TPR & Combusiton Air

Qusetion: Can two TPR extensions go in to one pipe?
And if burner chambers are sealed, is combustion air still required?

Sierra 012.jpg

I believe they have to go full size and separately to an acceptable location. :wink:

Absolutely not.

are you referring to a secondary form of combustion air?

Jeff, do you have any refference for the TPRs?

Im not jeff but…

P2803.6.1 states that the tpr drain must:

  1. Discharge to a termination point that is readily abservable by the building occupants.

  2. Not terminate more than 6 inches above the floor or wase receptor.

Also there is a good illustration of “Water Heater in Attic” In Code Check Plumbing…Page 21.

I know those TPR codes, I just want some solid info about two TPR extensions going into on line…Cant find anything that proves to me that the application is improper…

I can’t find the CA reference that specifically prohibits this, but I’ll keep looking.

In the mean time, here is the “generally accepted” rule.

**IPC 504.6 Requirements for discharge piping.
**The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:

  1. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.

If thats the case Tim then rule 4 would be:

  1. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.

2003 IRC:

[FONT=Times New Roman]P2803.6.1 Requirements of discharge pipe. [/FONT][FONT=Times New Roman]The outlet of a
pressure relief valve, temperature relief valve or combination
thereof, shall not be directly connected to the drainage system.
The discharge from the relief valve shall be piped full size sepa-
rately to the floor, to the outside of the building or to an indirect
waste receptor located inside the building. In areas subject to
freezing, the relief valve shall discharge through an air gap into
an indirect waste receptor located within a heated space, or by
other approved means. The discharge shall be installed in a
manner that does not cause personal injury or property damage
and that is readily observable by the building occupants. The
discharge from a relief valve shall not be trapped. The diameter
of the discharge piping shall not be less than the diameter of the
relief valve outlet. The discharge pipe shall be installed so as to
drain by gravity flow and shall terminate atmospherically not
more than 6 inches (152 mm) above the floor. The outlet end of
the discharge pipe shall not be threaded and such discharge pipe
shall not have a valve installed.[/FONT]

Thank to All for the help…

I don’t like to see them combined either, but I called the City of Seattle and they say it is OK as long as the pipe increases in size (lots of town houses where the heaters are back to back use this set-up). So like many things, it may vary from jurisdiction to jurisdiction.

did you check the underneath of the water heater to see if it had screening for ventilation?

Fred Lambert
JADES Home Inspection Service, LLC
ICC Certification # 5166981-R5
Phone: 770-448-8726
Cell: 404-314-6339
Below is a technical notice that I found on the American Water Heater website. It deals with the thermocouple in the FVIR water heater.

Flammable Vapor Ignition Resistant (FVIR) Gas Water Heaters
With the new safety standards that have mandated FVIR (Flammable Vapor Ignition Resistant) water
heaters, it is important for you (our customers and service technicians) to be able to easily diagnose and
implement solutions that will take care of operational problems with these types of water heaters. This
bulletin is intended to help you avoid typical installation issues with the water heater or the environment in
which it’s installed, and to help you understand what to do when you are trying to solve a problem.
The pilot thermocouple used in FVIR water heaters includes a one-shot temperature switch that opens the
thermocouple circuit if the water heater is not receiving adequate combustion air for any reason. With
several thousand FVIR water heaters now installed in the field, data suggests burner and pilot shutdown
problems are being perceived as a thermocouple problem. Feedback regularly includes ?my old water
heater never had a problem?. Let?s examine the reasons the temperature switch in your thermocouple is
being activated:

