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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Radiant Floor System – 2005 Installation…All Viega system

Customer Question

Radiant Floor System – 2005 Installation…All Viega systemHave existing Stadler Viega mechanical thermostats and one of them does not work. Can’t find the direct replacement – since I assume they have been replaced, so I purchased a new 18050 Stadler Thermostat.
The issue is (since I don’t want to short anything) is the terminal designations are changed from the older model. The thermostat appears to go back to one of your Viega Zone Controls.EXISTING Mechanical Thermostat:
Red -- “L”
Green -- “-”
White -- “N”
TR – Separate Wire is jumped to “N” – connects only to itself (does not come from wall wire)On the NEW 18050 Thermostat:
“A/B”Can you help me tie these two together? Thanks very much.
Submitted: 9 months ago.
Category: HVAC
Customer: replied 9 months ago.
The Green on the existing is labeled with a mark of an ARROW ==>
hope that helps.
Expert:  gotoman for ac replied 9 months ago.

You have line voltage system(115 volt) with thermostat controlling pump. The new thermostat is 24 volt thermostat and will not work on that application. Russ

Customer: replied 9 months ago.
Sorry, but I looked at the existing thermostat and it states it is a 24Vac - I have attached a photo of the inside which states that it is. Stadler Viega has discontinued the older model - this is their direct replacement. As the wiring codes have changed I am looking for the correlation.
Expert:  gotoman for ac replied 9 months ago.

Just looked up Viega thermostat. Will opt for another Expert. Russ

Customer: replied 9 months ago.
To assist, here is the picture of the 18050 Viega ProRadiant Digital Thermostat I am using to replace older model
Customer: replied 9 months ago.
Got my answer to this question outside of your company.. will request a refund.