Furnace in kitchen & Return air from outside

[Charles Smith]

Inspection yesterday.

- LP Gas: Furnace and water heater located in the kitchen. (had electric range)

- There were no Hi/Low combustion air vents installed.

- The cold air return was exterior grill / vent (outside air). There was no return air duct system installed returning interior air

- Can "all" of return air come from outside? Seems as though house would be pressurized??

- Living room was only room with heated air ductwork (crawl area).... wood stove in living room.

- Kitchen had no heated air ductwork (slab construction).

- Separate area had direct vent LP gas wall furnace.

By the way the living room area was a mobile home 10' x 55' with framed envelope built around it!!!! very strange!!!

Pictures show metal siding... metal frame and wheel hubs in crawl area!!

Electrical: Service entry wire (cable) from meter to SEC panel was exposed above ground

[Randy Clayton]

Charles, I don't deal with mobile homes but onne thing I did see is that where the furnace and wh exaust came together the size of the flue did not increase in size.

[Jim Luttrall]

Can "all" of return air come from outside? Seems as though house would be pressurized??


Prohibited in the IRC.

From the sound of it this is truly a "bubba built" POS.

[Charles Smith]

Yes, the furnace and WH exhaust vent had no Wye connector and the size was not increased to accomodate both gas appliances.

Trying to find the specific IRC reference on % of outside air brought into return and ran across...

"If the outside air duct is connected directly to the return air trunk line, the connection must be a minimum of five feet from the furnace blower. The outside air cfm cannot exceed 10% of furnace flow."

Any other input would be appreciated.

Thanks

[Jim Luttrall]

Can "all" of return air come from outside?


2003 IRC Section M1602 Return Air
M1602.1 Return air. Return air shall be taken from inside the dwelling. Dilution or return air with outdoor air shall not be prohibited.

The idea is that the system should be balanced so that the return air and the supply air to the dwelling should be roughly equal. If there is a return strictly from outdoors, it is wrong, no calculation needed. Otherwise, see M1602.2 in the IRC to start with if you are under the IRC.

[Darren Miller]

If the furnace was fan assisted venting, the WH vent may have been increased to accomadate the fan and there would be no need to increase the the vent after the connection.