Wire Size for 3-ton Heat Pump?
Paul W. Jones
one installed now, but the higher efficiency ones start at 3 ton, and
I'm wondering if I have to ask the installer to upgrade the wire,
which for various reasons would not be easy. The one that's there
seems to have markings on it "Type U 6 AL" on it. Looks fairly hefty.
HeatMan
news:bc03b57c.02100...@posting.google.com...
I get rid of the aluminum wire without a doubt....
Inside unit or outside unit? Outside may run off a 30 amp( most likely) or
a 40 amp(possible).
If you're asking us, do you trust your installer?
Big Balls Willie
"Paul W. Jones" <pwj...@hvc.rr.com> wrote
> What's the right wire size for a 3-ton Heat Pump?
Depends on the spec plate of the equipment. The condensing unit (outside)
will probably have smaller guage wire than the indoor unit because of the
backup heat package, but equipment varies.........
Noon-Air
"Paul W. Jones" <pwj...@hvc.rr.com> wrote in message
news:bc03b57c.02100...@posting.google.com...
First and formost, get rid of the aluminium wire, and correctly size the new
copper wire using the equipment name plate data and the NEC. Second, If you
are asking this question, you need to find another contractor....he/she
should have addressed and explained all this to you when they quoted a price
for the new system. Third, If the decission to increase the size of the
system was not based on a Manual J heat load calculation, don't walk, but
RUN AWAY from these contractors.
The brand name doesn't matter.... what DOES matter is having a top quality
installation done.
This is the single most expen$ive appliance in your home.... You can get
cheap, or you can get good.....either way you will get what you pay for.
--
Steve @ Noon-Air Heating and A/C
noon...@netdoor.com
There are very few personal problems that cannot be solved
by a suitable application of high explosives
Jabarco
Are you wondering what I'm wondering? I'm wondering maybe if Paul awarded
that HVAC installation job to the lowest bidder had anything to do with it?
I'm not saying.....but....I'm just saying.
Jabarco
"Noon-Air" <noon...@netdoor.com> wrote in message
news:GKCcnRHfMOK...@News.GigaNews.Com...
Paul W. Jones
Alcan Stabiloy Type SE Cable Style U Type XHHW CDRS 600 Volts 3 CDRS 6
AL (UL) 1985
Looked it up and came up with this web-site:
and give or take the long run, it looks like the cable will do 50
Amps, if I'm reading the table properly. Looks like the breaker is 40
Amps, so I think it all should be OK for a 3-ton heat pump. Gotta
check a little further, though.
pwj...@hvc.rr.com (Paul W. Jones) wrote in message news:<bc03b57c.02100...@posting.google.com>...
p...@see_my_sig_for_address.com
wrote:
>and give or take the long run, it looks like the cable will do 50
>Amps, if I'm reading the table properly. Looks like the breaker is 40
>Amps, so I think it all should be OK for a 3-ton heat pump. Gotta
>check a little further, though.
What you gotta do is stop playing electrician, and get a
qualified HVAC or electrical contractor to make this determination for
you. You are obviously unqualified in this area, and it is your life
you are playing with.
I don't care * what * you 'found on the web', the information
is meaningless since you don't know how to apply it safely. Kind of
like me finding a recipe for TNT 'on the web' - guess what ? It might
be right, but I'm likely to blow myself up trying to use it !!!!
Paul ( pjm @ pobox . com ) - remove spaces to email me
>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~
Please look at http://helpthecritters.com/ , my new domain for helping critters !!!
My personal WWW site is at http://www.pmilligan.net ,
featuring free HVAC, stock market, and other free software
Those who say a thing can not be done
should get out of the way of those
who are actually doing it.
Ken Mulchi
<pjm@see_my_sig_for_address.com> wrote in message
news:k819qusr1m3hmkc12...@4ax.com...
Tom Gauldin
consider using it. When sizing between copper and aluminum, I would just
drop down a size (larger wire) for aluminum.
If the connections appear to have any oxidation, try cutting back a few
inches to clean aluminum. If using bolt-type lugs or connectors, make sure
they're labeled ALCU to reduce oxidation.
