4 wire thermostat on 2 wire system?

[pybyr]

Here's a question for the hydronic pros:

My parents' house has radiant in-floor heat, and uses Wirsbo 2 wire digital thermostats.

After about 10 years, some of the Wirsbo thermostats have ceased functioning.

Turns out that these Wirsbo t-stats are _quite_ expensive- about $80 each (ouch).

I've been very impressed with some of the Azel products that I have used in my own system, and see that they have a digital thermostat at a more modest price-- the D-135

http://www.azeltec.com/catalog.0.html.0.html#D-135

However, this is a 4 wire thermostat- with the power leads and switching contacts separated.

Anyone know whether these can be used on a 2 wire system by running the power leads in parallel with the switching leads?

Also open to other suggestions.

thanks

 

[2.beans]

i bought all my wirsbo 2 wire thermostats for 50$ each from pex supply

 

[juddspaintballs]

Honeywell makes 2 wire digital T stats for $25. You can pick them up at Home Depot.

 

[2.beans]

i changed out all my honeywells for the wirsbos. there built for radiant heat unlike honeywells that were installed in my house. by the way if any wants some honeywells cheap i have a bunch.