Controller to centralize control for heat and AC

mnicholas

Setup: The home uses forced hot water banister heat that has five zones. Each zone has its own thermostat with independent pumps run by the zone controller on the boiler. I have five thermostats for heat, all of this works fine. The home also has three independent HVAC systems for AC. To complicate the conversation, each HVAC system also has electric heat elements just in case there is a critical failure to the boiler. The goal is not to use the electric heat unless it is an emergency. Each HVAC system has its own thermostat. To summarize, to control heat, there are five thermostats, one for each zone in the house. To control AC, there are three thermostats, one for each HVAC system. In total, there are eight wired thermostats in the house.

The problem: The house is now a vacation rental and explaining the heat and AC is difficult at best. For a homeowner, you know to run heat when you need heat, or run AC when you need AC. Unfortunately, this is not as simple to explain to people who are just staying for a weekend and really don’t care. The result, we come in to reset the house and find the heat and AC both running.

I am looking for a solution that will provide centralized control for both the heat and AC with a single digital controller located at one location. Since there are eight (8) wired controllers in the system (5 heat and 3 AC). I would imagine that each existing thermostat will need to be replaced with something that will wirelessly communicate with the single controller. I don’t necessarily need the controller to change from heat to AC to meet a specific temperature as much as I need a controller that will let you have either the heat on, or the AC on, but not allow both to be on at the same time.

Jamie Hall

And it may be that the whole thing is more complicated by the electric heat elements in the AC units? How are they controlled?

I'm not sure however that wireless control is needed, at least for the heat, since you already have nice reliable hard wired signals coming together at the boiler. Something to said for that. If you could run similar signal wires from the three AC thermostats to the same location -- which presumably would have three signal wires each; common and heat command and cool command -- you would have all the information you needed in one place.

I'm an old fogy, so if I were to do it I'd set it up with relays. But I daresay there's someone out there who could set up a small computer and interface arrangement to do the logic more elegantly, if not necessarily more reliably.

exqheat

Simply I would look at the Honeywell 8000 Thermostat with redlink WIFI. You can control each thermostat on a central redlink ap showing all stats. The 8000 is progrsamable and can be locked. I love them.

pecmsg

Manually shut off the strip heaters unless needed!

109A_5

Hello @mnicholas,

Interrupting (selectively disabling) the heating functionality of the AC system probably is not that hard.

The hard part is detecting the Boiler failure, and then switching the Heating functionality of the AC to bring the living space to normal temperatures without the 'New' controller thinking the boiler is working again and disabling the AC heat function or maintaining a lower 'emergency' temperature.

Then once the boiler is repaired is it a manual reset to disable the AC system's heating functionality until the next emergency ?

And then what about any temperature setbacks during non-use times.

It could be done with dedicated thermostat and relays that detects the loss of boiler heat and then 'latches' on the AC heating functionality. Or a PLC (Programmable Logic Controller) or PLR (Programmable Logic Relay) with a temperature sensing device.

I'm not sure the Honeywell 8000 will do all those zones with that many heating / cooling units and the emergency heat logic mixed in also. To me the brochure got kind of vague there. With multiple Honeywell 8000 units, it may give you remote control so you can do the cut-over manually and remotely if there is 24/7 internet there.

JMWHVAC

As exqheat said, wifi stats would be neat and then you can control them remotely. If all you want is to prevent heat and AC fighting between themselves, a simple electronic temperature control can give you a warm weather shutdown for heat and possibly a cold weather shutdown for AC. That's something I have done for houses that otherwise have the capability to both run at same time.

ratio

I think the Honeywell 8000 plan was a stat per zone, possibly 5 heat/cool & two heat only. Expensive (those stats are 150-250 each depending on the model), but the more hands-off the solution is the more it's going to cost.

Just FYI, the 8000 stats are available as WiFi or RedLINK—not both; however, there is a RedLINK router that will get at most four RedLINK stats on the interwebz. You can have (nearly) as many stats under a Honeywell account as you want, though; I know of several sites with 20+ stats. The reason why this is important is because the RedLINK stats can use wireless remote sensors while the WiFi version can only use wired remote temp sensors.

In case you can't tell, I like the Honeywell stats as well. They would be my go-to, middle-of-the-line solution, with a box of relays my low-end solution & BACnet or a PLC my high-end solution.

