Omnistat turns on and off and on and off and ...

[chrisdias]

I just tried to install an Omnistat RC-1000. When I power up the system, the screen flashes on and off for repeatedly (about 2sec intervals). None of the buttons do anything. It appears that the temperature is accurate as it changes between 69 and 70 degrees.

I have a single stage conventional furnace as far as I can tell. It has a fan and heat, no cooling.

The current wiring to a Honeywell programmable thermostate works fine. There is a red, white, and blue (which is actually wired to the "G" terminal in the furnace and on the Honeywell). I checked on the furnace side and White is run to W1 and W2, Red is run to R, and the Blue wire is run to G. There is no common wire run.

So, i put the red (hot) in in slot 1 and left the jumper to slot 2. I put the White (heat) into slot 6, and put the blue/green (fan) into slot 8.

Do I need to run a common wire? What color would that be on the furnace side? I'm guessing its the screw marked "BK" (Black), right next to the Red, but I want to make sure I don't screw things up.

Or, is there insufficient power do you think? If so, what do i need to do? I read another post that suggested there isnt sufficient power and I need another power supply.

Clearly, this is my first time doing this , so thanks for the help in advance.

Chris

 

[chrisdias]

I've left it on for a few minutes and this is what i now notice:

- no more flashing
- the clock seems to be advancing
- temp appears to be accurate

but no buttons work, at all.

thanks again -

 

[chrisdias]

I think I've discovered that the "B" in the furnace is the 24vac common, per this document:

http://www.scribd.com/doc/7267240/Trane-40...ce-Operation-99

On P65 in the system wiring legend for the 50A51 model, it says B is "24 VAC COMMON side of compressor contact coil"

There is currently nothing connected to B in the furnace. I dont know what the compressor contact coil is .

time for bed!

 

[edselrt]

I just tried to install an Omnistat RC-1000. When I power up the system, the screen flashes on and off for repeatedly (about 2sec intervals). None of the buttons do anything. It appears that the temperature is accurate as it changes between 69 and 70 degrees.

I have a single stage conventional furnace as far as I can tell. It has a fan and heat, no cooling.

The current wiring to a Honeywell programmable thermostate works fine. There is a red, white, and blue (which is actually wired to the "G" terminal in the furnace and on the Honeywell). I checked on the furnace side and White is run to W1 and W2, Red is run to R, and the Blue wire is run to G. There is no common wire run.

So, i put the red (hot) in in slot 1 and left the jumper to slot 2. I put the White (heat) into slot 6, and put the blue/green (fan) into slot 8.

Do I need to run a common wire? What color would that be on the furnace side? I'm guessing its the screw marked "BK" (Black), right next to the Red, but I want to make sure I don't screw things up.

Or, is there insufficient power do you think? If so, what do i need to do? I read another post that suggested there isnt sufficient power and I need another power supply.

Clearly, this is my first time doing this , so thanks for the help in advance.

Chris

I did'nt experience that problem when I installed my RC-1000 and I have a conventional single stage furnace too. The only difference with my install is I connected a common wire (slot 3 of RC-1000) to a terminal labelled as "com 24v" on my furnace. Now, to find where to connect common wire on your furnace, (by looking at page 6 of installation manual for RC-1000) if you have a multimeter set to AC, you should be able to measure 24VAC between your red terminal ® and your common.

 

[chrisdias]

I did'nt experience that problem when I installed my RC-1000 and I have a conventional single stage furnace too. The only difference with my install is I connected a common wire (slot 3 of RC-1000) to a terminal labelled as "com 24v" on my furnace. Now, to find where to connect common wire on your furnace, (by looking at page 6 of installation manual for RC-1000) if you have a multimeter set to AC, you should be able to measure 24VAC between your red terminal � and your common.

Thanks -

I used a multimeter and found 28V between the Red and multiple other terminals on the furnace. The B, W, and one of the Y terminals. Not sure if this helps me .

Chris

 

[pete_c]

Over the years I had some major issues relating to my HAI thermostat and its connectivity to the single state furnace.
This caused comm problems/thermostat resets between my HAI OmniPro II and HS which in turn would cause the thermostat to set itself to extreme temperatures (either the high or low limits).
It was relating to the "power stealing" of the thermostat and the furnace MB. I ended up putting in a separate power supply for the thermostat and that has fixed all of my problems. Before adding the power isolation module tried / purchased all of the HAI suggested fixes.