  1. The water heater may be starved for combustion air. This causes the burner flame to get lazy
    and waiver around in the combustion chamber, causing the temperature switch inside the
    thermocouple to trip. Here are the things to check for and correct:
    a. The water heater may be located in a closet or space that does not have openings for
    combustion air to get to the water heater. Openings in the closet must be provided per the
    installation instructions, which tell you how much open area you need. IMPORTANT:
    The instructions only cover the needs of the water heater. The air requirements of all
    gas-fired or air-consuming appliances in the closet or space must also be considered.
    Don?t forget an electric dryer, it also consumes air.
    b. The openings in the closet are smaller than what is needed to supply adequate combustion
    air. Review the installation instructions and information as noted in (a) above.
    c. The water heater may be installed in a utility room or closet along with a furnace or air
    handler, with a return air duct that has not been attached, or it may have leaks that are not
    sealed. When this condition exists, the return air system creates a significant negative
    pressure on the installed space and significant down draft of the flue occurs at the water
    heater. Even if the utility room or closet has a door with louvers in it, a negative pressure
    may still exist. (When checking, be sure the furnace or air handler is ON and the doors
    are closed). When a down draft is created, the combustion products from the water heater
    can no longer exit up through the vent system. The flame inside the water heater will
    become lazy and wander around, causing the temperature sensor inside the thermocouple
    to trip. If you can?t fix the problem, notify a water heater service organization. THIS IS
    duct system corrected. For a temporary solution, keep any doors on the utility room or
    closet wide open.
  2. There may not be a draft at the water heater draft hood. With the water heater operating for 3
    to 5 minutes, check for a draft at the inlet to the draft hood with a match or a small amount of
    smoke. Remember, when checking, be sure all appliances in the installed space are on and the
    doors are closed. If there isn?t a draft, and you have ruled out or corrected items a, b and c above,
    check the vent system for restrictions or obstructions. Correct these and recheck for draft. You
    should also check the vent termination to be sure it is the correct height when it exits the home or
    structure. Refer to the installation instructions for how to evaluate this. Correct the vent height if
    needed and re-check the draft.
    March 2005
  3. The installed environment may be dirty.
    The flame arrestor (stainless steel slotted plate) in the bottom of the combustion chamber is
    precision designed to combust flammable vapors safely inside the combustion chamber in the
    event that flammable vapors are present around your water heater. Although the flame arrestor
    tends to shed lint from the surface, in some cases it can become restricted. When this happens, the
    burner flame will become lazy and overheat the combustion chamber causing the temperature
    sensor inside the thermocouple to trip. You can diagnose this condition by inspecting the flame
    arrestor. To correct this and improve the environmental condition, clean the flame arrestor using
    a soft brush to clean the slots in the flame arrestor. A toothbrush works well. Be sure to clean
    both sides of the flame arrestor. Then vacuum the area free of any lint, etc. If you think the
    installation will be prone to repeated plugging, an external filter is available that can be easily
    installed. This will greatly extend the run time of the water heater in a dirty environment and will
    allow for easy periodic external cleaning. Call our service assistance number found in your
    installation manual or on your water heater to request the filter and installation instructions.
  4. A flammable vapor accident has occurred
    Of course, our desire to reduce the likelihood of a flammable vapor incident is the main reason
    that the new technology has entered the marketplace. So, if a flammable vapor event occurs, the
    temperature inside the combustion chamber will increase, causing the temperature sensor inside
    the thermocouple to trip. This event can be diagnosed as a flammable vapor accident if you see
    that the flame arrestor has been discolored like it has been overheated. There is no repair for this
    condition and the water heater must be replaced. If a flammable vapor incident has occurred, you
    must call the service assistance number found in your installation manual or on your water heater
    and report it. We will ask you to return the water heater to us at no cost to you.
    Included in this kit, you?ll find all parts and instructions necessary to complete your installation of this kit.

I would look at the instruction/service manual for the specific unit in question.

They are supposed to be in a protected pouch on the side of the unit.

Aren’t they? YES

This is what I saw on the roof. Then I went into the garage and saw the combustion air vent blocked on the garage wall and… look at the HWT pic.



vent is covered (Medium) (Small).JPG

blanket touches flue (Medium) (Small).JPG

You still need combustible air in the room but usually these water heaters are screened at the bottom to get air. They’re just built in a way to eliminate gas from getting into the burner.

not very nice