# HVAC Design for my house



## djadavpmp (Feb 1, 2014)

Hello, 

Is there any online service etc who can do hvac design for my house?

I want to get install done by someone who does not do the design. Also, I want design to be done right. 

How much does it usually cost for 3000 Sq. Ft house for design. I live in central NJ. 

Thanks,
DJ


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## beenthere (Mar 5, 2009)

Check your area for local mechanical engineers that do load calcs and designs.


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## greg24k (May 19, 2007)

djadavpmp said:


> Hello,
> 
> Is there any online service etc who can do hvac design for my house?
> 
> ...


You looking at about tree fiddy per SF give or take a few grand...


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## ScipioAfricanus (Sep 13, 2008)

It has been over two months and this "how much is it...?" thread has not been dumped yet?

Andy.


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## flashheatingand (May 3, 2008)

My reservation would be congruent to Bill Parcels statement "if I am going to cook three dinner,I buy the groceries. If the system does not work to expectations, who its going to be responsible?


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## Z=ke (Sep 21, 2008)

flashheatingand said:


> My reservation would be congruent to Bill Parcels statement "if I am going to cook three dinner,I buy the groceries. If the system does not work to expectations, who its going to be responsible?


I'm new but this caught my eye. The OP said the installer he would like (I assume if the installer can buy the equipment, he is a licensed contractor dealing with heating and cooling) doesn't do the design. So what's wrong with getting a separate design?

I'm asking because I had contacted a member of the ACCA that works as a consultant to the industry. From what I am reading here it would seem that you assume every installer is capable of designing the most efficient system for the situation.

Can everyone who installs be that good?

From talking to those that have given me an estimate (2), I already see that this science is not exact.

And, to the OP, even though this is an old thread, my quote for 1300 sq ft single story stucco SoCal house was $950.


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## flashheatingand (May 3, 2008)

I am not assuming anything. I am sure that lots of times, two separate companies have worked together and it works out alright. But, mistakes happen, and there is potential of "he said, she said".

If I design a system poorly, and I do the install, all liability is on me. If I hire a guy to design, and the designer messes up, again, it's on me. But, in this scenario, I install, and it passes code, yet the design is wrong, who is going to be at fault? Thats why I was using the dinner and grocery analogy.


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## Z=ke (Sep 21, 2008)

Being a newbie here I certainly want to mind my manners. But I just finished reading Flash's baby room thread. All I could think of while reading about all of the possible solutions is that someone with a lot of knowledge and good software might have been able to pinpoint the problem. It seemed obvious that whoever designed and installed the defective system didn't do the due diligence.

I'm not sure myself that the issue is closed regarding using a specialty consultant and letting the contractor follow the prints. I don't see how there is a problem if the prints are followed to the letter.

In my work as a contractor I sometimes had to follow what a structural engineer indicated. If an inspector didn't like what he saw then a change order was executed to make corrections. Sadly, I never saw an engineer fund those corrections. I don't have a whole lot of respect for engineers away.

I apologize if I contradicted myself.


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## coolmasterca (Apr 7, 2015)

Just check with the local contractors, or you might have goggled for best contractors in your location


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## marbledust (Jun 20, 2014)

Seems a stamped set of plans will have a T24 page in it(in California this is a requirement on that page you can collect the heat gain and heat loss cfm for each room.
I always install systems in the same environment and can size rooms by doing a walk thru,
each fau offers a cfm rating as 400 cfm per ton = about 500 feet per ton
each unit needs the correct return ducting to allow the correct static pressues which allows the compressor to run at specfic ranges of head pressures.
Long story short...any a/c guy can size a system if that guy has been trained well.

And any hvac guy will give you a start up report from his imanifold...


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## beenthere (Mar 5, 2009)

marbledust said:


> each fau offers a cfm rating as 400 cfm per ton = about 500 feet per ton
> 
> 
> And any hvac guy will give you a start up report from his imanifold...


500 ft per ton is an old rule of thumb that usually over sizes the equipment.


