View single post by Jay
 Posted: 05-17-2007 06:06 pm
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Joined: 08-05-2005
Location: Canton, Ohio USA
Posts: 73
Last night I set out to change out the old thermostat with a new fail-safe new one.
Before I install the new one I wanted to ask for the members opinions of the differences that I noted between the two thermostats. I have attached a photo. The brass colored one is what I removed and the other one is the fail-safe design.
  1. The fail-safe design appears to employ small metal clips located inside the spring to grab the spring and lock the valve open. I understand that this type is not to be reused after the clips have engaged and locked the unit open.
  2. The thermostat that I removed is a two stage type with a little giggle relief valve.
  3. The opening of the old 2 stage thermostat is noticeably larger that the new single stage one. Assuming similar thermal expansion rates between the two, I would think that the old one would be less restrictive than the new one.
  4. There is a small sort of weep hole with a giggle valve in the old thermostat, but there is no hole in the new one. I was wondering if the lack of such a hole would make it difficult to bleed any trapped. Are there any other concerns with the lack of such a hole?
I would welcome any thoughts of the appropriate design for the 907.

Thank You.

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