AC + Heat Pump replacement

FlyGuyTyJune 11, 2014

Hi all,

I've been reading a lot of older posts from this forum would appreciate some comments on these 3 quotes for replacing my heat pump / ac system. I live in Durham, NC and have electric heating and cooling. My house, built in 2001, is 2 stories, 1,100 ft^2 on the first floor and 650 ft^2 on the 2nd floor with some very high ceilings and an open balcony from the 2nd to the 1st floor. The existing system is a set of two 2.0 ton units, one for each floor, Carrier FB4ANF024000AFAA air handlers and Carrier 38ycc024 heat pumps, now both leaking refrigerant at a fairly rapid pace. All the vendors say that the existing ductwork is in good condition and that the attic and crawlspace have plenty of room for replacement systems. Existing returns are via a 20" square inlet in both levels. Aside from the refrigerant leaks, our main complaints with the existing system is the high velocity of flow out the vents (especially upstairs), the noise from the outdoor units & poor efficiency in heating mode. The quotes are as follows, given with as much specificity as the vendor provided:

#1 - $11,066: Upstairs - Trane XR15 1.5 ton heat pump, Trane TAM7 air handler. Downstairs - Trane XR15 2.0 ton heat pump, Trane TAM7 air handler. This vendor plans to replace the existing supply return plenums. Both units have 5kW heat strips and new thermostats. 2 year labor warranty, 1 year satisfaction guarantee.

#2 - $11,344: Upstairs - Bryant FV4C air handler, Bryant Preferred 226B 2.0 ton heat pump. Same units downstairs. No mention of work on the supply return plenums, 5kW heat strips in the air handlers and new thermostats. Byrant Space Guard media cabinets quoted at an additional $350 each. 1 year labor warranty.

#3 - $11,376: Upstairs - Trane XL15i 4TWX5024B 2.0 ton heat pump, Trane TAM7 A0B30 air handler. Downstairs - same as upstairs. Supply return plenums to be modified as necessary, 5kW heat strips in air handlers, new thermostats. 1 year labor warranty

All vendors plan to use the existing line sets. All quoted programmable thermostats without giving any model # details. All quotes include new pads for the outdoor units, disposal of existing equipment and a new drip pan and alarm for the attic air handler. Vendor #2 also provided an alternative quote using lower grade Bryant equipment (FX4D air handlers & 215B heat pump) for $9,488. All parts warranties are 10 years.

So - do these look like reasonable quotes for the proposed systems and what other information would be useful to have? Vendor #1 performed the least through assessment of the house before proposing a system; #3 the most detailed. Vendor #3 also suggested that a 1.5 ton unit might be adequate for the upstairs but since the existing 2.0 ton unit seemed to be performing fine planned to stick with that size.


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All of these quotes are excellent equipment. The only question seems to be whether 2 ton or 1 1/2 ton for upstairs. I prefer Trane because it has electronic demand defrost feature which Bryant/Carrier does not offer.

What size heat strips do you have now? 5 KW may be too light. I would consider a 7.5 KW which would better temper the air on a defrost call.

5020850 Active Systems XL15I WEATHERTRON TRANE 4TWX5024B1 *AM7A0B30H21 835 24000 13.00 16.00 22600 9.00 13400 1 HRCU-A-CB Yes 186 552 Yes

The XL15i system has an extra 2 yrs on compressor warranty over the XR15 plus the proprietary funky top which I like and have myself.

Prices may be a tad high but certainly not unreasonable.

I would want HW Mdl 8321 thermostat. Same as Trane's 803. It has humidity sensor for dehumidification in cooling mode.

How do you filter your return air? Several returns for each system?


    Bookmark   June 11, 2014 at 6:44AM
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Noisy air flow usually indicates the duct work is too small to handle the air flow. I would think the 1.5 ton for 650 sq. feet on the second floor would be fine. It would also mean less noise.

    Bookmark   June 11, 2014 at 8:12AM
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If 1 1/2 ton then system below. a 5 KW heat strip would be fine for this size system.

4655312 Active Systems XL15I WEATHERTRON TRANE 4TWX5018B1 *AM7A0A24H21 605 18800 12.50 15.00 17100 8.40 10000 1 HRCU-A-CB Yes 155 355

Pay attention to thermostat recommendation.


    Bookmark   June 11, 2014 at 8:38AM
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The prices aren't bad for our location. Get a thorough Manual J heating/cooling calculation done as I think both units are oversized. You may well be happy with two 1.5 ton condenser units with variable speed air handlers which would reduce the airflow/noise (unfortunately, 1.5 ton is the smallest split system made otherwise a 1 ton would probably suffice for upstairs). Two ton will cool the house down just fine but it won't dehumidify as effectively.

