New home owner needs advice for new system

[southernutah]

I am a new homeowner, and I need some advice. First off, I live in the Southern Utah desert, so it's very hot, very dry, with mild winters, hardly ever humid.

I currently have a 3.0 TON, SEER 10, RUUD split system that is as old as my house (17 years old.) My house is 1500 sq. feet, typical exterior stucco/tile roof home. I had one company come over and do a bid on a new system, and the big question is whether to stay with a 3.0 Ton or get a 3.5 ton? Either way, the system will be made by Bryant, it will use Puron, and it will be a SEER 13 rated unit. And yes, they will also be replacing the indoor coil so the system is matched properly. They claim they can do 3.5 tons without any mods to my air ducts, or intake in the hallway.

During the summer on the hottest days when it gets over 100 degrees, the house will only cool down to 73 degrees. The unit does not cycle off at all, until it cools down late at night. (I keep my T-STAT set at 71 when I am home, I am only comfortable when its very cool inside my home.) On milder summer days when it only gets to 90 degrees outside, that seems to be the threshold of when my system can bring the temp down to 71 degrees and cycle off for a few minutes. According to the company who gave me the quote, they said the reason is because my system is undersized. I don't think they are trying to milk me for my money because they said they'd be glad to just replace it with a 3.0 TON if that's what I wish, but they strongly recommended to go up half a ton, to 3.5 TONS. They also said it would save money because the system would be more likely to cycle off, saving me money.

So here are my TWO questions:
1. Do you agree with the philosophy that putting a 3.5 ton on will save me money over the 3.0 ton because it will cycle off more instead of run continuously?

2. Lets say I replace my 17 yr old. SEER 10, 3.0 ton unit, with the Bryant SEER 13, 3.5 unit (w/Puron refrigerant). Will the newer unit use LESS electricity than the old unit? I don't know what the answer is to this, simply because in this situation, I am going up in tonnage which uses more electricity, while at the same time, I am going from SEER 10 to SEER 13 which will use less electricity. (I WOULD get a more efficient unit than SEER 13, but I don't have the money right now, I already have to finance my new unit)

One other thing to consider: My attic is insulated, but it's not the best. It has rolled bats of fiberglass insulation of R-19 factor. I will wait until new A/C is installed to take care of this problem, because I don't want the A/C guys walking around up there, compressing the insulation as they walk through it.

Last, I want to say THANK YOU to anyone who can provide answers to my questions, or any other insight you wish to add.

[beenthere]

A new 13 SEER 3 ton will save you money. And a 13 SEER 3.5 ton would probably save you some money also. But not because it would shut off.

Instead of getting a 13 SEER 3.5 ton that will use more electric then a 13 SEER 3 ton.

Increase your insulation in the attic, so you lessen the load on the A/C.
Plus, any other improvements that you can do, that will decrease the load(window tinting).
Then the 3 ton won't have to run as long. And you will save much more money.

The amount of off time you currently have. Is not related to the size of your A/C. But to how quickly your home heats back up(gains heat).
Lessen that, and you save money. Both in upfront installation cost, and in operating cost.

[dan sw fl]

new homeowner,
, I live in the Southern Utah desert,


I currently have a 3.0 TON, SEER 10, RUUD split system that is as old as my house (17 years old.)
My house is 1500 sq. feet, typical exterior stucco/tile roof home.

I had one company come over and do a bid on a new system, and the big question is whether to stay with a 3.0 Ton or get a 3.5 ton?

During the summer on the hottest days when it gets over 100 degrees, the house will only cool down to 73 degrees. The unit does not cycle off at all, until it cools down late at night. (I keep my T-STAT set at 71 when I am home, I am only comfortable when its very cool inside my home.) On milder summer days when it only gets to 90 degrees outside, that seems to be the threshold of when my system can bring the temp down to 71 degrees and cycle off for a few minutes.

So here are my TWO questions:
1. Do you agree with the philosophy that putting a 3.5 ton on will save me money over the 3.0 ton because it will cycle off more instead of run continuously?

2. Lets say I replace my 17 yr old. SEER 10, 3.0 ton unit, with the Bryant SEER 13, 3.5 unit (w/Puron refrigerant).

Will the newer unit use LESS electricity than the old unit? I don't know what the answer is to this, simply because in this situation,

I am going up in tonnage which uses more electricity, while at the same time, I am going from SEER 10 to SEER 13 which will use less electricity. (I WOULD get a more efficient unit than SEER 13, but I don't have the money right now, I already have to finance my new unit)


3.5 ton will obviously remove more BTUs if the t-stat remains set at 71'F

13 SEER would be about 25% more efficient that 10 SEER.

In effect,the new 3.5 ton unit would be expected to cost aobout 10 - 15% less than your current energy use for cooling.

