My gas furnace continues to work well, as it has for 25
years. The air intake to it is from an enclosed space below
the furnace which in turn has a screened opening (12" x
18"?) into my living room about 1 foot off the floor. That
space also has a small opening (4" x 6"?) to the outside of
the house. Thus the cooler air from the living room, mixed
with some air from the outside, is sucked into the furnace,
heated, and sent out through the vent system.

I just had my home fumigated, and when the gas company
technician was turning the gas back on, and lighting the
furnace pilot, he suggested that I close off the small
opening to the outside. He said it would prevent rodents
from entering the house, and would decrease my gas bill by a
small amount.

This small opening to the outside was purposefully placed
there, along with a rain shield on the outside, by the
builder of this group of tract houses. The home is on a
concrete slab.

Any safety or other reasons NOT to close off this opening,
as the gas company representative suggested? In case
climate is relevant, I live in the greater Los Angeles area.

Thanks.

--
----------
CWLee
"I appreciate those who walk out from the edges with
torches or even in the dark with their hands out in front
of them. We need those explorers and weirdos. I am
so grateful when I find that I am not the first." - Sally
Amsbury.

"CWLee" wrote in message
...

My gas furnace continues to work well, as it has for 25
years. The air intake to it is from an enclosed space below
the furnace which in turn has a screened opening (12" x
18"?) into my living room about 1 foot off the floor. That
space also has a small opening (4" x 6"?) to the outside of
the house. Thus the cooler air from the living room, mixed
with some air from the outside, is sucked into the furnace,
heated, and sent out through the vent system.

I just had my home fumigated, and when the gas company
technician was turning the gas back on, and lighting the
furnace pilot, he suggested that I close off the small
opening to the outside. He said it would prevent rodents
from entering the house, and would decrease my gas bill by a
small amount.

This small opening to the outside was purposefully placed
there, along with a rain shield on the outside, by the
builder of this group of tract houses. The home is on a
concrete slab.

Any safety or other reasons NOT to close off this opening,
as the gas company representative suggested? In case
climate is relevant, I live in the greater Los Angeles area.

Thanks.

There are several legal ways to vent a gas appliance. I suggest that you
check with the local authorities about any changes your planning. Now days
the Plumbing code requires 2 vents one high and one low. My water heater
can draw air from the outside and the attic.

Personally I would not have the heater using inside air for combustion. It
is legal and is the way it was done for a long time, when gas was cheap. For
me it defeats the purpose of the heater. Moving all that air from inside the
house then replacing it with cold air. Properly sized vents to the outside
would allow you to pressurize your home (slightly) and keep the chances of
Carbon monoxide in the furnace room. Not where you breathe.

"SQLit" wrote:

There are several legal ways to vent a gas appliance.

I may not have expressed myself clearly, or perhaps I don't
understand what you mean by venting, but the situation I'm
talking about is the air to be heated and circulated through
the house. The issue is whether that incoming air should
remain a mixture of inside and outside air, or whether it is
better to use only inside air.

He also wrote:

I would not have the heater using inside air for
combustion. It
is legal and is the way it was done for a long time, when
gas was cheap. For
me it defeats the purpose of the heater. Moving all that
air from inside the
house then replacing it with cold air.

Sorry, but I'm having trouble understanding what is meant
here. I'm not talking about the air used for combustion,
but the air to be heated and circulated through the house.
The savings in dollars the gas company representative had in
mind was from NOT heating up cold outside air but rather
heating the inside air, which would be at a higher temp than
the outside air, and thus require less gas to increase its
temp to the desired level.

He also wrote:

Properly sized vents to the outside
would allow you to pressurize your home (slightly) and
keep the chances of
Carbon monoxide in the furnace room. Not where you
breathe.

I assume it is already properly vented, since it has passed
several inspections by those familiar with local building
codes. I futher assume that the gas company representative
would not be suggesting something that would result in an
improperly vented furnace. As I understand the concept of
venting, it is a means to draw off the carbon monoxide and
other undesireable fumes so they are expelled to the
outside, and not circulated into the house. The gas
comopany representative did a "venting test" and told me
that the fumes were going just where they were supposed to
go, up the vent and through the roof.

Pehaps you can clarify what you meant after reading my
comments.

Thanks.

=======================

in message ...

"CWLee" wrote in message
...

