Tip – Be careful with change-outs. Ductwork deteriorates and sometimes has to be replaced. It is only if the ductwork is in fantastic condition that you should get a change-out without ductwork (Remember – the ductwork has already been there for 15-20 years, and now it will be there another 15-20…it has to be in good shape). However, many HVAC installation companies like to push change-outs because the ductwork is the most time consuming part of the job, and a change-out is quick, easy money. Realize that it’s only about 15-20% of the jobs that qualify for a change-out, so be careful.
The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as room air distribution.
I think that the coding and permit industry is a joke!! They will not allow the homeowner to apply for the permit it has to be the licenced contractor. It would make since to allow the homeowner to apply for this. But it is all about money!! They really don't care if its up to code because if they did then they wouldnt care who applied and payeed for it, but they want the contractor to do it so if they do something wrong they can fine them instead of just pointing it out and allowing them to do it right.
If you are replacing your air conditioning system, make sure that the unit is the proper size for your needs and that all ducts are sealed at the joints. A unit that is too big will cycle on and off frequently, resulting in poor moisture removal, particularly in areas with high humidity. Also make sure that your new system is designed to manage condensation effectively.
Ok what you said is true but in most cases ducts are in a duct flex format, and knowing that the dust in people's flex duct is just surface dust, any real debris that are in the duct itself will result in very little to no air flow which will keep your unit from performing properly, but if it is true allergy reasons then replacing your duct system is better for overall better air quality, plus if you do pay attention to the warranty on flexible duct is that it only has a 10 year warranty and typically only lasts for 20 years so do your research before having a duct cleaning, and to add one more thing if your duct work is completely metal and you can't see visible insulation then your duct on the inside has insulation inside of it, if you replace that with duct work that is clean metal on the inside and wrapped with insulation on the outside then it will further reduce the air bourne fiberglass and dust.
Your cleaning service should involve all aspects of your duct work to maximize energy efficiency and air quality. This includes attending to the heat exchanger, blower, drain pan, plenum and coils as well. In the process, your service provider may find that you're facing larger issues than debris and build-up. The professional may recommend having your furnace repaired if they notice, for example, damage to your heat exchanger or blower motor. Generally, a furnace repair costs between $130 and $500. They may also find that an A/C coil needs to be replaced rather than cleaned and would then recommend A/C repair.
You may consider having your air ducts cleaned simply because it seems logical that air ducts will get dirty over time and should be occasionally cleaned. Provided that the cleaning is done properly, no evidence suggests that such cleaning would be detrimental. EPA does not recommend that the air ducts be cleaned routinely, but only as needed. EPA does, however, recommend that if you have a fuel burning furnace, stove or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning.