Super efficient heatpump thermostat?

[EbS-P]

So it’s during this time of year when my wood stove is cold, and so are the nights but the days are are nice that I manually run my thermostat in this manner. I like a temp of 72F. But once the temps drop below 40 outside I set it back to 68. Once it starts warming up outside and gets above 45 I will increase the set point 2 degrees at time (to avoid the heat strips from kicking on) until I have achieved 75 or 76 degrees. Once the temps drop so does the thermostat back to 68.

Why do this. I know the capacity of my heatpump and the efficiency is 30% greater at 45 vs 32 (outdoor temp).

My question (and I posed the to the HVAC talk forum and didn’t get very far, the HVAC pros don’t want to make heating more complicated than it is already) is there a thermostat a available that prioritizes efficiency over comfort and could operate in a manner where you can set the max and minimum allowed temperature inside and I can compute the most efficient run schedule, based on current and 24 forecasted temps, for your equipment. It’s going to need some “learning” or be programmed with heat load and capacity curves.

It seems to me this could result in substantial savings if the owner were tolerant of indoor temp swings. Am I missing anything? Does a product exist? Can. One hack an existing product to run in this manner. This could also happen in the summer. Although the temp swings in my region are less resulting in less efficiency gain but I calculated I loose 5% efficiency for every 5 degrees above 80 degrees outside.

Is this just a set back schedule? (Kinda but the ability to adjust run times based on the forecast seems to be important but how much am I gaining with a complicated thermostat and programming vs a traditional set back routine?

Thoughts. (I was really disappointed that HVAC crowd didn’t jump on this). Save it for the wood stove geeks to dig into the weeds thinking about how much energy a really smart thermostat could save.

Evan

 

[peakbagger]

Time to buy a PLC and learn how to program it. No doubt a raspberry Pi hobbyist could do the same.

 

[Brian26]

I'm pretty sure the Cielo Breeze Plus thermostat units I use on my mini splits could do just what your looking for. These are IR based and just mimicking the remote so not sure if they work on a wired thermostat. They have a mode where you can have it make adjustments based on a range of setpoint. Here is a screenshot from the ap.

 

[semipro]

I'm using an Ecobee thermostat, Google Home, and a Smartthings hub.
I think I could do what you're trying to do if I were to set up some IFTTT routines.
I'm not sure whether I'd do this on Smartthings https://ifttt.com/smartthings
or Google Home https://ifttt.com/explore/customize-google-home
I might have to add an internal and/or external temp sensor in case I couldn't get that data from the thermostat or the WWW, respectively.
I don't know of any thermostat alone that will do what you're wanting.

 

[EbS-P]

Time to buy a PLC and learn how to program it. No doubt a raspberry Pi hobbyist could do the same.

The concept seems simple enough use your home as thermal storage when it’s cheaper. Add in time of use billing as another optimization parameter. I need to figure out the reversing valve and the logic that programmed on the units board ( defrost, and some other wait/lock out period ). It’s going to need thermal load calculations.

It seems to me it could be a really good marketing message for any of the smart thermostats. “Look at our super eco mode it saves xx$ a year! (Fine print at bottom of last page).

At any rate if I just disconnected my 3 heat stage wore(heating strips) I could just set a program that assumes warmer temps noon. Colder by 8 pm. And it will all be unnecessary once the stove is lit.

I'm using an Ecobee thermostat, Google Home, and a Smartthings hub.
I think I could do what you're trying to do if I were to set up some IFTTT routines.
I'm not sure whether I'd do this on Smartthings https://ifttt.com/smartthings
or Google Home https://ifttt.com/explore/customize-google-home
I might have to add an internal and/or external temp sensor in case I couldn't get that data from the thermostat or the WWW, respectively.
I don't know of any thermostat alone that will do what you're wanting.

That is a good idea. It’s time to upgrade thermostats I think. I asked my HVAC tech and he said the American standard smart ### ?? Was good and he didn’t like the third party to many call outs for people not getting settings correct on install. Can the Ecobee run a stand alone dehumidifier?

 

[woodgeek]

I've been using an EcoBee 3 for years.... and it has a feature that locks out the backup strips above a specified outdoor temp (retrieved from the internet). I know my pump can keep up to 20-22°F outdoor, and lock it out above 25°F outdoor. And that is that.

