Help with sizing on Furnace and AC estimates

[beachtech]

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please follow the AOP forum rules.

a link can be found in my signature line.

reply posters to homeowner concerns must be a professional member, with a * by their name.

thanks

[mlstark]

7 bids?
I'm biting my tongue.

[beenthere]

Wow, that's a lot of questions.
Concerning the sizing of the A/C. I couldn't find the design temps. for Cape May but Atlantic City is 92 so 90 sounds about right. This is a .5% design temp. which means it is only exceeded .5% of the summer hours.. The design temps for 1% and 2% are 86 and 84. I usually design for 2%. Whoever did the Manual J may not have accounted for shading and the solar coefficient of the glass which have a huge effect on the heat gain. Assuming the house has average insulation, glass is usually the most significant influence.
Having said all of that, you have already done the calculation empirically. You said 15,000 seemed to satisfy your needs, so I think 2 tons is plenty. Air conditioners get their best efficiency when they are running fully loaded, so if you can tolerate the house being a little warmer when it's scorching outside, go for the smaller unit.
To get the highest moisture removal (latent heat) you want the smaller coil. Bigger coils give more sensible (temperature drop) heat and less latent. So I recommend 2 ton condenser and 2 ton coil.
60,000 or 80,000 furnace doesn't make much difference, as, if you're buying a 2 stage furnace, it will be running on 1st stage 90% of the time. Alsol, Manual J doesn't account for internal heat gain (lights, refrigerators, electronics etc.) in the heating calculation, so it's usually a little conservative.

Please read our AOP rules.

[dsc3507]

Wow, I realize now I am in the wrong forum and not likely to get any useful information here. Just mostly "professionals" protecting "professionals" Note I used quotes! The snide remarks back and forth do a lot to make your industry look professional - NOT! It would be nice to get some real useful and trustful information.

As for the many estimates, I have to strongly disagree. I could probably write a book on what I have learned and the BS I have gotten from these quotes. Believe me no two are alike. I realize the average person would just be overwhelmed and totally confused with so many quotes but a more savy person could truly benefit from the experience. If you haven't done your homework first it would be a waste of time.

It is ashame when someone gives some advice on here which is more than a few snide remarks they are !! Oh well thanks for nothing! This is definitely NOT a place for a homeowner to get any meaningful information or at least any he can trust.

[simplyrollin]

Wow, I realize now I am in the wrong forum and not likely to get any useful information here. Just mostly "professionals" protecting "professionals" Note I used quotes! The snide remarks back and forth do a lot to make your industry look professional - NOT! It would be nice to get some real useful and trustful information.

As for the many estimates, I have to strongly disagree. I could probably write a book on what I have learned and the BS I have gotten from these quotes. Believe me no two are alike. I realize the average person would just be overwhelmed and totally confused with so many quotes but a more savy person could truly benefit from the experience. If you haven't done your homework first it would be a waste of time.

It is ashame when someone gives some advice on here which is more than a few snide remarks they are !! Oh well thanks for nothing! This is definitely NOT a place for a homeowner to get any meaningful information or at least any he can trust.

Well, from our points of view, we have all been on estimates that homeowners get 7 estimates. Which means, they wasted 6 others time. I too, will not do a load calc until I have a signed contract. And as far as oversizing the evaporator coils, that was probably done to achieve a higher seer rating. It will only minimally increase your btu capacity. And maybe the 80k furnace had the proper blower motor to achieve the required CFM's.

[dsc3507]

Oh the ego of HVAC installers! So let me understand what you are saying. You are the one and only best HVAC installer so no one needs to get any other estimate than yours. The rest are a waste of time. At the same time you are so experienced that you can do an accurate estimates without any calculations. So you want me to first only pick you because of course I would know you are the best and then trust your estimate based on no data and sign up with you. Later you will do a (hopefully) real analysis and then come back to me and possibly up your estimate based on the real data. Fat chance.

[second opinion]

Take what you read here with a grain of salt. Most are trying to help but unfortunately you will get people that will post and you just need to stop and say HUUUH! getting multiple estimates is a good thing, if an individual does not want to give you a manual j and assess your needs before they do the job, is only guessing at best. Without looking at your whole house and determining what can be done to save you energy and provide you with comfort they do not have your best interest at hand.

[b26440510]

If you were buying a new car, how many places would you shop?

If you were buying a new car, and the dealer wanted you to sign a contract without even listing the make/model or any details of the car you were buying, would you go ahead and sign?

Do you just go to a car dealer and look for a car blindly, or do you research what you want and what is available to determine what make/models would fit your needs?

Is it better to be a well-informed consumer or just accept what is given?

Dont worry -- as a consumer, you'll be blamed for not educating yourself before the sale, or blamed for educating yourself too much. Keep looking around for that car dealer that makes you feel comfortable.

[jpsmith1cm]

Wow, I realize now I am in the wrong forum and not likely to get any useful information here. Just mostly "professionals" protecting "professionals" Note I used quotes! The snide remarks back and forth do a lot to make your industry look professional - NOT! It would be nice to get some real useful and trustful information.