Finally, it doesn't hurt to check the connections every now and then and
make sure they're clean and tight.
--
Tom Gauldin, Las Vegas NV
NEW EMAIL tgau...@lvcm.com
NEW PHONE (702) 263-8804 voice/fax
"Paul W. Jones" <pwj...@hvc.rr.com> wrote in message
news:bc03b57c.02100...@posting.google.com...
p...@see_my_sig_for_address.com
wrote:
>If there is no corrosion, AND if it's difficult to replace, then I'd
>consider using it. When sizing between copper and aluminum, I would just
>drop down a size (larger wire) for aluminum.
Wrong - look it up in NEC instead !!! Section 316-10 if I
recall after all these years....
>If the connections appear to have any oxidation, try cutting back a few
>inches to clean aluminum. If using bolt-type lugs or connectors, make sure
>they're labeled ALCU to reduce oxidation.
Wrong. They are rated to better resist different expansion
rates of the wire. They do not 'reduce oxidation'. A good
application of No-Ox will help that.
>Finally, it doesn't hurt to check the connections every now and then and
>make sure they're clean and tight.
One out of three ain't bad :-(
JHitch1508
let your installer do his job ( and be inspected ).
Tom Gauldin
news:pl89quc31lnkti5ji...@4ax.com...
> On Wed, 09 Oct 2002 21:39:04 GMT, "Tom Gauldin" <tgau...@lvcm.com>
> wrote:
>
> >If there is no corrosion, AND if it's difficult to replace, then I'd
> >consider using it. When sizing between copper and aluminum, I would just
> >drop down a size (larger wire) for aluminum.
>
> Wrong - look it up in NEC instead !!! Section 316-10 if I
> recall after all these years....
I don't have my copy. The guy has an existing 6 ga. run of aluminum. He
says that it'd be difficult to replace it with copper. 8 ga copper and 6 ga
aluminum should be sufficient for 40 amps. What is the problem?
>
> >If the connections appear to have any oxidation, try cutting back a few
> >inches to clean aluminum. If using bolt-type lugs or connectors, make
sure
> >they're labeled ALCU to reduce oxidation.
>
> Wrong. They are rated to better resist different expansion
> rates of the wire. They do not 'reduce oxidation'. A good
> application of No-Ox will help that.
>
The different coefficients of expansion of aluminum and copper caused quite
a problem. The aluminum would expand and contract more than the copper AND
it would hold its shape (take a set) far more than copper when
contracting/cooling. The result was a connection that became progressively
looser. . . and thus hotter. The heat would encourage oxidation of the
aluminum to aluminum oxide and that's an insulator. It was a vicious cycle.
Then, there was also the problem of electrolysis between the dissimilar
metals. The AlCU connector was designed to help all those problems, but
certainly didn't eliminate them.
> >Finally, it doesn't hurt to check the connections every now and then and
> >make sure they're clean and tight.
>
> One out of three ain't bad :-(
>
I contend that I have 3/3. . . with a plus for the PRACTICAL advice I gave
on #1.
p...@see_my_sig_for_address.com
wrote:
>I don't have my copy. The guy has an existing 6 ga. run of aluminum. He
>says that it'd be difficult to replace it with copper. 8 ga copper and 6 ga
>aluminum should be sufficient for 40 amps. What is the problem?
You don't size a wire by ' just make it bigger than what's
there'. Yes, the wire you suggest is probably correct, but the
methodology for deciding it is terrible, which makes it bad advice.
>> One out of three ain't bad :-(
>>
>
>I contend that I have 3/3. . . with a plus for the PRACTICAL advice I gave
>on #1.
Bzzztttt. :-)
Paul W. Jones
To answer some of the questions posed:
Low cost contractor:
I didn't go with the low cost contractor, haven't gone with one at all
yet, although of course I'll use one. I recognize a professional would
know more and be able to do a better job than I would, I figured there
was no harm in checking a few basics, while I'm waiting for
appointments and proposals to flow through the process. I'm not
looking to go cheap, we're not talking huge amounts of money here, one
way or another, just want to get it done right.
