How to interlocking AC and Electric heat with Smart Controls and Apple HomeKit (prevent AC and electric aux heat from being on at the same time )

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Level 1

4 points

How to interlocking AC and Electric heat with Smart Controls and Apple HomeKit (prevent AC and electric aux heat from being on at the same time )

Hi

Is it it possible through apple HomeKit to interlock the central AC system that the main household heating/AC thermostat controls with 4 electric baseboard heaters each with their own independent Mysa smart

thermostat?

What I mean by interlocking is that through homekit, triggers, automations, configuration settings or even IFTT is there a way to prevent the 4 electric baseboard heaters from turning on when the ac is either running or set to ac/cool mode?

2 Reasons for this ?

1. In order to satisfy electrical load calculation requirements if the ac and auxiliary heat can be configured via software to not be on at the same time that will meet the code requirement without expensive upgrades. This would be a software based solution versus a mechanical loading shedding of the same heat load via current sensing clamps on the main panel feed and a relay to cut power to the baseboard heaters. The software solution would be the cost of a thermostat versus $23,000 to run a new underground service line and upgrade the panel to 200A.

2. It’s a waste of energy lol to heat cool at the same time

i have yet to buy the thermostat and am considering ecobee though I’m open to anything that will work. It’s really simple logic but the api needs to be capable of a trigger based on configured values (ac mode = true (enabled) then elec aux heat set to off (disabled ) or active state (ac = on (running).

alternatively a HomeKit compatible current clamp fixed around the ac 240v cable might work if the system latency is not too high.

thanks for your help in advance

cheers

Ryer

Posted on Jul 29, 2023 12:23 PM

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Answer 1

turingtest2

Level 10

279,581 points

Jul 30, 2023 8:03 AM in response to Ratk670

If you're trying to prevent a potential over current situation then I don't believe HomeKit on its own is either powerful enough or reliable enough to rely on for this type of application, but that is just my 2 cents. I would suggest interlocked relays such that it is simply not possible for both services to pull current at the same time, regardless of the demand signals that might come from various thermostats or manual overrides. In short, if the AC system is active there should be no power available to drive the relay that supplies the heating circuits. Conversely if the heating is active then the A/C supply must be similarly inactive. When both are off either can be brought online.

tt2

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Answer 2

Ratk670 Author

Level 1

4 points

Aug 1, 2023 11:36 AM in response to turingtest2

Hi

Thanks for reply. I agree that interlocked relays would likely provide a higher reliability however I’m not a huge fan of power cycling electronics over and over multiple times a day as that’s hard on them. I should clarify that the AC is run through coil in the furnace (central air). The electric baseboard heat is on a separate 25A 240V cct as auxiliary heating in addition to the furnace in some cold rooms during winter. A master electrician has recommended a DCC-12 or load miser which sheds the load (elec aux heat) via a relay ONLY if the service mains demand hits 80A. In 2 years of use without any management it’s never flipped the main breaker. I do agree that home kit capability and reliability is a concern which is why I’m going to to approach this another way with current monitoring on the mains and local smart control (not cloud based) to set elec aux heat to off and leave them off when ac is on. Truly I’m trying to prevent accidental baseboard heat ON (which would have to be intentionally activated via the app as each thermostat is locked out) AND be drawing up to 100A to trip the main breaker. I can set that main amperage threshold at whatever level I need (60A, 70A,80A) to disable the electric baseboard heat. In practice it’s only an issue in summer as in winter the AC has an exterior disconnect to prevent damage if it’s accidentally turned on in winter

Again thanks for feedback it always helps to get another perspective

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How to interlocking AC and Electric heat with Smart Controls and Apple HomeKit (prevent AC and electric aux heat from being on at the same time )

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