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## flashheatingand (May 3, 2008)

B.T. Since you mentioned oversizing, I have a question. Do you guys design for latent heat removal (humidity)? Or sensible heat design?

It seems as though you don't want too big of equipment to deal with latent heat. But whe it gets real hot (95+) you also have to deal with sensible heat.


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## EricBrancard (Jun 8, 2012)

flashheatingand said:


> B.T. Since you mentioned oversizing, I have a question. Do you guys design for latent heat removal (humidity)? Or sensible heat design?
> 
> It seems as though you don't want too big of equipment to deal with latent heat. But whe it gets real hot (95+) you also have to deal with sensible heat.


I think I'd rather deal with a couple degrees warmer and dry than cool but damp.


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## marbledust (Jun 20, 2014)

beenthere said:


> 500 ft per ton is an old rule of thumb that usually over sizes the equipment.


True that...I was just looking at a home listed at 1850 with 9 foot ceilings..the plan was engineered and had a t24 page as well.

building required a total of 1350cfm. 
So 3.5 ton


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## GettingBy (Aug 19, 2010)

http://www.loadcalc.net/



djadavpmp said:


> I want design to be done right.


Depending on what you mean by this, I'd undersize or oversize the main unit and then fix the seasonal and day/night discrepancies with small units that heat, cool, dehumidify or humidify.
But, ASHRAE will tell you there are many constraints on how to get "comfort".

http://www.clrsearch.com/Iselin-Demographics/NJ/08830/Weather-Forecast-Temperature-Precipitation


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## flashheatingand (May 3, 2008)

No such thing as one size fits all. Some people want the home meat locker cold wheñ its 100 degrees out. Some don't like ac. So many difrent factors in determning comfort.


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## EricBrancard (Jun 8, 2012)

flashheatingand said:


> No such thing as one size fits all. Some people want the home meat locker cold wheñ its 100 degrees out. Some don't like ac. So many difrent factors in determning comfort.


This is why multi speed and modulating equipment shines.


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## flashheatingand (May 3, 2008)

Until stuff breaks down, and the warranty runs out.


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## EricBrancard (Jun 8, 2012)

flashheatingand said:


> Until stuff breaks down, and the warranty runs out.


Which is true of all things mechanical.


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## flashheatingand (May 3, 2008)

True. But with standard efficiency equipment parts are readily available, and one isn't required to purchase o.e.m. parts at a convenient markup. 

Iam not hating on modulating equipment or variable speed motors in the way they operate. Its just a homeowner of modest means can be put in a vulnerable situation. And, all savings from the utility bills are negated.


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## EricBrancard (Jun 8, 2012)

flashheatingand said:


> True. But with standard efficiency equipment parts are readily available, and one isn't required to purchase o.e.m. parts at a convenient markup.
> 
> Iam not hating on modulating equipment or variable speed motors in the way they operate. Its just a homeowner of modest means can be put in a vulnerable situation. And, all savings from the utility bills are negated.


I agree. The consumer has to be educated on the HE equipment enough to make the decision for themselves. I see so many just say "if we replace your old oil boiler with this new 96% efficient boiler, you'll save $$$$$$ every year." Then they try to push oversized equipment that defeats the purpose of upgrading.


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## flashheatingand (May 3, 2008)

I don't have a problem with the availability of the equipment. I do have a problem with the proposed mandated minimum efficiency equipment. 

Soon, the 80% gear will likely be 86ed, and many homes were built in a manner in which running a new flue venting system (including the condensate disposal) can become a major expense, again, negating any savings from the bill.

Lets face it most people aren't interested in mechanical efficiency, it's $ efficeincy that interests them.


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## beenthere (Mar 5, 2009)

Remember, most of the efficiency standards aren't to save the individual money. Its to save on energy and fuel reserves for the nation as a whole.


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## flashheatingand (May 3, 2008)

beenthere said:


> Remember, most of the efficiency standards aren't to save the individual money. Its to save on energy and fuel reserves for the nation as a whole.


