Heating, Air Conditioning, Fridge, HVAC/sealing ductwork

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Question
Hi John, thanks for this service you offer.

I have a forced air system and after realizing i didn`t have any dampers i installed them on all my lines and then i saw that i had air leaks everywhere on the ducts and take-offs so i sealed them with mesh tape and sealant or aluminum tape. I`m getting ready to seal the air handler portion of the system, is there any part of the air handler i shouldn`t seal with duct sealant. The access panel has 4 screws on it, i will seal the panel with the tape.

I always had trouble cooling the main bedroom in the summer(it is the furthest from the unit) it was always 2 to 3 degrees warmer but since doing the dampers and the sealing i have been able to balance my system and now my room is within less than 1 degree and this is why i wish to seal the whole unit. I hope this winter i shall be able to do the same with the heating, my room was always 2-3 degrees cooler???

Answer
Bruce,
 You will find it was not the dampers but the duct sealing that did the most work,  If you seal access at the Handler some tech will be curing you some day, but no, most duct systems have 40% or more loss from leaks and poor design.  If your ducts are very short and few turns and the correct size to match the C.F.M. with static pressure it is only leaks. I don't like to see dampers unless it is a bypass, as it just slows the air and adds turbulance.
 A straight piece of duct, say 8" can recieve about 200 cfm at .1 static and 5 feet away your hand would feel a LOT of air.  Take that same set up and add 100 feet of 8" duct in a straight line.  Amazingly No air comes out the end.  Air has not the properties of water, it has (static) pressure pushing back on it every inch of the duct from 360 degrees in  a circle.  So, it in effect slows the air untill it stops moving and although the fan is turning it no longer moves the air.  This experiment we did in an Engineering class for refrigeration Engineering and it was an eye opener.  
  S0,even if you had the perfect duct system in your home that could handle a little extra static pressure, you may be helpng the area in question, but you are shortening the life of the equipment as, that is where it backs up too.
 And rather it is an Air Handler, Furnace, or Coil from a heat pump, they are designed for a very specific amount of air as the manufacture has control of the size of air pathways.  You can set up over heating damage to parts that protect for that and so on.
 The internet has some pretty complete stuff on that if you are curious.  Have a good one.

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john t. borgman

Expertise

I am in Portland Oregon at Ben's heating 503-233-1779. I work days, so I can only answer early in the day or later in the evening. I only answer public questions for residential equipment. I am very well versed in gas, electric and heat pumps and will only answer residential applications. I have been known the past decade or so, by my employers as the guy you send when no one can figure it out. Trouble shooting is my special. I understand the physics behind air flow, refrigerants and electricity. I understand programmable t-stats, zone controls, economizers, fossil fuel kits and the engineering thought process in the wiring and construction of residential equipment

Experience

I was lucky enough to start in this field almost 30 years ago as an installer, for a company that installed the best duct systems I have ever seen, even to this day. The best ,as far as understanding the way air really flows through a duct system, from the return air to the very last supply register . They also had great pride and the duct work was put in, not only to last 50 years, but to look exceptional. Then as I started doing service work, I was again fortunate that I found a 3 year engineering class being put on be a man that was the educational director for the Entire united states for a society called " the Refrigeration Service Engineering Society " And for the next 3 years I schooled at night and practiced what I learned during the day, a great advantage over schooling and then trying to remember it years later.. Versed in duct design manual J heat gain/loss calculations.

Organizations
Refrigeration Service Engineer's Society

Publications
I have 2 inventions that have gone through the process and been recorded at the National Institute of Standards and Technology from start to finish and thus been invited to national innovation workshops by the dept. of Commerce and the dept. of Energy. They are waste heat recovery devices that N.I.S.T approved as valid and am currently looking for marketing partners to get this product into the hands of consumers and make a BIG difference in Energy savings for every Household and Eatery and take a big bite in the the peak hours power consumption that face our Utilities companies.

Education/Credentials
factory training in Lennox ,Rheem, Ruud ,Trane, Tempstar ,Carrier, Day&Night, Payne, Bryant, Coleman, Intertherm, York, Goodman, Ultra boilers, Unico, Mitsubishi,Sanyo, Taylor, Nicewonger, Navien. Associates degree in Refrigeration Engineering. Certified with Energy Department, Check-me Program, P.T.C.S (performance tested comfort systems ), have N.A.T.E. certifications in gas, a/c & heat pump.

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