Aluminum Wire:
The wire we're talking about runs from the house breaker box to the
external heat pump breaker box. Run's about 65' as the crow flies,
but I'm guessing it's up a third from that due to bends and x-y runs.
On the Al as versus Cu wire, I would of course have preferred that Cu
was used, but bought the house with everything installed. So what was
there is what I got. Didn't worry about it too much before, but
figured it was worth checking a bit more on a new install/replacement,
especially if I end up sizing up on the heat pump. There's an old 2.5
ton (30k BTU) Carrier unit installed now, interestingly enough with 30
Amp breakers specified on the plate (50 Amp breakers are installed
now, hmm...), which wasn't all that easy to read, but I'm pretty sure
I got right. The higher efficiency units I've discussed with the
installers (Carrier and Trane so far) seem to start at 3 ton. The
house pretty much heats and cools fine, with the exception of one room
upstairs which can get a little warm in the summer (mostly cause of
the computer equipment, probably the original design was fine, it was
supposed to be a bedroom, not a computer room), so a little more
cooling might help a bit there, but really not a big deal. Normally,
especially with the Al wire (although I don't have quite the aversion
some apparently do), if there were any question of if the wire is big
enough for that long a run, I'd say just replace it with a heavier
copper one, not that much money in the context of the whole job, but
it's not the easiest of pulls, and would involve ripping up some of
the basement, and some not very pleasant attic work, so some of the
installers are mostly pushing lower efficiency equipment that's at
least available in 2.5 ton, and using the existing wiring. I've found
some electrical work in the house that wasn't up to code (some of the
town inspectors for when the house was built are now in jail, draw
your own conclusions), and where I've found problems, I've gone off
and fixed them, but it's caused me to check and recheck things a bit
more carefully. Mostly though, somebody just got lazy.
__________
So I do appreciate those that tried to answer my questions. That was
useful input. But I do detect just a hint of paranoia out there, in
some of the posts. I will use a qualified installer. I'm not trying
to cheat anyone out of a living or anything. I suppose a lot of
professionals see a lot of people that are looking for the absolute
low-cost bid. I'm not. I'm happy to pay more to get it done right.
[I'd say chill-out, but I suppose that's kind of a cliche for those in
the business]
Thanks.
p...@see_my_sig_for_address.com
wrote:
>So I do appreciate those that tried to answer my questions. That was
>useful input. But I do detect just a hint of paranoia out there, in
>some of the posts. I will use a qualified installer. I'm not trying
>to cheat anyone out of a living or anything. I suppose a lot of
>professionals see a lot of people that are looking for the absolute
>low-cost bid. I'm not. I'm happy to pay more to get it done right.
That's good. My only concenr is that the wire is selected
based on ' what is needed, and is safe', not 'let's just pick a
number'.
Noon-Air
>
> To answer some of the questions posed:
>
> Low cost contractor:
>
> I didn't go with the low cost contractor, haven't gone with one at all
> yet, although of course I'll use one. I recognize a professional would
> know more and be able to do a better job than I would, I figured there
> was no harm in checking a few basics, while I'm waiting for
> appointments and proposals to flow through the process. I'm not
> looking to go cheap, we're not talking huge amounts of money here, one
> way or another, just want to get it done right.
>
> Aluminum Wire:
>
> The wire we're talking about runs from the house breaker box to the
> external heat pump breaker box. Run's about 65' as the crow flies,
> but I'm guessing it's up a third from that due to bends and x-y runs.
> On the Al as versus Cu wire, I would of course have preferred that Cu
> was used, but bought the house with everything installed. So what was
> there is what I got. Didn't worry about it too much before, but
> figured it was worth checking a bit more on a new install/replacement,
> especially if I end up sizing up on the heat pump.
Either way, any inspector worth his salt will not pass a
change-out/installation that uses aluminium wire.