For EXAMPLE, if your current HIGH summertime electric bill is $160, you might
expect bill to be $142 - $150.

The current energy use for cooling might be about $100 to $120 of the total $160 bill. The decrease in cooling cost might range between 10% of $100 up to 15% of $120.

Of course, there are a lot of if, ands and buts, however, you may get the overall picture that the energy bill would not be expected to increase
and the decrease in the summertime energy bill would be marginal IMO.

[southernutah]

I have been in my house just barely long enough to know what my electric bill is like. In the month of March when neither the heater or the A/C runs much, my electric bill is $100. During July and August, my bill jumps to $270. Yikes. I guess this is normal though since I am picky and run my A/C down to 71 degrees, so part of it is my fault. I blame the rest on the fact that my system is 17 years old, and only SEER 10 (and also on my poorly insulated attic.)


3.5 ton will obviously remove more BTUs if the t-stat remains set at 71'F

13 SEER would be about 25% more efficient that 10 SEER.

In effect,the new 3.5 ton unit would be expected to cost aobout 10 - 15% less than your current energy use for cooling.

For EXAMPLE, if your current HIGH summertime electric bill is $160, you might
expect bill to be $142 - $150.

The current energy use for cooling might be about $100 to $120 of the total $160 bill. The decrease in cooling cost might range between 10% of $100 up to 15% of $120.

Of course, there are a lot of if, ands and buts, however, you may get the overall picture that the energy bill would not be expected to increase
and the decrease in the summertime energy bill would be marginal IMO.

[BaldLoonie]

One thing that hasn't been addressed: most duct systems are undersized for what you have. So going bigger without adding ducts may be bad. In a dry climate, more airflow is better.

SO, make sure the dealer checks the duct system for size and integrity, insulate the attic and stay 3 ton. Even if you need 3.5 ton now, adding the insulation will likely knock .5 to 1 ton of need off the house.

[dan sw fl]

I have been in my house just barely long enough to know what my electric bill is like. In the month of March when neither the heater or the A/C runs much, my electric bill is $100. During July and August, my bill jumps to $270.

Yikes.

I guess this is normal though

since I am picky

and run my A/C down to 71 degrees,
so

MAJOR

part of it is my fault.


I know A SMALL PART
is due to the fact that my system is 17 years old,
and only SEER 10 (and also on my poorly insulated attic.)

57 % of the problem is the OWNER !

21 % of the problem is 10 SEER
15 % of the problem is air distribution
7 % of the problem is insulation

TAKE CARE of the Major problem FIRST !

71'F WILL MAKE THE SYSTEM WORK ABOUT TWICE AS MUCH AS 76'F.

[Roscoe]

WoW......that was good........

And don't forget to buy the installers a Pizza Pie........and don't forget to be picky when ordering, like extra cheese and pepperoni ............:couchhide:




oh


and beer goes good with pizza.............:D

[southernutah]

57 % of the problem is the OWNER !

21 % of the problem is 10 SEER
15 % of the problem is air distribution
7 % of the problem is insulation

TAKE CARE of the Major problem FIRST !

71'F WILL MAKE THE SYSTEM WORK ABOUT TWICE AS MUCH AS 76'F.

I don't view 71 as a "problem". That's what I need to have mine set on to stay comfortable, and I have no problem paying the extra money to do so. 76 won't cut it in my home. If that works for you though, then that's great. If you think I'm picky, meet my wife. If someone came over to visit and dared touch the thermostat, she'd slap them across the face:eek: (Remind me why I got married???)

Yes, having it at 71 will raise the bill, and yes, that is my fault (and my wife's), but it's not a "problem." The other issues are things I consider problems because they are addressable. If I am going to have it set at 71, I might as well try and do it in a way that works best for me, and try to save money at the same time if possible. Don't think I am upset by what you said, I respect your opinion, and the suggestion to turn it up to 76 is great, but unfortunately not an option for my situation. Thanks for your help though.:D

[southernutah]

BaldLoonie, yeah that is a great suggestion. I forgot to mention in my first post that they are going to add an extra 25 ft run in my attic over to my living room because it's the only area is my house that won't stay cool. One other thing is, what if I get the 3.0 ton installed, and then insulate my attic better, and my house still won't stay cool in the summer? Then I'd be wishing I had gotten the 3.5 ton. However, if the insulation will really keep my house a lot cooler, then I might be wishing I got the 3.0 ton. It would be nice if I could add the blow-in insulation right now before I bought the new unit just to test it out, but then the installers told me they'd have to walk through it, crushing and tamping it down as they walk and work through it. I will have to think about it some more and decide if I want the 3.0 or the 3.5 ton and hope that I chose wisely after my attic gets insulated better.


