Lennox HS26-060-2p condensing unit capacity

Posted by old dirtbeard on July 4, 2007, 11:46 am

>> Hi all,
>> I tried a Google search on this unit, but came up with nothing helpful.

> Does

>> anybody know the tonnage/capacity of this unit? Thank you.

> 60,000 Btu which is a 5-ton unit.
> Why do you ask?

I never had central AC before -- I bought this house and this unit was
installed.We just got into weather where we needed to use it and I am very
impressed how quickly it cools the house, it does not run as long as the
neighbors unit and is not too noisy. The guy who built this house went heavy
duty on most of the systems (1 1/2" copper plumbing, steel i-beams, 10' high
garage doors, etc.), and I was just curious about the tonnage required to do
the job. Just idle curiosity, I suppose. It seems like a good unit.

Thanks for the info.

doug

Posted by on July 4, 2007, 12:35 pm

> >> Hi all,
> >> I tried a Google search on this unit, but came up with nothing helpful.

> > Does

> >> anybody know the tonnage/capacity of this unit? Thank you.

> > 60,000 Btu which is a 5-ton unit.
> > Why do you ask?

> I never had central AC before -- I bought this house and this unit was
> installed.We just got into weather where we needed to use it and I am very
> impressed how quickly it cools the house, it does not run as long as the
> neighbors unit and is not too noisy. The guy who built this house went

heavy

> duty on most of the systems (1 1/2" copper plumbing, steel i-beams, 10'

high

> garage doors, etc.), and I was just curious about the tonnage required to

> the job. Just idle curiosity, I suppose. It seems like a good unit.
> Thanks for the info.
> doug

Yeah, well I wouldn't be too impressed with a unit that can quickly cool the
house down. Especially close to the design temperature!

All that's doing is cooling the air and not running long enough to remove
the humidity. That can not only lead to comfort issues, but to mold
problems!

Short cycles also raise your operational cost, as the unit is more efficient
when running longer cycles. Think of it as a car that has an increased fuel
efficiency when you're on the highway vs. short runs to town.

This is one area that you don't want to oversize. I sure hope the ducting
will allow for proper airflow, or the unit is costing you even more than it
should to operate!

Bigger is not always better!

Posted by old dirtbeard on July 4, 2007, 6:10 pm

> Yeah, well I wouldn't be too impressed with a unit that can quickly cool
> the
> house down. Especially close to the design temperature!
> All that's doing is cooling the air and not running long enough to remove
> the humidity. That can not only lead to comfort issues, but to mold
> problems!
> Short cycles also raise your operational cost, as the unit is more
> efficient
> when running longer cycles. Think of it as a car that has an increased
> fuel
> efficiency when you're on the highway vs. short runs to town.
> This is one area that you don't want to oversize. I sure hope the ducting
> will allow for proper airflow, or the unit is costing you even more than
> it
> should to operate!
> Bigger is not always better!

Makes perfect sense, thank you. About how long should a run cycle be? I
timed a few run cycles and on average it runs for 17 minutes and then cycles
off for 18 minutes, about a 50% run-time at 2:30 p.m. with an ambient
outdoor temperature of 87 degrees F. The inside humidity hovers around 48%..

The house is a 3,300 sq. ft.ranch style located in the Los Angeles area near
the coast. It was built in 2000 so it is fully insulated (floors, walls,
attic), has dual glazed windows, good weather stripping, etc. The ducts are
wrapped in insulation but appear to be 12" and 10" diameter. It has a Space
Gard 2400 filter box.

Does it sound like the unit is too large for the house? Maybe you need more
information to make that determination. I guess it is moot now as I
probably would not change it out. I have a photovoltaic system that produces
a surplus most days, so the electricity consumed really does not really
matter.

I was making a comparison to my neighbor's run time -- once his condensing
unit starts running, it seems to run continually until the end of the day. I
was thinking it probably is being over-worked, but I do understand how
starting cycles will use a lot more power than steady running. Also, every
time it starts, it has to blow the hot air out of the ducts again. I guess
the optimally sized unit would not cycle at all -- just run continually to
hold the temperature constant. Tough to do, though depending on the varying
outside temperatures (e.g., need capacity to keep it cool on a 95 degree
day), but it seems like my neighbor's unit probably is better sized than
mine. His unit has a very busy/annoying buzz to it,though, like it is
straining to keep up -- that is why I noticed it to begin with.

Thanks for the info,

doug

Posted by udarrell on July 4, 2007, 11:43 pm

old dirtbeard wrote:

>>Yeah, well I wouldn't be too impressed with a unit that can quickly cool
>>the
>>house down. Especially close to the design temperature!
>>All that's doing is cooling the air and not running long enough to remove
>>the humidity. That can not only lead to comfort issues, but to mold
>>problems!
>>Short cycles also raise your operational cost, as the unit is more
>>efficient
>>when running longer cycles. Think of it as a car that has an increased
>>fuel
>>efficiency when you're on the highway vs. short runs to town.
>>This is one area that you don't want to oversize. I sure hope the ducting
>>will allow for proper airflow, or the unit is costing you even more than
>>it
>>should to operate!
>>Bigger is not always better!
>>

>Makes perfect sense, thank you. About how long should a run cycle be? I
>timed a few run cycles and on average it runs for 17 minutes and then cycles
>off for 18 minutes, about a 50% run-time at 2:30 p.m. with an ambient
>outdoor temperature of 87 degrees F. The inside humidity hovers around 48%..
>The house is a 3,300-sq.ft. ranch style located in the Los Angeles area near
>the coast.

