STC 1000 defective out of the box.... anybody else?

I have a brand new STC 1000 which has been sitting in a drawer for about 6 months, and finally got it out and set it up to operate a heating system. In the process of figuring out how to set it &c, I discovered that the heating function will work, but the cooling function does not..... I was testing the continuity of both sets of contacts using hot and cold water. I originally bought this to use on my fridge but never got around to using it. Currently I have it hooked up on a propane powered overhead radiant ceramic plaque catalytic heater I built.

Anybody else run into defective units?

I bought the standard 110 V STC 1000, as I figured that it was about time I learned temp in C. I can translate millimeters, meters and kilometers effortlessly to inches yards and miles, rods, and fathoms, and I find myself using grams and kilograms more and more. Not much point in using the goofy English / American system really.......... just because that's what we grew up with. It's unquestionably vastly inferior......... Quick, how many feet in a rod or square feet in an acre?? ( 16.5 & 43560 )... how about acres in a quarter section? Yards on a fathom? (160 & 2 )............. How about standard railroad gauge width? (56.5"). One has to wonder how we became saddled with such a collection of oddball measurements. Why should water boil at 212 and freeze at 32 ? Why should there be 5280 feet in a mile? Metric is as logical as our system is illogical.

H.W.

I had a similar problem with a new STC-1000 except mine would only cool. At first I thought I must have wired it wrong and spent a lot of time troubleshooting only to determine the relay for the heater power was bad. After convincing the seller that it was not functioning properly they sent me a new one.

Also keep in mind that it will not start cooling right away when it gets above the set temp. There is a delay built in to keep your fridge from short cycling. If you haven't already, try giving it a minute to cycle on.

The indicator light by 'Cool' will flash if it's the compressor delay.

Do you have it wired to an outlet or hardwired? If wired to an outlet you'll need to break the tab to separate the two circuits.

iijakii said:

The indicator light by 'Cool' will flash if it's the compressor delay.

Click to expand...

I bet this is the reason....... though it does the hot cycle virtually instantly.... I didn't notice if the light was flashing....... I did get the circuit to close once..... thanks for the heads up.

Fortunately I'm using it for heating.....but I'm only using it for heating because I don't have any other thermostats that are simple enough to work on a two wire system. Ultimately I hope to replace it with one of the old mercury switch thermostats...... those were far and away the most reliable thermostats ever built. I'm using a standing pilot and a millivolt control valve that runs on the voltage produced by a thermopile. That makes it kind of silly to have a thermostat that requires 120 volt, or 24 volt to operate. I want this to be a system that needs no electrical source except the thermopile voltage.

H.W.

xpops said:

Do you have it wired to an outlet or hardwired? If wired to an outlet you'll need to break the tab to separate the two circuits.

Click to expand...

You lost me there.......... all 4 circuits are completely separate, The 120 volt power circuit, the thermocouple circuit, the heating circuit and the cooling circuit as far as I can tell. Please clarify this..... perhaps mine is different from yours. The wiring diagram shows no internal connections.......... My regular honeywell thermostats have a jumper that has to be removed under certain circumstances... such as when your power source to the thermostat is separate from the switched source.....but not the STC 1000


H.W.

Owly055 said:

You lost me there.......... all 4 circuits are completely separate, The 120 volt power circuit, the thermocouple circuit, the heating circuit and the cooling circuit as far as I can tell. Please clarify this..... perhaps mine is different from yours. The wiring diagram shows no internal connections.......... My regular honeywell thermostats have a jumper that has to be removed under certain circumstances... such as when your power source to the thermostat is separate from the switched source.....but not the STC 1000 H.W.

Click to expand...

He means that if you have it wired to a standard 110vac outlet (one outlet for heat, one for cool) you need to break the connector between the two circuits.
If you have yours wired directly, disregard.

Yes sorry. That's what I was getting at

iijakii said:

The indicator light by 'Cool' will flash if it's the compressor delay.

Click to expand...

You were correct about the flashing light. Last night I did some further observations and determined that the cooling circuit does in fact work once past the flashing light mode. Interesting that there doesn't seem to be any provision for delay in the heating mode...... obviously not suitable for a heat pump. I overlooked the "compressor delay" function which is set to 3 minutes by default. The instruction sheet is a bit sketchy.


H.W.

Glad it's working.

Owly055 said:

I bought the standard 110 V STC 1000, as I figured that it was about time I learned temp in C.

Click to expand...

For the limited ranges we use, I've found that the easiest way to convert C=>F is to 1) double the C reading, 2) subtract the first digit in the doubled reading from the doubled value, and 3) add 32. It generally gets you to within 1F. Close enough for me most of the time and I can do it in my head.

Examples:

12C => 12x2=24, 24-2=22, 22+32 = 54F. Actual value is 53.6F
23C => 23x2=45, 46-4=42, 42+32 = 74F. Actual value is 73.4F
8C => 8x2=16, 16-1=15, 15+32 = 47F. Actual values is 46.4F

b-boy said:

For the limited ranges we use, I've found that the easiest way to convert C=>F is to 1) double the C reading, 2) subtract the first digit in the doubled reading from the doubled value, and 3) add 32. It generally gets you to within 1F. Close enough for me most of the time and I can do it in my head.

Examples:

12C => 12x2=24, 24-2=22, 22+32 = 54F. Actual value is 53.6F
23C => 23x2=45, 46-4=42, 42+32 = 74F. Actual value is 73.4F
8C => 8x2=16, 16-1=15, 15+32 = 47F. Actual values is 46.4F

Click to expand...

Good plan.......... I'll remember the subtract part...... I taped a conversion chart to the wall anyway.

H.W.