Question Re: Nest

[cbrunny]

I have a nest and I love it most of the time. But I don't understand 'Eco' mode.

I set a schedule. When no one is home it does not keep the schedule to save energy.

When I get home, it's freakin hot in my house and super humid, so the nest runs the A/C for 6 hours to get back to the temp its supposed to be at.

How is that 'Eco'? Wouldn't it take way more energy to bring the temp from 25C down to 23C and humidity from 300% to ~50% than it would take to just keep the house at 23C and 50% all day?

I mean, what's up with that?

 

[dave_the_nerd]

Depends on the size of the house. There's probably a tradeoff point where if you're going to be gone longer than X hours, it's better to turn it off, but if not, then it's better to keep it on.

 

[dullard]

How is that 'Eco'? Wouldn't it take way more energy to bring the temp from 25C down to 23C and humidity from 300% to ~50% than it would take to just keep the house at 23C and 50% all day?

Unless you have a heat pump that is only efficient while keeping temperatures steady, then no, it is FAR more energy efficient to let the house drastically change temperatures when you are away. FAR more.

To oversimplify things, the amount of energy that you have to use to cool the house is proportional to the integral of the temperature difference from inside to outside. The smaller the difference in temperatures, the less energy you use. Letting the inside temperature reach closer to the outside temperature means less energy used. Doing it while you are gone means that you won't notice and can rake in the savings without being hot or cold when you are back.

 

[Red Squirrel]

That's a common misconception. It actually is more economic to not try to keep the house at a certain temp all day, and then just bring it up even though it takes longer. The total hours the unit has to run is still less than if it cycled on/off all day to keep up to a certain temp. The greater the temp difference between inside and outside the more the unit will have to run. This works with heat too.

In winter I let my house go down to around 12C. I'll probably let it go lower once I get around to adding sensors around all the water pipes. It may take longer to bring it up to 20C, but considering a typical stretch of 4-5 work shifts, during that stretch of shifts, I never need to actually bring it up to 20 because I'm either sleeping, or not home. When I'm off, then yeah the furnace may need to run for like 5+ hours to bring the temp up to 20, but that's still less run time than if I had kept it at 20C the whole time.

If anything it may be a comfort thing more than economic. If you let the house temp change drastically and it takes so long to bring it to where you want, it means it will take longer for you to get comfortable. To me that's a sacrifice I'm willing to take weather it's heat or AC as it saves more energy.

 

[lxskllr]

I have a nest, and the sticks and pin feathers poke my back. Overrated imo.