All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.

Any thoughts, comments, suggestions, or discussion would be great.

Thanks.

wrote:

All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.

Any thoughts, comments, suggestions, or discussion would be great.

Thanks.


100% correct.

You will need to provide a combustion air inlet from the outside
into the boiler room. May be necessary to close off the room
so it doesn't communicate with the rest of the house too.

wrote:
...A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

Your big attic fan needs to draw air from somewhere, usually from open
windows. Air will be drawn in from the path(s) of least resistance,
including a downdraft from the water heater vent. This also creates
problems with combustion air. So open enough windows before starting
the fan.

wrote in message

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test.

Any thoughts, comments, suggestions, or discussion would be great.

Yep, it is a real concern. CO poisoning is not because the gasses are
quickly drawn up and out of the house, but you still don't want the flue to
be reversed.

Before turning the fan on, be sure there are plenty of other openings to
draw air through. Open the windows and a screen door so that a minimum is
the same size as the fan opening. If possible, close off the area with the
water heater so it cannot suck air from there. You can always add another
vent so the heater can get a supply of outside air for combustion.

We left our teenaged children at home on evening and my daughter almost set
the kitchen on fire with a smoking overheated pan. They got that out so my
son figured he'd ventilate the kitchen with the whole house fan. The oil
burner was running and it was then smoking up the house as the fan drew
through the flue, the only opening in the house. By the time we got home,
the fire trucks were gone and everything was back to normal.

wrote:
All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.

Any thoughts, comments, suggestions, or discussion would be great.

Thanks.


My attic fan came with a warning regarding a similar situation with
attic fans and attic-mounted furnaces. There may even be something
in the code that requires interlocks between the devices.

Did you carefully read the instructions and do your research before
mounting the fan?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

On Thu, 05 Jul 2007 02:51:38 GMT, "Edwin Pawlowski"
wrote:


We left our teenaged children at home on evening and my daughter almost set
the kitchen on fire with a smoking overheated pan. They got that out so my
son figured he'd ventilate the kitchen with the whole house fan. The oil
burner was running and it was then smoking up the house as the fan drew
through the flue, the only opening in the house. By the time we got home,
the fire trucks were gone and everything was back to normal.

This should have been enough to make them submissive for a few weeks.
WAs it?

Edwin Pawlowski wrote:
wrote in message

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test.


Any thoughts, comments, suggestions, or discussion would be great.


Yep, it is a real concern. CO poisoning is not because the gasses are
quickly drawn up and out of the house, but you still don't want the flue to
be reversed.

Before turning the fan on, be sure there are plenty of other openings to
draw air through. Open the windows and a screen door so that a minimum is
the same size as the fan opening. If possible, close off the area with the
water heater so it cannot suck air from there. You can always add another
vent so the heater can get a supply of outside air for combustion.

We left our teenaged children at home on evening and my daughter almost set
the kitchen on fire with a smoking overheated pan. They got that out so my
son figured he'd ventilate the kitchen with the whole house fan. The oil
burner was running and it was then smoking up the house as the fan drew
through the flue, the only opening in the house. By the time we got home,
the fire trucks were gone and everything was back to normal.


Any home with gas appliances should have a CO monitor. I know a couple
who were sick from CO poisoning because the fireplace in their brand-new
home was drawing too much and pulling CO from furnace or water heater
back into the home.

wrote in message
ups.com...
All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.


I sure hope your plastic fittings are not directly connected to the tank. If
so, it's against code.


A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.


Yep, not enough air for the attic fan and it's pulling air from your water
heater flu.


This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.


Yep, see it all to often and your store bought CO detector is more than
likely trash!! Have you ever read the specifications on the back? At what
level does it sound an alarm?

There are only two detectors that I'm aware of that will protect you from
low levels of CO. They're both in the $200 plus range. Yeah I know, you can
get a so called "good one" at any local store, but they are giving you a
false sense of security.

"mm" wrote in message

This should have been enough to make them submissive for a few weeks.
WAs it?


About as much as any 16 year old

wrote in message
ups.com...
All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.

Any thoughts, comments, suggestions, or discussion would be great.

Thanks.


I remember reading an article about bath fans in basements sucking air down
the chimney.

Thanks to everyone for your input.

Now I am wondering if I did any permanent damage to the hot water
tank. It seems to be OK.

Also, in response to the question regarding the plastic fittings - I
used copper nipples coming off the heater. The plastic pipe (pex) is
6" from the flue. The plastic that melted was the escutcheon like
grommets between the shell of the heater and the factory installed
pipe nipples.

Thanks.

On Jul 4, 10:51 pm, "Edwin Pawlowski" wrote:
wrote in message

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test.
Any thoughts, comments, suggestions, or discussion would be great.

Yep, it is a real concern. CO poisoning is not because the gasses are
quickly drawn up and out of the house, but you still don't want the flue to
be reversed.

Before turning the fan on, be sure there are plenty of other openings to
draw air through. Open the windows and a screen door so that a minimum is
the same size as the fan opening. If possible, close off the area with the
water heater so it cannot suck air from there. You can always add another
vent so the heater can get a supply of outside air for combustion.

We left our teenaged children at home on evening and my daughter almost set
the kitchen on fire with a smoking overheated pan. They got that out so my
son figured he'd ventilate the kitchen with the whole house fan. The oil
burner was running and it was then smoking up the house as the fan drew
through the flue, the only opening in the house. By the time we got home,
the fire trucks were gone and everything was back to normal.

Wow. That sounds like an experience. Since it was winter the house
was sealed and you must have gotten a lot of backdraft.

wrote in message
ps.com...
Thanks to everyone for your input.

Now I am wondering if I did any permanent damage to the hot water
tank. It seems to be OK.

Also, in response to the question regarding the plastic fittings - I
used copper nipples coming off the heater. The plastic pipe (pex) is
6" from the flue. The plastic that melted was the escutcheon like
grommets between the shell of the heater and the factory installed
pipe nipples.

Thanks.


Yep, that's the correct way to do the connection. :-)

This is a well known issue especially in newer well sealed and insulated
homes, as well as older framed houses built with no insulation or
fire-stops in stud cavities. The attic should be provided with
ventilation openings so the fan pulls outside air through the attic
rather than air from inside your house. In the meantime, keep a window
open in the room with the water heater if possible.



--
The best argument against democracy is a five-minute conversation
with the average voter. (Winston Churchill)

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

"Larry W" wrote in message
...
This is a well known issue especially in newer well sealed and insulated
homes, as well as older framed houses built with no insulation or
fire-stops in stud cavities. The attic should be provided with
ventilation openings so the fan pulls outside air through the attic
rather than air from inside your house. In the meantime, keep a window
open in the room with the water heater if possible.



--
The best argument against democracy is a five-minute conversation
with the average voter. (Winston Churchill)

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
It is easy enough to check that the water heater flue is drawing when the
attic fan or other exhaust fans are on while the heater is burning. Just
move a lit match near the draft diverter and see which way the flame is
blown. Reverse draft is a very serious condition and should never be
permitted. Do not ever depend on opening or closing doors or windows to
prevent it. Proper installation and all codes require adequate unobstructed
(no way to close it off) air into the area where the heater is located. Do
it right and be safe.

Don Young