Question about replacement system - 3 different specs

[ewitte]

I would like opinions on the following for in the Houston area

Lennox XC16 5 ton or XC16 4 ton (with 2 zone)
or
Lennox XC21 5 ton or XC21 4 ton (with 2 zone)

That is 4 different combinations. The two zone options will allow turning off 65% of the house at night but the temps would be set the same during the day. There was also a difference where they recommended the 5 ton if I did not do the zoning. The load calculation was about 1500BTU higher than the 4ton could provide but they said the zone system would be able to handle the difference. For reference this is what I told (off the top of my head)

XC21 4ton - 17.7 seer
XC21 5ton - 15.7 seer
XC16 4ton - 15.7 seer
XC16 5ton - 15.2 seer

Pricewise the XC21 5 ton is slightly less than the XC16 4ton with the zoning. Replacing pretty much the entire system coil, evaporator, furnace, etc. The existing system is a 5ton Trane XE1200 that is now 12 years old. The home builder didn't do the best with install so there is some damage because there was water builduip inside the system.

Eric

[udarrell]

In Houston TX area...

The 2-Stage compressor is a good deal...

Are you sure your home needs 4 or 5-Tons of heat removal.

Have you had a Home Energy Efficiency Audit, followed up with improvements &, then a Manual J room by room heat-gain calc.

Before I made that large an investment I'd want to know all the things I could do to lower the required tonnage; as that could mean more in savings than going to a high 21-SEER.

--------
For those taking out energy saving loans...

Any low interest rate loans on energy savings work ought to be 'amortized' over a sufficient time period so the realized monthly savings more than pays for the loan payments.

That method along with 'micro-loans' whereby nearly anyone can qualify; only these energy loans should always require a very low rate of interest.

[ewitte]

They went around the entire house and got a load calc of about 51600 BTU. The 4ton provides 50000BTU (a bit more than most 4tons). That took into account the solar screens on the windows, etc. The load calc just plugging in the basics was about 54000BTU. BTW the house is 2381sf single story.

[udarrell]

They went around the entire house and got a load calc of about 51600 BTU. The 4ton provides 50000BTU (a bit more than most 4tons). That took into account the solar screens on the windows, etc. The load calc just plugging in the basics was about 54000BTU. BTW the house is 2381sf single story.

Five-Ton seems like a lot of tonnage for a 2381-sf home in Houston.

That is good information; however, a good energy efficiency audit will tell you where you can make changes that could possibly considerably reduce the heat-gain required tonnage.

The summer design for Houston is: 95-DB; with July average humidity levels of; 90% 7:30 AM; 58% 1:30 PM; & 66% @ 7:30 PM.
Source: the engineering ToolBox.

If air infiltration is not kept low enough (blower-door-test) there could be a needless very high latent/humidity load on the system.

Therefore, the system needs LONG Run-Times, you do NOT want an oversized system.

The 2-stage compressor will help more if the high-stage is not too oversized.

I wouldn't be overly concerned about how each unit is rated Btuh-wise, because many things depend on how close we get to those Expanded Engineering Data Ratings; think ballpark Ratings...

[fliks]

That sounds large to me. I just did a home near Houston that was the same size without solar screens and built I 1996. Load calc came out at 3 ton but they wanted it cold and quick. Installed 3.5 ton and it can bring the house down to 65* on a 104* day easily.

[second opinion]

I would like opinions on the following for in the Houston area

Lennox XC16 5 ton or XC16 4 ton (with 2 zone)
or
Lennox XC21 5 ton or XC21 4 ton (with 2 zone)

That is 4 different combinations. The two zone options will allow turning off 65% of the house at night but the temps would be set the same during the day. There was also a difference where they recommended the 5 ton if I did not do the zoning. The load calculation was about 1500BTU higher than the 4ton could provide but they said the zone system would be able to handle the difference. For reference this is what I told (off the top of my head)

XC21 4ton - 17.7 seer
XC21 5ton - 15.7 seer
XC16 4ton - 15.7 seer
XC16 5ton - 15.2 seer

Pricewise the XC21 5 ton is slightly less than the XC16 4ton with the zoning. Replacing pretty much the entire system coil, evaporator, furnace, etc. The existing system is a 5ton Trane XE1200 that is now 12 years old. The home builder didn't do the best with install so there is some damage because there was water builduip inside the system.

Eric

A lot more detail about the job would help. That is a lot of high en equipment to put into a retro fit home without improvements to support

[ewitte]

Going 4ton xc21 without zone and working on reducing leakage.

[ewitte]

A lot more detail about the job would help. That is a lot of high en equipment to put into a retro fit home without improvements to support

The entire system is being replaced that was just the main questions I had. Everything including the merv16 filter and humidity control.