>There's an old 2.5
> ton (30k BTU) Carrier unit installed now, interestingly enough with 30
> Amp breakers specified on the plate (50 Amp breakers are installed
> now, hmm...), which wasn't all that easy to read, but I'm pretty sure
> I got right. The higher efficiency units I've discussed with the
> installers (Carrier and Trane so far) seem to start at 3 ton.
Rheem/RUUD high efficiency equipment (13 + SEER) starts at 2 ton and goes up
from there.
> The
> house pretty much heats and cools fine, with the exception of one room
> upstairs which can get a little warm in the summer (mostly cause of
> the computer equipment, probably the original design was fine, it was
> supposed to be a bedroom, not a computer room), so a little more
> cooling might help a bit there, but really not a big deal. Normally,
> especially with the Al wire (although I don't have quite the aversion
> some apparently do),
Its not an "aversion", its the National Electrical Code.
if there were any question of if the wire is big
> enough for that long a run, I'd say just replace it with a heavier
> copper one,
The NEC specifies what size of wire for the load and length of wire
run.....and.... once you have done your homework, you will find that when
aluminium is replaced with copper, the copper wire is actually smaller with
the same capacity.
> not that much money in the context of the whole job, but
> it's not the easiest of pulls, and would involve ripping up some of
> the basement, and some not very pleasant attic work, so some of the
> installers are mostly pushing lower efficiency equipment that's at
> least available in 2.5 ton, and using the existing wiring.
Lazy contractors trying to "low-ball"
> I've found
> some electrical work in the house that wasn't up to code (some of the
> town inspectors for when the house was built are now in jail, draw
> your own conclusions), and where I've found problems, I've gone off
> and fixed them, but it's caused me to check and recheck things a bit
> more carefully. Mostly though, somebody just got lazy.
>
> __________
>
> So I do appreciate those that tried to answer my questions. That was
> useful input. But I do detect just a hint of paranoia out there, in
> some of the posts. I will use a qualified installer. I'm not trying
> to cheat anyone out of a living or anything. I suppose a lot of
> professionals see a lot of people that are looking for the absolute
> low-cost bid. I'm not. I'm happy to pay more to get it done right.
Its not that we see a lot of folks looking for the lowest bid, its that we
see and have to correct all the problems when they DO get the lowest bid.
> [I'd say chill-out, but I suppose that's kind of a cliche for those in
> the business]
>
> Thanks.
Your welcome
Paul W. Jones
>
> Rheem/RUUD high efficiency equipment (13 + SEER) starts at 2 ton and goes up
> from there.
>
By higher efficiency, I had meant something in the 17 + SEER range.
I looked over at the Rheem web-site, and they list models up to 14
SEER:
http://www.rheemac.com/residential/heatpumps/
The scroll compressors are obviously a nice feature. But anyway, the
Tranes and Carriers seem to have some higher efficiency models.
Carrier: http://www.residential.carrier.com/products/heat_pump/set_heatpump.htm
Lists up to 17.0 SEER/9.1 HSPF (38YDB) [starts at 3 ton]
Trane: http://www.trane.com/residential/rightproduct/xl1800.asp
Lists up to 17.65 SEER/8.5 HSPF (XL 1800) [starts at 3 ton]
If I look at the 2.5 ton models, the efficiencies then drop somewhat:
Carrier: Lists up to 14.5 SEER/8.5 HSPF (38 YXA)
Trane: Lists up to 14.0 SEER/9.25 HSPF (XL 14i)
(an oddity to this is that probably the heat cycle gets used more than
the cooling cycle, for me, so the HSPF rating might be the more
important one, but the Carrier, which is slightly ahead in the higher
efficiency unit, is lower in the 14.x SEER units. Still they're
reasonably close)
The highest efficiency 2.5 ton unit I've found is the American
Standard Heritage 14. Here's a web page for that:
http://www.amstd-comfort.com/products/residential/outdoor/herit_14_spec.html
Amstd: Heritage 14: Lists up to 15.00 SEER/9.85 HSPF
So that's a bit above the Rheems, Trains, and Carriers in SEER and
HSPF. But to be fair, I think that may be an R-22 unit, and there's a
lower rated model:
Amstd: EnviroWise Heritage 14: 14.75 SEER/9.25 HSPF
Still slightly ahead of the Carrier/Trane units in that class, by not
as much. There is a Carrier Freon unit that has a bit better numbers,
but for some reason the local installers aren't suggesting it. I'll
have to ask for more details, when I talk to them again.
