ReplyWhich one did the load calculation to show you need 5 ton? Which one tested the static pressure on the ducts to see how much air they would move and how well they would move it?
If you want to save money those two things are a must.
Regular Guest
We have a single story 1800 sq ft house with vaulted ceilings, built in '85 with an ~18 year old 5 ton Carrier unit. We live in Metro Phoneix. The unit a single unit on our roof with electric AC and propane heat (we have a propane tank in our yard). We have one return on the east side of the house, the kitchen is on the west and we do notice a temperature difference, but it doesn't bother us terribly. Two adults and a young child live in the home, we need to keep the house at a more "comfortable" temperature for our child.
We had been planning on replacing the unit to avoid it going out over the summer and to get back on some energy savings. Our propane costs were quite high last winter, and we'd like to avoid that again. (We intend to keep the propane for the gas stove, but want to convert to electric heat/heatpump).
We had 4 quotes and they all recommend incredibly different options. Each one seems to say that it "has" to be done their way. I've genuinely felt the salesmen (Yes I recognize they are sales men) are earnest and believe they are recommending the best for us, but I can't even begin to know what we really need.
1) Energy consult through our utility company.
--- Wants to replace unit withRUUD 5 Ton 14 SEER Package Heat Pump. 10 year parts/ 2 year labor. Aeroseal ducts, and/or add returns, R-8 flex runs, etc. Seal stove hood vent and dryer vent, add insulation to R 41.
2) HVAC company.
---- Wants to install Trane 14 seer, Trane 14 SEER, Trane XL15C (two stage?), or BOSH variable, add returns/grills, cut in larger hole in roof to convert over/under twist to a side by side. Aeroseal, add insulation to R49. Possibly convert 18" ducts to 22"
3) One Man HVAC company based on neighbor referral.
--- Replace HVAC only with Day and Night 14 SEER (no other add ons suggested, price was VERY low half of the first two, said there was no need to convert the side). PHD unit 10/1 3 year no hassle
--- Replace with 14 SEER horizontal unit PHJ unit 10/1
4) HVAC company through COSTCO.
---- Quote 4a: Gave two options 14 SEER Lennox with existing duct work. QUote includes new roof jack with drop boxes, filter grill, supply run with register, added return. 10 year parts and 10 year labor.
-----Quote 4b: Lennox 15.5 (two stage) with all of the other add ons but requires total reducting of whole house (says the registers are too far from windows and heat load would not allow for benefit of the low-fan setting -- this was NOT noted as a concern from Quote #2 when selling their two stage/variable units). This quote was approximately 3x Quote #3, and about 4k higher than than 4a.
---Noted concerns about aeroseal and excess static pressure. Said insulation was "fine."
Given these extreme differences, I can't even begin to understand what upgrades are necessary or complete BS. I like the idea of a two stage unit, but it seems like an unreasonable option if we must also reduct the whole house. My research shows Aeroseal should be a good addition, but maybe not? Is it necessary to convert the side x side twist or increase the size of the ducting to reduce the load on the unit and increase efficiency?
Our main goal is to reduce energy costs (obviously) while making the house more comfortable. We also need to be reasonably frugal with expenses, but can also afford a little more out of pocket for a better ROI.
Please help? Please also forgive my very emerging understanding of the terms and mechanical functioning.
Professional Member*
Which one did the load calculation to show you need 5 ton? Which one tested the static pressure on the ducts to see how much air they would move and how well they would move it?
If you want to save money those two things are a must.
Regular Guest
Only Quote #1 (We paid $99 for the Energy Audit). In the report, I see these values:
Duct Insulation Value: 1 R Value
Duct Leakage: Measured (CFM25)
Duct Leakage Value: 495 CFM25
Duct Eciency: 75.85%
Also they sealed the door and walked around with a little handheld machine to check numbers. I don't see those values on my report, nor do I remember them offhand.
The one other Quote #3, entered in various numbers into a formula on his ipad and said that unless we got all new windows, added a bunch of insulation and did like 1 other upgrade could we bring the unit down to a 4 ton unit.
I do not know how the other two came to the conclusion that 5 ton was the best size.
Professional Member*
Little if any energy savings with higher efficiency equipment. Much higher return on investment tightening the envelope.
Global Moderator
Sounds like #1 is saying that 25% of your conditioning is lost due leakage. That's sure a problem. If you seal the ducts and the house you could get by with smaller equipment. Also the 18" round is way too small for 5 tons so enlarging that would help with cooling. So would R41 in the attic. Get the ducts repaired or replaced first then blow that 12"+ over the ducts. Or better yet, foam the roof deck and the attic won't be nearly as hot.
I'm with mecmsg, proper size ducting, nice tight ducts, tightening the house, insulation in the attic, all going to much better for you than paying extra for high SEER 2 stage equipment.
Professional Member*
_ Define the BUILDING THERMAL ENVELOPE
I wonder what, IF ANY, enhancements may actually be
needed for a 4-ton Heat Pump System to be the Appropriate selection.
ACCA Manual S calc is needed to determine the cooling capacity
Derating impact at 110'F.
LOAD CALC EXAMPLE
_________
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
Professional Member*
FOLLOW The PROCESS
___________________ https://www.acca.org/HigherLogic/Sys...&forceDialog=0
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
Regular Guest
Thank you. Quote #5 just came in:
Installation to include the removal and disposal of the existing rooftop gas pack. New package heat pump to be installed. Includes new rooftop elbow, stand, disconnect box and included surge protector. New roof jack to be installed to properly allow for the correct CFM and modern configuration of the new unit. (Shingle repair closest match included if needed. The attic to receive new insulated drop plenums fro the new unit, this will allow for the included additional return (Master bedroom), and properly supply duct connections from the west kitchen side of the house where we are looking to achieve increased air flow for the kitchen and pantry. Eco bee pro smart wi fi thermostat included. (Comes with Bluetooth remote room sensor.) UNIT: Premier GPH14 2 stage.
dan sw fl -- thank you for your message, but I'm having trouble understanding. Is your comment inquiring about whether we can do any updates that would allow us to get a 4 ton unit vs the 5 ton one? If so, I am also curious. Each person has come in and said 5 ton is the way to go and that there is no way 4 ton would be enough, but I feel like our house isn't that large, so it seems curious that we would need such a large size.
