Tun off the AC/Furnace emergency switch using I/O Linc and Insteon Toggle Switch

[ArunGupta2014]

I do not want to bore everyone on why I am doing this but...the problem is that I need to have a power switch to power off my HVAC system if the condensate pump overflows.

The HVAC system in question is Carrier Infinity 58MVC system which uses proprietary protocols to communicate with Carrier's own thermostat. It does not use R/Y/W/C etc. thermostat wires. The condensate pump has a safety switch which can be wired in either NC or NO mode. If the pump fails, the safety switch will change from NC to open or from NO to close. When this happens, I want to power off the HVAC unit. The unit has an emergency ON/OFF switch which is a standard 15A paddle style switch. The power circuit is controlled by a 15A breaker in the box, so I am assuming that the current draw does not exceed 15A. The Carrier manual states that current should be 8.96A.

So, I want to replace the emergency ON/OFF switch with 2466SW. I want to wire the condensate pump's safety switch to I/O Linc. When pump tries to overflow, the safety switch will toggle from open to close or vice-versa. Then I/O Linc should send a signal to ISY994. That signal will then be used to turn off the 2466SW which will cut power to the HVAC system preventing further condensate generation.

I also want the 2466SW to remain off once triggered by the I/O Linc, till I manually turn it on again.

Are all these operations possible? Is the 2466SW is capable of handling the current for prolonged periods? The HVAC system is infinitely variable speed, so it keeps operating for hours at lower capacity thus providing comfortable heating/cooling. I do not want the 2466SW relay to melt...

All comments/ideas are appreciated, particularly if there is a better idea.

Thanks,

Arun

[Techman]

What you've described should work. The 2466SW is rated at 15 amps.  

The only concern I have  is if you shut off the HVAC power during a heating cycle the furnace fan which usually runs for a few minutes after the gas valve closes to cool down the heat exchanger, will not run and may cause the heat exchanger to overheat.

Did you explore the possibility of sending a signal to the thermostat to turn off the HVAC, that would allow the fan to continue to run for a few minutes if the heat is on. Do you know what protocol the HVAC uses to communicate with the thermostat?

 

[Brian H]

The condensate pump has a safety switch which can be wired in either NC or NO mode. Does it have anything connected to it now? As the I/OLinc's Sensor Input is made to use a dry contact connection with no voltage on it. As it supplies its own low current signal.

I have seen reports of some variable speed controls. Generating power line noise. So you would have to see if it effects the I/OLinc and 2466S are effected by it running. Both are power line only Insteon modules.

[LFMc]

15 minutes ago, Techman said:

The only concern I have  is if you shut off the HVAC power during a heating cycle the furnace fan which usually runs for a few minutes after the gas valve closes to cool down the heat exchanger, will not run and may cause the heat exchanger to overheat.

Good points, but I wouldn't expect the unit to be putting off condensate during the heating cycle, would you? There was no mention of heat pump or gas for heating. My concern would be the compressor lock out preventing a quick off-on cycle. As long as that can't happen you might be good. 

[ArunGupta2014]

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Did you explore the possibility of sending a signal to the thermostat to turn off the HVAC, that would allow the fan to continue to run for a few minutes if the heat is on. Do you know what protocol the HVAC uses to communicate with the thermostat?

Yes, but since Carrier Infinity system uses a proprietary protocol between HVAC system control board and thermostat, I cannot hack into it. It uses wires labeled as ABCD. I checked on a HVAC board and the experts familiar with the system said that you cannot just cut a cable and insert the switch. The installers had connected the wires to the switch and these wires were going into the unit. This gave me the false impression that they had connected the switch. But, couple of days ago, when the pump malfunctioned and water leaked all over the floor, I opened the HVAC system, got to the control board and checked, those wires were not connected to anything...They were just hanging in there. The installers probably did not connect them because they knew it cannot be done.

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The condensate pump has a safety switch which can be wired in either NC or NO mode. Does it have anything connected to it now? As the I/OLinc's Sensor Input is made to use a dry contact connection with no voltage on it. As it supplies its own low current signal.

The condensate pump safety switch is a plain micro-switch, absolutely nothing connected to it. I have checked manufacturer's data and physically opened up the pump to double check.

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The only concern I have  is if you shut off the HVAC power during a heating cycle the furnace fan which usually runs for a few minutes after the gas valve closes to cool down the heat exchanger, will not run and may cause the heat exchanger to overheat.

It is a dual fuel heating system and heat pump cooling system. The heat pump can also be used for heating instead of natural gas. When heat pump is being used for heating, if the temperature falls below a certain limit, natural gas will take over. I always keep it at natural gas heating only. But, condensate never forms during heating cycles. It always forms when system is cooling.

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My concern would be the compressor lock out preventing a quick off-on cycle. As long as that can't happen you might be good. 

The system has lock out prevention. So, if the power goes off and comes back on quickly, the system waits several minutes before turning on.

Thanks,

Arun

 

[Techman]

Another option would be to have the IOLinc send you an email or text message when the pump overflows, you could then remotely shut off the HVAC using the Carrier app on a computer or cell phone.

[ArunGupta2014]

23 minutes ago, Techman said:

Another option would be to have the IOLinc send you an email or text message when the pump overflows, you could then remotely shut off the HVAC using the Carrier app on a computer or cell phone.

This system does not have the Carrier app. It is a totally closed system, no internet connectivity. I might have to look for some other solution because the emergency ON/OFF switch is installed in a metal electrical box which is way too small to fit the 2466SW.

[MrBill]

39 minutes ago, ArunGupta2014 said:

This system does not have the Carrier app. It is a totally closed system, no internet connectivity. I might have to look for some other solution because the emergency ON/OFF switch is installed in a metal electrical box which is way too small to fit the 2466SW.

What's the model number of the Carrier Infinity system?  I'm curious if there's a wiring diagram available online.  I suspect there is likely a pair of terminals on the control board, or possibly just header pins for "Emergency Shutdown" or "firemans switch".

[ArunGupta2014]

It is a 58MVC 100-F-10120 dual fuel system. Wiring diagram is available in the installation manual. I can post it here but I already checked. There is no separate emergency shutdown. The emergency shutdown switch installed outside the unit cuts power to entire unit and the condensate pump. I was looking at using Insteon Remote Control Micro On/Off Switch Adapter but it is out of stock. It would have fit nicely in the metal box.