I'm replacing a 40 gallon gas water heater with a tankless version (Aquastar
250sx). As the water heater and furnace are within 5 feet of eachother in
my laundry room, I WAS going to just angle the existing vent that is
connected to the hot water heater now. It is a 3" galvanized vent. It is
connected to the vent which is used by the furnace (which looks like 4"),
then the pipe going up into the ceiling and out the roof looks closer to 6".
However, now that i get the new heater, it says that it needs stainless
venting and can not be vented in common.

Now for my question, and i know it sounds stupid, but just wondered what
everyone else is doing. Can i just use that vent or atleast that stack
that goes up through the roof and change it all to stainless? Or is there
any way to do this without running a new exhaust? If there isn't, what is
better to do, a horizonal or vertical exhaust? The heater is being mounted
on an outside wall so i believe the horizontal wouldn't be that hard, but
are there any issues with my siding being vinyl? The previous owner melted
some by placing the grill a little too close, i can't imagine that this
thing is going to fair any better.

Finally, it has the option to use in room combustible air or have a seperate
vent run for that, what are the advantages/disadvantages or doing it either
way. I live in Central New Jersey if it makes a difference.

Thanks in advance for your help.

"John Sheehy" wrote in message
news:FDnmf.56$qF6.43@trnddc01...
I'm replacing a 40 gallon gas water heater with a tankless version
(Aquastar
250sx). As the water heater and furnace are within 5 feet of eachother in
my laundry room, I WAS going to just angle the existing vent that is
connected to the hot water heater now. It is a 3" galvanized vent. It is
connected to the vent which is used by the furnace (which looks like 4"),
then the pipe going up into the ceiling and out the roof looks closer to
6".
However, now that i get the new heater, it says that it needs stainless
venting and can not be vented in common.

Now for my question, and i know it sounds stupid, but just wondered what
everyone else is doing. Can i just use that vent or atleast that stack
that goes up through the roof and change it all to stainless? Or is there
any way to do this without running a new exhaust? If there isn't, what is
better to do, a horizonal or vertical exhaust? The heater is being
mounted
on an outside wall so i believe the horizontal wouldn't be that hard, but
are there any issues with my siding being vinyl? The previous owner
melted
some by placing the grill a little too close, i can't imagine that this
thing is going to fair any better.

Finally, it has the option to use in room combustible air or have a
seperate
vent run for that, what are the advantages/disadvantages or doing it
either
way. I live in Central New Jersey if it makes a difference.

Thanks in advance for your help.



Combustion air has to come from some where. If you use inside air then that
air has to be replaced.
If you use outside air then the home does not have to replace the combustion
air. The directions and your local building department are good places to
ask these questions.

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

It's always best to use outside (that is, unconditoned air) for
combustion air.

Why heat or cool air just to send it up the flue after using it to
combust your water heater gas?

The flues (individual & common) have to be sized correctly to handle
the exhaust gases genrated by your WH & furnace.

The 6" is probably big enough to handle both, assuming the furnace at
4" was sized correctly (& it looks like it was)

The 3" might be a little small (depending on run length) to handle your
tankless........consider the BTU input to the furnace & compare it to
the BTU input to the furnace & the 40 gallon unit. Fues are sized
based on the combustion capacity of the units that they serve.

I have a furnace & a 75 gallon WH & they both go up through the roof in
a common 5" or 6"

cheers
Bob

On Fri, 9 Dec 2005 17:06:04 -0600, (m Ransley)
wrote:

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

Hmmmm. I guess Ive been doing it wrong all these years then? I also
guess that GAMA venting tables are all wrong too? Might I suggest you
follow this link:
http://icpindexing.mqgroup.com/docum...vent%20tab.pdf
It is on page 4 of the .pdf but is numbered page 1.
Look for "Fan + Nat" A little reading is in order
Bubba

Fresh air is best , but if incomming air is to close to unit freezing it
is a possibiity, even the exuast with a closeable hood can not be to
close in -20f. Ive seen mine drop very low near the coil in cold
weather apx to 45f. so I routed mine 7 ft away.