One thing that hasn't been addressed: most duct systems are undersized for what you have. So going bigger without adding ducts may be bad. In a dry climate, more airflow is better.

SO, make sure the dealer checks the duct system for size and integrity, insulate the attic and stay 3 ton. Even if you need 3.5 ton now, adding the insulation will likely knock .5 to 1 ton of need off the house.

[beenthere]

Use HVAC Calc (http://hvaccomputer.com/talkref.asp) to do your own load calc.
And then you can see if adding insulation will enable a 3 ton to cool your house to 71 as you want.

[dan sw fl]

I don't view 71 as a "problem". That's what I need to have mine set on to stay comfortable, and I have no problem paying the extra money to do so. 76 won't cut it in my home. If that works for you though, then that's great. If you think I'm picky, meet my wife. If someone came over to visit and dared touch the thermostat, she'd slap them across the face:eek: (Remind me why I got married???)

Yes, having it at 71 will raise the bill, and yes, that is my fault (and my wife's), but it's not a "problem."

The other issues are things I consider problems because they are addressable. If I am going to have it set at 71, I might as well try and do it in a way that works best for me, and try to save money at the same time if possible.

Don't think I am upset by what you said, I respect your opinion, and the suggestion to turn it up to 76 is great, but unfortunately not an option for my situation.

No one said 71'F was THE problem.

You just have to pay and
accept a little ( $170 /mo) extra usage charge
for a few/ several months
and regularly contribute to your local utility.

71'F just can not be provided at $20 per summer month in most states like UTAH.

[air2spare]

Use HVAC Calc (http://hvaccomputer.com/talkref.asp) to do your own load calc.
And then you can see if adding insulation will enable a 3 ton to cool your house to 71 as you want.

BAD ADVICE

[egads]

Perhaps if you can afford to run your unit to maintain 71 degrees you could also afford to add solar panels so it would not cost you anything. (or very little)

[southernutah]

Wow, I never said 71 was "THE" problem either, so I don't get where you are coming from. Look back further and you will see that it is "THE" major problem according to you. Look back and read your own words. I DO accept that I have to pay extra for the usage, which I also stated in my earlier post. OH, and I never expected my power bill to be $20 a month in the summer either. My goal is to save SOME money, and that I shall do by getting a more efficient unit, and adding insulation to my attic. Another poster suggested solar power which is a great suggestion. It is something I have kept my eye on, and will be taken into consideration. The price of having a professionally installed solar system is dropping, and I expect it to continue to drop further as technologies to make solar panels cheaper and more efficient develop. You are still entitled to your opinion, and if you want to say that 71 is "A" problem, I will say exactly what I said earlier: I respect your opinion, and the suggestion to turn it up to 76 is great, but unfortunately not an option for my situation.

I personally know MANY people who set their thermostat lower than 76, so I don't think my situation is all that unique.



In your post earlier: "57 % of the problem is the OWNER !
TAKE CARE of the Major problem FIRST !"


No one said 71'F was THE problem.

You just have to pay and
accept a little ( $170 /mo) extra usage charge
for a few/ several months
and regularly contribute to your local utility.

71'F just can not be provided at $20 per summer month in most states like TN.

[beenthere]

I set mine to 72 in the summer. :D

[dan sw fl]

BAD ADVICE

What, knowing the cooling loads IS Required!

GOOD PLANNING IS to define the most benefiicial work that enables one to reduce Life Cycle Costs. That includes, installation, operation and maintenance.

One does not need a program to determine the GENERAL benefits of ONE aspect of decreasing the cooling load.

Q = U A dT works just fine in the KISS world.

U = 1/ R = 19
A = 1,500 Sq. Ft
dT = T attic - T room = ~ 80' F when it's > 100'F outside.

Q existing ceiling = 6315. BTUh

Q new ceiling = ~3,160 BTUh with another layer of R-19.

SENSIBLE Cooling capacity of 3-ton in a dry environment = 36,000 * 0.9 SHR = ~ 32,400 BTUh

10% savings in cooling load would make a significant impact in being able to cool the residence. Apparently, the residence can be cooled to about 28' F less than the outside temperature ( > 100'F down to 73'F). 10% less cooling load "might" enable the existing equipment to cool to ~ 31'F less than outside temperature.