Los Angeles, CA summer design is 89 Dry Bulb & 70 Wet Bulb, a low 38%
RH; the humidity could be a little higher near the ocean.
A 48% RH in the conditioned space is okay; so the unit's size is not
hurting you in respect to humidity levels!
Since you produce your own electric by adjusting fan speeds you should
be able to get a little better runtime & comfort.
I always recommend using fans to circulate air in the conditioned space.
The "WindMachine 'Vertically Adjustable' 3spd 20" fan" is great!

>It was built in 2000 so it is fully insulated (floors, walls,
>attic), has dual glazed windows, good weather stripping, etc. The ducts are
>wrapped in insulation but appear to be 12" and 10" diameter. It has a Space
>Gard 2400 filter box.
>

I don't know what you are talking about 12 & 10 inch ducts (?) for a
5-Ton System.
Adding those two ducts together does NOT equal a 21" duct's capacity!
At Proper Residential Static Pressures & Duct Velocities:
A 10" duct = 327-CFM; 12" duct = 628-CFM or Both a Total of only
865-CFM; a 21" = 1745-CFM; a 22" = 2111-CFM.
That duct design might be way off base! Check it out with my Duct Sizing
Charts in the linked page below!

It is not easy to get the ductwork large enough along with the rated
Airflow.
For somewhat longer cycles, with an oversized AC you could go for
350-CFM per Ton of Cooling or 1750-CFM; or 400-CFM-perTon = 2000-CFM.
If the ductwork is properly sized, you can set a blower speed to get
close to the above air deliveries.
http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html

>Does it sound like the unit is too large for the house? Maybe you need more
>information to make that determination. I guess it is moot now as I
>probably would not change it out. I have a photovoltaic system that produces
>a surplus most days, so the electricity consumed really does not really
>matter.
>I was making a comparison to my neighbor's run time -- once his condensing
>unit starts running, it seems to run continually until the end of the day. I
>was thinking it probably is being over-worked, but I do understand how
>starting cycles will use a lot more power than steady running. Also, every
>time it starts, it has to blow the hot air out of the ducts again. I guess
>the optimally sized unit would not cycle at all -- just run continually to
>hold the temperature constant. Tough to do, though depending on the varying
>outside temperatures (e.g., need capacity to keep it cool on a 95 degree
>day), but it seems like my neighbor's unit probably is better sized than
>mine. His unit has a very busy/annoying buzz to it,though, like it is
>straining to keep up -- that is why I noticed it to begin with.
>Thanks for the info, doug
>

A manual J should have been done to figure the heatload & a manual S to
reveal the proper AC unit size.
A manual D should always be done for sizing the ductwork.
- udarrell

--
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Reality Is Not An Easy Thing To Be Confronted With, or to Accept!

Posted by Doug on July 5, 2007, 2:01 pm

> old dirtbeard wrote:

>>>Yeah, well I wouldn't be too impressed with a unit that can quickly cool
>>>the
>>>house down. Especially close to the design temperature!
>>>All that's doing is cooling the air and not running long enough to remove
>>>the humidity. That can not only lead to comfort issues, but to mold
>>>problems!
>>>Short cycles also raise your operational cost, as the unit is more
>>>efficient
>>>when running longer cycles. Think of it as a car that has an increased
>>>fuel
>>>efficiency when you're on the highway vs. short runs to town.
>>>This is one area that you don't want to oversize. I sure hope the ducting
>>>will allow for proper airflow, or the unit is costing you even more than
>>>it
>>>should to operate!
>>>Bigger is not always better!

>>Makes perfect sense, thank you. About how long should a run cycle be? I
>>timed a few run cycles and on average it runs for 17 minutes and then
>>cycles off for 18 minutes, about a 50% run-time at 2:30 p.m. with an
>>ambient outdoor temperature of 87 degrees F. The inside humidity hovers
>>around 48%..
>>The house is a 3,300-sq.ft. ranch style located in the Los Angeles area
>>near the coast.

> Los Angeles, CA summer design is 89 Dry Bulb & 70 Wet Bulb, a low 38% RH;
> the humidity could be a little higher near the ocean.
> A 48% RH in the conditioned space is okay; so the unit's size is not
> hurting you in respect to humidity levels!
> Since you produce your own electric by adjusting fan speeds you should be
> able to get a little better runtime & comfort.
> I always recommend using fans to circulate air in the conditioned space.
> The "WindMachine 'Vertically Adjustable' 3spd 20" fan" is great!

My thermostat has an option to run the fan continuously (higher speed when
the compressor is running, slower speed when it is off). Would this be a
good option? It would filter the air more, if nothing else.

Perhaps I could just have it run on the slower speed even when the condenser
is running. That should extend the run cycle, but perhaps it would
over-chill the air or cause icing or something. As you can tell, I know very
little about AC.

>>It was built in 2000 so it is fully insulated (floors, walls, attic), has
>>dual glazed windows, good weather stripping, etc. The ducts are wrapped in
>>insulation but appear to be 12" and 10" diameter. It has a Space Gard 2400
>>filter box.

> I don't know what you are talking about 12 & 10 inch ducts (?) for a 5-Ton
> System.
> Adding those two ducts together does NOT equal a 21" duct's capacity!
> At Proper Residential Static Pressures & Duct Velocities:
> A 10" duct = 327-CFM; 12" duct = 628-CFM or Both a Total of only 865-CFM;
> a 21" = 1745-CFM; a 22" = 2111-CFM.
> That duct design might be way off base! Check it out with my Duct Sizing
> Charts in the linked page below!

Oh, I understand. No it has a large "plenum" with a couple of very large
diameter ducts (probably around 20") but then with 10" and 12" ducts
branching off and running to the individual registers. I think it probably
is OK here.

Thanks again for all your help.

best,

doug

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Lennox HS26-060-2p condensing unit capacity - Page 2