Questions & Answers

Heating & Air Conditioning Tips from Vince

1. Design, installation, capacity


QUESTION: My house is 3,000 square feet. All but a guest room and bathroom are on the main floor. When we set the air conditioning at 78 degrees on a hot day, it does not cool the house and will only cool to 82 degrees downstairs and will be 90-plus degrees upstairs. We have a dual-control Lennox SEER-rated 12.45 air conditioner but only one compressor. Would a second compressor help pull the hot air out? If that is not feasible, what would you suggest to at least cool the upstairs (other than a window unit)?
C. Ogden, via email

ANSWER: Vince McDonald of McDonald Plumbing, Heating and Air Conditioning in Sacramento believes that your system failure is due to one or more of the following:
The system needs repair;
The system was not properly designed;
The system was not properly installed; and/or
The system’s capacity is too small.

“My first suggestion is to have an air-conditioning contractor check to make sure the system is operating according to the manufacturer specifications,” he says. “A good contractor will run a series of tests, including one to monitor the system’s refrigerant charge. If the charge is too high or too low, it can have a large impact on its cooling capacity and efficiency.”

“The contractor should also make sure the filter and indoor components are clean, he adds. “This has to be the No.1 problem we find that affects the overall system performance. Also, homeowners should regularly change or clean their filters. Something as simple and easy to rectify as a clogged filter can cause your problem.”

“The contractor should also inspect your air duct system to make sure the ducts are free of leaks, are properly supported and that any exposed metal is insulated.” If you are still having problems after the checkup or they discover the system is clean, airtight and operating properly, McDonald suggests having the contractor inspect the system for proper design, installation and sizing.”

“Two-story homes are always a concern when designing and installing a HVAC system simply because hot air rises,” he says. “it sounds like you may have a zone system, with on thermostat upstairs and one down, to direct cooled air where needed according to the individual thermostats. Zone systems should definitely help even out temperatures, so have the contractor make sure your system was properly designed and installed.”
“Finally, the problem may be an issue of capacity, meaning there may be nothing wrong with your current equipment. The largest single residential air conditioning system is 5 tons. If you already have a 5-ton system, and you have taken steps to make your home more energy efficient (by adding more insulation, etc.), you will need to add another air conditioning system.”

“One option would be to take the upstairs ductwork off the current system and add another system that will serve the upstairs only,” McDonald says. “You mentioned that the upstairs consists of a guest bedroom and bathroom. If you use this area only occasionally when guests come over, this option would allow you to direct the full capacity of the existing system to service the downstairs only, and save energy by not cooling the upstairs when it is not being used.” he says.

2. Contracts, Contractors State License Board, estimate, proposal

QUESTION: My home is a two-story, about 15 years old. I recently had to have a thermostat replaced. After the repairman was in the attic, he told me he noticed my ducting was beginning to deteriorate because of sunlight shining on it through the roof air vents. I asked for an estimate and he called yesterday to say it would cost $1,150. No written estimate was provided. Shouldn’t he provide a written proposal? Am I being overly cautious?
H.J. Hender, via email

ANSWER: “A verbal quote should be used only to give you a quick idea of the cost to perform the work prior to actually writing up a proposal,” says Vince McDonald of McDonald Plumbing, Heating and Air Conditioning in Sacramento. “The Contractors State License Board requires contractors to provide you with a written and approved proposal before they perform the work,” he says. “It should specify exactly what they propose to do, what kinds of materials they intend to use, and how they are going to perform the work including clean-up.”

“Other details about what must be included in written contracts are explained online at”

“Any company that is operating within the law and concerned with providing its customers with great service would want to make sure you are comfortable with the service it provides and address your concerns in writing. As a consumer, you have a right to insist on it,” he says. “Even if it were not required by law, a written proposal is just plain smart and can help everyone avoid a variety of misunderstanding.”

“It’s also important to understand that not all ducting is alike. Since the average home leaks 30 percent of the heated or cooled air that flows through the duct into unconditioned space such the attic or crawl space, having your ducts work as efficiently as possible could help you save a lot on your energy bills.”

