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Fred Weldin


I can't help you if your whatsis won't work, people (Especially if it's a refrigerator); I have no experience with appliances, and I haven't been involved with H&AC service and repair since March 08, 1996 (Thank the Lord); I always send a "standard" reply to appliance questions and H&AC "Service and Repair" questions (about 20 a month), so if you want to know why your whatsis isn't working like it used to, ask someone else. A lot of my answers arenít read by the questioners; in that event, I always send reminders to read the answers for a month or more (the word "idiots" comes to mind - actually there's another more appropriate word, but discretion prevents its use here). If you have questions about how big a unit you need, if one room's warmer than the others, if you want an opinion oas to scope of work on bids received, etc. just ask. Do visit www.askweldin.com, there's a lot of good information on sizing, ductwork, efficiency, as well as some techniques accomplished DIY-ers can use to troubleshoot and improve their H&AC. Finally, I want to thank all of the kind, serious people whom I meet here: I enjoy working with you. My wife says I'm "snarky" from time to time; as for you others, please use your imagination as to the responses swirling on the snarky side of my brain when I read your questions.

Experience in the area

53 years in the business. See www.askweldin.com




B of ME U of D 1965, numerous classes, seminars and a lot of "Hands On" learning since.

What do you like about this subject?

Helping homeowners who've gotten a raw deal. Really.

What do you still hope to achieve/learn in this field?

I would love to be put out of work because the industry cleans up its act.

Something interesting about this subject that others may not know:

Contractors frequently (deliberately?) misdiagnose ductwork problems as insufficient cooling: Some rooms are not cooling, so the system must be too small; it's good business for a contractor. In fact, I've never seen an undersized residential system; the most frequent problem is "Too Much Equipment, Too Little Ductwork". I normally reduce cooling capacity when I develop an Improvement Plan.

Something controversial or provocative about this subject

Installing ductwork is a labor intensive operation, and many contractors profit by doing it too quickly. The end result is energy intensive: Conditioned air leaks to/from unconditioned spaces, too much heat is gained/lost because of improper insulation, rooms are overheated/overcooled because the system can't be balanced, etc.

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Recent Answers from Fred Weldin

2014-07-06 Supply/return ducts:

Return grille: 20x20 H&C #672 (in a plenum base w/ unit in upflow configuration?).    Supply main: 16x8, reducing to 12x8 after four registers. Route the main along the center of the 38' dimension. Do

2014-06-24 Purchasing an Air Conditioner:

Ray:    This question borders on "Service and Repair", which as you've read I haven't been involved with since March, 1996 (probably before Amana and Maytag existed).    I haven't heard about the Class

2014-05-12 Residential AC RH:

I suppose indoor humidity could float, as does temperature when outdoor conditions exceed design. However, I can't recall many (I'd like to say "any", but that's such a restrictive word) times the outdoor

2014-05-11 Residential AC RH:

Skip:    AC speed is determined by the tonnage, climate and (of course) duct design: 350 CFM/Ton in moist climates, 400 for normal climates and 450 for dry climates. Heat speed is determined by the "ATR"

2014-05-11 Air Conditioner and house humidity:

Dustin:    Properly designed and installed AC should limit humidity to 55% at 75F. 70% at 74F is too high, as you've guessed.    With a new unit, my first question is "Is it oversized?" The compressor


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