The most common incompatibility for HAI single stage thermostats is installations with heat or cooling, but not both. In these installations the thermostat will work until a call for heat (or cool) is made. The thermostat will attempt to ‘steal’ power from the other system and reset.
There are 2 solutions: (1) Either source the 24VAC common connection © from the HVAC transformer, or (2) Use a Power Isolation Module (29A00-1) to power the thermostat from a separate 24 VAC transformer.
A second incompatibility exists when the heat and cooling have separate transformers. Source the 24VAC from one of the HVAC transformers and use an HAI Power Isolation Module (29A00-1). This runs the thermostat off of one transformer and isolates the power from the second transformer with a set of relays.
In a tiny percentage of installations where ‘power stealing’ should work, the feature is not compatible. Generally, this is because the HVAC system does not provide enough available current on the control line to keep the thermostat running. The best solution would be to connect the © common terminal from the transformer. This eliminates the need for ‘power stealing.’ Often this is not an option because the extra conductor is not available. The next best solution is the HAI Thermostat Power Supply Module (30A00-1), which increases the available power on the heat / cool control lines to allow power stealing to work reliably.
Occasionally there are reports of a backlit thermostat is resetting when a key is pressed on the thermostat. In some cases 'power stealing' offers enough power to run the thermostat but not enough to run the thermostat and the backlight. Attaching the C-Common connection will solve the issue. A simpler solution is to move the backlight option (jumper on the board) to off. Disabling the backlight will often reduce the current draw and allow the power-stealing feature to power the thermostat.

HVAC

All of these HAI thermostat issues caused some major WAF problems. There was a time a couple of years back that I actually adjusted the high / low limits so that the temperatures would not go to extremes. Another time where an old friend who owns an HVAC company spent a "few" hours diagnosing some issues and finally told me all of my issues were related to the Omnistat. (and to remove it - which I didn't).

 

[Steve]

It's mentioned in the quote above but a simple test is to dim the backlight. You may not have to turn it off completely, just turn it down to like 5 or less.

 

[chrisdias]

It's mentioned in the quote above but a simple test is to dim the backlight. You may not have to turn it off completely, just turn it down to like 5 or less.

how would i do this since the controls dont work at all? the post above mentions a jumper on the back...?

thanks,
chris

 

[edselrt]

I did'nt experience that problem when I installed my RC-1000 and I have a conventional single stage furnace too. The only difference with my install is I connected a common wire (slot 3 of RC-1000) to a terminal labelled as "com 24v" on my furnace. Now, to find where to connect common wire on your furnace, (by looking at page 6 of installation manual for RC-1000) if you have a multimeter set to AC, you should be able to measure 24VAC between your red terminal � and your common.

Thanks -

I used a multimeter and found 28V between the Red and multiple other terminals on the furnace. The B, W, and one of the Y terminals. Not sure if this helps me .

Chris

By process of elimination and based on page 66 of your furnace manual, we know already that your W is your call for heat, Y is your call for cool, and the only terminal that has 28V is your B which is 24VAC common side of compressor contactor coil. At this point your best bet is B.

 

[Steve]

It's mentioned in the quote above but a simple test is to dim the backlight. You may not have to turn it off completely, just turn it down to like 5 or less.

how would i do this since the controls dont work at all? the post above mentions a jumper on the back...?

thanks,
chris

um, yea, good point

The large dial doesn't do anything either?

 

[chrisdias]

[/quote]
The large dial doesn't do anything either?
[/quote]

it moves around in a circle nicely, and in both directions!

nope, it doesn't do anything. I'm going to try connecting a common tonight, hopefully without incident .

Anyone from HAI able to chime in here?

 

[chrisdias]

Fixed!

I hooked up a common wire and everything works like a champ now. I did attach it to the "B" terminal on the furnace.

Thanks everyone for the help.

Next up... installing the OPII!!

Chris

 

[edselrt]

Fixed!

I hooked up a common wire and everything works like a champ now. I did attach it to the "B" terminal on the furnace.

Thanks everyone for the help.

Next up... installing the OPII!!

Chris

sweet!!!