new furnace install -- several Qs

OK, so my old furnace dies, and I blow $3850 on a new one + some major duct rework.
Maytag 100 BTU, 2 stage furnace, 1 year old Trane AC units
They completely redo the supply side to my E side of the house (ranch w/ BRs there) and completely redo the return to the E side (since one was never done). The BRs did not have returns, so those were added.
Here are my Qs: What does the 2 stage furnace buy me? Do I need a 2 stage thermostat then?
They suggested I just leave my blower on 24x7 to get more even heat/ac distribution and to continuously filter the air. Sounds logical -- is it?
On my ac evaporator they plumbed 2 drain lines (Trane unit). One has PVC pipe all the way to the drain, the other has just a short pvc line directed towards the floor.
What is the significance to bending the refrigerant lines? The lines come into the house, are bent 90 to the N then 90 to the W then 90 down then 45, then back 45, and then 90 into the evaporator. The last 45-45-90 could be replace by two 45s (they just left the old 90 on and used the pair of 45s redirect the bad 90. Should I make them simplify the connection? or is the extra 90 no big deal?
Thanks, this will be a big relief.
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On Fri, 07 Jan 2005 15:18:46 -0700, nospam snipped-for-privacy@mesanetworks.net wrote:

Maytag is made by Nordyne. I find lots of these (Maytag, Nordyne, Gibson, Frigidare, Intertherm, etc) installed in trailers. Its a unit. Nothing to brag about here. 2 stage gives you 2 different heating btus. 100K on high fire and about 80K on low fire. If you paid for a 2 stage unit you should have a 2 stage thermostat installed. This way the thermostat senses whether you should have low or high fire going. With a single stage stat, the high fire is initiated by time set on your furnace circuit board (somewhere between 8 and 15 mins). If they suggested you leave the blower on 24x7 then you should have gotten the variable speed unit. You can still add that as an option. It will save you on your electrical consumption if you plan on running your blower 24x7. Running it constantly will cause your home to have more even temperatures throughout your home however a constantly blowing unit can feel drafty in the winter after the burners have gone off. Its mainly up to you as a comfort level. Your second drain piped halfway down is an overflow drain. IF you look at them, you will see that one is slightly higher where it comes out of your coil. If you see water coming from that one, your main drain is clogged. Bending the refrigerant lines? It sounds like you are describing some sort of "P-trap" in your refrigerant lines? Most manufacturers, including Trane dont use them anymore unless your cooling coil and your outdoor unit are separated in height by more than 20 feet or so. You will need to look in your A/C installation manual for the exact heights and requirements. Otherwise, in general, the fewer bends and elbows, the better. It just ads up to more friction/restriction in the line. Bubba
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So I took out my Coleman (which everyone told me was for trailer homes) and put in a Maytag (which at least you are telling me is about the same). I thought Maytag has somewhat of a high quality perception (at least a perception). The warranty was good, I guess. 10 years with a full replacement up to 5. Personally, both seem pretty pathetic. I know a lot of old houses where the furnaces have been running for 20 or 30 or more years.
The refrigerant "extra bends" is unlikely by design. When they put in the new furnace they "cleaned up" some of their shoddy work from the AC install. They spun the evap. 180 degress to put the lines on the same side as the furnace connections (back side is now clear of lines, etc). There was an elbow on the line into the evap. They pulled the new lines down at about a 90 deg. angle (imagine line coming from East and making a 90 to be bending down. Line is now running straight down, let's call this 180 deg.) They then put on a 45 (225 deg) attached to about 12" of pipe to another 45 back (back to 180 deg. or straight down) and into that 90 that turns (270 deg now) and goes into evap. IMO, that 90 is NOT needed. the straight down could hit a 45 then extend to evap and then attach to another 45. If they had enough line, they could have just made a 180 sweeping curve and been done with it. Not enough line and they had to muck around with fittings and short sections of pipe.
as best as I can draw is here:
90 curve furn rm<--90 curve to W<--90 curve to N<--condensor | (downward) | | 45 fitting \ \ 45 fitting | | 90 fitting --- evaporator
the small dia. pipe is just bent around to go straight into the evap. the small pipe i understand is the return refrigerant.
i'm no fluid mechanices expert, but I've setup a dust collection system in my shop, and rule #1 is minimize bends.
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nospam snipped-for-privacy@mesanetworks.net wrote:

