HVAC Question

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TomTank8

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A month ago, the compressor in our heat pump (~15 years old) died. We had the option of replacing the entire system or just the compressor. We decided for budgetary reasons to have the compressor replaced. Well, wouldn't you know, the evaporator coil now needs replacement. I have had three different HVAC specialists tell us three different opinions and would like to hear from experts on here as to what we should do next.
Here are the opinions:
  1. Replace just the evaporater coil. This would essentially give us a "new" system because two of the major components would be new. The warranty is only for 1 year on the coil.
  2. Replace the entire Air Handler: this option is to replace everything inside and have a mismatch with the air-handler and outside unit. The air handler would have a 10 year warranty and would cost a little more than just replacing the coil.
  3. Replace the entire heat pump: this would mean we would be out of the money we spent on replacing the compressor. It would give us a 10 year warranty on the entire system. Not sure if we have the money to do this but might be able to pull it off. I just dont like the fact that we will lose out on the money that we just spent a month ago.
In any case, please let me know what approach we should take.
 

Stuff

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It would be helpful if you answered a few questions first to clarify your situation.

Is it an R-22 or R-410a system?
Why was the compressor replaced?
Why does the evaporator coil need replaced?
Was just the compressor itself replaced or the entire outside unit including condenser coil?
Were you happy with the performance of the system when it was working?
 

Jadnashua

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The efficiency of a whole new system could be radically better than what you had...it's hard to say without knowing, and what you end up choosing, should you go that route. The design of the evaporator coil must be matched to the refrigerant and compressor, so you can't upgrade various parts without knowing what you're doing if you want it to work properly.

The second part of this is that an older system is almost certainly oversized, and a new one, properly designed for max comfort and efficiency might make things better for you overall and save considerably in operating expenses.
 

TomTank8

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Thanks for the reply.
  1. R-22
  2. I don't know exactly, but it started smoking and when the HVAC guy came out, he ran some tests and determined it was shot.
  3. Leaking bad and not keeping house cool.
  4. Just compressor was replaced.
  5. Performance was fine with the system before it broke.

I still don't understand how the leaking at the coil wasn't noticed when the compressor went bad. Would it just coincidentally start leaking when the new compressor was installed?
 

Jadnashua

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Some people only look at the thermostat to decide if the a/c is working, but it's more than that for best comfort. A properly sized unit will make the house drier with fewer temperature swings because it will run longer, removing more moisture along the way. One that is too large will cycle on/off much more, and not dehumidify anywhere near as well, affecting both comfort and longevity.

If they flushed the lines, pulled a good vacuum, and then refilled the system, that cycling might have found a weak connection somewhere. Don't have enough experience to comment further on that. If you're lucky, they can find the leak and repair it, but losing most of the refrigerant along the way is quite costly by itself.
 

DonL

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I still don't understand how the leaking at the coil wasn't noticed when the compressor went bad. Would it just coincidentally start leaking when the new compressor was installed?

Normally they put it in a vacuum and test for leaks.

If the compressor was a burn-out it contaminates the system and needs to be flushed out.

Now a days they have a additive with leak detector dye that claims to seal leaks too.

I have never used it, But hear it does work, Sometimes. It might be worth a try.

With R-22 at $100 a pound, a leak can cost big money.

Good Luck.
 

Stuff

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Some techs will attempt to fix a leak but it is more reliable (and profitable) to install new equipment.

So options 1 and 2 are both gambling that the other outside components will last. Repairs would most likely be high cost but hopefully would be less than the cost of a new system. Even with warranty you would still have the labor and R22 costs. You can ask each company what they would do if the outside coil started to leak in six months - patch coil, replace coil (parts available?), replace unit with R22, replace unit with R410a - and what the costs would be then.

#2 gets you a new motor (and heat strips) but may or may not be reused when outside unit finally gets replaced. New air handler should be rated for both R22 and R410a but may not be correct (coil/blower size, variable speed, etc.) when you eventually select a new system.

So no recommendations but you need to think about you can live with in terms of surprises.
 

Dana

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If you opt to replace the equipment, take jadnashua's comment to heart:

...an older system is almost certainly oversized, and a new one, properly designed for max comfort and efficiency might make things better for you overall and save considerably in operating expenses.

It will take some amount of analysis to get the sizing right- a Manual-J load calculation using aggressive rather than conservative assumptions on R-values & air leakage, etc. would be a good start. A RESNET rater or engineer, who is only selling the accuracy of their numbers ( and not an HVAC contractor who has other assumptions and incentives) is usually the right person to do that work. (Cost runs ~$500-800 in my neighborhood- YMMV.) Right sized equipment will run fewer (but longer) cycles which generally lowers the maintenance and improves the comfort.

With a heat pump it's likely that whatever you choose will be oversized for either the heating load or the cooling load. NC is still a heating dominated climate, but cooling loads can vary by quite a bit. Try to limit the heating capacity at the 99% outside design temp to no more than 1.4x the heat load at that temp. Undersizing it slightly (and relying on heat strips to make up the difference) would be better than a 2x oversizing factor.

I have read independent 3rd party raves about the this NC HVAC design company in terms of quality & cost of both the Manual-J and design work. SFAIK they are not installers/contractors- they are designers / engineers who can specify every duct & register for the new system if need be, but are certainly up to snuff on how to do the load calculations and specify the heat pump. I've never used them, so this is really third-hand information, but it's probably worth at least getting a Manual-J & Manual-S from them, if not the full system specification.
 

WorthFlorida

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By 2020 R-22 can no longer be manufactured or imported to the US. There are some refrigerants claim to replace R22 but most techs are not familiar with them, need to flush the system, maybe change out the expansion valve. All time consuming and after you rebuilt system is not any more efficient, maybe less.

http://www.achrnews.com/articles/127966-epa-finalizes-r-22-phaseout-plan
Contractors who have found virgin hydrochlorofluorocarbon (HCFC)-22 readily available at their local supply houses had best prepare for a drastic drop-off in such supplies very soon.
The U.S. Environmental Protection Agency (EPA) announced its final phasedown schedule regarding production and importation of HCFC-22 on Oct. 16. The order calls for an immediate drop from 51 million pounds allowed in 2014 to 22 million pounds beginning Jan. 1, 2015. Subsequently, 18 million pounds of new and imported R-22 will be allowed in 2016, 13 million pounds in 2017, 9 million pounds in 2018, and 4 million pounds in 2019. No new or imported R-22 will be allowed in the U.S. on or after Jan. 1, 2020.
 

DonL

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By 2020 R-22 can no longer be manufactured or imported to the US. There are some refrigerants claim to replace R22 but most techs are not familiar with them, need to flush the system, maybe change out the expansion valve. All time consuming and after you rebuilt system is not any more efficient, maybe less.

The last time I bought some it came from Mexico.

I got it from a drug dealer. :eek:
 
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