“Consider spending a little extra for flex duct made with a metalized polyester vapor barrier. The flex duct with the plastic outside vapor barrier is not the best product to use, especially in your situation, because the plastic breaks down over time, especially when exposed to sunlight. Ask about ducts with better insulation in the jacket. The standard insulation has an R rating of 4.2, but for a little more money you can buy R6 or R8 insulation duct. Make sure all the metal duct joints are sealed with duct mastic.”

“Ask your contractor if he has the equipment to test the ducts for leaks before and after the work is performed. Since you are changing the ducts anyway, this is the time to make sure the ducts are properly sized for individual rooms,” he says.

3. Odor, air conditioner

QUESTION: When we turn on our air conditioner, I get a strong odor of stale air that I think that it is coming from the attic, though my husband doesn’t agree. It has been happening for a year or so. Any ideas?
D.R. Gregory, Roseville, CA

ANSWER: “It sounds like you may have a problem with your heat and air duct system,” according to Vince McDonald of McDonald Plumbing, Heating and Air Conditioning in Sacramento. “The duct system transports the conditioned air into your home. The same air that comes out of the ducts (supply air), eventually flows back to the furnace or air handler and becomes the return air. This process continues over and over as long as the system is running. It is considered a closed system.

“If the ducts are in good condition, the pressures within your home are equal to the outside of the home,” he explains. “But If the ducts are not in good condition and leak, then there is going to be any number of problems.”

”What you describe is possibly a failure in your duct system. This can cause negative pressures in your home when the system is running. The stale air from the attic can now enter the house through the leaky or disconnected ducts. The average existing home in the Sacramento area has approximately 25 percent duct leakage into unconditioned space, such as attics and under the home, according to SMUD.”

“My suggestion is to have a licensed HVAC contractor at least conduct a visual inspection of your duct system,” says McDonald. “Better yet, have one perform a ‘blower door test’ with an instrument that enables the technician to accurately test and gauge your system for duct leakage. For best results, I suggest having the ducts tested again after the repairs to accurately monitor the work. Considering how much expensive conditioned air is wasted through leaky ductwork, I am sure you can appreciate that duct sealing is money well spent.”

4. Ventilation

QUESTION: We had some settling of our foundation along one wall of our house and had a foundation engineer evaluate the situation. One of his suggestions was to put in a ventilation fan under our house crawl space to keep the moisture out. We have no water runoff underneath just a large deck right next to this area that stays damp underneath. He suggested we call a Heating and AC company for this type of fan or go to Home Depot and get a large fan.

Needless to say, the two Heating and AC companies I called never heard of such a thing and I would have no clue as to what kind of fan or even where to put it if I just went to Home Depot. Besides that, running a fan whenever it was damp underneath our deck would mean that it would always be on. Our SMUD bill would be out of sight. Can you help me out as far as where to go next?
M. Terra, Sacramento

ANSWER: “The fans are a good option for an occasional dry-out but they certainly don’t sound like a good permanent fix.” says Vince McDonald of McDonald Plumbing, Heating and Air Conditioning in Sacramento. “It sounds like you need to go after the cause of the water rather than treating the symptoms,” he says. “My suggestion is to consult with a general building contractor, landscaper and or civil engineer.”

“What is the saying, ‘an ounce of prevention is worth a pound of cure’? If you prevent the water from going into the area then you won’t need the fans. If you have no leaks under the house I would suggest that you inspect and evaluate how the water from rain and irrigation runs away from the house. Pay particular attention to the downspouts and water that is shed off the roof. We commonly see downspouts terminating at a point next to the foundation and the slope of the surrounding ground prevents this water from running away from the house. If water is trapped and cannot naturally run away from the house due to the landscaping and lay of the land, then consult with a landscaping contractor to design and install a storm drain system to do the job. If it is fairly complicated, it may be best to also consult with a civil engineering firm.”

McDonald Plumbing, Heating and Air Conditioning is located in Sacramento, CA and serves the communities of Sacramento, West Sacramento, East Sacramento, South Sacramento, North Sacramento, Carmichael, Citrus Heights, Rancho Cordova, Gold River, Folsom, Fair Oaks, Orangevale, Roseville, El Dorado Hills, Antelope, McClellan, Mather, North Highlands, Granite Bay, Davis, Woodland, Arden-Arcade, Rio Linda, and Elk Grove.

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