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Old 07-23-2013, 12:45 PM   #31
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Is NOW a good time to replace my 1986 AC?


I have RARELY had a stuck compressor and ours sit idle all Winter with ACs. should not matter as they are sealed in oil in a hermetic shell, seizing would have to be caused by rust or oxygen in the system or corrosion which should never happen if it was installed with clean lines etc. we have a severe temp diff from -40F to 70 from Winter to Summer and they still don't seize. maybe the el cheapo Brizztol or other cheap compressors but I have not had that problem.

The OP really does need to consult with the utility companies as they have those facts you mentioned. Unlike the oil companies who would like us to drive V8's with 4 barrel carbs so they make lots of $$ most utility companies are helpful.

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Old 07-23-2013, 12:58 PM   #32
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Not sure what the cost of natural gas is in Northern VA, or what your winter heating requirement is, but don't let someone talk you into a high effeciecy furnace if the return on investment will never pay for itself.

I live in the Southern California desert, and while it can get cold, it doesn't stay cold. Our natural gas prices are also low, so my winter heating bills are only about $25 more a month for 3-4 months. I am looking at replacing my whole 32 year old system soon, and a high effeciency furnace costs several hundred more, plus the extra installation costs of not being able to reuse the old flue. It would never come close to paying for itself. When the time comes, I will get a basic 80% furnace that can simply go where the old one is.

The AC on the other hand, here the high effecency unit pays for itself quickly because of the number of cooling hours and sky high cost of electricity. (last month I used 2400KWh - $645)

This is why I would never suggest a heat pump in California. Even back in 1992, I was one of the very few people who was experimenting with cfl's, remember the cold white light and the flickering start ups?
We only had a swamp cooler in the house and the water heater and stove was gas. Our summer power bills were still up in the low 100's. Thats a lot of money for running evap cooling and cfl's.
Most of the people I know in California are running evap cooling, even if they have a/c, they just cant afford to use it.

Last edited by sammy37; 07-23-2013 at 01:02 PM.
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Old 07-23-2013, 02:22 PM   #33
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Is NOW a good time to replace my 1986 AC?


I am in MD so have similar heating/cooling conditions to the OP. It does get cold but really for only 4 months and heat needed only occassionally before or after winter.

I replaced my 80% furnace a couple of years ago with a 95% unit. But the vent and intake piping required a lot of work and creativity. I did that myself and if I had to pay for it not sure it would have made sense with gas prices and our climate here to bother going with the 95% unit vs another 80%er.

Also, I am getting closer to replacing my old split a/c condenser and a heat pump is an option. But I will likely just go straight a/c again due to all the factors: short/mild heating season (at least compared to Yuri!), cheap NG prices, and don't need the added complexity/points of failure of a heat pump.
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Old 07-23-2013, 02:26 PM   #34
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Is NOW a good time to replace my 1986 AC?


I have a 60% furnace and HWH so I think I need a chimney liner for either an 80% or 95% furnace, right? I think that's what the guy told me.
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Old 07-23-2013, 02:32 PM   #35
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I am not familiar with a 60%... an 80% needs a type B galvanized vent or maybe a chimney liner. On my 80% the vent was plumbed together with the water heater vent into a type B galvanized pipe up through the roof.

90% + needs to meet Cat IV vent criteria (you can google for specifics) that is PVC or stainless steel, no sharing with other appliances, also many requirements on pipe slope and vent location.
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Old 07-23-2013, 02:35 PM   #36
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Is NOW a good time to replace my 1986 AC?


technically U should have had one LONG time ago. reason being that the moisture in the smoke/flue gases from the furnace and water htr will attack the mortar in the bricks of the chimney and damage it. not so bad with a clay tile liner. then the code changed to make it necessary. also the amount of heat/flue gases with a 80% unit is much less than your old 60% unit so in some cold climates the chimney won't warm up enough and the moisture condenses inside the chimney and freezes it up or runs down backwards into the furnace etc. a smaller liner or insulated liner (B Vent) is required and that is code now.
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Old 07-24-2013, 08:42 AM   #37
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Is NOW a good time to replace my 1986 AC?


For me comfort outweighed ROI, so we went with a higher efficiency furnace. I need to keep the wifey happy and warmer.

Definitely replace that old thing - not worth investing any monies. Get several quotes for various install options (entry, mid and high end). Also, negotiate a labor warranty that matches the parts warranty, so that you don't need AHS. We also had an energy audit performed on the house and one of the recommendation was to bring up the R level in the attic to R40 (house built in '97), so I am working on that now. I keep hearing and reading that insulation is like money in the bank.

Just One Man's Opinion.

