.
Another basic idea is leaving the fan on in heating to mix the air and thus even out the temps, but this won't help much if you have inadequate ducting to the second floor to begin with.
I assume no easy fix will get you there, so I'm leaning towards balance dampers and probably new supplies and returns run up to the second floor. Not trivial, but it takes $ to solve problem correctly, you know?
Balancing dampers will probably improve your system performance.
Will it help to close off the registers on the first floor?
Drywall will have to be removed to expose the duct work coming off the trunk line.
Originally Posted by nic1067
People patch drywall all the time.
This is going to take money to fix correctly, you should get used to that idea, or get used to a cold second floor.
Do you have any cold air return in the upstairs or is the stair case the path for cold air to travel back to the furnace ? If you do not have any type of return air from upstairs you may want to look into what your options are to get 1 or 2 of them upstairs somehow or put a return at the foot of the stairs will help if you have no way of putting them upstairs. Dampers will help, so will sealing all your ductwork, as well as insulating them help to control heat lose for those long runs you have.
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run your thermostat to the 2nd floor and partially close your 1st floor registers.
My similar problem was solved by running the fan all of the time in the winter.
In the summer it was solved by closing some downstairs dampers/registers however I wouldn't start closing a bunch of registers or dampers without knowing the external static pressure of the system. If you cause to much back pressure it could impact your airflow as well as your temp-rise on heating (can lead to coil freeze during cooling).
What model furnace did you go with?
In the land of the blind.....the man with one eye is king....
If you are hoping to get by cheap, I would have a competent tech. check the total duct static pressure with all downstairs registers closed, if it is acceptable, try running it that way. Your furnace can be set to operate only on high stage also if that works better.
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