Load Calculations

[ECIndHVAC]

All this is academic without the heatloads and the data used to compile them and whether proper equipment selection protocol was applied.

Granted, this is all talk. We weren't there.

But we can still talk probabilistically.

If only 20% of contractors do proper load calculations, then the odds that all three of this guy's contractors is less than 1%. And when we figure in the chance that each contractor's equipment is that variable in tonnage ratings, you must concede that your hypothesis, while certainly possible, is highly unlikely.

My experience leads me to suspect that each of those three men did a cursory walk through and then based their bids on equipment that they've put in similar looking houses.

It is for this reason that I recommend to all of these homeowners who are so fussy about manual J to simply learn to do it themselves, then compare what they got to their most trusted contractor.

[pstu]

For the homeowner to do the heat load calc himself, makes a certain amount of sense. I have done it using the software from this site. But one obvious alternative is the homeowner oughta be willing to pay a fair price for the calc, then the guy who did it will get fair compensation for his labors.

I agree it is scandalous that a customer gets a load calc before the contract, has paid nothing for it, and then uses it to shop around to get a better deal using that info. Just not ethical.

Best wishes -- Pstu

[m kilgore]

I'm looking at the LACK of ability to compare bids as a homeowner from the other side of the fence.

Because I have a scientific and math background, I always want numbers to back up a proposal that is not in my area of expertise.

What has happened with my home geothermal proposal is that I got three estimates, all for different tonnage.

As a result I am inclined not to choose ANY contractor unless they can show me that they have justfication for sizing. This is especially important for geothermal.

So what matters most to my selection is (1) backup information and (2) backup references that I can actually call.

Without either of those things, no contractor is going to win my job.

Sorry, but I just won't go out and drop tens of thousands on speculation and blind trust, the way some people buy a used car. I don't believe the final answer merely because a contractor says, "I have XX years experience and I did the calculations." When the numbers don't match between bids as to sizing, that proves to me that NOT ALL CONTRACTORS CAN BE CLOSE TO BEING RIGHT.

Anyways, sorry you are having problems with people taking your results and picking someone else. However, I view this as the consumer has a right to know whether the decision they are making is based on good data.

I understand what you are saying completely. I like to have as much information as I can when I purchase pretty much anything.

That being said, I don't know you well either. When you say that you won't show other companies my calcs. how do I know what you are going to do. I have had this happen way to many times and feel that if someone wants my work they can pay for it and if they sign with me I will give them credit for it. My time is worth something. If I spend 2 or 3 hours at your house measuring and figureing out what and how to best solve the HVAC replacement for you is that to be done for free and then given to the next guy that only takes 15 min. to give his price?

That being said the load calc. is only one part of the whole proposal. I will give you enough other things to think about so you should have your 2 or 3 things to make a informed pruchase. You will need to pick the company that you trust the most in the short time that you know them. If you are just looking for price go with the cheapest.

As stated equipment selection for different brands is quite different. Ones 3 ton may be anothers 3.5 ton.

I know this most likely won't satisify some people but I do not work for free.

[adrianf]

My experience leads me to suspect that each of those three men did a cursory walk through and then based their bids on equipment that they've put in similar looking houses.

Absolutely so then if the OP goes to the trouble to do a proper heatload how could he be expected to just hand it over to the H.O.

[beenthere]

I'm looking at the LACK of ability to compare bids as a homeowner from the other side of the fence.

Because I have a scientific and math background, I always want numbers to back up a proposal that is not in my area of expertise.

Doubt you'll find any contractor that will refuse to provide you the load calc info, if you offer to pay for it.

What has happened with my home geothermal proposal is that I got three estimates, all for different tonnage.

It would not be out of line to have 3 different sizes on some larger houses. Plus they may be calculating the domestic hot water differently.

As a result I am inclined not to choose ANY contractor unless they can show me that they have justfication for sizing. This is especially important for geothermal.

So what matters most to my selection is (1) backup information and (2) backup references that I can actually call.

Hire an independent M E, and pay him to size and design your system. Then you can get prices on his design, and will have apples to apples comparisons.

Without either of those things, no contractor is going to win my job.

Sorry, but I just won't go out and drop tens of thousands on speculation and blind trust, the way some people buy a used car. I don't believe the final answer merely because a contractor says, "I have XX years experience and I did the calculations." When the numbers don't match between bids as to sizing, that proves to me that NOT ALL CONTRACTORS CAN BE CLOSE TO BEING RIGHT.

Anyways, sorry you are having problems with people taking your results and picking someone else. However, I view this as the consumer has a right to know whether the decision they are making is based on good data.

Yes a customer has that right.

But it doesn't mean we have to work for free.

Tell them you will pay for them to do a load calc and give it to you. If they refuse to, then you know not to use them.

[ECIndHVAC]

Absolutely so then if the OP goes to the trouble to do a proper heatload how could he be expected to just hand it over to the H.O.

Oh, I definitely agree with you here. If you do a proper heat load and give it to the HO, there is a very big risk that the HO will give those calculations to some cheaper contractor.

Unfortunately, I have no solution for this problem.

My solution is for the whiney HOs who have sand in their nether reigions because their contractors won't give them pretty looking manual J calculations.

[cook42]

For the homeowner to do the heat load calc himself, makes a certain amount of sense. I have done it using the software from this site. But one obvious alternative is the homeowner oughta be willing to pay a fair price for the calc, then the guy who did it will get fair compensation for his labors.

I agree it is scandalous that a customer gets a load calc before the contract, has paid nothing for it, and then uses it to shop around to get a better deal using that info. Just not ethical.

Best wishes -- Pstu

I cannot agree with you more! The sad part is the one's that's getting the job's are the people that do not take the time to do a load cal and basicly use my info to get the job's!! So I feel like I'm working for them!

[udarrell]

We have very serious over-sizing of A/C & heat pump systems that also do not match-up with the duct system & blower ratings.

In the name of serious "Energy Conservation & reducing the home occupants utility bills," it is my belief that we should have local level government & University & community college Vo-Tech extension programs that make available practical help to address these problems.

In Wisconsin, Iowa & other states there are excellent public broadcasting systems that could do a lot to inform home & business owners concerning reducing heat-gain, then proper sizing of equipment & duct systems.

Also, skilled personnel with the required instruments should be made available at reasonable rates to test & evaluate residential & commercial buildings. There are far too few HVAC contractors that are willing to spend the time or investment to do it due to inadequate remuneration.

Therefore, I see a major energy conservation problem that needs to be adequately addressed.

Some will disagree, however, if new homes, & all homes for sale had to have all that information available, - then it would be a simple step to require that information be made available (not by contractors) before changing out existing equipment. I would take the contractors out of the equations due to exploitation by potential customers!

All avenues possible Internet, broadcast, print, etc., should be used toward informative educational dissemination programs to residential & commercial owners of buildings.

IMO, that vital public interest responsibility will never be properly carried out, for many reasons, by HVAC contractors. - Darrell

[ECIndHVAC]

BTW,

do you know of any articles explaining how inadequate, poorly designed, or undersized ductwork reduces the efficiency of units?

I'm interested in learning the physics behind it.

[cook42]

BTW,

do you know of any articles explaining how inadequate, poorly designed, or undersized ductwork reduces the efficiency of units?

I'm interested in learning the physics behind it.

Manual D, and The Department of Energy website should help you! There should be more.