Anyone Here A Residential HVAC Expert?

Been googling like crazy so I figured I would ask here. Is anyone on this site a home HVAC expert. I need some help with a thermostat question regarding a home central air conditioning system.
Thanks.

 

Clarify what the issue is. I was in high end construction for years.

 

Not really an issue. Im looking for a basic thermostat that allows my central AC to be turned on or off at pre-selected times, not temperatures.
Thanks.

 

Most any programmable thermostat will do that. I would recommend the Honeywell 8000. They make several different sub-models depending on if you have an all electric heat pump or a gas furnace with air conditioning. They also make one that has WiFi built in so you can access it from your smart phone.

By definition, a thermostat controls based on temperature. So if you're looking for something that will turn the A/C on at a certain time regardless of temperature it isn't a thermostat.

 

I'm happy with my Nest.
Added the Nest Protect smoke/CO alarms a couple of months later... I can control the unit from my phone or from any computer in the world.

It keys on temperature, but you could theoretically have it trigger on time-only by simply setting it to some high temperature during the "off" time and an extremely low temperature during the "on" time.

Not sure about the Honeywell or other WiFi units, one thing about some of the programmables that I've had in the past is they are limited to only 4 intervals per day... morning home, away, evening home, and sleep.
The Nest allows for unlimited intervals.

It also allows for the fan to be turned on for specified intervals at certain times.... my wife is disabled and has sleep issues, and in the morning between 7 and noon, though it might be too cool downstairs to cause the AC to kick on, when the sun starts heating the building, the bedroom can get uncomfortably warm.
I have the fan set to run for 15 minutes every hour from 7 to noon and it moves the air enough to keep it comfortable for her.

 

Thanks for the info. I live in Hawaii so any heat pump/furnace settings wouldn't matter. My old place had a Fujitsu Spilt AC System. I really liked the "sleep" and "on/off timer" modes that it had. I used the sleep mode at night where I would run the AC at bedtime for about 2-3 hours and it would turn itself off when I fell asleep. I used the on/off timer to have it come on about 15 minutes before I came home from work during the summer.

Im looking for a central AC thermostat that has these features that is based on time rather than temperatures.

 

I really don't think one exists.

Like I said, you can cheat by using extremely high and low temperatures to force it to operate when you want... that's going to be the closest you're going to get.

 

Obviously one does exist due to the fact that he previously had one as he said in his last post...

OP, I have a Braeburn 5200 that does all of that. Give them a look.

 

I don't see why you can't use a simple 7 day or 5-2 day programmable t-stat.

With mine, I can set the time of day (4 times a day, each day) I want a particular temp set at.... otherwise you'll need an advanced control system (Crestron, Lutron, Control 4 and the like) linked to your air handler's controls.

..... or you can use an InterMatic timer wired after the service switch (line side) of your airhandler.

http://www.intermatic.com/en/Products/TimeSwitches/ElectronicSwitches/24Hour_7Day/GM40AVE.aspx

 

I read through the manual and it doesn't seem to do anything differently than any other programmable, other than having the option to run the fan after the compressor shuts down.

Still seems like he is going to have to use a combination of temperature and time to get the operation that he wants, and frankly, I don't see why this is an issue.
If you want it to run full-time, set it to cool to 65 (or whatever is comfortable, and yes, in Hawaii there's the dehumidifying properties that might mean you want it to run even if getting chilly).
If you don't want it to ever come on, set it to 85, 90, or whatever the max setting is.

The problem with most budget programmables is the limited number of set points.
My last one (Honeywell) did not offer enough set points to have more than a few intervals per day. Newer units may offer more... like I said, Nest is unlimited, as likely are most units with smartphone control.

What I dig about the smartphone control is that I don't have to be in the living room to adjust settings. If I'm in bed and it starts getting a little warm or cool, I can reach over to the nightstand and change the setting without getting up.

I think I've actually touched the Nest itself maybe 3 times to adjust temperature, and only to show my wife how it works. Even sitting 3ft from it, I'll use the web interface.

 

I wasn't trying to get into a pissing contest. My Braeburn can be programmed for 4 times a day. Just program it to turn on/off etc. when you want it to. From what he's posted, that's all he's really looking for.

 

Exactly.

If 4 times a day is enough, then any programmable 'stat can handle it.
If he wants more than 4, then there is at least the Nest, and I'm sure others that can do it.

That's what I'm trying to figure out about his request... he's asking about a unit that operates on time, rather than temperature, when the very nature of a 'stat is that it operates on temperature, and the more modern programmable units add the time element to it.

So it seems that anything made in the last 15 years SHOULD do what he wants... but since he felt the need to ask, apparently not.

I'm mystified as to the issue.

 

I think what he had was a hand held remote to control the ductless (split system) unit.

Those remotes have features like the sleep timer.. etc.

 

So one of the more expensive smartphone-enabled units (Nest, Honeywell, Bosch) will get closer to what he wants.

 

I agree 100%

 

Thanks for everyone's help. Looks like I will just go with a WIFI thermostat and the just set the temps to max when I don't want it on.

 

I'm happy with my Nest.
It's a small, round format, about the size of the old units from the 60s.
It comes with a rectangular backplate to cover existing holes if you are replacing a more modern unit.

The user interface is a bit unfriendly when using the unit itself. Thankfully, you CAN install and program the unit using the ring only to set up the Wifi configuration, then do everything else from the PC.