Slišali ste za priročnik J, kaj pa priročniki D, S in T?

Pravilna zasnova HVAC zahteva pozornost do podrobnosti. Vse od velikosti zunanjih in notranjih enot do števila zavojev v kanalih pomembno vpliva na udobje. Ne morete se zanašati na ugibanja, da bi te stvari uredili. Sistem morate načrtovati pametno .

To je eden od razlogov, zakaj mi strokovnjaki za HVAC uporabljamo tako priljubljeni ročni izračun obremenitve J. Ste slišali za to? Priročnik J je pravzaprav eden izmed več tehničnih priročnikov, ki jih je izdalo združenje Air Conditioning Contractors of America (ACCA).

Da zagotovite, da je vaša oprema HVAC prave velikosti, mora vaš izvajalec – in to ni izbirno – opraviti ročni izračun obremenitve J, preden karkoli namesti.

Priročnik J pa ni edini tehnični priročnik, ki ga uporabljamo pri inštalacijah HVAC v stanovanjih. Zanašamo se tudi na priročnike S, D in T.

Počakaj malo! Sosedova hiša je enake velikosti kot moja. Ali ne morem preprosto namestiti iste toplotne črpalke in namestitve kanala?

Ne, verjetno ne bi smeli uporabljati iste toplotne črpalke in kanalov, kot jih ima vaš sosed.

Za začetek je morda sosedova oprema HVAC napačne velikosti. Številni izvajalci se zanašajo na osnovna pravila in miselnost pri namestitvi "tako smo vedno delali". Ne uporabljajo tehničnih priročnikov ACCA. Namesto tega ugibajo predvsem na podlagi kvadratnih posnetkov.

Velikost vaše hiše ni vse, kar je pomembno. Če greste samo po kvadraturi, boste na koncu dobili pravo opremo HVAC le, če boste imeli srečo. Enako velja za vašega soseda.

Druga stvar pri sosedovi hiši je, da morda ni tako podobna vaši hiši, kot je videti. Ali ima enako velike vdove? Enako število sob? Enake ravni izolacije na podstrešju, podstrešju in stenah? Ali je naprava za pripravo zraka nad hišo ali pod njo? Koliko prostora je na voljo za kanale?

Vse te stvari so pomembne. Med pravilno namestitvijo HVAC je potrebno veliko predhodnega dela, da ugotovite, kaj potrebujete. Če naredite narobe, vam lahko ostane:

• Vlažne razmere poleti in suhe razmere pozimi
• Premajhen pretok zraka za kroženje klimatiziranega zraka med prostori
• Prekomerni statični tlak in prezgodnja okvara opreme

Skratka, za sistem udobja, ki v resnici ne zagotavlja veliko udobja, boste plačali več, kot bi morali. To je verjetno naredil vaš sosed in ni idealno. Zato je uporaba tehničnih priročnikov ACCA tako pomembna.

Priročnik J:vsem najljubši priročnik

O priročniku J smo že pisali, a povzamemo. Priročnik J je priročnik za "izračun obremenitve", ki ga uporabljamo, da ugotovimo, ali naj zamenjamo vašo obstoječo notranjo in zunanjo opremo z enotami enake velikosti. To je rezultat ročnega protokola J, vendar je veliko potrebnega za izračune.

V bistvu uporabljamo Manual J, da ugotovimo toplotne izgube in toplotne dobitke. Vaša hiša pozimi izgublja toploto, poleti pa pridobiva. Koliko? Ko to vemo, lahko začnemo ugotavljati opremo, ki jo potrebujete za pravilno ogrevanje in hlajenje vsake sobe.

Da pridemo tja, nas priročnik J poziva, da pogledamo:

• Izolacijske ravni nad, pod in okoli vašega doma
• Orientacija vaše hiše glede na sonce
• Stopnja infiltracije zraka (tj. relativna tesnost ali puščanje ovoja vaše stavbe)
• Velikosti oken in vrat
• Kvadratni metri od sobe do sobe
• Višina stropa
• Toplota, ki jo proizvajajo ljudje in naprave

Na koncu lahko ugotovimo, koliko BTU toplote vsaka soba izgubi ali pridobi glede na letni čas. Ugotovimo lahko tudi, koliko klimatiziranega zraka mora vaš sistem črpati v vsako sobo (izraženo kot kubični čevlji na minuto ali CFM).

