How do I determine if thermostat is currently calling for heat or cool? | Home Assistant | Page 1

cyan flower Oct 24, 2025, 9:23 PM

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I have just installed a Honeywell T6 Z-Wave thermostat. I've got it registered with ZW JSUI, and all is good.

I'd like to be able to determine when it's actually telling my furnace/AC to run and turn on the blower motor, so I can coordinate the duct-booster fan to run at the desired speed.

It looks like I need to look at the hvac_action attribute of my climate.thermostat entity. Am I on the right track? Where do I go to find all the values this could be so that I can account for them all in my automation?

Additionally, there's a fan_state attribute that looks like it could be what I'm after, but it reads Idle, even when I cranked the heat way up, forcing the furnace to kick on. Is that expected, or am I looking at the wrong thing?

Note that I'm not using MQTT, for my communications with the stat.

short condor Oct 25, 2025, 7:28 AM

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hvac_action is the correct attribute for conveying this information in the HA entity model, but whether that works in practice depends on the device supporting that feedback, and the integration implementing it correctly. The range of theoretical values can be found in the developer documentation https://developers.home-assistant.io/docs/core/entity/climate/#hvac-action (the user documentation only mentions heating, cooling and idle)

Climate entity | Home Assistant Developer Docs

A climate entity controls temperature, humidity, or fans, such as A/C systems and humidifiers. Derive a platform entity from homeassistant.components.climate.ClimateEntity

cyan flower Oct 25, 2025, 12:41 PM

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Sounds like that's exactly what I need, so long as it's actually working.
I'll add a history monitor to see if it's changing, so I don't have to watch it constantly.
Thanks!

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Hmmm... States currently reports hvac_action = idle, while the Template editor {{ states('climate.thermostat', 'hvac_action') }} is reporting heat.
I presume that means that either the T6 doesn't support this or that it's not implemented properly for the t6?

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Also, I'm noting that fan_state is reporting heat as well in the Template Editor, but idle/off in States

clear spear Oct 25, 2025, 2:34 PM

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Your template is invalid. You want state_attr.

cyan flower Oct 25, 2025, 3:39 PM

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It doesn't appear to be possible to put that in as an entity in a History graph card. How would I best show a track of that over time to see what states mine is actually calling?

clear spear Oct 25, 2025, 3:42 PM

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Make a template entity out of it

fickle maple Oct 26, 2025, 4:14 AM

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Would love to see what you come up with. I just installed three T6’s and I’m not entirely sure they are working correctly

cyan flower Oct 26, 2025, 8:07 PM

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fickle maple Would love to see what you come up with. I just installed three T6’s and I’m not...

So far, I've got a nice little graph that shows me this:

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The duct booster that we had installed receives power when the furnace turns on the blower.
It's a 3-speed blower and our HVAC guy wired it up to High. That is usually way too much, as it seems to actually be pulling air from the rest of the house! (Booster is for upstairs, which is minimally occupied now that the kids have moved out.)

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I wired up 3 Shelly 1s so that I can turn one of them on to get Low, Med or High (or have them all off).
Unfortunately, I've got them powered by the cable that provides power to the blower, so they loose power and HA can't control them.
My current automation waits for them to become available, then turns on the one that is currently called for. I'm reasonably certain, though, that constantly "pulling the plug" isn't going to be good for them, so I'm going to feed them all with constant power, then use HA to monitory my Furnace Fan, and whenever it's not idle, turn on one of the Shellys and turn it back off when it goes idle.

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Key is to make sure that only one Shelly is actually active at a time (they're set to default to OFF when they get powered on). Not sure what'll happen to the blower if I supply power on more than 1 "speed wire" at a time, but for the $4k+ that stupid fan cost, I don't want to find out!!!

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Right now, I'm simply using the T6 just like the old dumb stat it replaced.

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Not sure I'm fully bought into the whole heat/cool-only-when-you're-home thing...

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But, I'm all about having it switch from heating to cooling automatically, especially in the spring/fall when it can be 40°F one day and 80°F the next (or high of 80 and low of 40...)

fickle maple Oct 26, 2025, 9:26 PM

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That's really cool! Your setup would have been nice in our previous homes forced air system. Our heating system is a newly replaced boiler for in floor heat with ac mini splits in several areas of the house. The boiler system was completely replumbed in the boiler room so we haven't had a ton of time with it unfortunately. Currently I only have a temperature graph for display and it's kind of confusing due to the solar heating we get through the large windows we have. So the temperature graph is showing more like a 12 hour timed cycle than a thermostat temperature cycle. Another issue is the wild temp offsets I'm having to implement. In some T6's, I'm using the full 3 deg offset and could probably use a little more. Coming from Homeseer, I'm still finding my way with Home Assistant but really liking it so far. I would love to see how you are generating your graph as this would definitely give me the information I need. I hear you on the auto heat/cool operation. With the two separate systems we have, it's pretty tough going for the reasons you mention above. To compound this, the inherent slow temperature change of in floor heat kinda sucks. All said though, we really like the in floor heat, it's just slow to respond. Thanks for sharing your system, it's nice to see how others are using their T6's and other issues they are trying to solve.

fickle maple Oct 26, 2025, 10:03 PM

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Hmm, after rereading your post, I guess you are not using the hvac_action for your graph and instead using the fan state? It would be nice to monitor boiler state through other means too but our boiler is also used for domestic hot water as well.

cyan flower Oct 29, 2025, 8:20 PM

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fickle maple Hmm, after rereading your post, I guess you are not using the hvac_action for yo...

I am actually using climate.house_hvac in my template sensor, so I'm getting alternations between heating and idle in my graph right now.

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I should have called it Furnace Activity or HVAC Activity. But it's only for short term testing use, so I'll most likely delete it once I have everything working as desired.

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#namingishard

cyan flower Oct 29, 2025, 11:44 PM

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More specifically, I'm using {{ state_attr('climate.house_hvac', 'hvac_action') }} as the state for my template sensor that appears in the graph above.

fickle maple Oct 30, 2025, 1:58 AM

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Thanks @cyan flower. I was able to get that far with the template editor. I'm now trying to understand how to create template sensor.

cyan flower Oct 30, 2025, 10:40 AM

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Go to Devices & Services, click on the Helpers tab, click on the create helper button, then search for template.\

#How do I determine if thermostat is currently calling for heat or cool?