So then is it fair to say that a knowledgable installer could properly size
the venting so that the current vent could be used/modified. If that is the
case, then that would be something i would be willing to pay someone for
their expertise. I just don't want to have a bunch of vents coming out of
my house when i could have had 1.

"Bubba" ReMoVe wrote in message
...
On Fri, 9 Dec 2005 17:06:04 -0600, (m Ransley)
wrote:

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

Hmmmm. I guess Ive been doing it wrong all these years then? I also
guess that GAMA venting tables are all wrong too? Might I suggest you
follow this link:
http://icpindexing.mqgroup.com/docum...vent%20tab.pdf
It is on page 4 of the .pdf but is numbered page 1.
Look for "Fan + Nat" A little reading is in order
Bubba

I would think that if the instructions say it can not be vented in common
with another appliance that there is a valid reason not to do so. Whether
or not such arrangements with other appliances are approved or operate
satisfactorily is beside the point. Any installation not in accord with
manufacturer's instructions is likely to not be approved by inspectors, to
void the warranty, and to sometimes cause unexpected problems. Many things
"work" but are a really bad idea.
Don Young
"John Sheehy" wrote in message
news:FDnmf.56$qF6.43@trnddc01...
I'm replacing a 40 gallon gas water heater with a tankless version
(Aquastar 250sx). As the water heater and furnace are within 5 feet of
eachother in my laundry room, I WAS going to just angle the existing vent
that is connected to the hot water heater now. It is a 3" galvanized
vent. It is connected to the vent which is used by the furnace (which
looks like 4"), then the pipe going up into the ceiling and out the roof
looks closer to 6". However, now that i get the new heater, it says that
it needs stainless venting and can not be vented in common.

Now for my question, and i know it sounds stupid, but just wondered what
everyone else is doing. Can i just use that vent or atleast that stack
that goes up through the roof and change it all to stainless? Or is there
any way to do this without running a new exhaust? If there isn't, what is
better to do, a horizonal or vertical exhaust? The heater is being
mounted on an outside wall so i believe the horizontal wouldn't be that
hard, but are there any issues with my siding being vinyl? The previous
owner melted some by placing the grill a little too close, i can't imagine
that this thing is going to fair any better.

Finally, it has the option to use in room combustible air or have a
seperate vent run for that, what are the advantages/disadvantages or doing
it either way. I live in Central New Jersey if it makes a difference.

Thanks in advance for your help.

You can use the existing vent if it is the PROPER SIZE and PROPER
TYPE. If it needs stainless and you dont currently have stainless then
you CANT do it. It needs to be done By The Book! No cheating.
Bubba

On Sat, 10 Dec 2005 03:43:20 GMT, "John Sheehy"
wrote:

So then is it fair to say that a knowledgable installer could properly size
the venting so that the current vent could be used/modified. If that is the
case, then that would be something i would be willing to pay someone for
their expertise. I just don't want to have a bunch of vents coming out of
my house when i could have had 1.

"Bubba" ReMoVe wrote in message
.. .
On Fri, 9 Dec 2005 17:06:04 -0600, (m Ransley)
wrote:

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

Hmmmm. I guess Ive been doing it wrong all these years then? I also
guess that GAMA venting tables are all wrong too? Might I suggest you
follow this link:
http://icpindexing.mqgroup.com/docum...vent%20tab.pdf
It is on page 4 of the .pdf but is numbered page 1.
Look for "Fan + Nat" A little reading is in order
Bubba

Perhaps but it can also be that there is a right way to do it as Bubba says
and typically that will require removing what's there and replacing with
stainless and doing it by the book. Maybe the mfg figures it's safer to
say no no no than have too many hacks or DIY's just hook it on where the
old one was connected and call it a day.

Yeah, that's what i meant. Could a installer make/modify the venting so
that it could be used in common and that it is safe?


