Do it Yourself: [DIY] Re: Diagnose a COLD Room

20 January 2015

[DIY] Re: Diagnose a COLD Room

Since this house is only nine years old, this is probably not an
issue of large air leaks, or significant uninsulated wall/ceiling/floor
areas. That does not mean that the house is energy efficient, but
large enough heat losses to overwhelm the ability to balance the
system, are not likely. However, as a master bedroom, at least
partially, over the garage, it is at an end of the house, and may
also encompass three exterior walls, as well as the floor over
the garage, while maybe not having any larger ducting than
other rooms, that only have one exterior wall. So, unless
there is a large noticeable cold draft, we can probably assume
that this is an issue with heat distribution, not heat loss. We also
know that tuning the air flows, via registers and dampers, is
relatively simple (easy homeowner adjustment, with no material
cost) and that replacing or adding ducting is usually not financially
practical. So, we already know what probably needs to be done.
You need to increase the percentage of furnace air flow to that
room, by balancing the various air flows from the furnace
plenum. So......how to do that?

The ceiling registers may be return air intakes, going
back to the furnace, though they may be supply registers
for the air conditioning. So, the first step is to familiarize
yourself with where the hot air is coming into the rooms,
not just the Master Bedroom, but ALL of your rooms.
This is not just about the Master Bedroom. It is about
the "balance" of the air-flow, from the furnace to the
whole house. The hot air that you want in the Master
Bedroom, is going to other rooms. (There is also a
chance, if this is a long ranch house with the supply
ducting (and even the furnace) in the attic, that the
heat is just being wasted to warm an uninsulated
attic. Anyway, your solution may not be to open
up the flow-path to the Master Bedroom, but
instead, to limit the air-flow to some other
room(s).......balance.

1) identify the supply registers (the ones furnace air comes out)
2) Makes sure that the dampers on the Master Bedroom supply
registers are fully open. This is usually a simple slide lever on the
face of the grill, but it is not uncommon for register dampers to
stick, and not fully open. Since register grills are usually just
held in place with screws, you might remove the register grills
(Master Bedroom) to: 1) Make sure the dampers are open,
and 2) leave them off for a while to see if the room is warm
enough with them off. If it is, that will define your problem
as being too little air-flow to the room. In that case, you
might literally remove the dampers from the register grills,
or you can partially close down the register grill dampers
in the other rooms, which would send more of the furnace
air to the Master Bedroom. There may be dampers in the
duct system, that can be adjusted, but maybe not. With
modern flex duct it is less common than in the past. You
can probably adjust/balance this in the rooms, though, if
you have a defiant teen, who likes a very hot room, you
may have to jimmy the register damper in their room, so
that it can not be fully opened. Tape, on the back/hidden
side, would work, until they figured out to jab something
through the register grill, to punch holes through it ;O)

Anyway....This appears to be a matter of not getting
enough of the furnace air flow into the Master Bedroom,
because it is going to other rooms. Makes sure the Master
Bedroom registers are not closed down, and if not, then
close them, a little, in other rooms.

PS..There are also duct booster fans, for long, undersized
duct runs, if balancing creates too much duct pressure. The
comment about return air is also valid, though it is rare that
return ducting is not adequate in newer houses that have
air conditioning. Cold air returns do not (generally) have
dampers, to get closed down. This sounds like a balancing
problem.

-Laren Corie-
Natural Solar Building Design and
Solar Heating/Natural Cooling/Energy
Efficiency Consultation Since 1975
(Very economical, Anywhere, Via
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