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Old 07-03-2018, 10:47 PM   #1
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Asking an HVAC consultant for their load calculation of my home


This is my first time that I have to work with HVAC consultants to have them do an estimate to install a brand new HVAC system for my home. So I did a bunch of research online. All articles/websites that I've looked over thus far indicate that the best type of estimate work is the one where the consultant measure the load capacity of the home, then select the correct system from there.

A few articles/websites suggest that the customer should ask for the load calculation even if they don't understand it before signing/committing to the work contract. Seeing the load calculation ensure that the consultant actually made those suggestions based on some sort of number instead of pull stuff out of thin air that will cost as much as possible.

- So is the customer asking for the load calculation something that is widely accepted by the industry?

- And if a consultant or the hvac company refuse to share their load calculation, should I just walk away?

Thanks.
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Old 07-03-2018, 11:15 PM   #2
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Re: Asking an HVAC consultant for their load calculation of my home


I think as long as you donít mind paying for his time to do the load Calc you should be fine and thatís a reasonable request


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Old 07-04-2018, 07:46 AM   #3
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Re: Asking an HVAC consultant for their load calculation of my home


Here is our policy on load calcs:

1. It's free with a signed contract and you can have it.
2. We will sell it to you for about $300
3. You do not get the results on an estimate.

Here is the reason for the policy: We take the time to do the calculation. If we gave it on the estimate...then somebody gets the bright idea....Hey, this other guy is cheaper and didn't do the calc....I'll use the results I got for free and tell the cheap guy to put in this size!
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Old 07-04-2018, 08:19 AM   #4
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Re: Asking an HVAC consultant for their load calculation of my home


My company does them for free.

Actually the salespeople who are on a commission do them and it is their time that gets spent. They win some and lose some jobs.

They have it on a laptop and can do it fairly fast. Maybe they do the shorter version, I don't know as I have never watched them. They do take outside measurements as I have seen that.

However with the way they schmooze like car salespeople they have the "personal approach" down to a science.

Talk about the clients kids, pets, hobbies, family photos first and build that all important rapport and it usually works well.

We don't try win the race to the bottom with the hackers and Joe's heat em and cheat ems either and sell a lot of high end Lennox units and have a long term reputation in the biz.
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Old 07-04-2018, 09:35 AM   #5
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Re: Asking an HVAC consultant for their load calculation of my home


Garbage in = garbage out.

It could take a long time to properly check insulation r-values (there's still a degree of guess-work without being able to open walls) and really a blower door test needs to be done to be accurate on air leakage.

They can also easily fudge results to get the result they want; tweak air leakage, r-values here and there.

An accurate calc may take a long time and it would be crazy to give it away for free. I've played with software and couldn't imagine doing them well on the fly, especially for older homes that have been partially upgraded and have different exterior types (like brick main house plus framed addition) with varying r-values.

Can say something like 60 or 80 000 btu or whatever, pending result of load calculation if they make sure the ducts can handle the airflow both potential sizes need.

After doing many accurate calculations I'm sure they could correctly guess 9 times out of 10 what size is needed based on lots of experience with a specific home.

If the company is willing to do calculations, it's a good sign and it's more a question of asking for the type of equipment you want rather than accepting whatever they want to install. Stages, blower motor, how closely you want it sized, etc.
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Old 07-04-2018, 09:45 AM   #6
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Re: Asking an HVAC consultant for their load calculation of my home


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Garbage in = garbage out.
Exactly.

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It could take a long time to properly check insulation r-values (there's still a degree of guess-work without being able to open walls) and really a blower door test needs to be done to be accurate on air leakage.
For my first two hvac consultant visits. I didn't do any sort of research at all. So I didn't pay much attention to what they were doing. But looking back, they did not go into much depth as what you've mentioned. No software was used by either consultant.

For the first consultant, they took pictures of the spec of my current systems component, looked over the a/c unit outside, and look at my electrical panel to get the current amp and volt supply for the furnace and a/c unit. This first consultant did not ask for or look for the return air openings. But as you mentioned, he could just have specify these measurement based on other home he has done. Which still is not the most accurate method of measurement.

The second consultant, did all of what the first consultant did in addition to asking for the measurement of the return air ducts within my home. We talked about it, he wrote some stuff down, and took out some sort of ruler/reference device.

Neither used software, checked r-values, and did blower door tests.