With a little higher air flow rate, the units performance may increase marginally. 450 CFM per ton is generally recongized as a target airflow rate in a dry environment.
Set-up the new air handler to this higher flow rate. A 3-ton system should be able to handle most 1,500 square foot residences in UTAH. ( SouthernUtah, You're not at more than 6,000 feet are you ?, If yes, dry environment AND thin air are working against THE 3-TON System in providing it's design cooling capacity)

Tinting of south and west facing windows would have a noticeable impact on DECREASING the cooling load.

That is it on providing a brief KISS discussion on how to proceed in determining course(s) of action to increase comfort.

Also, use of ceiling fans would make the apparent temperature seem about 4'F less than without fans.

Wondering, How many hours per year does S. Utah expereince at > 94'F?

I likely can not improve on my current electric bill which is already down to less than $20 / month.

Program modelling (HVAC-Calc or other) is necessary to integrate the various factors that would be revised when changing equipment, air flow, insulation, windows, ...

[Junkers]

One other aspect not previously mentioned is checking the existing duct system for leaks which could be significantly reducing the effectiveness of your 3 ton unit. Finally, if your ducts run in the uninsulated attic which may well exceed 125 to 130F and have poor insulation on them, simply wrapping the ducts with additional insulation can help reduce the cooling lost in the attic. HVAC-calc would help give you an idea of how much this might help you and whether or not it would be worth it.

[southernutah]

I think the load calculation is a good idea too, even though I am no expert on the subject. I am not at high altitude (2,860 ft. above sea level). I am not sure where I would go to find out exactly how many hours its above 94 degrees here. I can tell you that during the hottest of summers, it can get that hot starting in May and can last until the end of September. Temperatures above 100 are common June thru August, and this month (September) we are still seeing temps close to 100. I was wondering one thing. I have heard a lot about the window tinting. Is this something I can easily install myself? I've never done it before. And is it expensive? Where's the best place to purchase the tint from?

As far as a 3-ton unit for my house, I am starting to think that if I insulated my attic, and did the window tint, I could stay with a 3 ton based on what most users are telling me on this forum. If I do get a new 3 ton replacement, and then insulate and tint, and it's still hot in my house on the days when its above 90 then I will regret very much staying with 3 tons. I AM having two more contractors come out this week, and give me a bid on the system, and I will ask their advice too, and hopefully after all that, I can decide if I really want to go up to 3.5 tons or stay. One more question for you A/C guys. Lets say you have a 3.0 ton and a 3.5 ton unit that uses Puron, same SEER ratings, same product line, same everything else, how much more wattage does a 3.5 ton use over a 3.0 ton?


What, knowing the cooling loads IS Required!

GOOD PLANNING IS to define the most benefiicial work that enables one to reduce Life Cycle Costs. That includes, installation, operation and maintenance.

One does not need a program to determine the GENERAL benefits of ONE aspect of decreasing the cooling load.

Q = U A dT works just fine in the KISS world.

U = 1/ R = 19
A = 1,500 Sq. Ft
dT = T attic - T room = ~ 80' F when it's > 100'F outside.

Q existing ceiling = 6315. BTUh

Q new ceiling = ~3,160 BTUh with another layer of R-19.

SENSIBLE Cooling capacity of 3-ton in a dry environment = 36,000 * 0.9 SHR = ~ 32,400 BTUh

10% savings in cooling load would make a significant impact in being able to cool the residence. Apparently, the residence can be cooled to about 28' F less than the outside temperature ( > 100'F down to 73'F). 10% less cooling load "might" enable the existing equipment to cool to ~ 31'F less than outside temperature.

With a little higher air flow rate, the units performance may increase marginally. 450 CFM per ton is generally recongized as a target airflow rate in a dry environment.
Set-up the new air handler to this higher flow rate. A 3-ton system should be able to handle most 1,500 square foot residences in UTAH. ( SouthernUtah, You're not at more than 6,000 feet are you ?, If yes, dry environment AND thin air are working against THE 3-TON System in providing it's design cooling capacity)

Tinting of south and west facing windows would have a noticeable impact on DECREASING the cooling load.

That is it on providing a brief KISS discussion on how to proceed in determining course(s) of action to increase comfort.

Also, use of ceiling fans would make the apparent temperature seem about 4'F less than without fans.

Wondering, How many hours per year does S. Utah expereince at > 94'F?