Baldloonie -- Quote 5 agent suggested that sealing around the vents and modifying some of the duct work and with the drop plenum and new register would likely solve "enough" of the leakage. Does that sound reasonable?
Can we install a 2 stage system and benefit from it without registers right over the west facing windows in the kitchen. (One said the unit would continuously run on high due to the heat load?)
Professional Member*
What written FACTS were provided that indicate theOriginally Posted by Strawbearlyjamm
Actual Heat Gains ?
Current performance at ~ 100'F:
1. Total Air Flow Rate.
2. Supply Air Temperature
3. Room Temperature
4. …
5. … …
---
Define BUILDING THERMAL ENVELOPE
WINDOWS - Double Pane ?
_________ U-FACTOR 0. _ _ [ 0.3 to 0.9 ]
_________ S.H.G.C. 0. _ _ [ 0. 2 to 0.7 ]
R-13 Walls ?
R-30 Ceiling ?
R- __ Floor
A.C.H. Natural _ 0. _ _ [ 0.3 to 0.7 ]
Review your Detailed electricity use
if you have a Smart Meter
which enables Daily & Hourly data collection.
https://www.aps.com/en/Residential/S...y-Your-Options
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
Regular Guest
Hi dan sw fl -- I'm sorry I really don't understand your last post nor do i understand what questions you are asking or how to respond. If it helps, we have original single pane windows that have a great deal of air leakage, but all my research suggests that the windows should not be the priority. We also have ceramic tile flooring throughout. The house is concrete block. We have reviewed our electricity and have verified that we are using the plan that best matches our use (e.g., peak/offpeak).
Is there more that you can suggest based on that information or do you have thoughts about what specifically I can ask the companies/agents?
Professional Member*
Example LOAD CALC [ Post # 6 ]
does Not apply to CONCRETE BLOCK construction.
I am not aware of the:
1. actual R- # Walls.
2. actual R- # Floor.
2. A.C.H. Natural
Also, without the Actual Monthly electrical use data
for Each of the last 24 months,
no further reasonable suggestion can be provided.
Re-read Post # 2.
Any modifications should be based on appropriate, accurate ACCA Manual J Calculation.
My gmail address: racingdan11
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
Professional Member*
I find it hard to believe an 1800 sqft home with R41 attic and sealed ducting requires 5 tons. I must have missed your location, it’s not by chance on the equator is it?
Just shooting from the hip, I’m leaning towards the first option. Hard to say without looking for myself.
"The only true wisdom is in knowing you know nothing" Socrates
Regular Guest
We're in Phoenix, AZ.
Regular Guest
Below is the Manual J calculations by the company who did our Energy Audit. However, we have reservations that they have embellished some of the numbers. Another installer said that they likely have done so to inflate the value/ratio of doing the upgrades. For example, R1 insulation is not accurate. I don't have a number, but we DO have insulation up there. Also, he said that the Duct Leakage Value (495 CFM25) and Duct Efficiency (75.85%) are shockingly high unless "a whole duct was disconnected" and we'd be able to see that when the blower is running and a door open just a little (it would slam shut). He also demonstrated for us (it didn't shut while the heat was on).
Everyone still seems to suggest going with the 5 ton. The one place we are leaning toward now has recommended the 5 ton Trane 15xlc with this rationale:
If you are considering the 2 stage unit, 5 tons will be perfect for the size of your home. In first stage it will operate around 3 tons of capacity, and have a full 5 tons of cooling when hot summer days demand it.
If you are considering a single stage unit, by adding insulation and sealing ductwork, would reduce heat load enough that we could use a 4 ton system.
In my opinion, a 5 ton 2 stage would be ideal for your comfort, efficiency, and the size of your home. And also provide enough air flow in the lower stage to reach all of the rooms.
Also keep in mind, with new technology in these systems, we have ability to adjust settings on the circuit board to make slight adjustments to capacity.
We can’t increase a 4 ton systems operational capacity, but we can decrease capacity on a 5 ton system through settings on the circuit board.
Is that accurate?
Also regarding the load calculations and corresponding modifications, we anticipate that our install will likely need: a new roof jack, a new return (if we do a 5 Ton Unit?) a Unit, Aeroseal on the existing ducts, new insullation, and at least some ductwork modifications/upgrades.
Regular Guest
I apologize for bumping, but I wonder if anyone can comment on the difference we will see in E bills and Comefort between a 4 Ton Single Stage and 5 Tone 2 Stage? Trane
See below:
"If you are considering the 2 stage unit, 5 tons will be perfect for the size of your home. In first stage it will operate around 3 tons of capacity, and have a full 5 tons of cooling when hot summer days demand it. If you are considering a single stage unit, by adding insulation and sealing ductwork, would reduce heat load enough that we could use a 4 ton system."
We do plan to add the insulation and seal the ductwork.
Professional Member*
Since your system works that means you have time to find the best possible contractor possible, which is far and away the hardest part. I'd highly recommend you either run a free manual J at Loadcalc.net and see what you come up with for your home as is and then adjust the inputs for windows or insulation to give yourself an idea of how much bang for the bucks you'll get, or get in touch with Dan SW FL, he will be much more thorough
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