Anyway, the American-Standard units seem to be the most efficient, of
the ones I've been able to find so far, in the 2.5 ton class. Still,
we're talking not large differences, I suppose, which may be just as
well as the major installers seem to be pointing mostly to Carrier or
Trane. One of the installers, factory trained on both Carrier and
Trane, seems to be currently suggesting the Carrier units. I found
that a bit curious, given that Trane has a slightly better reputation
for durability, and maybe slightly better numbers at 2.5 tons. Also,
last year, the same outfit had been recommending Trane. But according
to the installer, while Trane lasted longer, they had problems getting
parts quickly, so outages tended to be longer, and they thought the
Carrier heat cycle was better, so they were recommending Carrier these
days. They'll sell me either one, if I had a preference. I have
another Trane installer coming around to do an estimate, took some
time to get him scheduled, so we'll see what he has to say. My
experience with the Carrier unit that's in there now hasn't been all
that great, it had more repairs and died I think a bit on the early
side.
Noon-Air
> "Noon-Air" <noon...@netdoor.com> wrote in message
news:<sFadnT-Nfa0...@News.GigaNews.Com>...
> >
> > Rheem/RUUD high efficiency equipment (13 + SEER) starts at 2 ton and
goes up
> > from there.
> >
>
> By higher efficiency, I had meant something in the 17 + SEER range.
Is the extra couple of SEER points worth the the extra cost??
> I looked over at the Rheem web-site, and they list models up to 14
> SEER:
>
> http://www.rheemac.com/residential/heatpumps/
>
> The scroll compressors are obviously a nice feature. But anyway, the
> Tranes and Carriers seem to have some higher efficiency models.
The 13+ SEER systems I sell and install are based on a 12 SEER condenser....
I tried matching systems using 13 and 14 SEER condensers for higher
efficiency systems and figured out that for $1500+ (or more) dollars cost
for *maybe* a half a SEER point, wasn't worth it for my customers. The extra
cost could not be justified becaust the payback and value was just not
there.
> Carrier:
http://www.residential.carrier.com/products/heat_pump/set_heatpump.htm
>
> Lists up to 17.0 SEER/9.1 HSPF (38YDB) [starts at 3 ton]
>
> Trane: http://www.trane.com/residential/rightproduct/xl1800.asp
>
> Lists up to 17.65 SEER/8.5 HSPF (XL 1800) [starts at 3 ton]
>
> If I look at the 2.5 ton models, the efficiencies then drop somewhat:
>
> Carrier: Lists up to 14.5 SEER/8.5 HSPF (38 YXA)
>
> Trane: Lists up to 14.0 SEER/9.25 HSPF (XL 14i)
2 1/2 ton Rheem RPMC-030JAZ, RBHK-21J14/RCHA-36A1
13.75 SEER, 8.25 HPSF (national average yearly operating cost for heating
*and* cooling is $646.00)
> (an oddity to this is that probably the heat cycle gets used more than
> the cooling cycle, for me, so the HSPF rating might be the more
> important one, but the Carrier, which is slightly ahead in the higher
> efficiency unit, is lower in the 14.x SEER units. Still they're
> reasonably close)
>
> The highest efficiency 2.5 ton unit I've found is the American
> Standard Heritage 14. Here's a web page for that:
>
>
http://www.amstd-comfort.com/products/residential/outdoor/herit_14_spec.html
>
> Amstd: Heritage 14: Lists up to 15.00 SEER/9.85 HSPF
>
> So that's a bit above the Rheems, Trains, and Carriers in SEER and
> HSPF. But to be fair, I think that may be an R-22 unit, and there's a
> lower rated model:
>
> Amstd: EnviroWise Heritage 14: 14.75 SEER/9.25 HSPF
Seems that the highest efficiency systems are still R-22. Still you have to
decide regardless of what system you choose, which one will give you the
best value for your dollar.... which will actually pay for itself before its
time to replace it.
