710-402 – GAS VALVE

Robertshaw 710 Series low capacity 24 volt combination gas valve, an extremely compact control built for low-capacity, limited-space applications. Robertshaw lists the application as wall furnaces and specifies use with a standard thermocouple, i.e. a standing-pilot system. It has 1/2″ inlet and outlet with three-position outlets, and the regulator is factory set at 3.5″ W.C. for natural gas.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• Series710 Series 24V Low Capacity
• ApplicationWall furnaces
• Ignition SystemStanding pilot - standard thermocouple
• Inlet Size1/2"
• Outlet Size1/2"
• Capacity70,000 BTU natural gas
• Electrical Rating24V AC @ 0.2 A; 12V DC @ 0.18 A
• Pressure Regulation3.5" W.C. natural gas
• Pilot Outlet1/4" tubing
• Maximum Inlet Pressure14" W.C. (1/2 PSI)
• Dimensions3-13/16" H x 4-21/32" L x 1-29/32" W
• MountingAny position except upside down

Can I put any 24 volt gas valve on my furnace?

No. The ignition system has to match. A standing pilot valve, an intermittent pilot valve and an HSI or DSI valve are built differently inside, and the manufacturers state plainly that they are not interchangeable. A standing pilot valve has a pilot outlet and a thermocouple circuit. A hot surface ignition valve has no pilot at all and expects the board to prove flame through a sensor. Substituting one for the other either will not run, or runs without proving flame, which is the part that matters.

What is the difference between 24 volt and millivolt?

A 24 volt valve needs a transformer and a control circuit. A millivolt valve runs on roughly 750 millivolts generated by a thermopile sitting in the pilot flame, with no outside power at all. They look similar on the shelf and they are not swappable. If the appliance has no transformer anywhere in it, it is millivolt.

Single stage or two stage?

A two stage valve has two regulator adjustments and two 24 volt hot terminals so the board can fire low then high. Hang a single stage valve on a two stage furnace and you lose low fire and usually pick up board faults. Bring the old valve or the furnace model number.

Can I convert a natural gas valve to LP?

Only with the manufacturer's kit for that furnace, and the kit is more than a spring - you replace every burner orifice and reset the regulator. Ballpark manifold pressure is about 3.5 inches water column on natural gas and about 10 inches on LP high fire, but the rating plate is the number that counts. Most of DFW is on Atmos natural gas, and LP mostly turns up out past the county lines.