HVACNUT

Ideally you want an interlock to prevent heat and AC at the same time. That can be (MacGyverly) done remotely using a mobile app, but can easily be bypassed locally. Unless you use room sensors instead of accessible thermostats, or lockout the thermostats. That would of course require WiFi thermostats, which in turn requires 24 volts constant power that the heat only thermostats probably don't currently have.
Control wiring and relays is the only sure way to provide an interlock. 
The easy way is labels. I service many rentals and everything has a label.

mnicholas

Jamie Hall said:

And it may be that the whole thing is more complicated by the electric heat elements in the AC units? How are they controlled?

The HVAC systems have AC and Heat, so each HVAC thermostat can be placed in Cool / Off / Heat.

mnicholas

ratio said:

Just FYI, the 8000 stats are available as WiFi or RedLINK—not both; however, there is a RedLINK router that will get at most four RedLINK stats on the interwebz. You can have (nearly) as many stats under a Honeywell account as you want, though; I know of several sites with 20+ stats. The reason why this is important is because the RedLINK stats can use wireless remote sensors while the WiFi version can only use wired remote temp sensors.

In case you can't tell, I like the Honeywell stats as well. They would be my go-to, middle-of-the-line solution, with a box of relays my low-end solution & BACnet or a PLC my high-end solution.

Thanks for that little tidbit on the WiFi vs RedLINK.

mnicholas

HVACNUT said:

The easy way is labels. I service many rentals and everything has a label.

That is our current solution. A small placard by each thermostat. They Say "I am for Heat" or "I am for AC". We also include an explanation in the check-in process. That doesn't stop the phone calls or messages asking how to control the heat / AC. At least every other week I get "There is no heat coming out of the vents". I guess people are not use to having a boiler.

mnicholas

109A_5 said:

The hard part is detecting the Boiler failure, and then switching the Heating functionality of the AC to bring the living space to normal temperatures without the 'New' controller thinking the boiler is working again and disabling the AC heat function or maintaining a lower 'emergency' temperature.

I think notification settings for low temperatures in the home can resolve this outside of the overall solution. This past winter, I used basic home automation to send temperature notices out for low temps. I can easily go to the house and turn on emergency heat if I know something is wrong.

109A_5

Hello @mnicholas,
OK maybe I misunderstood the situation. If you have access to the wiring and/or control, maybe just make the two basic systems AC / Boiler mutually exclusive, so only one can be used at a time.

ratio

mnicholas said:

109A_5 said:

The hard part is detecting the Boiler failure, and then switching the Heating functionality of the AC to bring the living space to normal temperatures without the 'New' controller thinking the boiler is working again and disabling the AC heat function or maintaining a lower 'emergency' temperature.

I think notification settings for low temperatures in the home can resolve this outside of the overall solution. This past winter, I used basic home automation to send temperature notices out for low temps. I can easily go to the house and turn on emergency heat if I know something is wrong.

The Honeywell app can send out-of-range emails for temp & humidity…

Also, if you go with an equipment interface module (wireless unit control module [but the stat still needs 24VAC power]), you have IIRC three universal inputs that can be programmed for contact closure & custom text.

It's dependable enough if you're near enough to check on things yourself, but I wouldn't depend on it alone if I were out of the state or something.

Jamie Hall

Kindly [ay attention to @ratio 's second paragraph up there. All these lovely wifi and Redlink and home automation systems do work, some better than others, some more easily understood…

So long as the power is on.

If this is a vacation rental, and there is a chance that the area may freeze, keep in mind that none of them work if the power goes out. Not One Single One of them. And there is a very good chance that the power will be out when it is freezing.

You have two choices: fight with the insurance company when the building freezes and the pipes burst (you'll lose), or hire someone reliable, local, to keep an eye on the place and keep it safe.

WMno57

Jamie said: You have two choices: fight with the insurance company … , or hire someone reliable

There is now a third choice. Battery backup power.

Grid power is becoming more unreliable. Batteries, transfer switches, and inverters are now mature technologies. Integrating it all can become very complex.

General Motors now has an $8000 option on the new Silverado EV where the truck can power your house (until it's battery runs out). I think this option is called V2H (Vehicle to Home). This is not Uninterruptible Power, so one might still want a UPS for a computer that is monitoring the home.

https://news.gm.com/newsroom.detail.html/Pages/news/us/en/2023/aug/0808-v2h.html

Battery banks can be as inexpensive as a single 12 volt deep cycle battery, or as pricey as an array of Tesla Power Walls.

