Also it depends on what the manufacture recommends.
Round here most furnaces have their own regulator, no need for a second external gas line regulator.
Most areas use natural gas. If a home uses propane for main gas source I check the furnace to make sure it has a gas regulator rated for propane, since most of the furnaces come stock with natural gas regulators, same with water heaters.
So if the appliance does not call for it, then no it’s not needed.
So we have the service regulator owned by the gas utility that supplies gas pressure at 7", 2 psig or in some instances for residential 5 psig.
The** system regulator** that reduces 2 & 5 psig to 7’ wc
and finally the appliance regulator that reduces 7" wc to 3.5"wc
The system regulators should be mounted in a non concealed and serviceable area.
The gas utility supplies natural gas pressure to the home through the service regulator/gas meter typically at 7" wc at this pressure no system gas regulator is required. The appliance regulator then steps this pressure down typically to 3.5"wc or as per name plate
When the gas utilty service regualtor/gas meter supplies pressure at** 2 psig** a system regulator is required to reduce line pressure to** 7" wc** so the appliance regulator can reduce the pressure to 3.5" wc.
The gas contarctor usually requests what pressure he would like 7", 2 psig, 5 psig. The gas contractor can utiliize higher gas pressures to downsize his pipe size for a more economical installation.
I’ve seen individual regulators at NG appliances on occassion. I have even had to install them when I asked the gas company to elevate supply pressure to the meter location/home during major renovations/additions when it was more cost effective to use existing gas piping, rather than replacing and/or starting over to meet the new total demands for gas consumption. I was never comfortable with the customer having to depend on so many actuating/safety regulators to operate appliances, but it was his choice, for cost saving measures.
I would never recommend that approach to any customer today, unless absolutely necessary.
I still see it today in commercial applications…Office/Warehouses, Manufactuering Plants, Public Facilities, etc.