I don't dispute that. However, if there is a shortage of ___ it will be priced accordingly. Since we have such shortages, why aren't gas stations required to offer alternative fuels than simply gasoline?

If you do the Netflix streaming thing, check out the movie titled Pump. Its a documentary on the gasoline monopoly. It was an eye opener.


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## beenthere (Mar 5, 2009)

flashheatingand said:


> I don't dispute that. However, if there is a shortage of ___ it will be priced accordingly. Since we have such shortages, why aren't gas stations required to offer alternative fuels than simply gasoline?
> 
> If you do the Netflix streaming thing, check out the movie titled Pump. Its a documentary on the gasoline monopoly. It was an eye opener.


A long time ago. The gov decided that we would use up the fuel reserves of other nations before using up our own. So we would be the only one with large fuel reserves.

Then they allowed off shore drilling. And so many more oil reserves were found. That prices didn't continue to sky rocket.

Now, the gov has decided to conform to the rest of the world, and attempt to conserve. But conservation isn't always in the best interest of the fuel reserve owners foreign or domestic.


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## marbledust (Jun 20, 2014)

beenthere said:


> 500 ft per ton is an old rule of thumb that usually over sizes the equipment.


In our area we lack humidity...so 500 feet works good here.The new deal is zone control installs.Emc blower motors have a large range of CFM.
When the ambient air is over 104 you will want the bigger unit.


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## marbledust (Jun 20, 2014)

flashheatingand said:


> True. But with standard efficiency equipment parts are readily available, and one isn't required to purchase o.e.m. parts at a convenient markup.
> 
> Iam not hating on modulating equipment or variable speed motors in the way they operate. Its just a homeowner of modest means can be put in a vulnerable situation. And, all savings from the utility bills are negated.


It's hard to let the home owner know that his new EMC blower motor will cost them 1000.00 for the part and 650.00 labor to put it in for them.


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## beenthere (Mar 5, 2009)

marbledust said:


> In our area we lack humidity...so 500 feet works good here.The new deal is zone control installs.Emc blower motors have a large range of CFM.
> When the ambient air is over 104 you will want the bigger unit.


Not really. A member on another site, has a 4,000 sq ft home, that is cooled by a 2 ton A/C. 

If a 500 sq ft per ton rule of thumb would have been used, his A/C would short cycle, and give him a high cooling bill, and a short life span on the compressor.


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## beenthere (Mar 5, 2009)

marbledust said:


> It's hard to let the home owner know that his new EMC blower motor will cost them 1000.00 for the part and 650.00 labor to put it in for them.


VS ECM's very seldom fail. Its usually the module, and the module is not real expensive. 

X13s/ECMs are not real expensive either.

650 labor, I have got to raise my rates.


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## flashheatingand (May 3, 2008)

beenthere said:


> Not really. A member on another site, has a 4,000 sq ft home, that is cooled by a 2 ton A/C.
> 
> If a 500 sq ft per ton rule of thumb would have been used, his A/C would short cycle, and give him a high cooling bill, and a short life span on the compressor.


2 ton at 4000 ft/2? What do they keep their t-stat set at? Around here homeowners like about 72, and we have many high 95-106 cooling days. No way would I install a two ton without some type of "insurance policy" to make sure that I wouldn't have to eat that a/c unit, should the homeowner be dissatisfied.

Did they use foam insulation within the roof bays? I went to do a job in which the roof bays were insulated, and I was amazed (don't use that word ofter) at how cool the attic was.


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## beenthere (Mar 5, 2009)

Its an extremely tight constructed home. They did have a mini split installed for the master bedroom because they like it extra cool at night when sleeping(70 and lower sometimes). But stopped using it because the central 2 ton cooled the home and master bedroom better then the mini did the master(kept the humidity down better).

Yes, its foamed. Don't need a big A/C if the heat can't get in.

One of the biggest problems with foam insulated homes. Is HVAC contractors not understanding insulation and air tightness effects on a home. Many foam houses have A/C systems 3 times as big or more then is really needed. And much higher electric bills then they should have.


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