Coincidentally, I recently replaced two systems the same as your existing ones (only in 3 ton sizes). Leaking, frosting over, noisy, etc. I'm not sure that generation Carrier system was one of their better efforts! You will be changing over from R22 to R410 so make sure they flush out all the old refrigerant and oil and check for leaks in the old line sets. You might want to just go ahead and change them if they are accessible.

EDIT: I'm presuming you don't have access to natural gas, which is much cheaper to heat with in our area than electric?

This post was edited by sktn77a on Wed, Jun 11, 14 at 14:37

    Bookmark   June 11, 2014 at 2:33PM
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Thanks for all the comments, this is very helpful!

Here's some additional info:
* Existing heat strips are 5kW, these seem to have been sufficient in my experience
* Natural gas heat is not available in my neighborhood
* Existing air returns are a single 20" square inlet for each system with a 1 inch filter

Here are some additional comments from the Trane vendors:

Vendor #1: Air handlers are both TAM7AOA24 (2 ton); the other Trane vendor proposed the 2.5 ton both floors, thermostats are "Honeywell 7000 touchscreen programmable", adding Trane Perfect Fit media cabinets to each air handler would increase cost to $11,451

Vendor #3: When asked about his load calculation said that the upstairs came in at just over 1.5 ton. Thermostats are Trane tcont803a. Would add Trane Perfect Fit media cabinets at no charge, total of $11,376

At this time I am leaning toward Vendor #3 for providing slightly higher grade equipment at similar cost but would appreciate some insight into the different system sizes proposed, the 1.5 ton heat pump + 2 ton air handlers (#1) versus the 2.0 ton heat pump with 2.5 ton air handlers (#3); Also I don't know if the thermostats are comparable.


    Bookmark   June 11, 2014 at 4:53PM
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I wouldn't oversize the condensers. You can go up in size 1/2 ton with the air handlers and this usually improves dehumidification and efficiency. Just make sure the blower motors will step down the airflow to match the tonnage of the condensers, or you'll still have the noise problems you have now (maybe even worse).

Ask contractor #3 to show you why he thinks you need 2 tons of cooling upstairs (that's 1 ton per 325 sq ft - twice the usual rule of thumb). Unless you have a lot of south facing glass, no insulation in the attic, bad ductwork, and/or lousy envelope sealing, 2 tons sounds way overboard for 650sq ft.

Make absolutely certain the Honeywell thermostats control all of the features of the Trane air handler. If not, get the matching Trane thermostats.

    Bookmark   June 11, 2014 at 6:33PM
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"Vendor #3: When asked about his load calculation said that the upstairs came in at just over 1.5 ton."

I find this hard to believe. Ask for a copy of the calculation. Don't surprised he won't show it to you.

    Bookmark   June 11, 2014 at 8:09PM
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Obviously a question on the sizing of HP for second floor. I agree with Mike about wanting to see the load calculation. But I will also add that I don't want to be borderline sized for AC cooling in Durham, NC. Not certain if there is opportunity to reduce load with insulation improvements. If you want to perform the load calc yourself, I can provide a link but there is a nominal charge to use.


    Bookmark   June 12, 2014 at 6:54AM
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Hi all,

I thought I'd post a follow-up to this so future readers know how things turned out.

I didn't want to start doing the load calculations myself because I think it is pretty clear that a simple calculation would call for 1.5 tons upstairs and the 2 ton result is driven by adjustments for the particulars of the house, mostly cathedral ceilings with high windows, skylights & no attic in part of the upstairs and substantial air exchange between the first and second floor. I did talk with the 2 vendors who recommended the 2 ton upstairs units about their load calculations, explaining I wasn't interested reducing the cost, just in getting the best fit system, etc. One asked for copy of the floorplans but both got back to me later that week to say that even on further review the 2 ton was correct.

I went with the system proposed by vendor 3; 2 ton Trane XL15i with TAM7 air handlers. Install went smoothly and the systems worked great, there was a hiccup a month later where one of the air handlers failed, due to an issue with a valve not properly seated at the factory according to the technician who got it back up later that day.

Best features of the new system:
Outdoor units are much quieter than the old ones
Programmable thermostats

New outdoor units are much larger than the old ones

I can't comment on the efficiency or change to our electric bills yet since we haven't had a full month with the new units installed where we weren't also gone on vacation in part.

Finally, during the install the technicians changed some of the damper settings in the upstairs ductwork to reduce flow rates in some inconvenient locations; this helped.

Thanks for all the help!

    Bookmark   July 27, 2014 at 1:52PM
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if 5 KW heat strip on a 2 ton XL15i system, then too small to temper the air on a defrost call. And definitely too small for emergency heat. This is simply a rookie mistake.


    Bookmark   July 28, 2014 at 5:12AM
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