Q. Is it OK to pour drano or similar products down the pvc drain lines of your a/c unit to keep them clean? Also is there any reason I should not install a "T" PVC joint where the drain lines come out of the unit so that I can do this w/out having to detach the drain lines to do maintenance?

A. You can pour dilute chlorine down the drain, once you have cleared the line. It is possible to blow out the line with compressed air, CO2 or the ole' fashioned tuba method. You can install a clean out T in the line. They now manufacture a cleanable trap with a clear u joint so that you can monitor the drain. I'm not sure if is available at home stores, but you might be able to get one from a local company that installs HVAC equipment AND they sell over the counter. If you go with PVC T, install with the T junction up and add a 6-inch riser. Pick up a tight-fitting cap for the top of the T. Don't use glue on the cap, just snug it up.

Q. Hello. we are installing a Diesel Generator for running our house. We are off grid. We are buying a Cummins 15 KVA/12KW Prime Power Generator. This generator can supply 23 Amps per phase in the standby mode with a PF of .8 With the normal set up, we can run only 3, single phase 18,000 BTU ACs, one on each phase. I read somewhere that by installing Power factor Capacitors, we can install more than one AC on each phase. Do you know anything about that? Is it an easy task or do I need to get an engineering degree for this? I'm some what comfortable with doing electrical work and can do minor calculations as well. Any help would be really appreciated. Greetings from Iran

A. HVAC Tech.: You need an electrical engineer to solve this problem as it does not fit into Heating, venting, or air-conditioning.

Q. My aunt has not cleaned their air ducts in 5 years(ever since they moved into the house) and they have not been using an air filter since. She lives in northern cali and uses the heater during the winter and the a/c not so much during the summer. I saw the part where the air goes into the duct and it was covered with so much grey dust that i just HAD to vaccum it for her. There were 2 of these. They were both downstairs up close to the ceiling. Their house is 2 story. one was next to the stairs I told them they should buy an air filter because her whole family has asthma including her, but they're scared that the filter might catch on fire! Their youngest son (4) also just recently got asthma after winter. But they dont really get allergies in the house in the summer because they have windows open but its only in the winter when they have the heater on Dont you think they need this or is it just me? Do you suggest air duct cleaning? since its been so long without a filter

A. To give you an idea of how much dirt is in the duct work you can look inside the ducts or supply air runs by removing the diffusers. What you should be more concerned about is the dust that may be attached to the blower wheel and the evaporator coil and if the furnace is High efficiency it may have a secondary heat exchanger that may also plug up. If any of these actually plug right up with dust It may cause the air conditioning to freeze up. What is required is a full heating and cooling planned service maintenance check and cleaning. Many heating and cooling companies have a program in place and will go as called or will sign you up for an annual maintenance. The annual maintenance might be a good idea for them as they will also change the filter regularly. The usual cost of a maintenance program is what they would charge for 1 1/2 -2 hrs labour and any parts that you would need like a filter.

Q. Does anyone know a good website that teach me step by step how to service ( and do commonly needed replacement) my single room (Window /wall mounted) Air Conditioner. Googled website almost all only show companys that do air cond repair. I want this as new hobby ! T H A N K S !!

A. Try starting here: http://www.hometips.com/cs-protected/guides/centairfix.html Google diy air conditioner repair. gl

Q. I just moved into a new home that had never had the ducts cleaned. The house is a ranch with gas forced air heat on one zone with about 9 vents. I found this company on a coupon for $45 which included unlimited vents and a couple access holes. When the company began their work they found mold and the price skyrocketed from $45 to $1400. Does this sound like a screw job or is that price accurate for mold removal and duct cleaning?

A. Mold removal/remediation is entirely different from air duct cleaning. However, it is not uncommon to find mold in your air ducts. That is why we recommend the Electro Breeze Duct Mount UV kit at http://www.allergy-relief-air-purifier.com/air-conditioning-filters.html. This unit will eliminate mold and bacteria from your indoor air and keep your air conditioning coils clean from mold. You must consider that to remove the mold from your air ducts, the air duct cleaning company is entering into a potentially dangerous situation for their employees. This requires expensive equipment and a person with the skills to do the remediation properly. Now that they have knocked the mold loose, you will need the high efficiency filtration and ultra-violet light of the Electro Breeze DMUV kit to kill and capture the mold spores in your indoor air. I hope this helps.

Q. My car is getting older and I've noticed the air coming from the air conditioning ducts and air vents smells musty, dusty, and dirty. Is there a way I can clean the ducts and vents? Also, is this something I can get done at an auto detailer?

A. The answer to your 2nd question first. Maybe?! Some detailers will only clean/restore what they can reach, although there are some who might go the extra mile. The problem is, they don't want to be responsible for destroying your dash vents to get at the ducts. When I worked in a body shop, we simply used compressed air through the vents to blow out the dust and dirt accumulated while the car sat inside being worked on.......some people even put pieces of air freshner directly in the vents to sweeten the smell afterwards.

A. That is considered maintenance, you are responsible for cleaning your own air ducts or having someone come do it for you.

Q. My doctor told me I need to get my air duct cleaned, but I keep hearing all kinds of horror stories about air duct cleaners. Does anyone knows of a good air duct cleaner near San Francisco?

A. Here are some Union companies that do duct cleaning. They all do good work. Atlas Heating and AC Oakland, CA 510-893-1343 Advanced Solutions Heating and Air Conditioning San Mateo, CA 650-347-4828 Bell Products Napa, CA 707-255-1811