My gas furnace continues to work well, as it has for 25
years. The air intake to it is from an enclosed space
below
the furnace which in turn has a screened opening (12" x
18"?) into my living room about 1 foot off the floor.
That
space also has a small opening (4" x 6"?) to the outside
of
the house. Thus the cooler air from the living room,
mixed
with some air from the outside, is sucked into the
furnace,
heated, and sent out through the vent system.

I just had my home fumigated, and when the gas company
technician was turning the gas back on, and lighting the
furnace pilot, he suggested that I close off the small
opening to the outside. He said it would prevent
rodents
from entering the house, and would decrease my gas bill
by a
small amount.

This small opening to the outside was purposefully
placed
there, along with a rain shield on the outside, by the
builder of this group of tract houses. The home is on a
concrete slab.

Any safety or other reasons NOT to close off this
opening,
as the gas company representative suggested? In case
climate is relevant, I live in the greater Los Angeles
area.

Thanks.

There are several legal ways to vent a gas appliance. I
suggest that you
check with the local authorities about any changes your
planning. Now days
the Plumbing code requires 2 vents one high and one low.
My water heater
can draw air from the outside and the attic.

Personally I would not have the heater using inside air
for combustion. It
is legal and is the way it was done for a long time, when
gas was cheap. For
me it defeats the purpose of the heater. Moving all that
air from inside the
house then replacing it with cold air. Properly sized ven
ts to the outside
would allow you to pressurize your home (slightly) and
keep the chances of
Carbon monoxide in the furnace room. Not where you
breathe.

"CWLee" wrote in message
...

"SQLit" wrote:

There are several legal ways to vent a gas appliance.

I may not have expressed myself clearly, or perhaps I don't
understand what you mean by venting, but the situation I'm
talking about is the air to be heated and circulated through
the house. The issue is whether that incoming air should
remain a mixture of inside and outside air, or whether it is
better to use only inside air.

He also wrote:

I would not have the heater using inside air for
combustion. It
is legal and is the way it was done for a long time, when
gas was cheap. For
me it defeats the purpose of the heater. Moving all that
air from inside the
house then replacing it with cold air.

Sorry, but I'm having trouble understanding what is meant
here. I'm not talking about the air used for combustion,
but the air to be heated and circulated through the house.
The savings in dollars the gas company representative had in
mind was from NOT heating up cold outside air but rather
heating the inside air, which would be at a higher temp than
the outside air, and thus require less gas to increase its
temp to the desired level.

He also wrote:

Properly sized vents to the outside
would allow you to pressurize your home (slightly) and
keep the chances of
Carbon monoxide in the furnace room. Not where you
breathe.

I assume it is already properly vented, since it has passed
several inspections by those familiar with local building
codes. I futher assume that the gas company representative
would not be suggesting something that would result in an
improperly vented furnace. As I understand the concept of
venting, it is a means to draw off the carbon monoxide and
other undesireable fumes so they are expelled to the
outside, and not circulated into the house. The gas
comopany representative did a "venting test" and told me
that the fumes were going just where they were supposed to
go, up the vent and through the roof.

Pehaps you can clarify what you meant after reading my
comments.

Thanks.

=======================

in message ...

"CWLee" wrote in message
...

My gas furnace continues to work well, as it has for 25
years. The air intake to it is from an enclosed space
below
the furnace which in turn has a screened opening (12" x
18"?) into my living room about 1 foot off the floor.
That
space also has a small opening (4" x 6"?) to the outside
of
the house. Thus the cooler air from the living room,
mixed
with some air from the outside, is sucked into the
furnace,
heated, and sent out through the vent system.

I just had my home fumigated, and when the gas company
technician was turning the gas back on, and lighting the
furnace pilot, he suggested that I close off the small
opening to the outside. He said it would prevent
rodents
from entering the house, and would decrease my gas bill
by a
small amount.

This small opening to the outside was purposefully
placed
there, along with a rain shield on the outside, by the
builder of this group of tract houses. The home is on a
concrete slab.

Any safety or other reasons NOT to close off this
opening,
as the gas company representative suggested? In case
climate is relevant, I live in the greater Los Angeles
area.

Thanks.

There are several legal ways to vent a gas appliance. I
suggest that you
check with the local authorities about any changes your
planning. Now days
the Plumbing code requires 2 vents one high and one low.
My water heater
can draw air from the outside and the attic.

