HEATING & SHEET METAL STANDARDS
The heating and cooling systems are specified by code, with the equipment selection (size and capacity) being dependent upon the size of the home, outside design temperatures, and anticipated heat loss due to the home design. It should be noted that temperatures in the home may vary due to wind direction, windows, doors, etc. If parts of the home are colder than others, running the blower of the furnace constantly may help. Cleaning of furnace filters is a homeowner’s responsibility. Common Defects or Problems:
- Noisy ductwork
- Furnace not placed as per plan
- Inadequate heating
- Inadequate cooling
- Temperature in house is different than temperature set on the thermostat
- Kitchen or hood fan lets cold air into home
- Moisture runs back in at bath vent fan
- Furnace is noisy
- Condensation lines clog up
- Excessive humidity in home
- Settling of air conditioning slab
1. Common Defect or Problem – Noisy ductwork.
Performance Standard – When metal is heated it expands and when cooled it contracts. The result is “ticking” or “crackling” which is generally to be expected and shall be considered acceptable.
Builder Repair Responsibility – Installation to comply with codes.
Craig’s Comments: Another cause of noisy ductwork is air moving too fast through the ducts, out of the supplys or into the returns. Duct sizing and design is critical in controlling noise in ducts. See ASHRAE guidelines.
2. Common Defect or Problem – Oilcanning.
Performance Standard – The stiffening of the ductwork and the gauge of the metal used shall be such that ducts do not “oilcan”. The booming noise caused by “oilcanning” is not acceptable.
Builder Repair Responsibility – Builder will correct to eliminate this sound.
Craig’s Comments: Sometimes oilcanning occurs when filters are dirty, and the suction of the fan causes the noise. If the filters are dirty, change them too see if that makes a difference.
3. Common Defect or Problem – Furnace not placed as per plan.
Performance StandardDue to heating design, venting and layout, the furnace location is to be determined by a heating contractor.
Builder Repair Responsibility – None
Craig’s Comments: I disagree. HVAC design should involve the homeowner and/or architect as well as others especially if the equipment is going to occupy living space (or usable attic space.) If a location is chosen and or shown to the homeowner, and the location subsequently changes, the homeowner should not be out this space.
4. Common Defect or Problem – Inadequate heating.
Performance Standard – Heating system shall be capable of producing an inside temperature of 70 degrees, as measured in the center of each room at a height of 5 feet above the floor, under local outdoor winter design conditions of -10 degree specified in ASHRAE handbook. Federal, state, or local energy codes shall supersede this standard where such codes have been locally adopted.
Builder Repair Responsibility – Builder will correct heating system to provide the required temperatures. However, the homeowner shall be responsible for balancing dampers, registers and other minor adjustments. Builder shall not be responsible when installation follows guidelines of special rate programs offered by utility companies if utility standards are lower than manufacturers recommendations.
Craig’s Comments: Heating systems are designed based on local outdoor design conditions, which in SC are not near -10 degrees. Doing this would make a system well oversized and cost extra money. The code says that heating equipment is to be sized per MANUAL J or similar calculations, which account for local conditions. Another part of the
5. Common Defect or Problem – Inadequate cooling.
Performance Standard – Where air-conditioning is provided, the cooling system shall be capable of maintaining a temperature of 78 degrees, as measured in the center of each room at a height of 5 feet above the floor, under local outdoor summer design conditions as specified in ASHRAE handbook. In the case of outside temperatures exceeding 95 degrees, a differential of 15 degrees from the outside temperature will be maintained where there is excessive glass, this may not be attainable. Owner should be advised on the use of shading in that area. Federal, state, or local energy codes shall supersede this standard where such codes have been locally adopted.
Builder Repair Responsibility – Builder will correct system to meet temperature conditions, in accordance with specifications. Builder shall not be responsible for changes when installation follows guidelines of special rate programs offered by utility companies if utility standards are lower than manufacturer’s recommendations.
Craig’s Comments: The code says that cooling equipment is to be sized per MANUAL J or similar calculations, which account for local conditions and windows. Proper design should be able to keep ALL rooms in the house within the above performance standards, even when local utility company or similar programs predicate different conditions.
6. Common Defect or Problem – Temperature in house is different than temperature set on the thermostat.
Performance Standard – If thermostat is properly calibrated according to equipment specs, temperature should not differ more than 4 degrees.
Builder Repair Responsibility – Builder to repair if there is a difference of more than 4 degrees.
Craig’s Comments: Two things could be happening here. First, the thermostat could be defective, out of calibration or installed wrong. The thermostat might be installed too near a hot or cold spot. The hole in the wall for wires behind the thermostat might not be sealed. Second, if rooms in the house are significantly warmer or colder than other rooms (and what the thermostat says) The HVAC system could be designed or installed wrong.
7. Common Defect or Problem – Kitchen or hood fan lets cold air into home.
Performance Standard – All exhaust fans should have dampers, but drafts may develop during cold or windy weather. Because code requires boring through the outside wall, there also may be some condensation.
Builder Repair Responsibility – None Owner should check to make sure damper operates and notify builder to repair if it does not operate.
Craig’s Comments: A working damper should open when the fan is turned on and close when a wind tries to push air into the exhaust fan duct. You should feel very minimal if any outside air entering. IF so, something is defective.
8. Common Defect or Problem – Moisture runs back in at bath vent fan.
Performance Standard – See #11.
Builder Repair Responsibility – See #11.
Craig’s Comments: Bath fans are used to remove excess moisture from the bathroom. Moisture running back into the fan is an indication that the duct is not insulated properly, or that humid attic or outside air is condensing on the ductwork or fan cabinet. In any case, this situation should be addressed.
9. Common Defect or Problem – Furnace is noisy.
Performance Standard – New furnaces are noisier due to design and blower size.
Builder Repair Responsibility – Builder to have manufacturer’s representative determine if noise is excessive.
Craig’s Comments: New furnaces and air conditioners are QUIETER than older units. The noise may be from excess air speed in the ducts, the unit located too close to a supply or return register, or an oversized fan. In addition to checking out the actual fan noise, also check out these other items.
10. Common Defect or Problem – Condensation lines clog up.
Performance Standard – Condensation lines may clog eventually under normal use. This is a homeowner maintenance item. Builder shall provide unobstructed condensation lines at time of first occupancy.
Builder Repair Responsibility – None if installed properly. Builder shall provide unobstructed condensation lines at time of first occupancy.
Craig’s Comments: Clogged condensate lines are a potential disaster. Homeowners should maintain these on a regular basis. Most manufacturer’s also recommend that the secondary condensate drain be installed. In the event that the AC is located above living space, like in an attic, an overflow pan with a separate condensate line is to be installed. This condensate line should empty in an obvious location, like over a door or prominent window so that if the main drain clogs, the condensate will drain out the other line and be very visible to the occupants.
11. Common Defect or Problem – Excessive humidity in home.
Performance Standard – See Moisture Standards.
Builder Repair Responsibility – See Moisture Standards.
Craig’s Comments: See Moisture Standards.
12. Common Defect or ProblemSettling of air conditioning slab.
Performance Standard – Owner is required to maintain a proper slope and fill in dirt underneath slab.
Builder Repair Responsibility – Builder shall level within the first year.
Craig’s Comments: The outdoor AC or furnace unit should be installed on a firm pad that is at least 3 inches thick (per code). The builder should do something to keep this pad level if it is installed on questionable soil that has the potential for erosion. Small retaining walls, extra drainage, a poured slab or something similar should be done to provide a proper pad with any kind of life expectancy. After that, it is up to the homeowner to maintain a level pad.