Click Below For 75 Ways To Lower Cooling Without Replacing Your HVAC System

75 Ways To Lower Cooling Costs — Part 1 of 4

A Typical, Single Zone (whole house) HVAC System

• Maintains the thermostat’s temperature setting — where the thermostat is located.   It can’t react to the temperature anywhere else in the home.

• A thermostat is typically in a hallway — because the temperature varies less in hallways than in rooms with outside walls or near windows.
• So, the hallway is the most comfortable location in the home.

Zoned HVAC

• Zoning offers the option to only cool / heat the zone(s) you choose.   Unused zones can have less heating & cooling (as determined by you) — resulting in lower energy bills.

• Zoned HVAC allows each zone’s thermostat to react to temperature changes within that zone.

• Zoning ensures that each zone can be the temperature you choose — without affecting other areas of the home.

• A Common HVAC Zoning Configuration: Living Areas in 1 zone and Bedrooms in a 2nd zone.

Image Source: Shutterstock

• Zoning Can Be Accomplished With:

• Separate HVAC Systems.

• 1 Variable-Speed HVAC System PLUS (electrically controlled) Zoned-Dampers which are installed inside the ductwork.

A Single-Speed HVAC System With Dampered-Zoning With A By-Pass Air Damper 

• In some instances, dampered-zoning is added to a Single-Speed HVAC System.
• In this case, a By-Pass Damper must be installed — to relieve excess air pressure build-up within the HVAC System due to zones being closed off.
• The excess air is typically routed back into the Return-Air ductwork.

Routing Recently Cooled Or Heated Air Into The Return Air Ductwork Creates Potential Problems:

• The Indoor A/C Cooling Coil isn’t designed to have recently cooled air passing through it.  It’s designed to receive warm air returning from the rooms.
• This causes the coil to get too cold — then the water (from humidity collecting on the coil) can freeze and form ice.
• A frozen coil can damage the furnace blower (because air can’t pass through it).
• If the HVAC System runs long enough with a frozen indoor coil — it can freeze and damage the outdoor A/C unit.

Click Here To See A Frozen Indoor Cooling Coil: Frozen Central A/C Indoor Cooling Coil

Click Here To See A Frozen Outdoor A/C Unit: Frozen Central A/C Outdoor Unit

• The Furnace is not designed to have recently heated air passing through it.  It’s designed to receive cool air returning from the rooms.
• This causes the furnace to run too hot.  This causes the Heat-Exchanger (inside the furnace) to expand more than it’s designed to.
• This causes premature failure (cracking) of the Heat-Exchanger.  In nearly all cases, a cracked Heat-Exchanger requires furnace replacement.
• Also, if the furnace gets too hot — it will shut itself off to protect itself.  It will restart once it has cooled enough to safely operate again.

Click Here To See A Cracked Furnace Heat Exchanger:  Cracked Furnace Heat Exchanger

A Better Solution For Routing Excess Air From The By-Pass Damper

• Excess Air Can Be Routed Into A Common Area — such as a hallway or foyer (instead of directly into the Return-Air ductwork).
• This reduces the A/C & Furnace problems described above.
• Because the foyer is seldom occupied — it’s a better location to receive excess air.   This is especially true with a two-story foyer because it has double the amount of air.

• Any area receiving excess air will likely have frequent & substantial temperature changes.
• But — that’s a better solution than routing recently cooled/heated air directly into the Return Air ductwork.

• Even with a By-Pass Damper — a Single-Speed HVAC System can’t perform as well as a Variable-Speed System.
• A Variable-Speed System can slow its furnace-blower speed + the output of the Central A/C & Furnace — when some zones are closed.
• A temporary By-Pass Damper can allow you to wear out your existing HVAC System — then replace it with a Variable-Speed for improved comfort and energy savings.

How A Zoned-Dampers HVAC System Works  

• When any zone thermostat calls for heating / cooling — the dampers’ Control Panel opens the damper(s) to that zone.

• At the same time, the Control Panel closes dampers to zones not needing heating/cooling.  This is what causes Air-Pressure to build up inside the HVAC ductwork.

• The Control Panel activates the furnace or A/C to supply air.