I wish I had done research before meeting up with these consultants so I could have observed them more closely and ask more in-depth questions, but what's done is done. So what do you think of the work that these two consultants have done?
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Old 07-04-2018, 10:00 AM   #7
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Re: Asking an HVAC consultant for their load calculation of my home


The HVAC biz is a dog eat dog race to the bottom biz a lot of the time.

The per centage of people who even know what a load calc is , is miniscule so there is no great demand for contractors to get into any great details as hardly anybody knows about it.

Just the way it is.

The best bet is to do one yourself and work with a reputable contractor. If his sizing matches yours great and then go with him.

Usually if a customer has airflow problems and mentions them or the salesperson asks and they say yes then we pursue ductwork improvements.

Doing door tests etc is only for engineers and purists and nobody does them except for commissioning very expensive R2000 homes which need to be certified.

http://hvaccalc.com/main.asp
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Old 07-04-2018, 10:13 AM   #8
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Re: Asking an HVAC consultant for their load calculation of my home


You won't get a contractor doing blower door tests routinely even if it makes the calc more accurate.

You need to screen them over the phone and ask if they do load calcs.

Even a well done calc with accurate inputs may have a margin of 10%.

This is okay, it's not an exact science.

Furnaces come in like 20k btu increments.

So you'll always have a bit of surplus on the heating side.

For cooling, it's okay to be a tad bid undersized and they come on 6000 btu increments. Worst case, it the temp increases by a couple of degrees over setting 2-3 days each year. But the increased dehumidification compensates and it still feels cold compared to outside.

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Doing door tests etc is only for engineers and purists and nobody does them except for commissioning very expensive R2000 homes which need to be certified.
Energy auditors did them, they were mandatory to get rebates.
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Old 07-04-2018, 01:33 PM   #9
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Re: Asking an HVAC consultant for their load calculation of my home


You won't see my company "use software" either. Until you get the print out of the load calc.

I quit buying laptops 4 years ago since I would end up buying a laptop every year when they quit working. The desktop in the office is still going strong 4 years later.
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Old 07-04-2018, 01:35 PM   #10
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Re: Asking an HVAC consultant for their load calculation of my home


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I quit buying laptops 4 years ago since I would end up buying a laptop every year when they quit working.
Yeah. I too hate laptop. Such a flimsy device.
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Old 07-04-2018, 01:45 PM   #11
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Re: Asking an HVAC consultant for their load calculation of my home


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I quit buying laptops 4 years ago since I would end up buying a laptop every year when they quit working. The desktop in the office is still going strong 4 years later.
This is off topic.

But it could be because you're buying the wrong kind of laptop. The only ones worth spending money on are business grade, like lenovo T series. Cost 2 to 3 times as much as the consumer grade ones at the same specs but last like 10 years if you take care of them and are easy to repair.
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Old 07-04-2018, 01:47 PM   #12
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Re: Asking an HVAC consultant for their load calculation of my home


As a commissioned salesperson they can probably use them as a tax deduction as they are self employed. They can deduct vehicle expenses and have a home office and deduct that too.
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Old 07-04-2018, 05:16 PM   #13
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Re: Asking an HVAC consultant for their load calculation of my home


To the OP, when we had my sons bid and replaced about 2 years ago, the guy that ended up winning the job told us that after we signed a contract, he would review it with us and make changes as needed or concerns. The second guy, laughed and said why? so you can do it your self? and left. Bidders 3 and 4 were replacing based on what was there.


I had used a spreadsheet that I had found online and my calcs were the same as the guy that won, except for one room. His calc was smaller. He agreed that using what I had for that room would not be that big of a change.
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Old 07-04-2018, 05:19 PM   #14
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Re: Asking an HVAC consultant for their load calculation of my home


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The second guy, laughed and said why? so you can do it your self? and left.
What an idiot. Without proper training there's no way anyone can do these jobs. And if someone is capable of doing the job themselves, they would more than capable of doing a load calculation.

Thanks for sharing your experience.
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Old 07-04-2018, 05:56 PM   #15
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Re: Asking an HVAC consultant for their load calculation of my home


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What an idiot. Without proper training there's no way anyone can do these jobs. And if someone is capable of doing the job themselves, they would more than capable of doing a load calculation.

Thanks for sharing your experience.
Sad reality is that people who have mechanical skills including brazing pipes could spend a few weeks learning the theory, get the tools needed and probably do a better job than a lot of bidders.
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