Gas code question NH

sootmonkey

Thank you Allan, My question pertains to "Minimum Allowable Input Rating of space heating appliances on an exterior chimney." My code book is outdated, but from what I understand you can not connect a gas fired appliance to an exterior chimney if the "local 99% winter design temperature" is below 4 degrees F. Is this code still valid? I do not pretend to be a "Gas Man." I only went to the site as a favor to my sister in law. As a side note the Home Inspector found only one of many issues with the boiler. Just trying to chew this bannanna.

sootmonkey

Gas code question NH

I looked at a LPG gas heating system in a house that my sister in law is looking to buy. I found some problems with the gas fired hot water maker and some problems with the gas fired hot water boiler. The hot water maker was producing 1578 PPM of CO. The boiler has some pipeing issues. I am not well versed in gas code. I have a 1996 issue of NFPA 54. The two systems are bull teed into an exterior masonry chimney. The total input of both appliances is less than 180,000's btu. I am going to say the chimney is 30 feet high and has a 8x8 clay liner. The home is in/near Manchester N.H. Am I correct in saying that this is not allowed per NFPA 54? Just a monkey

Alan R. Mercurio_3

As you now gas is not my expertise but the part about the venting I think would be similar and still fall under NFPA – 211

According to NFPA 211-2000 Table 6-8 Interconnections(Chimney Connector and Vent Connector)

6-8.1 Connectors serving appliances operating under natural draft shall not be connected into any portion of a mechanical draft system operating under a positive pressure.

6-8.2 Unless listed for such connection, solid fuel-burning appliances shall not be connected to a chimney flue serving another appliance.

6-8.3 Gas utilization appliances and appliances burning liquid fuel shall be permitted to be connected to one chimney flue through separate openings or shall be permitted to be connected through a single opening, provided they are joined by a suitable fitting located as close as practicable to the chimney and provided both of the following apply:

(1) Sufficient draft is available for the safe combustion of each appliance and for the removal of all products of combustion.


(2) The appliances so connected are equipped with primary safety controls and all appliances are located in the same room.

6-8.4 If two or more openings are provided into one chimney flue, They shall be at different levels, and the smaller connection shall enter at the highest level consistent with available head room or clearances to combustible material.

The following information can be found in the 2000 Edition of NFPA 211 page 211-27

I hope this helps you some!


Your friend in the industry,
Alan R. Mercurio

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Sootmonkey

Even if the "Local 99% Winter Design Temperature" were 37°F or greater, the Total Combined Input of 180,000 btuh, 8" x 8" Nominal Flue and Chimney Height of 30' you have there would be "Not Recommended" according to the Code Tables, and that would be if they had B-Vent Connectors to boot. Just curious....when you say these appliances are connected together in "Bull Tee" fashion are you implying that they are connecting into a tee from opposing directions and then branching into the common flue?

Glenn Stanton

Manager of Technical Development

Burnham Hydronics

U.S. Boiler Co., Inc.

EBEBRATT-Ed

If the two appliances are "bull teed" with the branch connection going to the chimney as Glenn suggested then it is wrong, should be changed, and has never been right.

As far as the btu input and the clay lined chimney that is a maybe. It could have been code when it was done as the venting rules have been changed some time ago. How old are the appliances? and how old is the home? If the appliances are original it may have been ok when they wer installed.


ED

sootmonkey

Thank you Glen and EBEBRATT. The home was built in 1995. My copy of NFPA 54 is 1996 issue. The "bull head tee" is as follows: One appliance is piped into one end of the tee and the other appliance is piped into the branch of the tee. The other end of the tee goes to the chimney. The appliances are original.