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Re: Reasonable Cost of a central air/furnace unit??
Old 02-16-2007, 06:44 PM   #21
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Re: Reasonable Cost of a central air/furnace unit??

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Originally Posted by Cute Fuzzy Bunny
I've seen a few heat exchangers crack prematurely from using those "filtrete" air filters. Worst product on the market, IMO. Many heating/ac units dont get the airflow they require with one of those installed, causing the fan to kick into a higher speed (if its available) and cracking the heat exchangers or freezing the a/c coils.

Very bad news. Check with your manufacturer and you may find that about 95% of them do not recommend using them.

You can have the intake opening enlarged on installation or aftermarket to account for the reduced air flow. That having been said, I read an interesting site a year or two ago that produced a fairly comprehensive study of these 'allergen removal furnace filters' that showed they werent particularly effective either.
Filtrete filters are no worse than the next, imho, BUT when you get careless and dont change them every 30 dys, you have issues. Ive studied a lot of this because I sell permanent washable electrostatic filters on ebay.
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Re: Reasonable Cost of a central air/furnace unit??
Old 02-16-2007, 09:19 PM   #22
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Re: Reasonable Cost of a central air/furnace unit??

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was your problem with the ehat exchanger? goodman got lots of bad publicity about their cust serrvice and overall quality in the late 90's, but they've done a good job correcting those problems on late rmodels


i guess just take it fwiw
The problem we had was the capillary tubes on the metering valve....extremely poor workmanship on the solder joints......I figured they could be repaired, but of course nobody repairs anything these days....strictly remove and replace. What ticked me off was I called Goodman...unit was 30 days out of warranty, so I asked for goodwill...they literally laughed at me....so I asked for a discount using the logic that, this one looks like crap...why would I want to replace it with another Goodman part? ....more snickering. I told the repair guys to buy "any brand except Goodman".

Five tons of cooling is HUGE. One ton is 12,000 BTu/hr. New units are supposed to be very efficient. The efficiency rating (SEER) should be over 10, but 12-14 is better. I can't imagine you need that much cooling ( is it MN?). Heating units would be more like 60-90,000 BTU and efficiency should be >90%. I think you should shop around for more quotes and get the energy audit.

Todays Trivia: Cooling is measured tons because one ton of ice has 12,000 BTU's of cooling capacity.
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Re: Reasonable Cost of a central air/furnace unit??
Old 02-16-2007, 10:27 PM   #23
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Re: Reasonable Cost of a central air/furnace unit??

Quote:
Originally Posted by thefed
Filtrete filters are no worse than the next, imho, BUT when you get careless and dont change them every 30 dys, you have issues. Ive studied a lot of this because I sell permanent washable electrostatic filters on ebay.
Not picking on filtrete...I meant any filter other than the standard fiberglass job that the manufacturers expect you to use.

I learned from the cracked heat exchanger on my 7 year old high end Rheem system, and heard about it from the two repairmen that came out to look at it. They said they have a much higher incidence of cracked exchangers among 'allergen' filter users.

Not to cast dispersions on your business (although i'm about to), most allergens dont stay airborne long enough or get high enough off the floor to be pulled into an intake. If you seriously want to go the whole 9 yards I'll be glad to pull up the well done science I've seen that shows the filters remove almost nothing. I'm a bit overly educated in the matter because my wife has fierce allergies, severe asthma, and is a respiratory care specialist.

The big problems in these cases are from people walking around, sitting down on a chair/sofa, or other activities that cause a short term dispersal of allergens that were laying on a horizontal surface, most of which end up right back on the horizontal surface again in a minute or two.

Smoke and other very, very fine particles that stay airborne a while might be filtered out to a reasonable level if you leave the circulation fan in the heating unit running all the time. Otherwise most systems simply dont run long enough, often enough, to provide enough total cycle time to remove enough of the particles from the air.

Most stand-alone air purifiers suck too. While they have a decent psychological impact, most in-room tests show that they're pretty iffy on improving air quality very much.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 11:39 AM   #24
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Re: Reasonable Cost of a central air/furnace unit??

Resurrecting this one for a couple of different questions...

The furnace/ac unit in my new house is 17 years old. In decent shape and it might run another couple of years before upchucking something expensive. Considering its 100 degrees + up this way and air conditioning guys are pretty much slammed in the summertime, I might have to wait 4-5 weeks to get a unit repaired. Sort of starting to consider replacing the unit proactively in the next 4-5 months.

Two of the things i'm considering if I do this are an integral air cleaner and humidity control, and the UV light to kill mold in the unit. Every time I take my current unit apart for cleaning, its got a half inch of mold growing in the condensation tray. I have some good allergy problems and my wife is allergic and asthmatic.