Personally I would not have the heater using inside air
for combustion. It
is legal and is the way it was done for a long time, when
gas was cheap. For
me it defeats the purpose of the heater. Moving all that
air from inside the
house then replacing it with cold air. Properly sized ven
ts to the outside
would allow you to pressurize your home (slightly) and
keep the chances of
Carbon monoxide in the furnace room. Not where you
breathe.

Contact a licensed professional heating company and ask them. Anything more
I say will probably be misunderstood and I can not see the installation.

CWLee wrote:
"SQLit" wrote:


There are several legal ways to vent a gas appliance.


I may not have expressed myself clearly, or perhaps I don't
understand what you mean by venting, but the situation I'm
talking about is the air to be heated and circulated through
the house. The issue is whether that incoming air should
remain a mixture of inside and outside air, or whether it is
better to use only inside air.


(Snipped))

It is simple. Most or many older systems had no
requirement and have no way to supply outside air
into the system. With the construction of tighter
houses, it has been recognized that inflow of
outside air is required to provide a decent
quality of air in a building. In our
jurisdiction, new installation requires an outside
air inflow to provide a 10 percent air
replacement. All you need is a screened outside
vent to tie into the cold air return just above
the furnace filter. Other jurisdictions may
require different percentages.

"George E. Cawthon" wrote:


It is simple. Most or many older systems had no
requirement and have no way to supply outside air
into the system. With the construction of tighter
houses, it has been recognized that inflow of
outside air is required to provide a decent
quality of air in a building. In our
jurisdiction, new installation requires an outside
air inflow to provide a 10 percent air
replacement. All you need is a screened outside
vent to tie into the cold air return just above
the furnace filter. Other jurisdictions may
require different percentages.

Thank you. What you describe sounds exactly like what I
have, in a house built in Los Angeles County 25 years ago.
I had no reason to change that until the gas company
technician, here for other purposes, suggested that I close
off that outside air inflow to prevent rodents and to save a
small amount of gas. It seems strange that, in his official
duties, he would suggest something that may be against the
building code. I continue to be puzzled about the idea.

Thanks again.

Furnaces actually have two air flow circuits. One is the air which his
heated (or cooled). The second air flow is combustion air. the burner needs
air from some where, to burn and then the exhaust goes up the chimney. I
suspect the smaller vent is for combustion air.

Screen it if you want (coarse screen) but I wouldn't close it. Unless I knew
there was some other source of combustion air.

--

Christopher A. Young
Do good work.
It's longer in the short run
but shorter in the long run.
..
..


"CWLee" wrote in message
...

My gas furnace continues to work well, as it has for 25
years. The air intake to it is from an enclosed space below
the furnace which in turn has a screened opening (12" x
18"?) into my living room about 1 foot off the floor. That
space also has a small opening (4" x 6"?) to the outside of
the house. Thus the cooler air from the living room, mixed
with some air from the outside, is sucked into the furnace,
heated, and sent out through the vent system.

I just had my home fumigated, and when the gas company
technician was turning the gas back on, and lighting the
furnace pilot, he suggested that I close off the small
opening to the outside. He said it would prevent rodents
from entering the house, and would decrease my gas bill by a
small amount.

This small opening to the outside was purposefully placed
there, along with a rain shield on the outside, by the
builder of this group of tract houses. The home is on a
concrete slab.

Any safety or other reasons NOT to close off this opening,
as the gas company representative suggested? In case
climate is relevant, I live in the greater Los Angeles area.

Thanks.

--
----------
CWLee
"I appreciate those who walk out from the edges with
torches or even in the dark with their hands out in front
of them. We need those explorers and weirdos. I am
so grateful when I find that I am not the first." - Sally
Amsbury.

"Stormin Mormon" wrote:


Furnaces actually have two air flow circuits. One is the
air which his
heated (or cooled). The second air flow is combustion air.
the burner needs
air from some where, to burn and then the exhaust goes up
the chimney. I
suspect the smaller vent is for combustion air.

Screen it if you want (coarse screen) but I wouldn't close
it. Unless I knew
there was some other source of combustion air.

Thank you, "Stormin Mormon" for your comment.

I'll try to present this situation in a different manner,
since I think I'm confusing people with what I wrote before.

