I am going to remodel my kitchen. Currently there is only one forced air A/C
duct in the kitchen in the wall near the floor. This wall will be covered by
cabinets as well as all other available kitchen walls. Where is the best
place to relocate the only existing duct I have? I see the only place for it
is to move it higher above top cabinets. I also plan to add a couple of more
ducts and probably one return duct. Again the only place I see for those
additional ducts is in the walls above top cabinets. I cannot put them into
ceiling because of ceiling joists. Any advise would be appreciated.
Putting toe space grills in houses with A/C and a basement or
crawlspace can be a mistake. Normally, the duct is attached to the
floor under the cabinet under the cabinet. This pressurizes the space
under the cabinet with cold air. The subfloor under the cabinet
assumes supply air temperature. If there is any humidity in the
crawlspace or basement, moisture will condense on the underside of the
subfloor. Conditions are then ripe for mold growth or wood rot. Even
if you duct the air all the way to the grille, there can still be
problems. The floor in front of the grille will also approach the
supply air temperatures. About 10 percent of my business involves
fixing problems with damp crawlspaces. The biggest problems are with
houses with toespace grilles Avoid toe space grilles unless you are in
a very dry climate.
First, if I do it, it's ducted all the way to the grill.
Second, I live in an area where humidity isn't an issue.
Your thinking, and sharing your knowledge, that's good.
That's the nice thing about the NG, it's made up of people from all
different areas of knowledge.
Don't go adding ducts without understanding the impaceon the rest of
your system. A return duct in the kitchen sounds like a great way to
get kitchen odors spread throughout the house. In some jurisdictions it
is against the building code.
Your plan is workable, especially since you are adding other
supply ducts... you may want to eliminate the return duct
though as that will take cooking odors all through the house..
you want the kitchen exhaust to take those outside as a rule.
and you want the new supply air to move in a way that it does
not interfere with the kitchen or stove top exhaust ..that
means no supply air blowing on or around the stove top.
The supply air registers above the cabinets should ideally be
in a facia flush with the front of the cabinets and be rated
for wall placement, as contrasted to say ceiling registers
that are configured differently.
The air should not just be dumped in a space atop the
However adding more ducts could unbalance the system and
deprive other parts of the house of air, so that the kitchen
would run too cold in the summer and too hot in the winter.
To cure that put manual balancing dampers in the kitchen ducts
so you can 'balance' the system later. If you rely on the
supply air grill dampers you could get whistling. or you can
do it as planned and see how it operates ..then add balancing
dampers as required later.
There are thermostatically controlled dampers you can buy but
thats a lot of complexity for a slight gain in your situation.
Mech engr. HVAC contractor
Thank you for our response. I really understand now that putting a return
register in the kitchen is not a good idea. I however wonder how to install
forced air registers flush with cabinets facia. Registers are more then 4"
height, facia must be really huge. Are there online resources preferably
with pictures where I can see how registers are placed in kitchen?
We lived in the desert where COOLING was much more important than heating.
Our kitchen ducts were placed above the cabinets..Picture cool air
We were on a concrete slab so actually all the ductwork was "above" the
living space. It sounds like you could add a run from the existing duct,
up and along the tops of the cabinets and box it in with a bulkhead from
cabinet tops to ceiling. I like to do that anyway when I build..finishes it
off neater than just having the upper cabinets hanging on the wall and a
dusty, clutter collecting "shelf"/tops above.
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