> Still slightly ahead of the Carrier/Trane units in that class, by not
> as much. There is a Carrier Freon unit that has a bit better numbers,
> but for some reason the local installers aren't suggesting it. I'll
> have to ask for more details, when I talk to them again.
>
> Anyway, the American-Standard units seem to be the most efficient, of
> the ones I've been able to find so far, in the 2.5 ton class. Still,
> we're talking not large differences, I suppose, which may be just as
> well as the major installers seem to be pointing mostly to Carrier or
> Trane. One of the installers, factory trained on both Carrier and
> Trane, seems to be currently suggesting the Carrier units. I found
> that a bit curious, given that Trane has a slightly better reputation
> for durability, and maybe slightly better numbers at 2.5 tons. Also,
> last year, the same outfit had been recommending Trane. But according
> to the installer, while Trane lasted longer, they had problems getting
> parts quickly, so outages tended to be longer, and they thought the
> Carrier heat cycle was better, so they were recommending Carrier these
> days. They'll sell me either one, if I had a preference. I have
> another Trane installer coming around to do an estimate, took some
> time to get him scheduled, so we'll see what he has to say. My
> experience with the Carrier unit that's in there now hasn't been all
> that great, it had more repairs and died I think a bit on the early
> side.
The single most important point that needs to be made here (unless you have
more dollars than sense) is that brand/efficiency doesn't mean squat if you
have a poor installation. You can have an outstanding installation with a
cheap builders model and have a good servicable system. On the other hand,
you can buy the "latest and greatest" with a poor installation and you have
junk.
Paul W. Jones
One of the reasons I'm going with the variable air-handler, is that my
wife has always hated the clunk and air-flow noise of the older unit,
which is single speed. Costs more, of course, and we could probably
play around tweaking the system (I suspect it will need further
duct-work, anyway), but if it makes here happy, well worth the extra
money.
It's funny, I grew up with forced-air, so to me it's all normal sound.
I never worry about it, really. It's not that loud. My wife, grew
up with no AC and water baseboard heat. Once you get one of those
systems set up properly, there's only an occaisonal crack or ping from
heat expansion, but of course you cannot get AC that way. With
setbacks, the forced air heat tends to clunk on full an hour or two
before we're supposed to get up, and wakes her up.
On the 14 as versus 17 SEER units, you probably are right. Probably
we'll never make back the cost differential, in any real terms. The
first of the estimates rolled in over the weekend, and there was about
a $2k difference. Not sure why, exactly, as the external units
weren't priced $2k apart. Still, the HSPF ratings tend to be better
on the higher SEER units, and because the house has a lot of windows,
we end up paying a lot more for heating/cooling than the averages.
The house has a two story cathedral ceiling in the middle, so the
upstairs heat pump ends up cooling a lot of the downstairs, too. So
it's hard to figure exactly, but if we can get the prices reasonably
close, we'll probably go with the higher efficiency units.
I noticed the HSPF ratings on some of the single stage Carrier freon
units tend to be higher than a lot of the rest of their line (and
Trane's), at least those with Puron. Can anyone explain why Freon
does better at heating efficiency?
Mark J Strawcutter
>wife has always hated the clunk and air-flow noise of the older unit,
>which is single speed. Costs more, of course, and we could probably
>play around tweaking the system (I suspect it will need further
>duct-work, anyway), but if it makes here happy, well worth the extra
>money.
>
>It's funny, I grew up with forced-air, so to me it's all normal sound.
> I never worry about it, really. It's not that loud. My wife, grew
>up with no AC and water baseboard heat. Once you get one of those
>systems set up properly, there's only an occaisonal crack or ping from
>heat expansion, but of course you cannot get AC that way. With
>setbacks, the forced air heat tends to clunk on full an hour or two
>before we're supposed to get up, and wakes her up.
If you really want to make her happy, give her the best of both worlds - hot
water heat and a separate forced-air A/C system.
Mark