"Bubba" ReMoVe wrote in message
...
You can use the existing vent if it is the PROPER SIZE and PROPER
TYPE. If it needs stainless and you dont currently have stainless then
you CANT do it. It needs to be done By The Book! No cheating.
Bubba

On Sat, 10 Dec 2005 03:43:20 GMT, "John Sheehy"
wrote:

So then is it fair to say that a knowledgable installer could properly
size
the venting so that the current vent could be used/modified. If that is
the
case, then that would be something i would be willing to pay someone for
their expertise. I just don't want to have a bunch of vents coming out of
my house when i could have had 1.

"Bubba" ReMoVe wrote in message
. ..
On Fri, 9 Dec 2005 17:06:04 -0600, (m Ransley)
wrote:

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

Hmmmm. I guess Ive been doing it wrong all these years then? I also
guess that GAMA venting tables are all wrong too? Might I suggest you
follow this link:
http://icpindexing.mqgroup.com/docum...vent%20tab.pdf
It is on page 4 of the .pdf but is numbered page 1.
Look for "Fan + Nat" A little reading is in order
Bubba

Isnt it a power vent on your Bosch [ made by Takagi ], exuast is forced
out under pressure? So what keeps it from blowing furnace gas back
inside if you Dual use a vent , water heater and furnace on same line,
it sounds really wrong.

m Ransley wrote:

Isnt it a power vent on your Bosch [ made by Takagi ], exuast is forced
out under pressure? So what keeps it from blowing furnace gas back
inside if you Dual use a vent , water heater and furnace on same line,
it sounds really wrong.

Check Bubba's reference. It can be done safely.

On Sat, 10 Dec 2005 09:18:49 -0600, (m Ransley)
wrote:

Isnt it a power vent on your Bosch [ made by Takagi ], exuast is forced
out under pressure? So what keeps it from blowing furnace gas back
inside if you Dual use a vent , water heater and furnace on same line,
it sounds really wrong.

You gotta read man. READ. It isnt wrong. First of all, the flue gasses
are being pulled out of the home by the natural draft/suction of air
going up and out the vent. Blow some smoke at the vent or diverter and
watch witch way it goes. It goes up and out. NOT up and back down. If
it does, you have a venting problem.
"Swear man, Swear to god"
Bubba

John, I dont know how I can make it any clearer. Things can be
modified but they have to be done "to the letter". Follow the venting
tables however you also have to follow the manufacturers
recomendations. If you dont, the manufacturer can void your warranty.
Bubba

On Sat, 10 Dec 2005 14:32:38 GMT, "John Sheehy"
wrote:

Yeah, that's what i meant. Could a installer make/modify the venting so
that it could be used in common and that it is safe?


"Bubba" ReMoVe wrote in message
.. .
You can use the existing vent if it is the PROPER SIZE and PROPER
TYPE. If it needs stainless and you dont currently have stainless then
you CANT do it. It needs to be done By The Book! No cheating.
Bubba

On Sat, 10 Dec 2005 03:43:20 GMT, "John Sheehy"
wrote:

So then is it fair to say that a knowledgable installer could properly
size
the venting so that the current vent could be used/modified. If that is
the
case, then that would be something i would be willing to pay someone for
their expertise. I just don't want to have a bunch of vents coming out of
my house when i could have had 1.

"Bubba" ReMoVe wrote in message
...
On Fri, 9 Dec 2005 17:06:04 -0600, (m Ransley)
wrote:

It is a power vent I believe so combining 2 would force air back into
your furnace or inside, not good. I vent horizontal with my bosch
Aquastar 120 into a 12" stainless hood that pretty much directs geat
away, as I have flamable Cedar, But I still removed the cedar around the
vent any you could and use sheet metal. Outside air, what about freezing
the unit and ruining it, read the manual. You are aware you need a Big
gas line to feed it, is it 180000 btu, be sure you have the right size.