What I want is TOU or demand response options, so I can opt into a lower TOU rate. MY Ecobee has TOU support, but I haven't been able to get it enabled after a few minutes of digging through menus. Maybe I need to update the firmware?

 

[sloeffle]

I'm doing this with my OWB and a Auber ( I highly recommend buying from them and not fleabay or Amazon ) PID controller ( 2342 ) with an integrated relay . You could have a thermocouple sense the outside temperature, once the outside temperature hits a certain set point close the relay for Y1. Once the relay is closed for Y1, the heat pump compressor should turn on.

I've attached a couple pics of my setup. I have mine set to open Y1 at 145. This causes the geo compressor to not run. The green light comes on when the temp is above 165. I have it set that way because my water temps should never drop below that temp. If they are below that temp, I need to check the OWB. The alarm on the left is wired to the PID controller on the left, if outgoing water temps are below 135F, it will start beeping and light up. Last but not least, I have a cold water alarm on the the DIN board. I don't want my water-air HX possibly freezing up in the summer.

 

[semipro]

@EbS-P this thread may interest you if you're considering an Ecobee.
Thread 'Ecobee thermostat not calling for heat from Mr. Cool Universal Heat Pump' https://www.hearth.com/talk/threads...heat-from-mr-cool-universal-heat-pump.191235/

 

[sloeffle]

@EbS-P this thread may interest you if you're considering an Ecobee.
Thread 'Ecobee thermostat not calling for heat from Mr. Cool Universal Heat Pump' https://www.hearth.com/talk/threads...heat-from-mr-cool-universal-heat-pump.191235/

Seems like it’s definitely a solution to what the OP is trying to accomplish.

 

[begreen]

I've been using an EcoBee 3 for years.... and it has a feature that locks out the backup strips above a specified outdoor temp (retrieved from the internet). I know my pump can keep up to 20-22°F outdoor, and lock it out above 25°F outdoor. And that is that.

That's the way our 2006 Am Std. Heritage 16 is setup via the Honeywell digital thermostat. When it was installed it was state of the art, but I guess more basic by today's standards. No wifi, but I haven't needed that in 16 yrs, so it remains in service.

 

[EbS-P]

So I posted this same question to the HVAC Talk forum. They were little help other than to say as HVAC pros they don’t like smart thermostats. Very little help. And the whole forum will not allow DIY advice so it makes any progress over there difficult. Make me really appreciate out community here even more.

The EcoBee with 2 cool stages and 3 heat stages and an auxiliary wire for dehumidifier will allow me to run everything.

 

[ABMax24]

Anyone use the Honeywell T9?

I'm in a similar scenario, I'm looking for a thermostat with a remote sensor option. Our top floor (where the baby sleeps) gets cool when just using the wood stove. I'm going to modify the return air duct on the furnace to pull hot air from the basement and blow it around the house, but I'd like a programmable unit that when it senses about a 3c difference in temp between the main floor and upstairs it turns on the furnace blower to circulate the air.

Any ideas?

 

[woodgeek]

My Ecobee has remote sensors for temperature and motion. They run on a button battery for a couple years and work well.

 

[EbS-P]

My Ecobee has remote sensors for temperature and motion. They run on a button battery for a couple years and work well.

I read the the ecobee indirectly measured co2. I am trying to plan ahead and figure out if I want to add a fresh air intake on the dehumidifier. I Probably will but it would be nice if it could Bring in fresh air if co2 hits a certain level. I’m not confident that my HVAC contractor has done this. Maybe the dehumidifier needs its own controller with humidistat and air quality sensor

 

[woodgeek]

I read the the ecobee indirectly measured co2. I am trying to plan ahead and figure out if I want to add a fresh air intake on the dehumidifier. I Probably will but it would be nice if it could Bring in fresh air if co2 hits a certain level. I’m not confident that my HVAC contractor has done this. Maybe the dehumidifier needs its own controller with humidistat and air quality sensor

My unit is more than 6 years old, so I am pretty sure it doesn't do CO2.

Also, your house is unlikely to be tight enough to accumulate CO2 and need fresh air.

