Why 2 Regulators

retiredmt

Can someone please explain why I have 2 regulators for my 1000 gal propane tank that feeds into my house? There is one at the tank and the 2nd one is located at the house (outside). Thanks

EdTheHeaterMan

There is a primary at the tank and a secondary at the home. Outside the home you can have higher pressure. Inside the home you must be below 1 PSI for safety reasons. the pressure in the tank can be over 100 PSI. The primary (tank) regulator reduces that to a safer lower pressure but still above 1 PSI, This way the pipe from the tank to the house (secondary regulator) can be a smaller in diameter. The piping into the house is usually larger on the outlet side of the house regulator.

Some appliances even have a regulator at the appliance gas inlet. So, that would be a total of 3 regulators going to that appliance.

It is just like the electric company that generates electricity and sends it out at over 500,000 volts because higher voltage looses less electricity over the wires than lower voltage electricity. It travels more efficiently. When the electricity gets to the substation in your neighborhood the transformers reduct it to 2400, volts to the wires that go to your street. Then there is a transformer on the poll (or on the ground if you electric service is underground) that drops that to 240 Volts to use on your home. that is divided in your home to 120 volts for most appliances but your electric range or central air conditioner can connect to the more efficient 240 volt power.

The reason for stepping the pressure down in increments is efficiency of transmission, or lower cost to move it. If you had the regulator at the tank drop the pressure to the appliance pressure, you might need a 2" or 3" pipe to get that low pressure from the tank to the appliance. That would be a costly pipe!

retiredmt

EdTheHeaterMan said:

There is a primary at the tank and a secondary at the home. Outside the home you can have higher pressure. Inside the home you must be below 1 PSI for safety reasons. the pressure in the tank can be over 100 PSI. The primary (tank) regulator reduces that to a safer lower pressure but still above 1 PSI, This way the pipe from the tank to the house (secondary regulator) can be a smaller in diameter. The piping into the house is usually larger on the outlet side of the house regulator.

Some appliances even have a regulator at the appliance gas inlet. So, that would be a total of 3 regulators going to that appliance.

It is just like the electric company that generates electricity and sends it out at over 500,000 volts because higher voltage looses less electricity over the wires than lower voltage electricity. It travels more efficiently. When the electricity gets to the substation in your neighborhood the transformers reduct it to 2400, volts to the wires that go to your street. Then there is a transformer on the poll (or on the ground if you electric service is underground) that drops that to 240 Volts to use on your home. that is divided in your home to 120 volts for most appliances but your electric range or central air conditioner can connect to the more efficient 240 volt power.

The reason for stepping the pressure down in increments is efficiency of transmission, or lower cost to move it. If you had the regulator at the tank drop the pressure to the appliance pressure, you might need a 2" or 3" pipe to get that low pressure from the tank to the appliance. That would be a costly pipe!

Thank you. Great explanation.

hot_rod

The first stage assures that the 2nd  reg always gets a stable pressure, as tank pressures vary considerably   

It supplies 10 psi to the second stage which drops pressure to 11 inches. 

At least that is what they taught us in the LP certification classes🤓

EBEBRATT-Ed

And the tank pressure can vary widely depending on tank volume and how much gas is in it and the outdoor temperature the tank is in

Tim McElwain

Typically for residential application the first regulator reduces tank pressure to 10 pounds pressure the second regulator reduces pressure to 10 " to 12" water column for use on the equipment.

JUGHNE

When LP came out here in the 1950's, one delivery company had 98% of the business.

Their standard install was one large single stage regulator at the tank with maybe 3/4" OD copper running about 100' to the house. Apparently at that time regulators were an expensive item compared to copper tubing.

Lots of pilot lite outages and frozen regs.
Equipment was not as sensitive to pressure changes back then.

A single stage reg really gets overworked with outside temp changes.

vhauk

EBEBRATT-Ed said:

And the tank pressure can vary widely depending on tank volume and how much gas is in it and the outdoor temperature the tank is in

Tank pressure is solely dependent on temperature. Propane is actually a refrigerant. Unless the tank is empty the pressure will reflect the temperature of the liquid in the tank. 

GroundUp

Mybe this varies in different parts of the world, but very seldom is the 2nd stage regulator outlet in inches unless there's a low BTU requirement with the heating appliances very near that 2nd stage reg. Pretty much anything over 150k BTU will require 2psi until within 20 feet of the appliance, which is why the norm in my parts is to install a 2psi 2nd stage reg on the building and then a 3rd stage inside to feed the appliance(s) with inches.

hot_rod

GroundUp said:

Mybe this varies in different parts of the world, but very seldom is the 2nd stage regulator outlet in inches unless there's a low BTU requirement with the heating appliances very near that 2nd stage reg. Pretty much anything over 150k BTU will require 2psi until within 20 feet of the appliance, which is why the norm in my parts is to install a 2psi 2nd stage reg on the building and then a 3rd stage inside to feed the appliance(s) with inches.

With NG in my area you need a signed approval from the fuel provider and the city to get a 2 psi set, meaning 2 psi inside the building.

You also need an observed, inspected, 1 hour 30 psi pressure test on all the piping.

In rural areas that I lived the LP providers would pretty much give you what ever pressure you asked for