Living room air flows into a "space" adjacent to the furnace
which is located on the other side of the wall in the
garage. This air flow from the living room is through a
grill about 12" x 18" into the "space" which is perhaps 6
cubic feet of space. Also feeding into this "space" is an
opening to the outside, about 4" x 6". Above this "space"
is the air filter that is below the furnace intake. I
believe this is the air that the furnace heats and
recirculates through the ductwork in the house. I don't
know where the flame gets its air for combustion (perhaps
from the air in the garage, which has loose doors to the
outside as well as some vents in the walls), but there is a
vent above the flame that goes up through the roof. Per the
gas company technician this combustion vent is working just
fine. He held a burning match there and watched the smoke
go where he said it was supposed to go.

After checking the furnace, and before he replaced the
furnace filter he pointed to the small (4" x 6") vent to the
outside, and suggested I block it off to prevent rodents
from entering, and to save a small amount of gas by not
heating up cooler air from the outside, and just heating up
warmer air from inside the house.

I'm still curious about any safety issues associated with
closing that small opening to the outside, thus blocking off
a purposefully built entryway for air. The house was built
25 years ago and passed the various code inspections at the
time, and since then.

Thanks again.

"CWLee" wrote in message
...

"Stormin Mormon" wrote:


Furnaces actually have two air flow circuits. One is the
air which his
heated (or cooled). The second air flow is combustion air.
the burner needs
air from some where, to burn and then the exhaust goes up
the chimney. I
suspect the smaller vent is for combustion air.

Screen it if you want (coarse screen) but I wouldn't close
it. Unless I knew
there was some other source of combustion air.

Thank you, "Stormin Mormon" for your comment.

I'll try to present this situation in a different manner,
since I think I'm confusing people with what I wrote before.

Living room air flows into a "space" adjacent to the furnace
which is located on the other side of the wall in the
garage. This air flow from the living room is through a
grill about 12" x 18" into the "space" which is perhaps 6
cubic feet of space. Also feeding into this "space" is an
opening to the outside, about 4" x 6". Above this "space"
is the air filter that is below the furnace intake. I
believe this is the air that the furnace heats and
recirculates through the ductwork in the house. I don't
know where the flame gets its air for combustion (perhaps
from the air in the garage, which has loose doors to the
outside as well as some vents in the walls), but there is a
vent above the flame that goes up through the roof. Per the
gas company technician this combustion vent is working just
fine. He held a burning match there and watched the smoke
go where he said it was supposed to go.

After checking the furnace, and before he replaced the
furnace filter he pointed to the small (4" x 6") vent to the
outside, and suggested I block it off to prevent rodents
from entering, and to save a small amount of gas by not
heating up cooler air from the outside, and just heating up
warmer air from inside the house.

I'm still curious about any safety issues associated with
closing that small opening to the outside, thus blocking off
a purposefully built entryway for air. The house was built
25 years ago and passed the various code inspections at the
time, and since then.

Thanks again.

The entire installation sounds like one big safety nightmare that wouldn't
meet codes in any jurisdiction (seriously).

- Furnace in garage.
- Return not ducted.
- Only one combustion air vent.
- Who knows what else?

I suggest you get the factory authorized dealer to inspect your furnace and
situation and make any needed repairs to bring it up to code. Also, be sure
to get your local building inspector to check it out afterwards.

Fix it unless you don't care about poisoning your family with deadly carbon
monoxide and/or burning your house down.

I would shut the gas off to the unit and disconnect the power until you have
it fixed. That thing is a killer.

CWLee wrote:
"Stormin Mormon" wrote:



Furnaces actually have two air flow circuits. One is the

air which his

heated (or cooled). The second air flow is combustion air.

the burner needs

air from some where, to burn and then the exhaust goes up

the chimney. I

suspect the smaller vent is for combustion air.

Screen it if you want (coarse screen) but I wouldn't close

it. Unless I knew

there was some other source of combustion air.


Thank you, "Stormin Mormon" for your comment.

I'll try to present this situation in a different manner,
since I think I'm confusing people with what I wrote before.

Living room air flows into a "space" adjacent to the furnace
which is located on the other side of the wall in the
garage. This air flow from the living room is through a
grill about 12" x 18" into the "space" which is perhaps 6
cubic feet of space. Also feeding into this "space" is an
opening to the outside, about 4" x 6". Above this "space"
is the air filter that is below the furnace intake. I
believe this is the air that the furnace heats and
recirculates through the ductwork in the house. I don't
know where the flame gets its air for combustion (perhaps
from the air in the garage, which has loose doors to the
outside as well as some vents in the walls), but there is a
vent above the flame that goes up through the roof. Per the
gas company technician this combustion vent is working just
fine. He held a burning match there and watched the smoke
go where he said it was supposed to go.

