Nest Learning Thermostat

[DANandNAN]

I'm sold, I don't think it's a gimmick. I just I wish I had stats to take to my better half for backup They always help :lol:

 

[dhanson865]

Just curious, why two thermostats? Only have one heater and one a/c right?

We have two 3.5 ton A/C units for a house of 2800 sq. ft. I don't think one 5-ton HVAC is enough to cool that size of a house.

I have a single 3 ton heat pump for a house of about 2100 sq ft and I have it set in the thermostat to respond slowly so it acts more like a 2.75 ton heat pump. Either you have much less insulation than I do, have the tempature set noticably lower than I do, or your ambient temp is much higher than mine.

Mine is split foyer so it's like a two story house in terms of heating cooling, If yours is Ranch it would need more insulation and/or A/C tonnage to ofset that. I just don't know how much.

It's supposed to get to 106 F here in a couple of days so I'm curious to see how it behaves. I haven't been through the hottest part of the summer in the slow to respond mode but I've seen upper 90s already and it works fine for me.

 

[shrink]

I have a single 3 ton heat pump for a house of about 2100 sq ft and I have it set in the thermostat to respond slowly so it acts more like a 2.75 ton heat pump. Either you have much less insulation than I do, have the tempature set noticably lower than I do, or your ambient temp is much higher than mine.

Well, it is the Sonoran desert in Phoenix, so it is pretty hot. I'm no HVAC guy, but my old house in the Phoenix suburbs was 1941 sq ft, 2-story, and after a load calculation a 4-ton unit was recommended.

Current house is 2-story and per the HVAC guys anyway, for this climate and square footage, they said per their load calculations, this is what they recommend. I have heard that in Phoenix a 5-ton can cool up to 2500 sq ft, but anything larger, more than 1 unit is needed.

However, my knowledge in this area is very limited and based only on what HVAC techs here have told me.

 

[dhanson865]

I have a single 3 ton heat pump for a house of about 2100 sq ft and I have it set in the thermostat to respond slowly so it acts more like a 2.75 ton heat pump. Either you have much less insulation than I do, have the tempature set noticably lower than I do, or your ambient temp is much higher than mine.

Well, it is the Sonoran desert in Phoenix, so it is pretty hot. I'm no HVAC guy, but my old house in the Phoenix suburbs was 1941 sq ft, 2-story, and after a load calculation a 4-ton unit was recommended.

Current house is 2-story and per the HVAC guys anyway, for this climate and square footage, they said per their load calculations, this is what they recommend. I have heard that in Phoenix a 5-ton can cool up to 2500 sq ft, but anything larger, more than 1 unit is needed.

However, my knowledge in this area is very limited and based only on what HVAC techs here have told me.

I assume you are in area 2 on this map http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table" onclick="window.open(this.href);return false;

Energy Star roofing material (reflective), reflective barrier under the roof (http://en.wikipedia.org/wiki/Radiant_barrier#Roofs_and_Attics" onclick="window.open(this.href);return false, and as much insulation as you can stuff in the attic could reduce the AC load a ton (figuratively), I don't know how many tons it would reduce it AC wise.

I don't live in a desert so I have 40+' tall trees providing some shade, but then I don't have energy star roofing yet. My roof tiles are grayish black asphalt shingles the cheapest they made I'm sure.

I'm waiting for the roof to need replacing to upgrade to better roofing but I put in tons of insulation in the attic a couple of years ago. I'm probably between R40 and R50 in my attic. I'll probably do white or very near white (light gray or light brown more on price than my preference for color) roofing when I redo the roof.

If you are using that many tons of AC it'd pay for itself in very little time to look into upgrading the insulation and/or roofing.