手動 J 負荷計算の請負業者の選び方
この記事は、新しい HVAC 設置の手動 J 負荷計算に関するシリーズのパート 2 です。
ここまでで、手動 J 荷重計算が重要である理由がわかりました。 1 つがないと、自宅に適したサイズではない AC と炉を購入するリスクがあります。その結果、屋内では非常に不快に感じるかもしれません。 何年も
あなたは明らかにそれが起こることを望んでいないので、手動J負荷計算のために有能で有能な請負業者を選択することが重要です!しかし、どうやって... それを行うのですか? 請負業者が合法であることをどのように確認できますか?どのような質問をする必要がありますか?
以下の手順に従うことで、適切な仕事をする負荷計算請負業者を見つけることができます。
1. HVAC の販売員から始めますか?それらをテストしてください。
マニュアル J について典型的な HVAC セールス担当者に尋ねると、次のようなことがわかるはずです:
「私たちは平方フィートで行っています。すべて同じです。」
翻訳: 負荷の計算に手間をかけるスキルも知識も時間もありません。
そして、これがあります:
「その必要はありません。私たちはあなたがすでに持っているものを使います。エアコンは冷たい空気を吹き込みますよね?」
翻訳: 当社は、HVAC システムのサイジングに関しては経験がありません (または故意に無知です)。
または多分これ:
「ええ、そうです。ほら、ちょっと待ってください。」 *リビングルームの面積を測定します* 「うん、思った通り。3 トンのユニットがちょうどいいサイズです。」
翻訳: 負荷計算を実際に実行するのに何が必要なのかわからないので、いくつか測定を行いますが、違いがわからないことを願っています.
PV では、ほとんどの負荷計算を約 750 ドルと評価しています。他の人は多かれ少なかれ請求するかもしれませんが、それは問題ありません。 The point is that performing a load calculation is a specialized skill that nobody would ever do for free. If the person trying to sell you an HVAC system offers a free, on-the-spot "load calculation," you're not really getting a load calculation. Whenever a company can't do it, they should happily refer you to someone who can.
Basically, a load calculation shouldn't be a touchy subject with HVAC companies. When it is, you should look elsewhere.
2. Verify that the contractor uses ACCA-accredited software.
There are different types of load calculation software out there. However, only certain types are accredited by the Air Conditioning Contractors of America (ACCA). Seasoned pros will always use one of these accredited applications, and they should be able to tell you which one it is.
For example, our team uses Wrightsoft. It's a full-featured, ACCA-accredited application, and we've spent years refining and enhancing how we use it. In other words, we've got a lot of experience with Wrightsoft and are adept at using it to perform accurate, reliable load calculations.
Speaking of experience…
3. Insist on experience.
Doing a load calculation the right way isn't simple. For one thing, there are several potential pitfalls.
Think:measurements you forget to take, typos or "butterfinger" scenarios where you enter the wrong data into the software, faulty assumptions about things like window types and wall insulation levels… the list goes on!
An experienced contractor is far less likely to goof up. With the experienced gained through performing many load calculations, a contractor will:
- Always perform all necessary measurements, or will quickly recognize when they forgot something
- Avoid entering the wrong data into the software, or will immediately notice when something is "off" with the results
- Never rely on assumptions and instead work hard to always obtain accurate, complete data for your load calculation
The thing about load calculations is that even one small error - a "3.5" instead of a "4" or a decimal point in the wrong place - can wreak total havoc on the results and lead to bad HVAC recommendations. An experienced contractor will know how to avoid or correct those errors. A newb? Not so much.
Consider it a good sign when an HVAC contractor has an employee or a team that's 100% dedicated to load calculations. At PV, we've got a full-time, highly trained home performance expert whose primary duty is to run Manual J on all the homes where we're installing equipment.
Oh, and lest we forget:It just so happens that our lead consultant is also trained to perform load calculations. That's a rarity among Atlanta HVAC contractors, but it is true for PV!
4. See if they can modify their approach to suit your needs.
Load calculations have default temperature targets. Any time you get a standard load calculation, you're getting a recommendation for HVAC equipment that can cool your home to 75 degrees on the hottest days of the year and heat it to 70 on the coldest days.
That's just fine for many people, but what if your preferences are different? What if you want it to be 73 degrees in your home when it's 90+ degrees outdoors? And what if you want it to stay 73 indoors even after temperatures dip into the teens? Well, the standard load calculation won't necessarily result in a system capable of doing that.
But an experienced contractor can modify the load calculation to determine which system will meet those demands.
Assuming you require a system that's larger or smaller than a standard one, the contractor will also be able to explain any potential tradeoffs in comfort and efficiency.
5. Ask if they stand behind the systems they install.
Some load calculation contractors don't install HVAC equipment. They simply come to your home, perform the load calculation, and hand you the results. Maybe they refer you to a good HVAC installer. Maybe they don't.
That's a lot better than not getting a load calculation at all. However, an even better scenario is when the same company performs the load calculation, recommends properly sized equipment, installs the entire system, and - this one's big - provides a warranty for every single aspect of that process for years to come.
It's a pretty rare arrangement, but it's worth it when you can find it. Basically, the company should stand behind the equipment they're installing and the process they use to determine what to install.
At PV, we do that. All of it. And most of our systems all come with a 10-year labor warranty.
One reason we can warranty our labor for 10 years (besides the fact that we're sticklers for grade A+ HVAC installations) is because we always perform a Manual J load calculation. Put simply, we know our installations are very likely to perform well because we selected the right equipment to begin with.
Choose an HVAC company that does all of these things, and you'll enjoy optimal indoor comfort for as long as you own your system.