Anyone investigate these? Are they worth it? Do they work?
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 12:18 PM   #25
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Re: Reasonable Cost of a central air/furnace unit??

I'm skeptical about the UV light idea. Not listed in the brochures is the fact that the bulb's UV output declines greatly after a year, so have to replace the bulb once a year to keep the original concept going. The bulbs are big bucks.

I have seen a few reasons for excessive mold growth - Dirt that makes it though the filter in operation gets caught by the wet coil, creates a nice enviro as some of it drips off and builds up in the pan. Not enough slope on the unit to direct all water out the drain. Drain pan water outlet not extending exactly to the bottom of the side wall of the pan, leaving a "step" in effect right below the outlet that keeps a layer of water in.

Our furnaces are attic mounted horizontals. As I have replaced them, I did the same, suspended from the rafters. I put enough slope towards the outlets. So the whole return plenum, filter, any transitions, the furnace itself, evaporator case, and supply plenum all have some tilt together as a unit. This is in addition to any tilt of the drain pan in the evap case itself.

On the big unit I used a Honeywell F300 series electrostatic air cleaner. Has two expanded metal pre-filters in parallel, then the two grid units in parallel, then two post-filters in parallel. All are washable in detergent and warm water. That is for the unit that runs the day area of the house.

For the bedroom area, for the smaller unit I used a Honeywell F200 series 4 inch thick media filter setup, MERV 11 filtering. As this unit is only 2 Tons, I made a transition to use a big 20x25 filter box, as the price was the same no matter the size of the filter. So I have a real big filter on a small furnace. I sized the return plenum to match the filter box, then the transition narrows it down in total height to match the furnace return air input. My goal was to get at least 1 year of life out of the media filter. I'm heading ito year #2 on the same filter, looks good. The F200E comes with a dirty-filter pressure drop sensor, with a remote RF monitoring unit. It also has a 12 month timer in it, which I reset over a month ago when it timed out.

I do not know what method of "humidity control" you are considering.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 12:27 PM   #26
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Re: Reasonable Cost of a central air/furnace unit??

Appears some of the newer systems have add-ons that remove and add humidity. We enjoy extremely dry summers and extremely moist winters, and its not unusual for the humidity to drop to 15% or rise to 75-80%. We offset this with a console dehumidifier and a small humidifier, but if I could have the main system keep us at about 40-45% all the time with no monitoring...that'd be nice.

I have good slope on the pan, and the drain works fine...but the pan stays damp, its dark, and its hot...mine is in the attic too where it hits about 130-140 degrees in the summer. We get a nice coating of red mold, and its persistently showing up in the shower tile and anywhere else that gets moist in the house.

New house has the system in the garage, I have a lot of room, water, electricity, air and water venting all very accessible. The ducting has a problem of not actually being connected very well, so i'm already going to have to secure and tape all the ducts in the house, and the attic venting is exposed to some sunlight from the roof air vents and the insulation is starting to decompose from the UV, so it'll need to be replaced or re-wrapped with some uv reflective insulation.

With all this and an old system, I figured it may just be time to have an HVAC expert come in and do it up right.

I'm a bit of a believer in the UV systems. We've got some air purifiers that we've used that come with the UV lights. Their claim was that they'd kill mold spores along with the bacteria, and after a time...about 30 days...they'd kill enough of the mold spores that the dust mites would starve off as well. Mold spores are a primary food source for mites. We put two of them in my wifes older smaller house, and while she noticed an improvement right away in breathability, after 30 days she all of a sudden reported feeling much better. I hadnt even told her about the reputed time delay and 30+ day benefits, so I dont think it was a placebo effect. However the two units we have are just too small to fully control the air quality in the home we're in now, and definitely not in the new house. Looks like about $600-700 to make the furnace into a whole house purifier, and if you stick with the electrostatic jobs and steer away from filters that have to be replaced, the annual cost is under $20.

Since the unit is pretty accessible, changing the UV bulb once a year or so isnt that big of a deal.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 08:52 PM   #27
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Re: Reasonable Cost of a central air/furnace unit??

CFB,
I think the UV might be a good idea, though I haven't incorporated it into our HVAC yet. I did put a UV sterilizer in our drinking water system (well water, no chlorination). Yes, the bulbs do need to be replaced annually, amd the replacements can be pricey. However, the bulbs themselves are not expensive, they just happen to be mounted in a proprietary mount or some such setup. My guess is that, with a soldering iron and a fresh bulb, you could probably save a few bucks.

Here's a site that sells a wide selection of UV lamps to retail customers. I bought 3, and will be working to figure out how to mount them in the proprietary holder/indicator lamp setup in our water system.