(off topic) To the OP, I see you have a Mystic Cobra. I have one of the last pushrod.
Cobras.

Keep us informed
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Old 07-24-2013, 10:23 AM   #38
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Is NOW a good time to replace my 1986 AC?


I think we are going to replace the whole system at once. Thinking about waiting til the fall hoping to get a better price offpeak. The leaking coil lasted at least a year with the last "fill-up" and the cold air temp has not dropped a degree yet (60F) in three days so no urgency.

Both contractors have estimated it's going to cost 2000-2500 extra to relocated the outside AC unit from the patio to the far end of the house away from the patio. I am considering running the AC lines and electric myself to cut that down. The current outside unit is about 10 feet from the furnace and would be about 60 ft away in the new location. Any thoughts on this?

As for insulation, I've already started on that project. I did one of our three attics in the spring following my kitchen renovation and I am planning to do the other two attic areas in the fall. I'm also going to be insulating my attached garage. I just realized this month that the wall between my living room and garage not insulated. It is concrete block with brick on one side and the other side is concrete block with furring strips and drywall but no insulation. I had planned to skip framing/insulating that wall altogether but I am rethinking that.

As for the Mystic Cobra, I have owned two and don't currently own one. I put all my money into road course racing and have not been able to get another Cobra street car yet. I know they are still out there and I will get another one hopefully later this year or early next. Other than my track car which is a resurrection of my first Mystic Cobra (4.6 4V), I also have a '94 V6 coupe, a '65 289 hardtop, and a 97 Cobra parts car. I'm a bit of an enthusiast...although my wife calls it something else.
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Old 07-24-2013, 11:41 AM   #39
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Is NOW a good time to replace my 1986 AC?


Personally I don't like AC lines going over 50 feet, plus you will have to use much more expensive larger copper tubing. Heck for the extra cost they want you could buy a MUCH higher SEER/cheaper to run and quieter unit and be $$ ahead in the long run. Look at the Lennox website and others and they will have the sound db ratings for the higher end units. we have units so quiet you can barely hear them run. 70 db for an XC14 14SEER and other brands can do that also. Beware the footprint/base size is larger on the higher SEER units so they need to make sure it fits in the present location.
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Old 07-24-2013, 12:04 PM   #40
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Why is that, Yuri? Bigger coils? My GF has a Trane 16 SEER heat pump and it is enormous.

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Beware the footprint/base size is larger on the higher SEER units so they need to make sure it fits in the present location.
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Old 07-24-2013, 12:06 PM   #41
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I like this idea but I don't know the difference between 66 and 70 and 74 db. I'd love to know what kind of noise mine makes. Another tool purchase?
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Old 07-24-2013, 02:25 PM   #42
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Is NOW a good time to replace my 1986 AC?


If you have a iPhone or Android OS, you can get free Sound meters that will give you a decent measurement.
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Old 07-24-2013, 03:03 PM   #43
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Why is that, Yuri? Bigger coils? My GF has a Trane 16 SEER heat pump and it is enormous.

That really is why they are more efficient (except for the super high 25 SEER and up units which use an ECM compressor). The larger coil radiates the heat away faster which decreases the workload on the compressor causing it to use less juice.
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Old 07-24-2013, 03:06 PM   #44
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I like this idea but I don't know the difference between 66 and 70 and 74 db. I'd love to know what kind of noise mine makes. Another tool purchase?
Apparently and don't quote me but you can research it. One of my Engineer customers or Musician ones told me that going up 3 db is one octave or equivalent to talking twice as loud. Must be some info on that on the net but I cannot find it quickly. Apparently 3 db is a huge change in sound so go figure when you see those results. I have sold many 70 db Lennox XC14s and can talk to my customers across them comfortably. The higher SEER units you can barely hear run but they are big and have LOTS of rubber mounting and isolation and special sound dampening methods inside. Great for shift workers or people who have to sleep days or have it outside a bedroom window.
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Old 07-24-2013, 04:23 PM   #45
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Is NOW a good time to replace my 1986 AC?


1dB is the smallest incriment, or change in sound, most people can decern
3dB incriment is double the sound energy, but NOT what we perceive as double the volume. (This is where some confusion comes from) In audio terms, it takes twice the power to increase the sound by 3dB, but we do not perceive 3dB to be twice as loud, only somwhat louder
10dB incriment is an order of magnitude more sound energy (10x), and what we perceive as "twice as loud" In audio, it takes 10x the power to make something twice as loud.

In terms of ACs, you will notice some difference between 74,70, and 66, the 74 will seem about 75% louder than the 66. Don't pay a bundle to gain 3dB for something that sits outside, air handler is a much larger factor for the noise in the living spaces.

(yea, I am an engineer )

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