We have dual units at our home that need replacement. The cost difference between the single and two stage is negligible so the discussion is whether to go with a 2 stage vs a variable speed. The replacements would be Trane's. I had one AC guy tell me to stay away from variable speed his reasoning was there are circuit boards, drivers, etc, in short more things that can break, the second guy that came out swears by the variable speeds. Is there a reason I shouldn't install the variable speed (I speed a small fortune on electric bills so looking for the most efficient system). If it matters the systems would come with a 10 warranty. Any advice/help would be appreciated
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AC Replacement: single stage vs two stage vs variable speed
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Last: 2 mo ago by Hodor
I plan to have a true variable speed with rigid ducts when we buy or build our "forever home". Since we plan to move, I just replaced my 21yo Trane condenser with a 2-stage XR16 paired to the existing Trane XV80 variable speed furnace. I would base your decision on how long you plan to be in the house, since ROI will take years.
Our experiences with heat pumps since 1980 that last ~20 years each
1. Single stage, a 1/4ton undersized cost a lot to run, ran a lot, uncomfortable in extreme weather (+ over $300/mo bills), leaked, repairs galore.
2. Single stage, a 1/2ton oversized "deal" cost a lot to run, over $300/mo bills in extreme weather, leaked, repairs galore ~70% of new install costs, over cooled, heated, jet sounding breezes
3. Variable stage, perfectly sized, cost only a bit more than other options, never ever a $300 bill + rarely over $200!!!, comfort pampered (even in 107F feels like temps), finally blessed and no fear of costly parts after the rape of #2. The "extra" costs have already been recaptured in reduced energy bills over a 38 month period!
Always semi-protected by the annual maint.contract
Always had the very best, top techs in town ... it was the equipment brand options & problems, totally.
Am NOT a HVAC guy ... too complicated for me!
1. Single stage, a 1/4ton undersized cost a lot to run, ran a lot, uncomfortable in extreme weather (+ over $300/mo bills), leaked, repairs galore.
2. Single stage, a 1/2ton oversized "deal" cost a lot to run, over $300/mo bills in extreme weather, leaked, repairs galore ~70% of new install costs, over cooled, heated, jet sounding breezes
3. Variable stage, perfectly sized, cost only a bit more than other options, never ever a $300 bill + rarely over $200!!!, comfort pampered (even in 107F feels like temps), finally blessed and no fear of costly parts after the rape of #2. The "extra" costs have already been recaptured in reduced energy bills over a 38 month period!
Always semi-protected by the annual maint.contract
Always had the very best, top techs in town ... it was the equipment brand options & problems, totally.
Am NOT a HVAC guy ... too complicated for me!
Ten words or less ... a goal unattainable
I appreciate the input. This is our forever home. Have a seat, and no I am not kidding, last months electric bill was $751. Based on responses so far I see no reason not to go variable speed. I think the cost savings and comfort are going to pay for cost of the install. The other thing is if I go 2 stage they will reuse the furnaces, if I go variable speed everything is new and warrantied.
Any of the 3 will have control boards and other controls. That wouldn't scare me off from a variable speed. The cost analysis may scare me off.
MarylandAG said:
I appreciate the input. This is our forever home. Have a seat, and no I am not kidding, last months electric bill was $751. Based on responses so far I see no reason not to go variable speed. I think the cost savings and comfort are going to pay for cost of the install. The other thing is if I go 2 stage they will reuse the furnaces, if I go variable speed everything is new and warrantied.
Before dropping variable speed dollars (or at the same time), I'd make sure that you've got good/straight/sealed ducts, and deep insulation. Adding insulation is very cheap.
I have no experience with two stage. We went from single stage in a Stylecraft home (can't remember the brand) to a variable stage Lennox in our forever home where the entire house is spray foamed. As someone mentioned earlier, even on the hottest of days, that variable speed is money. Consistent comfort all day. Really helps keep the humidity down.
Mine produces a report of daily run time and operating capacity. During this time of year, it runs almost all day, but it's usually only at 30-35% of its capacity.
Mine produces a report of daily run time and operating capacity. During this time of year, it runs almost all day, but it's usually only at 30-35% of its capacity.
Another vote for variable speed if this is a long term house. We did this for our sleeping portion of the house and then mini splits in the other separate section of the house. While I still wish I had mini splits everywhere the variable speed A/C is amazing at the consistency AND the quiet. Since it is on so much it is rarely above 50% so the noise is almost nothing. Add it has dramatically reduced our humidity levels.
Will add to what others said. If you are spending that kind of money then do your homework on ducts, insulation, and sizing. You are just wasting money if you don't do a comprehensive assessment of what you really need.
Will add to what others said. If you are spending that kind of money then do your homework on ducts, insulation, and sizing. You are just wasting money if you don't do a comprehensive assessment of what you really need.
Variable speed will not only use less energy and keep the temperature more consistent, it is much more effective at managing indoor humidity because the fan speed and compressor speed are both variable. After living with a Trave XV20 with the 1020 controller we will NEVER buy a fixed speed unit again.