Hmmmm. I guess Ive been doing it wrong all these years then? I also
guess that GAMA venting tables are all wrong too? Might I suggest you
follow this link:
http://icpindexing.mqgroup.com/docum...vent%20tab.pdf
It is on page 4 of the .pdf but is numbered page 1.
Look for "Fan + Nat" A little reading is in order
Bubba

John-

Find yourself a knowledgable installer.

Just about "anything" can be done, undone, repaired, replaced or
retrofitted.

I read Bubba's link, if you want to educate yourself on exhaust vent
sizing, read it.

Done wrong, the installation might give you problems;

Done right it will be fine. It's all about getting the "plumbing"
right.

cheers
Bob

On 2005-12-10, Steve Kraus wrote:

Perhaps but it can also be that there is a right way to do it as Bubba says
and typically that will require removing what's there and replacing with
stainless and doing it by the book.

Bubba's link was for venting Category I furnaces and solely for the
purpose of rebutting m Ransley's comment that you can never common
vent a forced draft Category I appliance with a natural draft Category
I appliance (apparently not true). Tankless water heaters like the
Bosch 250SX are Category III appliances, and they must be separately
vented in a vapor tight stainless steel flue.

To the OP: do you live in a climate where it does not freeze? If so,
consider mounting the water heater outside (cheaper and less hassle to
vent). If not, then vent it horizontally with the shortest vent
possible (the vent can be expensive). Do use outside air for
combustion, it is safer and slightly more efficient. Also be aware
that the Bosch 250SX has a high natural gas demand, usually best
served by a dedicated supply line from the gas meter: 3/4" if it is
under 35' or so, 1" if it is farther.

Cheers, Wayne

Wayne , Venting the exuast as close as you can poses a freeze threat to
the coil in cold climates. I did 7 ft and coil still gets cold apx 45
with a closeable stainless hood.

On Sat, 10 Dec 2005 23:56:30 -0600, Wayne Whitney
wrote:

On 2005-12-10, Steve Kraus wrote:

Perhaps but it can also be that there is a right way to do it as Bubba says
and typically that will require removing what's there and replacing with
stainless and doing it by the book.

Bubba's link was for venting Category I furnaces and solely for the
purpose of rebutting m Ransley's comment that you can never common
vent a forced draft Category I appliance with a natural draft Category
I appliance (apparently not true). Tankless water heaters like the
Bosch 250SX are Category III appliances, and they must be separately
vented in a vapor tight stainless steel flue.

Thus, the reason I also explained that you need to not only follow the
proper venting guidelines, you also need to follow the manufacturers
directions. This isnt for kids, folks, but the OP did seem slightly
"bent" on reusing that common vent no matter what.
In the end, my equipment is running safely, properly vented and my
home is nice and warm. If the OP chooses to do differently, I cant
change a thing.
Bubba


To the OP: do you live in a climate where it does not freeze? If so,
consider mounting the water heater outside (cheaper and less hassle to
vent). If not, then vent it horizontally with the shortest vent
possible (the vent can be expensive). Do use outside air for
combustion, it is safer and slightly more efficient. Also be aware
that the Bosch 250SX has a high natural gas demand, usually best
served by a dedicated supply line from the gas meter: 3/4" if it is
under 35' or so, 1" if it is farther.

Cheers, Wayne

If it's not too late, return that Bosch heater while you still can. The
Bosch heaters are very high maintenance. Maintenance costs will eat up
all your gas savings and more. How do I know? I own one myself. It's
nice when it works, but I do not recommend them at all.

What BS Ive had No maintenance issues in 3 years with my bosch 120. I do
have a whole house water filter and whole house surge supression and
upgraded grounds, its called logic.

m Ransley wrote:
What BS Ive had No maintenance issues in 3 years with my bosch 120. I do
have a whole house water filter and whole house surge supression and
upgraded grounds, its called logic.

Check out the epinions.com site. A lot of people have complained about
the high maintenance cost of the Bosch. The fact that you haven't had a
breakdown--yet--does not make other people's experiences "BS".

Also, who is going to take lessons in logic from a person who is
incompetent on elementary issues of grammar and punctuation, and who
thinks that she can generalize from only her own experience?