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HVAC man needed

Posted: Tue Jul 19, 2011 7:40 pm
by Coyote
Here's the deal. I have a wall mounted window unit that provides me with both heat and air conditioning in my workshop. It is a 110 volt (line voltage) thermostat. This thermostat operates a set of contacts that kicks in (or out) the 220 voltage the unit needs to operate. Still works well and has been operating now for about 15 years. However......
This is a bi-metal thermostat. It's a Honeywell and it's a POS.
Let's say it's a 100 degrees outside. I set the thermostat to 80. It will kick in at about 84 and won't shut off till you have icicles hanging off your mustache. This is an exaggeration of course, but the real range between on and off is about 10-12 degrees.
I have searched endlessly for a line voltage (110) digital thermostat. The one I have indoors is a White Rodgers and will hold the temp at whatever you set it at. Set it at 77 and it will kick on at 78 and off again at 77.
The bottom line is I can't find a 110 volt digital thermostat. There doesn't seem to be one in existence.
Any ideas???

Re: HVAC man needed

Posted: Tue Jul 19, 2011 8:57 pm
by Suzsmokeyallan
Chris, 220 volts single phase has two live 110 volt feeds and a ground so how is that 110 volt switch working? Does it have two pair of contacts for the two live 110 feeds and a solenoid coil energized by a 110 source from the thermo sensing circuit to open and close the circuit?

Is this going to work for you its 110 volts, its digital and handles HVAC

http://cgi.ebay.com/LCD-thermostat-digi ... 2c5da5cb18" onclick="window.open(this.href);return false;

Re: HVAC man needed

Posted: Tue Jul 19, 2011 10:04 pm
by 650hardtail
any bi metallic line voltage tstat is a pos..the easiest way to change it to a 24 vac t stat would be to use a
2 pole 24 vac ( coil ) contactor ..a 40 va 115 v transformer for control / tstat voltage...set the window units tstat full cool
( since the stat/ contactor will break line voltage to the whole unit )
or you could just wire the units temp control thru the contactor...the 24v stat/contactor will break the power thru the old ( in unit )
temp control..
or we could just gut your line voltage stat..

i could draw ya up a couple possible schematics

id guess parts..$25 - $ 50 + ( depending on your tstat selection )

could you provide internal pics of the pos stat ? ( wire connections )