FAQ’s For Contractors
ESP Services Inc specializes in working with contractors and all types of new construction. The following is a list of common questions we hear from contractors and our answers.
Typically our schedule runs about 2-4 weeks out during the off season (November – March) and 4-6 weeks out during the summer (April – October). On average, you should call to schedule HVAC installation about 3-4 weeks before the house you are building is ready for HVAC install.
All dropped ceilings and soffits must be built and complete, plywood roof must be on, proposal must be signed (if this is the first phase on HVAC work to be d3), and we must have dryer vent and kitchen hood locations.
Outdoor stucco must be complete, indoor paint must be complete, indoor and outdoor disconnects must be up, condenser pads must be poured and dry, rough-in portion of job must be paid in full, exterior doors must be hung (including garage doors if units must be set inside of garage). What needs to be in place before ESP can perform a unit start-up?
The home must have finished floors down, gas turned on, electric fired up, and all exterior doors hung.
The worst method for sizing air conditiong systems is the square footage method. This method uses a standard that 400 square feet of floor space is equal to 1 ton of air conditioning. So, using this method, a home that is 1600 square feet would require a 4 ton air conditioning machine. This is completely incorrect and is nothing more than a lazy guess. Think about it this way: I’ve got two 400 square foot buildings, one has walls 8 foot high made of double masonry block and has one tiny window and one door, the other building is made of un-insulated 2×4 walls 15 feet high and has 20 – 12×3 single pane windows and a screen door. Now, do you think it is going to take the same size air conditioning unit to equally cool both buildings? The answer is no. The second building would probably need 4-5 times the cooling capacity as the first. Many HVAC contractors incorrectly use the square footage method and that is the reason why there are so many homes out there with poor air conditioning systems. It doesn’t work unless you get very lucky, bottom line. A full Manual J load calculation is the only methodESP will use to size units and ductwork.
It varies based on the size of the furnace or air handler required. In general, the minimum size of a mechanical closet/room for a gas furnace must be 56″ wide by 39″ deep. This dimension only accounts for the furnace and necessary ductwork. It does not include combustion duct and flues that may be needed. For a heat pump, the mechanical closet/room must be a minimum of 56″ wide and 30″ deep.
The general rule for required attic space is; the size of the ductwork plus 18-20″ for house insulation, duct insulation and truss members. Example: 24″ tall ductwork would need 42-44″ of attic space in order to fit..
Manual J load calculation should always be used to size heating and cooling systems. It is mandated by local codes and the DOE (Department of Energy) Manual J calculates the heat loss and gain through walls, windows, floors, infiltration and the roof. It also accounts for internal heat loads such as people, appliances, electronics, etc. No other method does this. ESP uses Manual J load calculation to size all of the systems we install. The design conditions that Hamstra uses for Tucson are:
104 degrees Outdoor DB (Dry bulb) with 75 degrees Indoor DB, 67 degrees Indoor WB (wet bulb). These design conditions/standards are per the model energy code.
It is always best to have insulation above the ductwork at the roofline. This maximizes the energy efficiency of the home because the ductwork won’t gain as much heat from the attic space because the attic space won’t get as hot.
You need to submit a floor plan with house orientation, roof insulation values, wall construction and insulation values, window sizes, window type with U-values and solar shade coefficient, and interior elevations (illustrating ceiling heights). You need to let us know of any additional expected internal heat loads (computers, flat screen TV’s, electronics, etc.) that will be added to the home. We also need know if the customer is satisfied with the standard model energy code design conditions (104 degrees outdoor dry bulb, 75 degrees indoor dry bulb, 66 degrees indoor wet bulb). Lastly we need to know if the customer wants gas equipment or heat pump.
Yes, very much so. Example: Take a house that has 400 square feet of glass with no porch facing west versus the same house but with the windows facing north. The house with the west facing windows will need roughly 2.5 tons more cooling capacity than the home with the north facing windows.
Fresh air intake is a code requirement. The code says that we must provide 15 CFM per bedroom plus one of fresh outdoor air for the home. Example: A home with 4 bedrooms must have 75 CFM of fresh air. New homes must have fresh air intakes because they are built much more air tight than they were in the past. Fresh air intakes are ducted into the return air of the air conditioning system and the fresh air is then filtered through the systems filter.
Transfers are a means of returning air supplied to a room back to the system’s main return(s). Only about 100 CFM of air can undercut doors and make it back to the main return(s). Any room that has more than 100 CFM of air supplied to it must have a transfer in order to get this air back. If air supplied to a room cannot get back to the return, the supply air quantity will be reduced and the room will become uncomfortable. Also, the area where the main house return(s) is/are located will become negatively pressured, which can back-draft fireplaces and increase outdoor dust and air infiltration.
ESP uses Manual J load calculation to size all of the systems we install. The design conditions that ESP are:
104 degrees Outdoor DB (Dry bulb) with 75 degrees Indoor DB, 67 degrees Indoor WB (wet bulb). These design conditions/standards are per the model energy code and will be used exclusively unless more stringent standards are requested by the contractor before the system designed.
Physics. Hot air rises, cold air falls. This is why ESP recommends separate systems for upstairs and downstairs or zone controls. It is impossible to have a balanced, comfortable system in a two story house with one unit and no zone control. Many HVAC contractors wrongly install one unit on a two story house as a way to save money. While this does indeed save on the initial cost, it will lead to an uncomfortable home that is impossible to balance. We are only interested in happy and comfortable customers. This is why we will not install a single unit on a two story application unless it is equipped with an electronic zone control system.
You should never close more than one register in your home if the air conditioning system was installed by ESP. If your duct system was not installed by ESP, you should not close any registers. CLOSING OFF REGISTERS DOES NOT SAVE ENERGY! If you close off air to rooms they will still have heat gain from the outside. This heat gain is transferred to the rest of the house through doors, walls, ceilings, etc. This heat gain will cause your unit to work just as hard as if all the registers were open. There is no energy savings to be gained from closing off registers.