As for the many estimates, I have to strongly disagree. I could probably write a book on what I have learned and the BS I have gotten from these quotes. Believe me no two are alike. I realize the average person would just be overwhelmed and totally confused with so many quotes but a more savy person could truly benefit from the experience. If you haven't done your homework first it would be a waste of time.

It is ashame when someone gives some advice on here which is more than a few snide remarks they are !! Oh well thanks for nothing! This is definitely NOT a place for a homeowner to get any meaningful information or at least any he can trust.

Dsc,

You've gotten some good advice here and some snide comments as well.

You've gotten some good estimates and some poor ones as well, I'm sure.

We are in the process of making some administrative changes here to make this a better place for home owners to come for advice.

[Dad]

Oh the ego of HVAC installers! So let me understand what you are saying. You are the one and only best HVAC installer so no one needs to get any other estimate than yours. The rest are a waste of time. At the same time you are so experienced that you can do an accurate estimates without any calculations. So you want me to first only pick you because of course I would know you are the best and then trust your estimate based on no data and sign up with you. Later you will do a (hopefully) real analysis and then come back to me and possibly up your estimate based on the real data. Fat chance.

Thus the problem with having a home owner come to a professional site, ask questions, then becoming impatient with the answers they get. Spouting off will give you more information... NOT (as you put it)

As mentioned. This site is "trying" to open itself to answering questions that were not before allowed due to liability issues. Thousands of home owners had patience and I allowed these questions to be answered. Impatience will only disrupt this site and the thread deleted.

Please carry on and all will show respect.


thx

[heaterman]

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[jeremyhall.tech.sc]

I have had two estimates on furnace and AC and have about 5 more lined up. I am trying to educate myself on some things to help me evaluate the estimates.

One of the estimates was very incomplete. No load calc, and very poor description. I will assume that one is out.

The other did "manual J" calculation and gave me the printed results. The bottom line is a total heat gain of 37,023 BTUH and a heat loss of 57,481 BTUH. The installer spec'ed a 80K BTUH Bryant with a 42K BTUH evaporator coil and a 36K BTUH compressor.

The installer used a 70F inside temperature and 95F outside temperature in the calculation. I currently use two window AC units totaling 15K BTUH that although not uniformly but adequately cools and most importantly reduces the humidity in my home. It is a one story 3 bedroom (2 bedrooms rather small) home. I feel the 3 Ton unit is over sized and a 2-2 1/2 Ton would be more than adequate. I am concerned about over sizing the AC.

How is the Compressor matched to the evaporator? To the furnace? Is matching a 36K compressor to a 42K evaporator proper? What size evaporator would be used if it were a 24K or 30K compressor?

If I am getting a 92-95% furnace would 80K be overkill for a 57K heat loss? This heat loss is based on a 72F inside and 13F outside temperature.

I am located at Cape May, NJ near the water. Although weather extremes have seemed to increase it is rarely over 90F in summer and below 15F in winter. The temperatures are more moderated by the water. Humidity in the summer can be high.

My feeling is that over sizing of the furnace is not a big deal. It will more than likely be a two stage.

Any help would be appreciated.

i will not comment on the sizing of the equipment and wouldnt feel like i could help with out alot of hands on data collecting and a personal look see.

here is what i will say based on your personal outlook and a few other post you have written..............

if you have concerns about humidity then you should get a system with a dehumidifier as part of the system , this can be done in many ways you could spend hours doing research and finding the data needed to design and install the "perfect" system . this is a costly process not one contractor on this site should be expected to just tell you what to do and i wont either, but if youll channel your questions and give the pros that are working with you a chance youll be fine ... and yes as a professional i will help other professionals cover their behinds it who i am and many people will agree with me , i enjoy helping people and you should value the input that every individual here has taken time to answer, respond , and give valuable advice . you keep saying that you feel like you "are at the wrong site" i am sorry you feel this way and hope youll see that every member that responded and took time ( they could have charged for, time away from their family, and placing trust in you to be polite about the advice given) to help you and a few who were probing you and derailing this thread . also you have contractors in your area giving you quotes and doing the work thats more than ANY of us can do from behind a keyboard and monitor. you seem like a very intelligent person and im sure youll do fine with whichever unit and company you let install for you.

you could however ask for a fresh start on this topic by apologizing for you last post , it almost made me think you are stirring up trouble please show me i am wrong.


J. Hall

[jeremyhall.tech.sc]

Appears that the equipment choice(s) listed are a bit oversized. Manual J results are #1, only as good as the information used (junk in = junk out). #2 there is a "fudge factor" built in to the program that gives a slight increase to the final figures. See what happens with the other companies. As for the first company, the fact that you did not get a print out of a manual J does not mean that they did not or will not do one. There is a fair amount of time involved in doing one properly. I do not provide one with a proposal nor will I give one until I have a signed proposal with a deposit.

i agree completely; time=money.