Silicon based life forms are taking over the world. Still a need for carbon based life form property managers to put eyes and hands on the situation.

Hardware, Software, and Meatware. They all have there pluses and minuses.

exqheat

If the power goes out Redlink will notify disconnect from thermostat. An automatic generator would help.

The notification can trigger an owner call to local help (handyman neighbor)

Jamie Hall

Battery backup is a good option — if you have enough of it. For Cedric's home, for example, about 90 to 100 KWh would be the minimum for reasonably foreseeable power outages around here — and that doesn't come cheap. Not do the necessary inverters — you're looking at a conservative 50 amp 240 volt peak load (100 amp would be better).

The majority of the population doesn't need that kind of backup — but rural folks, and vacation homes (which tend to be rural) do. Or Silas, down the road, with a big generator and the necessary plugs and cables… and committed to helping out with a problem (which, since Silas is no fool, means a retainer…)

WMno57

I have a 16 KW Generac, auto transfer switch, and Natural Gas. It's wired whole house, although at some point I would be tripping (hopefully) breakers on the Generac. Should be nirvana, right? It's not, I don't like it.

I'll explain. Its LOUD! 3600 rpm air cooled lawn mower engine. Right outside my home office window. The auto transfer switch sounds great, until you realize it will run when you're not home until the power comes back on. Even if you only need 100 watts for a few light bulbs. Waste of fuel, engine hours, and rude to the neighbors. I don't have freezers full of meat, and my sump pumps run less than once per year, so I reconfigured to manual operation. This was after my neighbor told me it ran for 9 hours.

A better solution would be a small battery bank, and have the Generac configured to recharge the battery bank as needed. I know, complain, complain. First world problems. But maybe someday.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1802680#Comment_1802680

Yeah,

Those are pretty spoiled complaints….

Jamie Hall

Yep. Different strikes fur different folks. Some people don't need a good sized generator, fueled, ready to go. And they even have natural gas available! And they only lost power for nine hours once! The horror!

Others not so much… in the last month Cedric's home has only lost power three times; the longest was only four hours, so no big deal. The freezers can hold that long (and there's almost a year's worth of food in there…) and the horses didn't need water. The longest we've been out since last fall was five days in January, and it was below freezing all five days. There was a week and half failure (ten days) last summer).

We don't have automatic transfer. No need for it — the structure is always monitored by real live people. One of the generators gets run when power is needed.

Oh yeah — and no natural gas out our way, of course, and no hope of getting any.

As a cautionary tale — one vacation rental nearby (which we don't care for) was caught without power in that long outage in January. He had all the bells and whistles on his internet connected thermostats and alarms — very sophisticated first world man (nice man, too). When the power did come back on… the water pump ran… and ran… and the house is now a half million dollar total loss. The insurance company has declined payment on the grounds of negligence; he's suing, but it doesn't look good.

JakeCK

I can count on one hand the number of times we've lost power for more than a few moments/flickers over the 14 years I have lived here. I consider myself fortunate.

I still would like a battery backup for the house just so I can better optimize my solar usage but also keep the essentials on. Freezer chest, fridge, lights, boiler for as long as I have it.

That said, my recommendation is to remove the option from renters altogether. Set it to 72 and tell them to deal with it. Lol The inability of people to comprehend simple instructions always amazes me. I don't know if its an actual limitation of intellect or inattentiveness because they don't see how it pertains to them at the time its explained. I see it at work all the time with coworkers. You explain something to them, you watch their eyes glaze over and then when shtf they're like "th-th-th-th-thats all folks!"

exqheat

A real person backup is essential. Too much can go wrong.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1802959#Comment_1802959

What?

exqheat

If you have a home that is not attended to due to multiple residences, it is wise to have a real person keep an eye on it. Many locals provide his service to vacation and second home owners. s a local tradesman, and they probably know a reliable person that does this kind of checking on a periodic basis. They can check for alarm status, sprinkler operation and leaks, gardening maintenance, deliveries to be taken in, contractor work being done. flood monitoring. HVAC operation and more. They will have keys to get in with alarm codes. In case of an incident they will be your eyes and feet on the ground. I used yt do this kind of stuff for my customers, and they were most appreciative. I would put the time on their bills, and never got a complaint. That's What.