Pg3t Posted October 21, 2017 Posted October 21, 2017 My gas-fired boiler (hydronic hot water heat), no AC, has been controlled with a simple two-wire thermostat, connected to R & G connections on the boiler transformer. The transformer connections available are R, G, C, W, and Y. I tried connecting C to 24V COM, R to 24RG, and W to W1. No luck. Any suggestions?
stusviews Posted October 21, 2017 Posted October 21, 2017 Transformers have only two connections, do you mean the control panel at the boiler?
Pg3t Posted October 23, 2017 Author Posted October 23, 2017 I'm thinking that my boiler may have a multiple winding transformer (also known as a multi-coil, or multi-winding transformer). But maybe that aspect is mute. Let me say it this way: My boiler has R, G, C, W, and Y connections available.
stusviews Posted October 23, 2017 Posted October 23, 2017 You need at least 3 wires for heat only, R (24VAC in), C (24VAC return) and W (heat). G is used for fan, but in a single mode system (e.g., heat only), that's not always needed, that is, it's taken care of automatically by the control board. Y is for cooling which you don't have so you can ignore it. Sometime a 2-wire cable actually has a third wire. Strip back the outer layer of the cable a bit (if you have one).
G W Posted October 23, 2017 Posted October 23, 2017 I'd use copper wire. Sent from my Nexus 6P using Tapatalk
stusviews Posted October 23, 2017 Posted October 23, 2017 I'm not aware of any thermostat wire that's not copper.
G W Posted October 23, 2017 Posted October 23, 2017 I'm not aware of any thermostat wire that's not copper.I certainly wouldn't use bailing wire. Sent from my Nexus 6P using Tapatalk
stusviews Posted October 23, 2017 Posted October 23, 2017 I certainly wouldn't use bailing wire. Sent from my Nexus 6P using Tapatalk That's baleful.
Pg3t Posted October 23, 2017 Author Posted October 23, 2017 Well... I tried R (24VAC in), C (24VAC return) and W (heat) with no luck. Both of my attempts lit up the display on the Insteon thermostat, but didn't ignite the burners. When I opened the access cover and checked the wiring for the simple 2-wire thermostat, the connections were to G and R. I know that G is typically for the fan, but maybe a gas boiler is different for some odd reason. I attached a photo of the transformer and a photo of the schematic. Any ideas?
stusviews Posted October 23, 2017 Posted October 23, 2017 It appears that R and C are in their usual role to provide power to the thermostat and that G is the connection for heat (W).
Pg3t Posted October 24, 2017 Author Posted October 24, 2017 Success! Here is what worked: C to 24V COM R to 24RH G to W1 Thanks to everyone who contributed, balelessly.
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