Adding a Duct

[GOLDENBEAR1]

I am replacing my 45 year old 100,000 btu furnace. My house has only 7 ducts, one in each bedroom and bathroom and one in the living room and one in the dinning room. The old system kept the house comfortable, except for 10 -15 of the coldest days, when the living room (15 x 25 feet) wouldn’t get warm enough. My ducts are covered in asbestos. As an alternative to replacing all the old ducts, one contractor suggested augmenting the current ducts by adding an overhead duct and register to the living room. Does this work well? He was also recommending a 75,000 btu Rheem modulating downflow furnace.

[dash]

If he did the calculations correctly,adding a supply should correct the issue.

[GOLDENBEAR1]

So, adding a overhead duct to a downflow furnace and mixing with floor vents does not create a problem if the duct is sized right?

[dash]

So, adding a overhead duct to a downflow furnace and mixing with floor vents does not create a problem if the duct is sized right?


No,not in my opinion,ceiling grill shoul also be located properly with the correct typ and size supply grille.

Floor grille is fine too.

May have issues gettinng the branch duct to the ceiling,like a very long run with turns,which means it needs to be larger then you might think to get enough air to the problem room.

[GOLDENBEAR1]

Thanks for the help and Merry Christmas.

[deejoe]

A well placed FLOOR supply will do more good than a ceiling supply(especially in the heating mode) , after all this where you are,at the floor level, sitting or lieing, or standing on the floor.
You are not near the ceiling, you are at the floor level, so why not place the heat there to begin with.
IMO, a ceiling supply intended for heating is for the birds
otherwise ,a ceiling supply for the cooling mode is quite efficient, but not so for the heating mode

[geodude]

Ceiling registers should work fine if the register installed is placed properly and the correct register is chosen. ( shoemaker 950 for example ) instead of the commonly installed 850. Proper air throw is the key. Look at most commercial duct/registers and where they are installed. Adding a low return close to the floor will also help.

[tb21234]

Ever think about ductless units?