daveva Posted November 20, 2014 Share Posted November 20, 2014 Wired a C4 thermostat to a Williams wall natural gas heater. This heater has no electrical power. The heater contains two wires from the gas valve red and white. Taking the red wire from the original thermostat to the RH and the white wire to W1 on the C4 thermostat and placing the jumper from RH to RC the thermostat operates the heater correctly. The problem is the battery icon is on which indicates that there is no power to the thermostat. The instructions say that the C4 thermostat is compatible with millivolt wall heaters. Any ideas as what could be wrong ? Thanks Link to comment Share on other sites More sharing options...
Cyknight Posted November 20, 2014 Share Posted November 20, 2014 Where does it say that?In the distant past you could power the t-stat purely on battery and because rh/c to w connection is no more or less than a relay it might work on a millivolt heater.However, with ZigBee Pro the battery drain got to large, you'll likely find that battery to be dead in a week. Either way - on millivolt you cannot operate the thermostat using power from the furnace/heater. Link to comment Share on other sites More sharing options...
kajphotos Posted November 21, 2014 Share Posted November 21, 2014 witch stat are you wiring ..on my c4 therm st has 2 wires and its set for power stealing and it works fine Link to comment Share on other sites More sharing options...
daveva Posted November 21, 2014 Author Share Posted November 21, 2014 Where does it say that, I assume you mean where does it say compatible with millivolt heat only-floor or wall furnaces. Page 5 of the thermostat install guide. I'm using CCZ-t1-W Link to comment Share on other sites More sharing options...
Cyknight Posted November 21, 2014 Share Posted November 21, 2014 witch stat are you wiring ..on my c4 therm st has 2 wires and its set for power stealing and it works fine Then you're one of the lucky - the powerstealing does not work on many furnaces, even with the resistor installed. It certainly won't work on a millivolt system. See page 4 of the mentioned install guide. Where does it say that, I assume you mean where does it say compatible with millivolt heat only-floor or wall furnaces. Page 5 of the thermostat install guide. I'm using CCZ-t1-WYes that's what I meant, and indeed what it says - and I'm surprised it does.As I mentioned, this would have been relatively well possible early on (and the thermostat available right now is the same one there always was with mainly some minor revisions) by running it on battery, but running it under ZigBeePro purely on battery just isn't realistic - even possible. Even under the old Embernet option it was against recommendation. See page 4 and 5 of that manual about power requirements for the device. That then leaves only the option of using an external transformer to power the T-stat and isolation relays to separate the 24VAC from the milivolt option. I'll link the diagram on how to do that - you'd only need a single across W1 as you're not using the others (as I understand it).https://www.dropbox.com/s/so5f2mjgxw8zfja/Thermostat%20with%20Transformer.pdf?dl=0 You could try to use it on just battery, but with ZigBee Pro (system 1.8.0 and up) the thermostat no longer goes to sleep - which is why battery drain becomes so high. Link to comment Share on other sites More sharing options...
daveva Posted November 21, 2014 Author Share Posted November 21, 2014 Thank you Link to comment Share on other sites More sharing options...
wingzz Posted November 21, 2014 Share Posted November 21, 2014 You can always power it with a 24 VDC power supply Link to comment Share on other sites More sharing options...
Cyknight Posted November 21, 2014 Share Posted November 21, 2014 You can always power it with a 24 VDC power supply Err see the post I made - you CANNOT 'just' power it with 24VAC on a millivolt system - you'd fry it. Link to comment Share on other sites More sharing options...
wingzz Posted November 23, 2014 Share Posted November 23, 2014 I missed the millivolt part, you are correct sir!! Link to comment Share on other sites More sharing options...
Cyknight Posted November 23, 2014 Share Posted November 23, 2014 By the way, even if you have a 24VAC furnace, it's recommended to use isolation relays to prevent the dual powersupplies/paths from causing issues. Link to comment Share on other sites More sharing options...
daveva Posted November 23, 2014 Author Share Posted November 23, 2014 Could you show me the isolation relay I should use? Thanks Link to comment Share on other sites More sharing options...
Cyknight Posted November 23, 2014 Share Posted November 23, 2014 There's lots to use, we get them from a local supplier so I don't have the exact model nr on hand, But you'd need something with a coil voltage that can handle 24VAC which is really the only important thing. http://www.zorocanada.com/i/G1724527/?gclid=CKP3n5WykcICFZSIfgodPzAA0ghttp://www.zorocanada.com/g/RIB%20Relay%20in%20a%20Box/00061844/?category=4844 Are just some examples. Keep in mind that even relays rated for VAC can hum when used on VAC, so you may want to try a few out and/or find a way to place them where the noise isn't a bother. Link to comment Share on other sites More sharing options...
daveva Posted November 24, 2014 Author Share Posted November 24, 2014 Thanks again I appreciate your input. Link to comment Share on other sites More sharing options...
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