Hot air derriere question.

[Larry2]

Thinking my condensor unit was shot, I inquired of a vendor about buying only the condensor section of a heat pump system they offered for sale. My indoor coil is a 4 ton coil with 1650 cfm air flow according to a couple of folks who responded to earlier questions here and elsewhere. This system is from the early 90's and for an EER system performance of 10. I'm at a loss to explain why a four ton coil and blower cannot keep a 2006 4 ton R22 system happy at a performance of EER 10 or higher. I know there are some advancements in coil design that improve effective fin surface area, add rifling to the tubing and such. These enhancements were somewhat achieved with large coils in the early 90's. I'm at a loss to believe that a new condensor built in 2006 won't work with an older coil manufactured in 1992.

The reply from the seller was that a new R22 pump/condensor unit was unworkable with my existing coil. I am actually fairly astonished. My thinking is that if you blow enough air through the coil and can evaporate the requsite amount of refrigerant, who cares who's name is on the evaporator coil or what year it was made.

Here is the seller's response:



If your present heat pump has any age on it meaning more than 5 or 10 yearsold, you will absolutely need to replace both the indoor and outdoor unitbecause the newer systems won't match up. You'll lose efficiency and cause ashort life term from premature failure. No HVAC manufacturer's warrantycovers replacing just the outdoor unit unless it is to the manufacturer'smatching air handler. And even then the warranty would be subject todispute. The only way to properly replace the system is to replace theindoor and outdoor unit. We don't and won't sell just the outdoor units forheat pumps and air conditioning systems unless it comes as a factory matchedpackage. Newer equipment is much higher efficiency and that means that both theindoor and outdoor coils have much larger surface areas. Trying to match upan older indoor coil with insufficient surface area to a newer outdoor unitwill result in poor performance and refrigerant will return to thecompressor as a liquid thus destroying the new compressor in a short periodof time. That's why manufacturers do not provide a warranty for systemswhere a new outdoor unit has been matched to an older less efficient indoorunit. Yes there are sellers out there selling outdoor units only. But checkand see if those sellers have any affiliation with the manufacturer and whattheir level of experience and training are in the HVAC industry. You willfind that any factory authorized dealer or distributor is not sellingoutdoor units only. The sellers that sell boxes and have no knowledge of theHVAC industry are selling outdoor units only. But if you want to do the job right and replace the entire system we'll beglad to assist you.Thank you for your inquiry!


I feel like I've just had a dose of hot air up my derriere. I invite comments.

Larry

[Andy]

Thinking my condensor unit was shot, I inquired of a vendor about buying only the condensor section of a heat pump system they offered for sale. My indoor coil is a 4 ton coil with 1650 cfm air flow according to a couple of folks who responded to earlier questions here and elsewhere. This system is from the early 90's and for an EER system performance of 10. I'm at a loss to explain why a four ton coil and blower cannot keep a 2006 4 ton R22 system happy at a performance of EER 10 or higher. I know there are some advancements in coil design that improve effective fin surface area, add rifling to the tubing and such. These enhancements were somewhat achieved with large coils in the early 90's. I'm at a loss to believe that a new condensor built in 2006 won't work with an older coil manufactured in 1992.

The reply from the seller was that a new R22 pump/condensor unit was unworkable with my existing coil. I am actually fairly astonished. My thinking is that if you blow enough air through the coil and can evaporate the requsite amount of refrigerant, who cares who's name is on the evaporator coil or what year it was made.

Here is the seller's response:




I feel like I've just had a dose of hot air up my derriere. I invite comments.

Larry

Larry:)

I would tend to agree with him. If I fitted a new outdoor to your indoor (assuming I was able to get a good match) the risk would be with me. Remember R22 would not be available, or advisable in new equipment (probably R407c). HFC refrigerants require a different oil and the old oil flushed or removed in some way. Even if it was permitted to install an R22 unit, this unit will be out of date and old stock;)

Shop around, you might be able to buy a complete system for the price of a Trane outdoor, try Dunham and Bush, they are good quality and we are able to buy them worth the money in the UK (they are American0.

Kind Regards Andy:)

[Sir Josiah Sodd]

I feel like I've just had a dose of hot air up my derriere.