• Once all zones’ heating/cooling needs are satisfied — the Control Panel turns the HVAC System off.

TIP: In a 2-Story Home — Keeping bedroom doors mostly or completely closed reduces A/C cooled air (meant for the bedrooms) going downstairs.

Why Different Rooms Have Varied Cooling & Heating Demands

• The natural effect of cold air sinking & warm air rising causes 2nd-floor rooms to have more cooling & less heating demand than first-floor rooms.

• In Two-Story Homes (that are well-insulated & sufficiently airtight) — the second floor is typically 10+ degrees warmer than the first floor.

• The temperature gap can be increased by sun exposure — and varies at different times of the day (Example: west exposure is hotter in the afternoon & evening).

• This temperature gap will be notably increased due to too little attic insulation.

In Single-Level Homes:

• The rooms farthest from the HVAC system can be 10+ degrees different from rooms closer to the furnace.

• This is because cooled/heated air must travel through longer ductwork.  Most DFW homes have attic ductwork.  Attics can reach 170 degrees during DFW summer.

• The temperature gap is affected by sun exposure — and varies at different times of the day (Example: west exposure is hotter in the afternoon & evening).

• The temperature gap can notably increase with too little attic-insulation.

Some Rooms Have Changing Cooling & Heating Demand

• The kitchen needs less heat and more cooling while cooking.  When not cooking — the kitchen’s heating & cooling demand is the same as adjacent rooms.

• Rooms with fireplaces have less heating demand when the fireplace is used.  When the fireplace isn’t used — the room’s heating & cooling demand is the same as adjacent rooms.

• If the thermostat is near the room with the fireplace — the rest of the house can become quite cold while the fireplace is used.

Details For Zoned HVAC

** Copy The Link Below Into Your Browser To Read Detailed Information On HVAC Zoning:

http://zonefirst.com/wp-content/uploads/2013/01/DesignManual.pdf

Which Home Sizes Can Benefit From Zoned HVAC

DFW Homes Of Any Size Can Have Zoned HVAC.  This Is A General Guide:

• In homes up to 2,000 — zoning is not likely needed.  That doesn’t mean you can’t zone — only that zoning’s benefits likely won’t justify the cost.
• To help balance temperatures — it’s ok to partially close some air vents OR completely close 1 or 2 vents.  This forces more air into spaces that need it.
• NOTE: No more than 10% of total vents can be closed without affecting the System.

Zoned HVAC Typically Decreases Cooling & Heating Costs

• If you have unused rooms that are being cooled or heated all the time — you are likely a candidate for HVAC Zoning. 

• Perhaps The Best Examples Are; Living spaces that are cooled / heated at night OR Bedrooms that are cooled / heated during the day.

NOTE: Closing more than 10% of ducts creates problems for Single-Speed HVAC Systems — by causing air pressure to become too high in the ductwork.  Single-speed, Whole-House HVAC Systems are designed, built, and installed to operate with all vents open all the time.

Image Source: Shutterstock

During DFW Summer In One-Level Homes — The Rooms Farthest From The Furnace Can Be +10 Warmer (or more)

It’sBecause Cooled Air Must Travel Through Longer Ductwork (that’s typically in the hot attic).

Current Texas Building Code Requires These Insulation Values In Newly-Built DFW Homes:

• R-38 Attic Insulation
• R-6 Attic-Ductwork Insulation — (ducts under 3 inches in diameter).
• R-8 Attic-Ductwork Insulation — (ducts over 3 inches in diameter).

• The reason for the low R-Value of ductwork insulation — is based on how little time cooled / heated air spends inside ductwork.
• BUT, attic ductwork will be much hotter / colder when the HVAC System first turns on.
• The HVAC System must completely cool / heat the ductwork before the full effect of the HVAC System’s output reaches the rooms.
• The longer the duct — the longer it takes to cool / heat it.

• Zoning allows ductwork lines to be shorter in larger homes.

• Zoned HVAC Sytems are sized for the amount of space within each zone (versus the entire house).

• Zoning allows for smaller & less expensive HVAC Systems for each zone — though the purchase cost for 2 smaller HVAC Systems is more than 1 larger system.