You should have a two stage thermostat to get the most out of your new furnace, but it should work on a single stage.
As to why a two stage is good, I stole this off the Lennox site, I doubt if they will mind. It is good information.
Two-stage heating means the furnace has two levels of heat output: high for cold winter days and low for milder days. Since the low setting is adequate to meet household-cooling demands 80% of the time, a two-stage unit runs for longer periods and provides more even heat distribution.
Longer, low-capacity operation has many advantages: Consistent comfort Two-stage heating eliminates the temperature swings associated with standard furnaces, regulating temperature to within as little as one degree of the thermostat setting.
Quiet operation Two-stage furnaces start in the first stage, when the amount of heat required is lower, instead of reaching full capacity all at once. That means there's no sudden "kick" or blast of air.
Improved air filtration Low-speed operation allows your filters to capture more contaminants (because air is constantly passing through them), so you can breathe easier.
Efficient performance Because the furnace operates mostly in its lower-capacity first stage, it burns less fuel than a standard furnace that always runs at full capacity and shuts off when the heating demand has been met.

You should get most of the advantages with the two stage unit. 24x7 will give you even more advantage, but also more cost and noise etc. It's your call.

Just guessing, the second one is an overflow and when you see it draining you know the other is clogged. Not a bad idea if you don't have anything valuable on the floor between it and the drain.

Total SWAG with very little "S" work here. It may help in vibration, expansion and contraction or maybe they needed to use up a couple feet of pipe.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math
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'Here are my Qs: What does the 2 stage furnace buy me? Do I need a 2 stage thermostat then?'
The 2 stage furnace buys you some greater economy during times of the heating season when you are not at full heating load (as determined by the outdoor temperature for your locale). THis is obviously most of the time. So, 2 stage operation of a furnace is almost always a good feature. You dont necessarily need a 2 stage thermostat ; some manufacturers of furnaces bring on the 2nd stage after 'x' amount of minutes while others base it on how long it took the previous cycle to complete the task of satisfying the thermostat (runtime). The installer should know if a 2stage stat was absolutely required or not.
'They suggested I just leave my blower on 24x7 to get more even heat/ac distribution and to continuously filter the air. Sounds logical -- is it?'
Its good if you want a cleaner house ; it tends to work out ok for a/c use, but, for heating...when the burners are not firing, youll feel the cooler air objectionable especially if youre anywhere near a supply air register. Try it and see how it is for you.
'On my ac evaporator they plumbed 2 drain lines (Trane unit). One has PVC pipe all the way to the drain, the other has just a short pvc line directed towards the floor.'
THis is common. The pvc drain plumbed toward the floor is your backup/secondary overflow in case the other one becomes plugged up .
'What is the significance to bending the refrigerant lines? The lines come into the house, are bent 90 to the N then 90 to the W then 90 down then 45, then back 45, and then 90 into the evaporator. The last 45-45-90 could be replace by two 45s (they just left the old 90 on and used the pair of 45s redirect the bad 90. Should I make them simplify the connection? or is the extra 90 no big deal?'
Its not a big deal 99..9 percent of the time. When running freon lines, you always want to try to make long radius turns or 45's if practical ; It reduces the internal friction and reduces the change of kinking which is more prone to doing 90's especially with the larger suction tubing which is insulated. It also enables better oil return to the compressor under many situations. I wouldnt insist they redo it.
Regards.
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The furnace model is Maytag PGF1TA100CVBB, which I interpret to be the 80 effciency, variable speed, 2 stage, 100 btu (per the Maytag website)
re: a 2 stage thermostat, I looked at the wiring diagram on the furnace and it shows the normal 4 wires from the thermostat, R, W, G, Y; nothing near as I can tell about some extra wires for a 2 stage thermostat. Now, there are a pair of wires coming in from the AC condensor, apparently an outside air temperature. Those go to both the humidifier and furnace. The website mentions using the outside air temp to determine the low or high output.
re: leaving furnace on 24x7. The fan only option runs the fan at a slower speed than when the furnace fires. According the the specs, the is a VS unit. If VS though, doesn't that imply many speeds from 0 to X? Is there a way to set those? Or is there some optimal logic to set both fan-only speed and heat/ac speed?
re: ac evaporator drain lines. It kindof makes sense to have a main drain and backup drain. With my logic though, it does not make sense to drain one to the floor drain and the other just onto the floor next to the furnace. When I'm on vacation for 2 weeks, that 2nd option is going to aggrevate me. Why not route both to the floor drain? I suppose the opposing logic is then the "user" will realize they have a block in the mainline.
re: the extra 90 bend in the incoming refrigerant line. This IMO is just common sense -- minimize bends in any fluid or gas line. They just did not want to cut off the 90 that was already there. So they added an extra 90 degress of bend to make it work. Shody IMO.
On Fri, 07 Jan 2005 15:18:46 -0700, nospam snipped-for-privacy@mesanetworks.net wrote:

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