I'm planing an install of a Takagi T-KD20 in the first floor of a 2
story addition. I'm a little confused by their install instructions. Do
I need to go through the second story roof with the exhaust vent?
My first choice would be to make it as short as possible. There are no
first floor windows on that wall, & only 2 on the entire wall, both 15'
or more from the intended location, there is a gable vent ~ 20' above
the intended location.

Eric in North TX wrote:
I'm planing an install of a Takagi T-KD20 in the first floor of a 2
story addition. I'm a little confused by their install instructions. Do
I need to go through the second story roof with the exhaust vent?
My first choice would be to make it as short as possible. There are no
first floor windows on that wall, & only 2 on the entire wall, both 15'
or more from the intended location, there is a gable vent ~ 20' above
the intended location.

Perhaps I should have mentioned that a Takagi T-KD20 is a direct vent
tankless ho****er heater.

Eric in North TX wrote:
Eric in North TX wrote:
I'm planing an install of a Takagi T-KD20 in the first floor of a 2
story addition. I'm a little confused by their install instructions. Do
I need to go through the second story roof with the exhaust vent?
My first choice would be to make it as short as possible. There are no
first floor windows on that wall, & only 2 on the entire wall, both 15'
or more from the intended location, there is a gable vent ~ 20' above
the intended location.

Perhaps I should have mentioned that a Takagi T-KD20 is a direct vent
tankless ho****er heater.

I just installed the same thing... Works great, but beware of the
temperature. (It gets REALLY HOT). Also, be aware of your flow rate, we
had to change a few aerators (sp).

As far as venting, I would vent it out the side of the first floor as
long as there are windows close...

.. Works great, but beware of the
temperature. (It gets REALLY HOT). Also, be aware of your flow rate, we
had to change a few aerators (sp).

As far as venting, I would vent it out the side of the first floor as
long as there are windows close...

Could you elaborate?
Temperature; too hot or too cold?
Flow rate; seriously reduced? I'm running an 85 psi booster, I hate
wimpy water pressure.
Vent; I plan to run it out the wall behind the unit, curious if I need
to get it above the roof.

On 2006-07-14, Eric in North TX wrote:

Vent; I plan to run it out the wall behind the unit, curious if I
need to get it above the roof.

My understanding is that a direct vent appliance typically has its
vent terminated at the side wall and that there is no need to get
above the roof. The appliance's manual should list the necessary
clearances between the vent termination and varous other features of
the house.

BTW, if you live in a climate where it never freezes, consider an
exterior model, it makes venting very easy.

Cheers, Wayne

The Takagi Exhaust Venting instructions place a lot of burden on the installer to be in accordance with the section on venting of equipment in the latest edition of the National Fuel Gas Code. Based on your criteria, if the gable vent has a negative pressure or in other words does draft inwardly, then there should be a concern.

For venting parts that would comply with Wall Thimble Termination consider visiting www.plumbersurplus.com .

For the actual 4” ProTech Systems FasNSeal Wall Thimble with Termination Telescoping Elbow Appliance Adapter mentioned in the Takagi Exhaust Venting instructions, click here….
http://www.plumbersurplus.com/Produc...=26849&Cat=306


Here some instructions from another manufacture “Rheem”
http://rheemtankless.com/tanklessWeb...2%20Indoor.pdf

They talk about horizontal termination in the installation section.

I have these installed in several buildings as sidewall vent units.

1) If your's is a freezing climate, make sure you install a TK-TV03
back draft preventer.

2) If you want output hotter than 122F, you will need to install an
external TK-RE02 controller.

3) You will need a TK-BK01 wall mount kit.

4) Takagi specs a TK-TV05 wall-mount terminator kit. It's a big unit,
make sure that you allow a full 16" stud bay for its installation, and
plan the heater location with this in mind. It's helpful to have the
fill kit on site so plumbers and electricians can visualize what's
involved.

5) Don't forget that the unit will need 120V power.

6) You will need 2x wall SS vent pipe and fittings (check with Takagi,
at the time I installed they had approved two manufactures), and HT
sealant. It's simplest if you order the pipe, fittings and TV-03 (if
used) from the same source, so everything fits.

7) You will need .75" gas pipe (or equivalent CSST) ALL THE WAY to the
heater - you are putting in a 190,000 BTU appliance - probably, larger
than your gas furnace or boiler - and you may need to upsize piping or
even, on low pressure NG systems, an unsized meter!

8) You will need a TPRV rated for 200K BTU.

On later installs I used these isolation valves, they make for a
cleaner install, you can order either .75" sweat or IPS:

http://www.plumbingstore.com/images/...lves-50443.jpg

Michael Thomas
Paragon Home Inspection, LLC
Chicago, IL
mdtATparagoninspetsDOTcom
eight47-475-5668

Thanks for your reply! That's a very detailed and helpful post.
I'll be using LPG and the proposed site is a couple of yards from the
tank, so a new line shouldn't be much problem, I'll talk to my propane
guy to see if I can flow enough gas to run it, and what to do if not,
he is a certified, licenced, LPG plumber, he will know what to do. I
may not need much chimney, as the unit should mount right to the
TK-TV05 wall-mount terminator kit. Everything is right there as it will
replace an electric one already occupying that site. It does freeze
here maybe 2 weeks a year, but the spot it will occupy will be somewhat
heated, it is a large utility closet under landing for the stairs.
though it won't be directly heated it should stay 50 degrees or better,
I'll still look into the back draft preventer.