I put in a single speed on a tight budget about 7 years ago. I hope it craps out soon so I can put in a variable speed instead. Like the above, being able to manage humidity and temp together is a huge benefit.
Just got quoted for (2) 4ton SL28's and a 2ton SL28 with the Pure Air add ones. All in $75K.
I want to change out all my systems with 410a before the transition.
I want to change out all my systems with 410a before the transition.
Dill-Ag13 said:
I put in a single speed on a tight budget about 7 years ago. I hope it craps out soon so I can put in a variable speed instead. Like the above, being able to manage humidity and temp together is a huge benefit.
Have you considered a whole home dehumidifier?
When we built a couple of years ago, I put one ion my main unit. Will likely be adding one to my smaller unit that serves the MBR and another room.
I bit the bullet and went variable with our downstairs last year. It has been great. I do worry a bit about "it will be more expensive to fix" boogeyman stories, but they seem to be mostly that. It was definitely more expensive, but with rebates available at the time, it got close enough in price for me to justify making the leap.
The key with variable (any AC, really, but especially variable) is air flow. Properly sized and balanced intake/outflow because keeping air moving in a balanced manner is key to exchanging heat effectively for these systems that will run long at less power. I had new returns installed to make this happen; my old ones were ****ty just using interior wall voids and way undersized. They also replaced a couple of ducts (ended up being "free" for that).
Had a couple of different bids from some reputable places my dad and I have each used over the years/decades, one a Trane dealer and the other a Carrier. Ended up going Carrier
The key with variable (any AC, really, but especially variable) is air flow. Properly sized and balanced intake/outflow because keeping air moving in a balanced manner is key to exchanging heat effectively for these systems that will run long at less power. I had new returns installed to make this happen; my old ones were ****ty just using interior wall voids and way undersized. They also replaced a couple of ducts (ended up being "free" for that).
Had a couple of different bids from some reputable places my dad and I have each used over the years/decades, one a Trane dealer and the other a Carrier. Ended up going Carrier
When we replaced the AC at our last house we did variable speed. Weren't going to originally but 2 stage were backordered (after they told us they had them in stock and ready) so company gave us a deal on variable speed.
Obviously depends on the house, but not sure I see the efficiency making up the cost delta. I knew it wouldn't when we installed it at our last house and wouldn't use it as a factor in this new house.
But I didn't regret it at all. It just made the house so much more comfortable. The AC just running at a low speed all night and maintaining a constant temp was way better then cooling below the set point, shutting off, warming up, repeating....
I won't hesitate to install variable speed in the new house if/when these units kick the can. Maybe do 2 stage upstairs as it's just the kids' rooms, but downstairs for sure.
Obviously depends on the house, but not sure I see the efficiency making up the cost delta. I knew it wouldn't when we installed it at our last house and wouldn't use it as a factor in this new house.
But I didn't regret it at all. It just made the house so much more comfortable. The AC just running at a low speed all night and maintaining a constant temp was way better then cooling below the set point, shutting off, warming up, repeating....
I won't hesitate to install variable speed in the new house if/when these units kick the can. Maybe do 2 stage upstairs as it's just the kids' rooms, but downstairs for sure.
More power to you guys with the variable units. I damn near choked when I got the 40k quote to replace both of mine. I had single stage before and was perfectly comfortable, so I went with single stage again and have no complaints. House stays at 72 and 45-50% humidity.
Crispin Torque said:
More power to you guys with the variable units. I damn near choked when I got the 40k quote to replace both of mine. I had single stage before and was perfectly comfortable, so I went with single stage again and have no complaints. House stays at 72 and 45-50% humidity.
This was 2020, but my 4 ton variable speed trane was $14k. The single stage was around $10k and 2 stage just under $12k.
My 4ton variable was $17,500 all in last summer, which included the returns being redone entirely (new locations, etc) and ducts to the living and master being replaced. That said, I did get a combo of $3500 in oncor and other rebates. Carrier infinity 26. I think the single was about $13k and 2stage about $14.5.
If I'd been doing 2 units, I may have considered 2stage to save $6000, but my upstairs was replaced in 2020 so I figured I could make the leap. One thing that has been nice is the noise - it's near our master so never hearing it is nice.
If I'd been doing 2 units, I may have considered 2stage to save $6000, but my upstairs was replaced in 2020 so I figured I could make the leap. One thing that has been nice is the noise - it's near our master so never hearing it is nice.
Prices have definitely gone up quite a bit since 2020.
I just replaced a 5 ton and a 3.5 ton. The installer I used does all American Standard.
I just replaced a 5 ton and a 3.5 ton. The installer I used does all American Standard.
Little late to this thread, but in mid 2020, got both systems replaced at my house.
Original was 2004 Ruud system (single stage). A 5 ton and 4 ton (down/up). Fun fact: the downstairs only had a 3 ton return and the upstairs only had a 3 ton return. So I was paying for 3 tons of cooling that I could not fully use.
