My friend just paid $12 000 for a new furnace 3 years ago. She pays the same company that installed it a monthly fee to do the maintenance on it. Yesterday they did the yearly inspection and they said the static pressure was high. 1.1 something. They gave her a quote for $3500 to fix it. Wouldn’t they have made sure it was done right originally?
Your friend should have used my New Furnace Checklist to avoid hiring idiots: shop.askthebuilder.com/furnace-boiler-installation-contractor-hiring-guide-checklist/ Rarely is the static pressure HIGH. It's often LOW because the ductwork was not sized properly. Your friend should do a consult call with me. Tell her/him to go here to set up the call: shop.askthebuilder.com/15-minute-phone-or-video-conversation-with-tim/
Great quick info on static pressure. I would like to ask, does the main trunk need to reduce a certain amount of feet? How would I know when to reduce it?
The sizing in this case is based on the equal friction method. I’ll reduce when doing so will allow me to reduce duct size by 15%-20%. It really comes down to balancing the cost of a reducer vs running air through slightly oversized duct for a short distance and then reducing more. Not rocket science, more of an art, but in general you decide whether to resize duct after each runout with the goal of keeping the pressure drop per 100 ft approximately equal throughout the duct system. For example, for a 24” duct, I probably won’t reduce until a 20” duct will have the same pressure drop/100 ft as the 24” did before it dropped of some air at some registers.
If the trunk and branches are sized correctly, there's no need. Keep in mind this is one giant room - the gym - in the school building. All the conditioned air ends up in this one room.
Do you really think that a laser dot 1/16th-inch in diameter would show up on that steel duct from 30 feet away? I urge you to test it, make a similar video, upload it to your channel, and then come back here and post the URL in your follow-up comment so I can see how clear the dot shows up. TNX in advance!
My friend just paid $12 000 for a new furnace 3 years ago. She pays the same company that installed it a monthly fee to do the maintenance on it. Yesterday they did the yearly inspection and they said the static pressure was high. 1.1 something. They gave her a quote for $3500 to fix it.
Wouldn’t they have made sure it was done right originally?
Your friend should have used my New Furnace Checklist to avoid hiring idiots: shop.askthebuilder.com/furnace-boiler-installation-contractor-hiring-guide-checklist/
Rarely is the static pressure HIGH. It's often LOW because the ductwork was not sized properly. Your friend should do a consult call with me. Tell her/him to go here to set up the call: shop.askthebuilder.com/15-minute-phone-or-video-conversation-with-tim/
Well done. Hydrodynamics in a nutshell. Giving people knowledge to make informed decisions is good for everyone!
Thanks. In this case it's aerodynamics. But it's absolutely the same principal in our bodies and all water distribution systems.
Very helpful thanks !
Great quick info on static pressure. I would like to ask, does the main trunk need to reduce a certain amount of feet? How would I know when to reduce it?
Yes. Simple. Read a Mechanical Engineering textbook about static pressure.
The sizing in this case is based on the equal friction method. I’ll reduce when doing so will allow me to reduce duct size by 15%-20%. It really comes down to balancing the cost of a reducer vs running air through slightly oversized duct for a short distance and then reducing more. Not rocket science, more of an art, but in general you decide whether to resize duct after each runout with the goal of keeping the pressure drop per 100 ft approximately equal throughout the duct system. For example, for a 24” duct, I probably won’t reduce until a 20” duct will have the same pressure drop/100 ft as the 24” did before it dropped of some air at some registers.
@@twm1452you know we are learning this in rocket science.
Very informative
Glad it was helpful!
I don’t see any vcd’s on those duct branches to balance the supply air.
If the trunk and branches are sized correctly, there's no need. Keep in mind this is one giant room - the gym - in the school building. All the conditioned air ends up in this one room.
Great explanation. Please use laser pointer.
Do you really think that a laser dot 1/16th-inch in diameter would show up on that steel duct from 30 feet away? I urge you to test it, make a similar video, upload it to your channel, and then come back here and post the URL in your follow-up comment so I can see how clear the dot shows up. TNX in advance!
Great example you used.
I looked up and had instant inspiration.
The tube gets plugged into the static pressure pickup port, and goes back upstairs into the rooftop unit. Where does it go exactly inside the unit?
Engage your critical-thinking skills. Where do you think the return air goes????? CLUE: How does your heart work?
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