2 wire thermostat

David Sutton

hello, are you looking to just start the boiler or are you looking to raise temp as well, if you are looking for a t-stat that will start the system try the white-rogers 906 use to be maple chase or any other programable will do it they are all capable of running on two wires they may have more uses just use the r + w post

jim_14

1 pipe steam controlled by that standard Honeywell round thermostat, heat only. Currently only 2 wires are used for triggering the boiler. I remember a few years ago looking for a t-stat that I could program to start the boiler at a set time in the AM rather then by temperature, but no luck.

You guys know of any T-stats for me? I just want it to come on every morning at a set time, and the rest of the day to come on according to room temp. The t-stat cable has multiple wires in its sheath, just two are being used ,if that makes a difference.

thanks

J.C.A.

T-stat?

Any programmable thermostat will do what you want . The older mechanical ones sometimes have "pins" to knock a switch from 1 position to another , and the pins will only allow a 2 hour run up time .(can't be programmed to run any less than 2 hours). Most digital thermostats can be programmed to do what you want . Chris.

jim_14

I tried to find a digital one a few years back, but couldnt find one for a 2 wire steam system.

question: since I would have the boiler come on every morning at a set time ,say 6am, would a prg t-stat shut off at a certain time or at a certain temp? reason Im asking is that I dont want it getting too hot if the boiler runs for a hour, that would be a waste

ed wallace

tstat

is it gas or oil fired ? if oil the control voltage is probably 24 volts if gas and is older system might be millivolt if 24 volts you can get a digital setback tsat to do what you want

Terry

why not a timer?

Why not install a timer (24 hr) that engages boiler at preset time (overriding T'stat). wire timer & t'stat in series so that if EITHER calls - the boiler fires?

Just an idea..

Terry

Terry

correction.

Parrallel not series....

Bill

Thermostat

To control the system properly, you should try a battery powered digital/programmable thermostat that has an optimum start feature. Make sure the thermostat has been tested on steam applications, the anticipation has to match the characteristics of a high mass steam system. There are a several on the market and you might want to try a Danfoss TP75.

BillW@honeywell

Stat

Try a Honeywell T8602D2018. It is battery powered, and make sure you set it for 1 cycle per hour (CPH) by going into "Installer Setup" mode. If you are on a budget, try the T8002C1000. Available from any Honeywell distributor, or try the "Find a Contractor" feature above.