Replaced down with a 'variable' (5 stage) system and the upstairs and a dual stage. Down was 4 tons and upstairs 3 tons, while adding 2 new returns. The new downstairs was at the top of the stairs in a 2-story entrance area and the upstairs new return was a mirror point in the upstairs (game room with bedrooms on either side) from the original suction. They also replaced all of the 1986/7 ducts in the attic as far as they could.
Total cost was $25k, cash. I think officially the split was $10k/$10k/$5k (up/down/ducts), but it could be different. The units were Comfortmaker (Carrier). To date, the only issues we've had are 3. The main board on the down unit (twice) and the upstairs fan/controller/fuse (?) once. The upstairs issue did not affect it from actually working, but I did have to 'reset' the unit once a day. I would go up and flip the switch for the air handler, wait a minute, then turn it on. The downstairs issue was the main board. Talking to the tech, the diagnostics was measure voltage at the cut-off and then at a point on the unit. If both were 220V and the red light was not on, replace the whole board. We were out of AC for 2 nights total.
Units came with 12 year parts AND labor, so part of the reason I went with them.
I recently put on a energy monitor on my panel and, to date, the variable unit has used 385 kWh vs. the upstairs unit using 957 kWh. The upstairs is set a little lower than downstairs and tends to run most of the day during the heat, but helps keep the downstairs 'even' during the day. The downstairs unit will run most of the early morning removing humidity (dehumidification mode vs. Stage 1/2/5), so this helps 'unload' the unit and makes it feel cooler.
When I installed the units, I was able to lower the setpoint for the unit about 5-7 F and kept out power bills mostly flat. My kids went from complaining about being hot to being cold during the summer. It also made cooling down the house from a 1-2 hour event to less than an hour. Like recently, after Beryl, I got the house down to mostly comfortable in about 2-3 hours after being without power for 132 hours.
~egon
Original was 2004 Ruud system (single stage). A 5 ton and 4 ton (down/up). Fun fact: the downstairs only had a 3 ton return and the upstairs only had a 3 ton return. So I was paying for 3 tons of cooling that I could not fully use.
Replaced down with a 'variable' (5 stage) system and the upstairs and a dual stage. Down was 4 tons and upstairs 3 tons, while adding 2 new returns. The new downstairs was at the top of the stairs in a 2-story entrance area and the upstairs new return was a mirror point in the upstairs (game room with bedrooms on either side) from the original suction. They also replaced all of the 1986/7 ducts in the attic as far as they could.
Total cost was $25k, cash. I think officially the split was $10k/$10k/$5k (up/down/ducts), but it could be different. The units were Comfortmaker (Carrier). To date, the only issues we've had are 3. The main board on the down unit (twice) and the upstairs fan/controller/fuse (?) once. The upstairs issue did not affect it from actually working, but I did have to 'reset' the unit once a day. I would go up and flip the switch for the air handler, wait a minute, then turn it on. The downstairs issue was the main board. Talking to the tech, the diagnostics was measure voltage at the cut-off and then at a point on the unit. If both were 220V and the red light was not on, replace the whole board. We were out of AC for 2 nights total.
Units came with 12 year parts AND labor, so part of the reason I went with them.
I recently put on a energy monitor on my panel and, to date, the variable unit has used 385 kWh vs. the upstairs unit using 957 kWh. The upstairs is set a little lower than downstairs and tends to run most of the day during the heat, but helps keep the downstairs 'even' during the day. The downstairs unit will run most of the early morning removing humidity (dehumidification mode vs. Stage 1/2/5), so this helps 'unload' the unit and makes it feel cooler.
When I installed the units, I was able to lower the setpoint for the unit about 5-7 F and kept out power bills mostly flat. My kids went from complaining about being hot to being cold during the summer. It also made cooling down the house from a 1-2 hour event to less than an hour. Like recently, after Beryl, I got the house down to mostly comfortable in about 2-3 hours after being without power for 132 hours.
~egon
Considered an aprilaire, what setup did you get?Hodor said:Dill-Ag13 said:
I put in a single speed on a tight budget about 7 years ago. I hope it craps out soon so I can put in a variable speed instead. Like the above, being able to manage humidity and temp together is a huge benefit.
Have you considered a whole home dehumidifier?
When we built a couple of years ago, I put one ion my main unit. Will likely be adding one to my smaller unit that serves the MBR and another room.
Dill-Ag13 said:Considered an aprilaire, what setup did you get?Hodor said:Dill-Ag13 said:
I put in a single speed on a tight budget about 7 years ago. I hope it craps out soon so I can put in a variable speed instead. Like the above, being able to manage humidity and temp together is a huge benefit.
Have you considered a whole home dehumidifier?
When we built a couple of years ago, I put one ion my main unit. Will likely be adding one to my smaller unit that serves the MBR and another room.
It's an aprilaire, but I don't know the model.
Not sure if this is something that's a limitation of the unit or how it was installed, but I have to change the set point on the unit in the attic rather than on the thermostat. That's the only thing I'd change. Luckily, I don't need to change it often.
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