Thermostat Problem!

Hi folks:
I heat my home with hot water baseboards - two zones, upstairs and downstairs. Both zones are run on standard non-digital two-wire thermostats.
Upstairs zone runs perfectly fine. No problem with the thermostat either.
Downstairs zone has a problem. If left alone, the thermostat seems to maintain the heat it it set at. If I try to increase the temp by moving up the lever manually, you can hear the boiler get ready to run (zone valve opens, circulator starts), but then it clicks off and stops. Moving the lever back down will sometimes cause the same sound - as if it is ready to go, and then dies again.
I have replaced the basement thermostat with another non-digital one. Same problem.
Any thoughts on a cause?
Dave
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On 2 Feb 2005 18:26:26 -0800, snipped-for-privacy@hotmail.com (Dave Gallant) wrote:

I would change the thermostat again. And, if that doesnt work, Id change the stat again, and again. Bubba
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Dave, there is an end line switch built into the zone valve. When the valve is completely opened ( electrically ) the end line switch closes and energizes the relay for the circulator. From what you're saying it sounds like you've got a problem with this switch. Not knowing who's zone valves you've got I can't tell you how to test it

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