Hi,

I would like to replace my broken old 50-gal tank water heater with a tankless one (Rinnai R75Lsi). I had 2 plumbers who gave me estimates for the job. Both of them are rated 5 stars on the Rinnai website. However, their proposals for gas line connection are completely different. I am wondering if anyone can answer my questions regarding the gas line.

My existing gas line has a 1 1/2 inch diameter and runs 40 feet from the meter before splitting into smaller lines to my gas appliances: gas stove & double oven (less than 80,000 btu), gas furnace (125,000 btu), and my old water heater (40,000 btu).

The new Rinnai with a max. 199,000 btu will bring my total max btu to 404,000 btu. The two plumbers told me how they would provide gas for the new Rinnai:

#1: Add another gas line from the Rinnai all the way to the meter and request the gas company to provide a 2 PSI Split meter system to provide proper pressure for the Rinnai while keeping the furnace and stove & oven on the old (low pressure?) line.

#2: My existing 1 1/2 inch gas line is enough to provide up to 650,000 btu. Therefore, all I need to do is to request that my gas company upgrade my meter to 425 CFH.

I suppose choice #1 will definitely work for the Rinnai, but the 2nd gas line going all the way to the meter proposal costs a few hundreds of dollars more than proposal #2. Does anyone know if #2 will work just fine for all appliances or not? Does adding a new 199,000 btu water heater to the original line affect the performance of the furnace and stove?

Any comments/suggestions will be greatly appreciated.

Thanks.

Onlearningcurve

I would like to replace my broken old 50-gal tank water heater with a tankless one (Rinnai R75Lsi). I had 2 plumbers who gave me estimates for the job. Both of them are rated 5 stars on the Rinnai website. However, their proposals for gas line connection are completely different. I am wondering if anyone can answer my questions regarding the gas line.

My existing gas line has a 1 1/2 inch diameter and runs 40 feet from the meter before splitting into smaller lines to my gas appliances: gas stove & double oven (less than 80,000 btu), gas furnace (125,000 btu), and my old water heater (40,000 btu).

The new Rinnai with a max. 199,000 btu will bring my total max btu to 404,000 btu. The two plumbers told me how they would provide gas for the new Rinnai:

#1: Add another gas line from the Rinnai all the way to the meter and request the gas company to provide a 2 PSI Split meter system to provide proper pressure for the Rinnai while keeping the furnace and stove & oven on the old (low pressure?) line.

#2: My existing 1 1/2 inch gas line is enough to provide up to 650,000 btu. Therefore, all I need to do is to request that my gas company upgrade my meter to 425 CFH.

I suppose choice #1 will definitely work for the Rinnai, but the 2nd gas line going all the way to the meter proposal costs a few hundreds of dollars more than proposal #2. Does anyone know if #2 will work just fine for all appliances or not? Does adding a new 199,000 btu water heater to the original line affect the performance of the furnace and stove?

Any comments/suggestions will be greatly appreciated.

Thanks.

Onlearningcurve

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