Replace or repair HVAC system?

msa62001

9 years ago

The unit conditioning our second floor (square footage for the floor is about 1,700) is about ten years old, and has been diagnosed with a bad indoor coil. The existing heat pump is a Trane model 2ASH8048A1000AB, which appears to be 4 tons (not 100% certain).

One option we've been shown is to replace the coil for $1,800, with one year warranty on parts and labor. I've been given this model #: TWE049E13FB2, and serial #: 01841DA2V.

The other option is to replace the entire unit with these three heat pumps and prices:

4A6H5049E1000B ($7,050; 15 SEER)
4A6H7048A1000A ($7,250; 17 SEER)
4A6Z0048B1000A ($7,550; 20 SEER)

For all three proposals:
Air Handler - TAM7A0C48H41SB
Electric Heater - BAYEVBC15BK1AA

They warranty labor for one year.

My questions include:

- Should we repair or replace, given costs and age of existing unit?
- Is the current unit somewhat oversized for the space?
- The upstairs is where our kids' rooms are. We are two years away from all three being away at college, which means that demand upstairs will become much more sporadic (when they're home, when guests are over). How should we factor that into our thinking?
- What else am I not asking that I should be asking?

I know virtually nothing about all this. Hoping for some help in framing a fairly large home expenditure. Many thanks!

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Comments (5)

mike_home
9 years ago
If you plan to move within the next 5 years, then I would be inclined to do a repair. If it is going longer, then replacing makes sense since you will eventually have to a replacement.

What is your location? A 4 ton AC for a 1700 sq.foot upper floor seems over sized. I would think 3 tons would be fine.
msa62001
Original Author
9 years ago
We live in Central VA. So we get warm summers and cold winters...but neither the heat nor the cold lasts too long.

How do I factor in the fact that the second floor will be used far less in the next 10 years (the length of time I assume we'll live here) than has been the case in the last 10 years (with the kids all off to college shortly)? Should that impact how we size the system?

What about efficiency? My uneducated view is that environmental considerations aside (and these matter too), the limited demand on the system (demand will be high only when we have kids/guests at home) means it will take much longer to realize economic benefits from a more efficient system. Of course, the price differential isn't that great.

Do the prices I've been quoted seem reasonable (for the systems quoted)? What else should I ask for in the install (assuming I replace)?

Thanks again.
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Thanks all! I am learning a lot. The reason I am thinking it is coil that is leaking is because the AC guy who performed initial diagnostic last Spring used some kind of a device which looked to me like "electronic leak detector", according to the posted description. At this time, I don't have a reason to believe he did a bad job last year. He poked his instrument in different places. One of the places that (according to him) showed the "leak" was the coil (which was, by the way, located inside the furnace cabinet in the basement, not outside.) The reason I am not completely sure about the diagnostic is the following. He said that according to his instrument's reading the leak was pretty minor. That's probably why he recommended simply recharging puron. However, the puron he put back into the system apparently leaked out over the course of last summer. So maybe the leak at the coil was not so minor in the first place? Or it could be because there was more than one place where the system has a leak? Anyway, I am going to call a different company this time. Based on the info I have so far, the coil might be only part of the problem. That's why I try to keep an open mind and consider alternatives. Yes, I read that 16 SEER is a minimum rating to qualify for tax credit. My concern is that I already replaced the gas furnace not so long ago. Can I pair my furnace (Carrier 58CVA110-20) with another modern Carrier AC unit of 16 SEER or higher so that they work seamlessly together? If yes, what model would match my Carrier furnace? If a new (comprehensive) test confirms that the leaking coil is the only problem, how much I should be prepared to spend on fixing it? The company that quoted me the price of ~$1600 last Fall told me that they would have to first evacuate the puron from the system (which is expensive), then replace the coil, and then put another load of puron into the system. That's why it is so expensive, they told me. Does it sound right? I've seen quotes for complete AC system installs at around $6K. Considering what I have to spend on diagnostics and repairs anyway, plus accounting for $1500 tax credit, I figured I will end up only couple of $thousands short of being able to replace the whole AC system... Or am I missing something and the difference between repairs and replacement is actually a lot more?
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mike_home
9 years ago
The size is determined by the cooling load and not by how often you use it. If you want the upper floor to be 75 degrees on a typical summer day then, the size is the same whether you use the AC once a year or everyday.

If the AC is not being used very often, then it does not make sense to spend extra money on a higher efficiency model. You are unlikely to ever get the extra money back.

I am not very familiar with all the Trane models, but my feeling is the prices are high. The coil replacement is within the range others have posted.
udarrell
9 years ago
Your existing system is either a 10 or 12-SEER unit; they were good performing units, & a new one, especially if oversized may not produce any savings over the older unit.

A 3-Ton properly installed & setup unit should cool your 1700-sf home at your location. You can always do cost effective things to reduce the heat-gain. It is all in how well everything is design-engineered...

In fact a 2.5-Ton unit might cool it; that is only 600-sf per/ton of cooling. I cool my farm home with a mere half-ton window unit for the entire 1st floor; that's around 1200-sf per/ton of cooling in very hot & humid weather extremes.

Slightly less than a half-ton upstairs -.cooling 2 bedrooms a bath room & hallway; usually only run it for a while before going to bed unless a real hot day & night.

A 5th grader can perform that LINKED load-calc print the instructions & follow them!

Here is a link that might be useful: Free Whole house Load-Calc
udarrell
9 years ago
CORRECTION: In fact a 2.5-Ton unit might cool it; that is only 680-sf per/ton of cooling; not 600.

Replace or repair HVAC system?

Comments (5)

mike_home

msa62001
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Replace or repair HVAC system?

Comments (5)

mike_home

msa62001Original Author

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msa62001
Original Author