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amorak · Nov 27, 2007, 07:47 PM

Hi everyone,

I have two wires coming out of my wall, RED and BLACK.

I have Wirsbo infloor heating, which is a radiant in floor water heating system.

I have attempted to hook up a honeywell programmable thermostat, hooking up RED to Rh and BLACK to the W hookup, I believe. However when I do this, the heat runs all the time.

I think the problem lies in the way the system works - That is, the hot water flows through the pipes when the wires are DISCONNECTED and the heat stops when the wires are CONNECTED.

I think the normal thermostat is operating in the opposite fashion - that is, connecting the wires for heat, when I need the opposite to occur.

Any ideas on a decently priced, programmable thermostat that will work with this system?

Thanks!

hvac1000 · Nov 28, 2007, 05:19 AM

If yours is wired to start the flow when the thermostat is off/wires are disconnected there is a problem somewhere else. For the time being I would put the old stat back on and then look at the system to see why it is doing this. There are many suggestions to make like a reverse acting relay etc but that does not fix the problem just temporarily works around it.

labman · Nov 28, 2007, 08:12 AM

If somebody installed a thermostat with normally closed contacts, likely the system was designed to work that way. You can do the same with the thermostat you have. Move the wires to RC and Y. Set the thermostat to cooling. With the room below the set point, the thermostat will open the contacts, turning the system. When it reaches the set point, it will close the contacts, shutting the system off.

hvac1000 · Nov 28, 2007, 10:59 AM

Originally Posted by labman

If somebody installed a thermostat with normally closed contacts, likely the system was designed to work that way. You can do the same with the thermostat you have. Move the wires to RC and Y. Set the thermostat to cooling. With the room below the set point, the thermostat will open the contacts, turning the system. When it reaches the set point, it will close the contacts, shutting the system off.

While moving the wires to RC and Y might physically work you have lost all control over the heat anticipation circuit. This is especially bad with a radiant heating system which has a slower recovery than most. The system still needs to be checked and if it is a true reverse acting thermostat it should be replaced with like same or a relay should be used so the anticipator circuit can still perfore its intended function.