[Coco] OT: Heat / A/C controller replacement

Thu Jun 7 23:21:27 EDT 2012

With these thermostats you would need more than 2 wires to operate the heat and air conditioner.  They all have a mode switch built in, slide a lever to select either heat or a/c.  

From what you have said your previous set up had a normal 2 wire heat only thermostat and you built a secondary one that selected heat it the temp was below a set point and ac if above the set point.  Probably should have had some hysteresis in it so it did not toggle near the setpoint temperature.

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-----Original Message-----
From: "Stephen H. Fischer" <SFischer1 at Mindspring.com>
Sender: coco-bounces at maltedmedia.com
Date: Thu, 7 Jun 2012 20:13:36 
To: CoCoList for Color Computer Enthusiasts<coco at maltedmedia.com>
Reply-To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Subject: Re: [Coco] OT: Heat / A/C controller replacement

Hi,

If I was talking about the heat / AC control that was installed downstairs ~ 
1970, then a simple replacement like you suggest would work.

BUT the problem is, how do you connect TWO of these with 5-6 wires at the 
SAME time.

If there is an understandable diagram online then I might be able to figure 
out what I did, looking at the wires connected to the heat / A/C it is 
puzzling to me right now what I did.

I just have two wires that when shorted turn the heat or A/C on. The 
downstairs controller sets the mode and will turn the heat / A/C off it it's 
setting is exceeded.

SHF

----- Original Message ----- 
From: "gene heskett" <gheskett at wdtv.com>
To: <coco at maltedmedia.com>
Sent: Thursday, June 07, 2012 7:54 PM
Subject: Re: [Coco] OT: Heat / A/C controller replacement

> On Thursday, June 07, 2012 10:37:14 PM Stephen H. Fischer did opine:
>
>> Hi,
>>
>> My Heat / A/C was installed ~ 1971.
>>
> So?  The control interface probably hasn't changed enough to care in 60
> years.  The typical micro controlled Honeywell wall stat you can get at
> Lowes/Home Depot for 50-60 dollars still talks to the usual 24 volt 
> control
> circuitry, 5 or 6 wires, that could very well come from a 70 year old coal
> stoker, just as easily as it hooks to my AC and a Bryant 90+ natural gas
> furnace that is now about 8 or 9 years old & vents thru 2" white PVC pipe
> out thru what used to be a basement window.  I paid $50 for this one, 
> gives
> me 4x a day settings plus weekends.  I've replaced the 2 backup the clock
> penlight cells in it twice in 15 years.
>
>> Today's Heat / A/C controllers likely have an wireless internet address.
>
> For a price I suppose that is available, but this one I have to program
> from its panel, in person.
>
>> I just am looking for ideas as to how a old heat / A/C controller could
>> be used like the one I built ~ 30+ years ago.
>
> If all you did was close a relay, then any of the stats available today 
> can
> do that.
>
> I don't think it has to be old, the actual interface itself has not
> markedly changed in yonks.  The "fan only" switch might not work. I think
> that was the last addition to the low voltage protocol, probably 40 years
> ago, if not more.  The only time I use that is if the AC freezes up the
> inside coils, then you turn off the AC and turn on the fan till it thaws
> out.
>
>> Links to the old controllers available today might be a starting point.
>>
>> I fear walking into a hardware store would produce smart phones to
>> control Heat / A/C from Perth.
>>
>> SHF
>>
>> ----- Original Message -----
>> From: "Louis Ciotti" <lciotti1 at gmail.com>
>> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
>> Sent: Thursday, June 07, 2012 6:50 PM
>> Subject: Re: [Coco] OT: Heat / A/C controller replacement
>>
>> >I assume you need something unique that a standard Heat/AC thermostat
>> >
>> > will not work?
>> >
>> >
>> >
>> > On Thu, Jun 7, 2012 at 5:02 PM, Stephen H. Fischer
>> >
>> > <SFischer1 at mindspring.com> wrote:
>> >> Hi,
>> >>
>> >> HELP!
>> >>
>> >> My hand constructed Heat / A/C control failed when the power went off
>> >> and it
>> >> is beyond my current ability to fix it. (data sheets are hidden, I
>> >> did not
>> >> draw up a plan, just wired the chips up looking at the data books
>> >> many decades ago.)
>> >>
>> >> ---------------------------
>> >> The basic operation was a LM3911 that sensed the temperature and
>> >> CMOS chips drove a triac (AC power relay).
>> >>
>> >> There was a pot that controlled the set point and more parts to trim
>> >> the pots range and drive LED's.
>> >>
>> >> ---------------------------
>> >> What I am looking for is a off the shelf controller that I can change
>> >> the desired temperature easily and have an off switch for use when I
>> >> do not use
>> >> the heat or A/C.
>> >>
>> >> The present controller is just a relay that just shorts the heat /
>> >> A/C power
>> >> just like a switch which is how I will be doing it if an replacement
>> >> cannot
>> >> be found. The normal house controls are used to switch from heat to
>> >> A/C and
>> >> prevent the house being heated too much or cooled too much in case of
>> >> a failure
>> >>
>> >> It was good that the power failure did it's damage when the home-brew
>> >> controller was off/
>> >>
>> >> I know this is a weird request and will not make sense to those who
>> >> know how
>> >> heat / A/C work.
>> >>
>> >> No timed options needed and other bells / chimes that the current
>> >> controllers have, I want to just set the temperature and turn it on
>> >> and off.
>> >>
>> >> SHF
>> >>
>> >>
>> >>
>> >>
>> >> --
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>> >> Coco at maltedmedia.com
>> >> http://five.pairlist.net/mailman/listinfo/coco
>> >
>> > --
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>
>
> Cheers, Gene
> -- 
> "There are four boxes to be used in defense of liberty:
> soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
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