My house is low enough (verified by blower door test) that if I improved it much more, I would need to provide ventilation during the shoulder seasons (when stack effect is small). In practice, I have a timer on one bath fan that provides about 30 cfm, and I used to set that to on during the mild seasons. Now that my kids have moved out, I don't bother.

 

[ABMax24]

My Ecobee has remote sensors for temperature and motion. They run on a button battery for a couple years and work well.

Can you set it up so that if a remote sensor hits a set low temperature the furnace will kick on, regardless of the temperature at the main control?

 

[EbS-P]

Can you set it up so that if a remote sensor hits a set low temperature the furnace will kick on, regardless of the temperature at the main control?

I would assume so. It’s not a multi zoned thermostat. I just ordered the EcoBee 2022 premium with extra sensors. Cyber Monday! Take my my money!

 

[woodgeek]

Can you set it up so that if a remote sensor hits a set low temperature the furnace will kick on, regardless of the temperature at the main control?

I'm not sure what it does with the info TBH, but I think that is what it is doing. Perhaps gated by motion activity in the spaces.

Sometimes the stat decides I'm at work and turns the heat down a little, and then turns it back up when I come home. Without the remote sensors this would be very annoying (since I might not walk past the stat upstairs). But the sensor downstairs knows I came home.

 

[ABMax24]

Can you set it up so that if a remote sensor hits a set low temperature the furnace will kick on, regardless of the temperature at the main control?

So I answered my own question, I bought the ecobee premium 2022, with 3 extra sensors. Yes, you can set it up to use one, or that average temperature of whichever sensors you like to control from. For instance at bedtime our house is controlled based on the temp of our master bedroom and my daughter's room.

Now here the real issue I need to solve that I can't find a simple answer for, at the bottom are all 4 temperature readings, my basement (where the wood stove) is 10c (18f) hotter than the bedrooms. I need a program to turn on the furnace fan at a set differential, or alternatively I'll setup a fan and ducting to blow the heat from the basement to the top floor that could also be controlled by the ecobee.

 

[EbS-P]

It has one accessory terminal that could switch a relay in the duct fan. Mine is wrapped and under the tree. I have not looked at the FTTT. Does it need to be a differential temp could it just be if the basement temp is above xx?

 

[ABMax24]

It has one accessory terminal that could switch a relay in the duct fan. Mine is wrapped and under the tree. I have not looked at the FTTT. Does it need to be a differential temp could it just be if the basement temp is above xx?

Basement temp above xx would also do the trick. I might have to try switching the furnace blower to the acc terminal, and see if different options show up in the Ecobee.

I don't yet have a dedicated blower to the upstairs, but if the programming is easy and will be effective to work with the ecobee I can install one before we finish the basement.

I have briefly looked at IFTTT, but because I don't have a PC or other device that consistently runs for it to operate on its a less attractive option. The ecobee could easily do what I want it to if the programming was available.

 

[EbS-P]

Basement temp above xx would also do the trick. I might have to try switching the furnace blower to the acc terminal, and see if different options show up in the Ecobee.

I don't yet have a dedicated blower to the upstairs, but if the programming is easy and will be effective to work with the ecobee I can install one before we finish the basement.

I have briefly looked at IFTTT, but because I don't have a PC or other device that consistently runs for it to operate on its a less attractive option. The ecobee could easily do what I want it to if the programming was available.

My I can control my blower from my thermostat I’m sure the Eccobee has a blower terminal that you could or should use for the furnace blower. I had to pull a new tstat wire with extra conductors to hook it up. Save that accessory slot from something else. The whole room sensor aspect could be really neat say there is a room that’s always colder even though it’s being heater you could put in an in-line booster on the accessory and have it turn on when the room is occupied. You something even crazier like turn on and off the something else based on occupancy.

 

[ABMax24]

My I can control my blower from my thermostat I’m sure the Eccobee has a blower terminal that you could or should use for the furnace blower. I had to pull a new tstat wire with extra conductors to hook it up. Save that accessory slot from something else. The whole room sensor aspect could be really neat say there is a room that’s always colder even though it’s being heater you could put in an in-line booster on the accessory and have it turn on when the room is occupied. You something even crazier like turn on and off the something else based on occupancy.

That's how the blower is hooked up now, I'm just wondering if hooking it to acc would give me different options. Right now I can set a run time per hour, or manually turn the blower on, but I can't program it to do anything else.