I’m looking for a central air/gas furnace system that has no exposed insulation in the airstream. Read that ASHRAE 62R outlawed it, and that was adopted in May, 2003. Does that mean any new unit I buy now will comply with that reg? Or do manufacturers have a time lag to convert over?
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Replies
ASHRAE 62 did not outlaw insulation exposed to the air steam. Never has and most likely never will. You have been misinformed.
ASHRAE 62 has been arouund for years, the first version I personally worked with, is 62-1989. Subsequent versions are 62-2001, 62-2004 and the latest 62-2007. It is a ventilation standard, properly titled "Ventilation for Acceptable Indoor Air Quality" and havery little to do with equipment manufacturing, though some of the issues that can cause poor indoor air quality can be remotely attributed to unsealed, matt-faced type of insulation.
Hmmm. I didn't think ASHRAE had the force of law. I thought it was just a set of standards by consensus. Although ANSI adopts them, for whatever that means.Anyway, the source of my info said that ASHRAE 62r is a revision of Standard 62--1989. And that it recommends: "exposed internal insulation shall not be used from the exit of the coil to the downstream end of the drain pan unless the insulation is impermeable to water." Which would mean no matte-faced fiberglass insulation . For those manufacturers who choose to adopt the standard. 62r was put forth by ASHRAE and approved by ANSI on May 27, 2003. And that is the extent of what I know. It is less than helpful.I'm awash in a sea of confusion and misinformation.
That would just prohibit such insulation in the AC heat exchanger, the way I read it.
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>>not be used from the exit of the coil to the downstream end of the drain pan I'm not sure what they mean "exit of the coil" and "downstream end of the drain pan" but, seems to me that it would be meaningless for an updraft, next to meaningless for a downdraft and of pretty minor significance for a side draft - but I might be construing those terms incorrectly.
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ASHRAE does not have the force of law, unless the Authority Having Jurisdiction adopts the ASHRAE standard in toto. Typically, standards, as references listed in applicable codes, are de factor part of the law. All that is unimportant to some fine hair splitting details.
Coils (and associated drain pans) are external to, and therefore beyond the control of the manufacturer of, the furnace. While the Standard is good practice for sheetmetal benders, it does not apply to gas furnaces. Manufacturers of cased cooling coils, and of air handlers that include cooling coils, do not use plain matte-faced FG insulation in the units. At least no so far as I have ever seen in the past decade or so. Most are foil faced, some may be neoprene sealed fiberglass, some may be closed cell neoprene foam, depends on the application.
The salient point here, is that as pertains to a furnace, as the OP refered to, the excerpt you quoted is not applicable. The "exposed internal insulation" refers to either duct or plenum "liner" which is still primarily a matte FG product but most is sealed with a rubberized coating.
BTW, ASHRAE standadrs are not "approved" by anyone but ASHRAE. Other agencies my "adopt" them as they chose to do so, but most simply reference the standards by others.
Okay. If I'm understanding all this, then it's the A/C manufacturer I need to be asking about insulation. The inside of the companion gas furnace has no effect on the air quality in the house?Several years ago Trane was lining their air handler with foil-faced insulation. But they don't have a high-efficiency forced air system with a dehumidifier (which we need here). So, I'm thinking Carrier's Infinity/Bryant's Evolution. They're condensing furnaces with a secondary heat exchanger. I don't like that the furnace's secondary heat exchanger is laminated polypropylene (the Trane one is stainless steel). So, I can't seem to get all the features from one manufacturer.Any ideas who I would ask to speak to at a manufacturer? (Or, is their janitor as knowledgeable as anyone else??)
I'm not saying the cabinet interior has absolutely no effect on the air quality, but unless there is a significant regress in processes from any of the major (there are 6) manufaturers in the US, the impact is minimal. What I am saying, is the area of (your)concern, i.e. downstream of (and adjacent to) the cooling coil and drain pan, are external to the unit, as far as gas furnaces are concerned.
Of much greater importance to the air quality of theair in a space is: 1) proper sizing of the equipment (and associated distribution system); 2)filtration (my preference is a large media filter rated at MERV 13 or higher); 3) introduction of fresh air into the system in a controlled and accounted for (in the equipment capacity selection) manner; 4) proper and adequate exhaust of all sources of "contaminants"; 5) accurate system balancing; and 6) suitable controls.
Most manufacturers have plenty of detail on their products available on their websites. Trane's furnaces are lined with foil faced insulation in the heat exchager section. Both of my personal furnaces (a 7 year old Heil and a 2 year old Goodman) have foil-faced insulation in the heat exchanger section and matte-faced fiberglass in the blower compartment
>>large media filter rated at MERV 13 or higher); Is it likel/possible the blower speeds will need adjustment with that high a MERV?>>introduction of fresh air into the system in a controlled and accounted for (in the equipment capacity selection) manner; Such as a Skuttle make-up air vent on a fresh air supply to the return? http://www.alexwalter.com/webapp/GetPage?pid=225Or an HRV?
May your whole life become a response to the truth that you've always been loved, you are loved and you always will be loved" Rob Bell, Nooma, "Bullhorn"
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Bob,
It is a given that a high efficiency filter (by residential standards) will create a greater pressure drop, and the selection of the speed at which to run the unit in cooling mode as well as the capacity of the unit, should be selected to accomodate that. A Honeywell EnviroCare filter, selected appropriately (and not allowed to foul badly) will add about 0.25" of static when dirty, less than 0.1" when clean. I use a 1" pleated pre-filter (MERV 7) in front of a 2" (MERV 11) pleated final filter in the AprilAire filter box on my main furnace. Its cheaper to but these by the case. On my smaller furnace, I use the Honeywell F200.
I like Skuttles for houses because they can be adjusted to maintain the slightest bit of positive pressure. Pressure control is more important to control moisture migration in imperfect contruction (i.e. all man-made structures) than is generally given credit. The Skuttle, as a barometric device, will respond to increased "outflows" of air (multiple exhausts going, while the dryer is operating and the non-sealed combustion appliances are operating, etc...) . It is quite common in my hosue to have mutliple bathroom exhaust fans, the kitchen hood and the water heat all exhausting inside air at the same time. It is also quite common for nothing to be using or exhausting air from the house.