After checking the furnace, and before he replaced the
furnace filter he pointed to the small (4" x 6") vent to the
outside, and suggested I block it off to prevent rodents
from entering, and to save a small amount of gas by not
heating up cooler air from the outside, and just heating up
warmer air from inside the house.

I'm still curious about any safety issues associated with
closing that small opening to the outside, thus blocking off
a purposefully built entryway for air. The house was built
25 years ago and passed the various code inspections at the
time, and since then.

Thanks again.


Ok. The rule for combustion air and dilution of
flue gases depends on whether the furnace is in a
confined space or an unconfined space. Your garage
is probably leaky enough to satisfy the unconfined
definition. You do not need any specific openings
to the outside for combustion and dilutions in
unconfined spaces.

In confined space, you need one opening within l2
inches of the ceiling and one within 12 inches of
the floor for combustion air and dilution.

It is obvious from your description that the 4" x
6" vent has nothing to do with the gas combustion
and dilution since it opens into the air
distribution system and not into the garage
directly. Therefore it's purpose is to provide
fresh air to the interior and has nothing to do
with combustion or dilutions of exhaust gases.
The outside opening definitely should have a
screen of hardware cloth of 1/4" squares followed
by regular window screen to keep both animals and
bugs out.

The solution to your question is simple.
Construct a small sliding gate so that you can
regulate the opening where it enters the "space."
Or simply tape a piece of cardboard across the
opening with duct tape. For example start by
closing off 1/2 of the opening and see if there
are any adverse effect, e.g., stuffiness, and if
not close off 3/4 of the opening. How much you
can close off is like to depend on how tight your
house is--drafty house means close the opening off
completely, very tight house means don't close off
any of the opening.

"Oscar_Lives" wrote

The entire installation sounds like one big safety
nightmare that wouldn't
meet codes in any jurisdiction (seriously).

- Furnace in garage.
- Return not ducted.
- Only one combustion air vent.
- Who knows what else?

I suggest you get the factory authorized dealer to inspect
your furnace and
situation and make any needed repairs to bring it up to
code. Also, be sure
to get your local building inspector to check it out
afterwards.

If you are serious, and not pulling my leg or being
inappropriately alarmist, then I think I have not adequately
explained the situation.

There must be 10s of thousands, if not 100s of thousands, of
homes in Southern California which have their furnace in
their garage. I don't think that is contrary to local
building codes or manufacturer's recommendations.

"Return not ducted" may or may not be correct, based on what
I understand, observe, and have written about the situation.
The heated air from the furnace is in fact distributed
through an extensive system of ductwork throughout the
house. Is that the "return" you are talking about?

"Only one combustion air vent" again may or may not be
correct, but the fact that the gas company technician, and
the local building inspectors have all found nothing
hazardous about the installation cause me to believe there
is a second combustion air vent, or that such a second one
is not necessary due to the location inside a garage.

Thank you for your comments.

By return air not being ducted, I THINK he is referring to the fact that you need your return air (the air being pulled from your house into the furnace) to be sealed off totally from the combustion air (air used for combustion). You would accomplish this by ducting the return air directly to the furnace, rather than just funneling it into this space, which also contains combustion air. Not sure if that's what yours is doing or not...


___________

If you are serious, and not pulling my leg or being
inappropriately alarmist, then I think I have not adequately
explained the situation.

There must be 10s of thousands, if not 100s of thousands, of
homes in Southern California which have their furnace in
their garage. I don't think that is contrary to local
building codes or manufacturer's recommendations.

"Return not ducted" may or may not be correct, based on what
I understand, observe, and have written about the situation.
The heated air from the furnace is in fact distributed
through an extensive system of ductwork throughout the
house. Is that the "return" you are talking about?

"Only one combustion air vent" again may or may not be
correct, but the fact that the gas company technician, and
the local building inspectors have all found nothing
hazardous about the installation cause me to believe there
is a second combustion air vent, or that such a second one
is not necessary due to the location inside a garage.

Thank you for your comments.[/quote]