I likely can not improve on my current electric bill which is already down to less than $20 / month.

Program modelling (HVAC-Calc or other) is necessary to integrate the various factors that would be revised when changing equipment, air flow, insulation, windows, ...

[udarrell]

I am a new homeowner, and I need some advice. First off, I live in the Southern Utah desert, so it's very hot, very dry, with mild winters, hardly ever humid.

I currently have a 3.0 TON, SEER 10, RUUD split system that is as old as my house (17 years old.) My house is 1500 sq. feet, typical exterior stucco/tile roof home.

I had one company come over and do a bid on a new system, and the big question is whether to stay with a 3.0 Ton or get a 3.5 ton? Either way, the system will be made by Bryant, it will use Puron, and it will be a SEER 13 rated unit.

And yes, they will also be replacing the indoor coil so the system is matched properly. They claim they can do 3.5 tons without any mods to my air ducts, or intake in the hallway.

During the summer on the hottest days when it gets over 100 degrees, the house will only cool down to 73 degrees [27-F below OAT]. The unit does not cycle off at all, until it cools down late at night. (I keep my T-STAT set at 71 when I am home, I am only comfortable when its very cool inside my home.)

On milder summer days when it only gets to 90 degrees outside, that seems to be the threshold of when my system can bring the temp down to 71 degrees and cycle off for a few minutes.

According to the company who gave me the quote, they said the reason is because my system is undersized.

I don't think they are trying to milk me for my money because they said they'd be glad to just replace it with a 3.0 TON if that's what I wish, but they strongly recommended to go up half a ton, to 3.5 TONS.

They also said it would save money because the system would be more likely to cycle off, saving me money.

So here are my TWO questions:
1. Do you agree with the philosophy that putting a 3.5 ton on will save me money over the 3.0 ton because it will cycle off more instead of run continuously?

2. Lets say I replace my 17 yr old. SEER 10, 3.0 ton unit, with the Bryant SEER 13, 3.5 unit (w/Puron refrigerant). Will the newer unit use LESS electricity than the old unit?

I don't know what the answer is to this, simply because in this situation, I am going up in tonnage which uses more electricity, while at the same time, I am going from SEER 10 to SEER 13 which will use less electricity.

(I WOULD get a more efficient unit than SEER 13, but I don't have the money right now, I already have to finance my new unit)

One other thing to consider: My attic is insulated, but it's not the best. It has rolled bats of fiberglass insulation of R-19 factor. I will wait until new A/C is installed to take care of this problem, because I don't want the A/C guys walking around up there, compressing the insulation as they walk through it.

Last, I want to say THANK YOU to anyone who can provide answers to my questions, or any other insight you wish to add.

All the prior posts have provided you with excellent advice.

There are a lot of unknowns concerning the actual nominal BTUH performance of your present A/C system. Your rated 3-ton may not be delivering its nominal three ton.

All aspects of the duct system efficiency should always be checked for air leaks & proper insulation, plus all aspects of manual D sizing, etc.

A 27-F drop below the outdoor temperature is very good.
If the interior humidity is low, with good low cost air circulation using fans, it would seem one ought to be very comfortable at 73-F.

Also, as beenthere & others stated, doing cost effective ways to lower the heat-gain/heat-loss is a win-win every month heating & cooling are used.

It appears there is around 800 to 900 cooling hours per season, therefore, it would appear to be more cost effective to, check the systems' performance including the duct system airflow, & reduce air infiltration & do least cost ways to reduce both heating & cooling costs.

With some cost-effective retro-work, your present 3-Ton system can be made to perform down to 71. :det: ha :pop: - Darrell

[beenthere]

If the 3 ton, is only loosing 2° on those days over 100°F outside.

Adding insulation, and a little sealing will enable it to reach 71 on those days.

[dan sw fl]

I am not sure where I would go to find out exactly how many hours its above 94 degrees here.

Temperatures above 100 are common June thru August, and this month (September) we are still seeing temps close to 100.

One more question for you A/C guys. Lets say you have a 3.0 ton and a 3.5 ton unit that uses Puron, same SEER ratings, same product line, same everything else, how much more wattage does a 3.5 ton use over a 3.0 ton?

3.5 / 3.0 = about 16% more.

www.wunderground.com

http://www.degreedays.net/#generate2

[southernutah]

Thanks for that website Dan, I ran the calculations and there are about 168 days a year where the temp runs 94 degrees or above where I live.



3.5 / 3.0 = about 16% more.

www.wunderground.com

http://www.degreedays.net/#generate2