Thank you so much for the responses so far. It is definitely not the thermostat. Just when the weather turned cold this year we lost power to our old thermostat and called our friend who works in HVAC to come take a look. He tripped the breaker which fixed the issue and that is how we knew to do that this time around. When researching causes my husband decided he wanted to Nest and we got it mostly for aesthetic purposes. So, definitely not the Nest or its set up causing the issue. Bare with me as I am new to all of this but will try my best to describe our system. I thought it was Carrier but was wrong. It is a 1988 Amana all-electric heat and cooling system. It was a tested factory model that the previous owner got from her father who worked at the plant and it was installed in September 2001. The breaker is in the crawl space and we have a 1700 square foot two story home. Are there any other details that might be helpful? My husband has a good friend who has worked in HVAC repair for several years. He is a friend but still not cheap! I think we may just call him back over to test what is pulling so much power that it is tripping the breaker, but thought I would check here first for some tips. Thank you everyone!

The biggest problem with HVAC zone systems is knowing when to choose it as a solution and when not to. Some HVAC companies it's about "sell, sell, sell" whether or not it works... there's more money in "sell, sell, sell" --- when it's only about money? So does the comment above mean I do it for free? No. If you think that you are reading things that aren't there. New construction? best to choose separate systems 9 times out of 10. In order for a zone system to work, you have to know what you are doing. Most HVAC companies staff (the techs they send you) are 20-30 year olds. How much practical experience could they possible have? It's best for HVAC zone systems to be an elegant solution. A HVAC zone system is a tool in the tool bag. Not all homes are suitable for zone systems. Some homes there is no other way, and in some cases complications to those problems will make an HVAC zone system design possibly more prone to problems. You have a problem now, do you want more problems. These decisions among others are decided "in person" --- so considering that becareful what information you decide upon from the internet. Just because it's here doesn't necessarily mean it's true. That said: Depending on equipment level chosen, how many different floors you have in your structure, how much room you have available... will all be factors that make you decide one way or another. From there it's in your best interest to pick a contractor that is skilled: especially when it comes to HVAC zone systems. (there's a lot of garbage out there.) (click to enlarge if necessary) I service the Katy, Texas area.

Sizing can be less of an issue when you have multiple units. Because each unit is controlled independently, provided of course the unit itself is not over sized for the area in which it serves resulting in excessive short cycling. In your case 3 ton plus 2 ton isn't necessarily equal to 5 tons of cooling... unless you drive those thermostats really low. By having two systems with total capacity of 5 tons (which, most of the time this would be oversized for a 1700 - 1800 sq ft structure) has a few advantages. 1. You have the ability to use one system only during low heat days or set the opposing unit higher. The unit set higher only runs if load conditions warrant.... meaning if it's not hot, the thermostat controlling the unit does not call... the unit can not run without a call... 2. Utility bills can be much less... because you rarely use both systems at the same time. You run the bedroom system when you sleep, the other when you're awake. If you have a home office in one the bedrooms you may need to rethink things a bit. 3. Extra capacity for when it's hot out. When it's hot you have the capacity to cool the home. (even while entertaining guests --- additional people add heat) Remember heat waves come, heat waves go... a so call 'properly sized' AC system is essentially properly sized roughly 10% of the time... especially if that system is a single speed AC system. Alot of people I come across like to sleep cool. So for that reason I doubt I would change the configuration of the space. Once you realize what you have, the choices you make are mostly budget type concerns. Essentially a set up like this runs like a 2 stage system. This kind of subject is above the pay grade of many... choose your contractor wisely. I service the Katy, Texas area.

The contractor included a Honeywell VisionPRO 8000 (TH8321WF1001) with my Trane XR17 system installed a couple months ago. It has a large array of setup parameters including several related to control of system stages. 7-day 4-period programmming, although I'm not doing setbacks. Supports an outdoor temp sensor (and several other kinds of temp sensors, although only one choice can be installed) or can reference an online source (which isn't identified) for a "local" ambient. edited to correct 800 to 8000