HVAC Design: a Crucial Step
HVAC Design: Hints You Need It
- Uneven Temperatures. Some rooms/floors are a lot warmer/cooler than others. For example, You can’t proof bread on the counter because the surface is too cold.
- On and Off. Your system cycles frequently. It does not run for long periods of time. On the coldest or warmest day of the year, your equipment should run 24 hours straight.
- Noise. You have to turn up the TV when the system runs.
- High Energy Bills. Your heating/cooling costs have been unusually high, especially for the size of your home.
- Temperature Stratification. You experience different layers of temperature within rooms.
- Lifespan. Your equipment is needing frequent repair or is failing prematurely.
- Sticky. You have difficulty maintaining proper relative humidity levels, and in winter some windows frost up.
- Smells. You can still smell what you had for dinner 24 hours later
HVAC Design: Why You Want It
Lowest Utility Bills
best Humidity Control
best value HVAC Equipment
best Indoor Air Quality
Quietest HVAC Operation
Even Temperatures THROUGHOUT THE House
Looking for the cheapest HVAC equipment to throw in your home? This isn’t the page for you. Seeking the best value solution (cost and comfort) for your home? Keep reading. HVAC design services pay for themselves.
Forgoing an HVAC design is unwise. Imagine you’re buying a new pair of shoes. Would you buy a pair that’s twice as big just in case your feet grow? No, of course not. It sounds silly, right? Well, a lot of new and existing homes have the same problem, but with their heating and cooling systems. They’re often way bigger than necessary. We see this all the time. Why does this happen?
HVAC contractors usually use shortcuts (“rules of thumb”) to figure out how big a house’s heating and cooling system needs to be because doing the detailed calculations takes a lot of time. They often base the size of the system on the size of the house, like how many square feet it has. But the thing is, every house is unique. Even if you took the exact same house and just turned it around, the heating and cooling needs could be way different.
You might think that having a bigger furnace or air conditioner is better, but in reality, going big like they do in Texas doesn’t always work out well. You don’t want an oversized system. You don’t want extra capacity “just in case.”
The best way to figure out the right size for a furnace and air conditioning system for your home is by doing something called a Manual J load calculation. It’s a method created by the Air Conditioning Contractors of America (ACCA). Manual J calculations show exactly how much heating and cooling a house requires. It used to be done manually by engineers using pens, paper, and slide rules, but nowadays, computers do most of the work. However, completing a Manual J takes time and effort, which costs money. That’s why contractors sometimes prefer using simpler rules of thumb.
At Madison Home Performance, we use Energy Gauge to perform our Manual J load calculations, shown in the images below. Contact us if you’d like more information about how we can help you with your HVAC project.
Pro advice: All homes need an ACCA approved room-by-room heating and cooling load calculation, equipment selection, and duct design. Never shop for new equipment until you first know the needs of the house. If you decide against this, please, and for your sake, at least as your HVAC contractor the five essential questions listed below. It will be eye opening for you.
Ask Questions, Get Answers
Never settle for answers that seem unclear or misleading. Keep asking questions. You deserve clear, complete answers to your HVAC questions in language you can understand. You should know all your options, the decisions being made for you, why they’re being made, and any information that might be left out. Wondering what HVAC stands for? Curious about Manual J load calculations or what a 2-ton system means? Keep reading our FAQ page to find out. Getting answers today will make you a smarter buyer tomorrow.
HVAC Design: Who It’s For
The ideal client for this tier…
- Is looking to replace their HVAC equipment within the next 1-3 years. The current system could be end of life, or just the wrong equipment.
- Wants to know if their present equipment is properly sized for their home.
- Is doing building shell upgrades.
- Is looking to electrify their house and install a cold climate heat pump.
- A person who is serious about home comfort and wants to control of their indoor environment. This person cares about optimizing (tune) their home.
- Not for someone looking for a home energy audit like tier 1 or tier 2, nor for someone wanting the cheapest HVAC equipment installed in their home.
HVAC Design: What To Expect
- 10-20 page report detailing the room-by-room heating/cooling loads that is ACCA approved.
- 30 minute technical debrief session to explain important features of the report
- The original HVAC design files and created 3D images
- Targets for airtightness and ventilation strategy, with an option to consult further on specific systems or installation strategies
- Optional consultation with your builder/HVAC installer to discuss system installation and duct design calculations
- Pricing varies according to home size, shape, and features, but most homes fall between $1500-$2500 for heating/cooling load (Manual J), and double that for the whole package including system selection (Manual S) and duct design (Manual D).
- Packages are pre-paid, and turnaround time is 3-6 weeks.
Must Ask Questions For Your HVAC Contractor
- What is the heating and cooling load (in BTUs) of my house? How do you know? (Do you use ACCA approved software?)
- What’s my blower door number? Did you incorporate that specific number in the load calculation?
- How much air flow (in CFM) do I need to each room in my house? How do you know?
- What is my duct pressure (total external static pressure)? How do you know? What is my current system rated for?
- How is fresh air mechanical ventilation being incorporated into the system? What are my options?
- How much fresh air mechanical ventilation does my house need? How do you know?
- What’s the pressure drop across my air filter? Is that within spec for the filter I have?
- How did you verify that my system is operating at it’s full capacity? (How do you commission systems after install?)