If you really want a project--some of these CFL lamps look like they'd plug right into a standard compact flourescent light set (the kind built for wall sconces in hotels, etc, not the CFL bulbs that are a direct replacement for incandescent bulbs). You could probably buy/install the lamp base yourself in the plenum on the "wet" side of your evap coil (and illuminating your drip pan). It would be best to instal a small window (with UV filter glass--maybe taken from a castoff set of sunglasses?) so you could verify periodically that the lamp is on.

Obviously, don't ever look at the light or let your skin be exposed to it for longer than brief periods.

http://www.bulbs.com/Category-/resul...ty=1&kw=grmcdl
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 09:44 PM   #28
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Re: Reasonable Cost of a central air/furnace unit??

Bought a Goodman heat pump 13 seer and 2 1/2 ton A/C unit with 2-stage Goodman furnace (gas) with variable speed motor (75k/42k btu) 92%eff installed for $4500. Purchased Nov/05.

That was the most reasonable cost for units in my area.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-06-2007, 09:52 PM   #29
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Re: Reasonable Cost of a central air/furnace unit??

Just skimmed through previous posts, would highly recommend contacting local utility and see if they can do a blower door test to calculate proper sizing.

I dropped from a 110kbtu furnace to the 2-stage 75k/42k and have lowered my heating bills by a minimum of 30% AND spent less on the furnace than just replacing with the same size (which was grossly oversized).

Do not go blindly into letting someone guess your requirements by asking how many sq/ft your home is. An educated decision now will reduce your energy bills and increase your comfort. It is actually rocket science.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-07-2007, 12:10 AM   #30
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Re: Reasonable Cost of a central air/furnace unit??

Quote:
Originally Posted by Cute Fuzzy Bunny
....New house has the system in the garage, I have a lot of room, water, electricity, air and water venting all very accessible. The ducting has a problem of not actually being connected very well, so i'm already going to have to secure and tape all the ducts in the house, and the attic venting is exposed to some sunlight from the roof air vents and the insulation is starting to decompose from the UV, so it'll need to be replaced or re-wrapped with some uv reflective insulation.....
Well, there ya go! Duct in sunlight via a Solatube or the like, to a cutout in the evap cabinet. Put a insulated glass panel over the cutout to seal it for airflow and to prevent condensation, and you've got yourself a sun-powered no operating cost UV coil lamp

Tapes, all available at HD:
- I've had very good luck with Nashua 324a foil tape, has a release paper on the back. Sticks permanently to any clean surface. Does not stretch, so any 3-dimensional curve needs to be a piece-wise approximation, which can get very tedious. But it has a tenacious grip.
- Right at the end of the last project, I used some Nashua 557 flexible tape. It's heavy stuff, also UL rated for flexible duct. No release paper. But a year later, it's lifting up wherever it lapped over itself. And have seen at least two places that it's lifting up off of flexible duct's outer mylar cover.

I've seen a lot of contractor-applied flexible tapes letting go in the last few years. Seems somethings wrong with the formulation.

Electrostatic Air Cleaners:
I clean the grids and pre and post filters outside in a plastic tray. I use compressed air out of a tire inflator to blow off most of the rinse water. But even then, the grids have to be back in the cabinet with the blower "ON" for about 15 minutes before they become dry enough that the HV power supply won't go into shutdown due to moisture shorting. My PS has a neon bulb on it, its lit when HV is applied, goes off when shorted or in shutdown. So after installing grids and buttoning it up, I turn the PS off, and turn blower on. Later I'll turn on the PS and all will be OK. If your setup is going to be in the garage, that will make grid handling a lot easier than carrying delicate assemblies up and down attic stairs!

The instructions with the EAC said ozone may be noted for the first week of operation, before the sharp edges get rounded off (ionization). I sure noticed it, DW didn't most of the time. After a while, I realized they meant one week of actual run time, not just one week! So it took over a month to total up enough run time. After that, I usually haven't noticed it at all. Under the PS cover, there is a resistor that can be clipped out that reduces HV by 25% or so, for situations where ozone is deemed too noticeable. But as that would also reduce the electrostatic attraction, I wanted to wait it out to see if it would be okay as-is, which it was after a while.
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Re: Reasonable Cost of a central air/furnace unit??
Old 03-07-2007, 08:53 AM   #31
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Re: Reasonable Cost of a central air/furnace unit??

I use that foil tape ALL the time for all sorts of stuff. EXTREMELY good, although very expensive...must be a different brand because the stuff I use sticks to dirty surfaces very well, and even adheres to a seam thats currently under water. I sealed my whole blower unit with it and a few main ducts Handles heat pretty well too...when I put in my water heater I lost interest in soldering for a while and used a hunk of the tape to join two pieces of pipe to connect the pressure relief valve on the heater to the outside drain. Worked so well I still havent gone back to finish it :P

I've heard some complaints about the ionization problems with the electronic air cleaners. Good to know the smell goes away after a while.
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