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Posted by Harold hydronicnetwork.net on February 25, 2004 at 07:55:43:
In Reply to: Re: White Rogers 3-wire posted by JTW on February 24, 2004 at 16:48:47:
You see; if you buy the premise, you buy the bit. The story here is that the 8022 is good for 3-wire heat. However, that means the manufacturer classified a wiring system with an R a W and a G terminal as three-wire.; but that only controls the heat and the fan switch. It isn't meant for a 3-wire zone valve which is something else.
The premise that is supposed to catch us is that the guy at the store who makes $8 an hour stocking shelves determines the heating future of the nation by educating everyone who comes in all about heating and getting 'the right thermostat.'
The old 3-wire thermostts drove a zone valve head that had the RW pair of terminals drive the zone valve open and the RY terminals drive the zone valve closed.
It is easiest to get a new 2-wire zone valve or the head only and replace the old head. The system has to be drained down first and the head is slipped off by pressing the clip underneath the head to twist the old head off and slip in the new one on the same brasss body.
http://www.accentshopping.com/store/heating/hydronic/valves/1361102.asp
Another way is to get the 1F90 or 1F97-391 programmable thermostat and use the original three-wire zone valve:
Notice that it has a terminal 6 to wire to the zone valve:
(on page 1l )
http://www.white-rodgers.com/pdfs/instruction_sheets/0037-6459.pdf
The old thermostat was:
200-901 24 Volt Zone, 3 wire
Dial Temp. Rang: 48°-86°F
Switch Action: SPDT
http://www.icca.invensys.com/robertshaw/200.htm