Opomba: Odkar smo prvič objavili ta članek, smo objavili celotno serijo o ročnih izračunih obremenitve J. For even more in-depthinfo, dive into the series!

After performing Manual J, we can say, "your house should have a 3-ton system," or, "you should replace the 2-ton heat pump in your condo with a 1.5-ton system." But we're not done yet.

Manual S:Equipment selection

Manual J doesn't actually help us select equipment. It just shows us what size you need. That might sound like the same thing, but it isn't.

Drawing on the Manual J results for your home's sensible heat load , which has to do with temperature, and latent heat load , which has to do with humidity, we use Manual S to identify equipment capable of cooling and/or heating a certain percentage of each. Basically, we pull up specifications for an AHRI matchup to figure out which indoor and outdoor unit combinations will satisfy the load requirements for your home.

Tonnage aside, different equipment has different capacities for sensible and latent heat. That's why we need Manual S. For example, two different 4-ton systems aren't necessarily going to have the same sensible and latent heat capacities. For your home, one might be better than another.

Ultimately, Manual S goes beyond tonnage to help you find HVAC equipment that's properly sized and meets your load requirements for sensible and latent heat.

Manual D:Getting your ductwork right

Would you tow a boat with a smart car? Would you fish for tuna with a hook smaller than your thumb? No, you wouldn't.

And you wouldn't connect the wrong sized ducts to your air handler either, would you?

As easy as it would be to just add the same duct types and sizes to every home, it wouldn't be a good idea. For starters, the location of your ducts, their sizes, and their position relative to the air handler are really important. How far does the air need to travel? How many bends can we add without inhibiting airflow? How can we balance airflow given the static pressures in the system?

You've got to consider all of these things to get your ductwork right.

The ACCA's Manual D protocol helps us sort out all things related to ductwork. During most HVAC installations, we at least have the ability to optimize the ductwork closest to your air handler (ducts in your walls are trickier). Instead of guessing or relying solely on past experience to select and install the right ducts, we use Manual D specifications as much as possible.

Here's one way to think of Manual D:If you increase the tonnage of the system, you will need to increase the ductwork. Manual D's specs help us nail down the details.

Manual T:That's a nice grill you've got there!

If you've got ducts, then you've got grills. Air grills, also known as grilles (with the "e"), vents, diffusers, and registers, might seem like a trivial detail. Does it really matter how big they are or where they're located?

Yep. It matters. Not putting an air register in the right spot or making the opening too small or too big can cause air not to mix properly.

Have you ever been in a room when the heat was running but it all seemed to sit on top of the register - never circulating properly throughout the room? That's what happens if you don't situate your air registers properly or size them appropriately.

Thankfully, we've got Manual T to help us solve all problems related to air registers. Specifically, Manual T shows us:

• How big your supply and return registers should be
• The best places to put the supply and return registers in each room
• How many supply and return registers you need
• What types of diffusers will best distribute the air

With few exceptions, Manual T is limited to new construction, major system overhauls, and renovations. Otherwise, changing the location of your air registers is a big, messy project. Few homeowners are in a position to pursue that sort of thing, so it's often best to make the most of your existing registers.

ACCA technical manuals are a big deal.

And you've got to utilize all of them if you want a high performance HVAC system.

Assuming everything is installed properly, an HVAC system designed according to Manuals J, S, D, and T will outperform the typical HVAC setup by leaps and bounds . At the very least, your heating and air contractor should perform the Manual J load calculation before suggesting equipment.

Ask them about the other manuals, too. Are they willing to rely on S and D as well as J? Do they know how?

In the end, you want a high performing system that keeps you comfortable and lasts a long time. It's possible to get there, but your HVAC contractor needs to understand established industry standards - and use them.