I invite comments.

Larry


Lie back and enjoy it.

Some folk would pay a lot of mony for that.

As for that old condenser, what's the point of throwing good money after bad?

Stick with the hot air, dear boy.

[Larry2]

It was my intent to stay with an R22 condensor unit. That is the system that was offered for sale on eBay. I inquired about buying only the condensor unit only. I think R22 will be available for another several years and unless the system leaks, it won't need refrigerant anyway.

My reasons for wanting to keep my indoor coil are not only the cost but also the inconveniance involved. The coil was installed in the attic when the home was under construction. To swap the coil now, the attic would need to have floors installed for workers to carry the air handler across. The ceiling would have to be cut out and later patched to carry the old unit out and the new unit in.

[Andy]

It was my intent to stay with an R22 condensor unit. That is the system that was offered for sale on eBay. I inquired about buying only the condensor unit only. I think R22 will be available for another several years and unless the system leaks, it won't need refrigerant anyway.

My reasons for wanting to keep my indoor coil are not only the cost but also the inconveniance involved. The coil was installed in the attic when the home was under construction. To swap the coil now, the attic would need to have floors installed for workers to carry the air handler across. The ceiling would have to be cut out and later patched to carry the old unit out and the new unit in.

AHU's are usually made in sections, never thought that the indoor would be all one piece:confused:

What you need is an indoor that is really a mini air handling unit, one that can be assembled in sections in the roof space.

As for R22, we can't install R22 systems over here and I know that the restrictions are in the US also;) you may not be breaking the law, but enviromentally this is a no no:(

Kind Regards Andy:)

[Larry2]

Andy, the first air handler installed here was for an inadequate 3 ton system. Actually, I'm thinking back now it was a 2-1/2 ton unit. It was lifted between the ceiling joists with exta help sent to the job. At the time, the house was under construction, so no ceiling was in place. They pass the unit up between the ceiling joists. I wasn't here when that unit was swapped out for the current larger one. I believe this one was also carried in as one piece. The electric heat backup elements were later added as a separate kit. Of course the plenum is fabricated and attached later after measurements are taken.
http://i6.tinypic.com/1z190sl.jpg

These air handlers are sized to just fit through the 24" joist centerline spacing used as standard roof construction here in the US. They pass by with about 1/2" to spare. Once the access stair is installed, the unit isn't coming down from the attic in one piece without demolition. The drop stairs would need to be removed and the large crew brought in. Sections of the attic are not floored, so carpentry would be needed as well.

Here in the US, HCFC-22 is being phase out with a goal of 65% use reduction by 2010.

http://www.epa.gov/ozone/title6/phaseout/hcfc.html

After 2010, HCFC will be available only for use in equipment manufactured before 1/1/2010. There is plenty of this old technology being sold. Some home owners are quite disappointed to discover their contractor installed complete new systems with HCFC22. One must carefully read the contract before signing. I recently bought a window a/c and a shop dehumidifier from the appliance shop. HCFC22 was installed in both. I don't think you would find these in R410 yet. HCFC22 is still a very popular refrigerant here.

I understand what you mean about environmentally sound use. I have been studying the EPA 808 certification exam materials with a mind of learning how to do this equipment exchange myself and by the books and to obtain my certification status. These are hermetic systems, the gas is not lost in signficant amounts, expecially if soldered connections, not quick-connects are used. When I worked on home a/c systems in the late sixties, it seldom we found a problem was due to leaks or low gas. It is illegal to vent refrigerant to the atmosphere here and mostly this law is followed. A home owner can call about a contractor caught venting and the fine is high. When I had a refrigerator compressor fail, the mechanic captured all of the refrigerant in my presence. The procedures now are to reclaim and recycle for future use. We are pretty good about that here in Maryland. If you bring any appliance to the recycle center, there is someone there who will reclaim the gas before it is scrapped. I think the big discharge of these refrigerants now is through commercial units where it escapes through compressor shaft seals. Those units are covered by very loose laws for topping off leaking systems when they should be repaired or scrapped. I cannot vent 1/2 PSI residual from a home system, but a large user with 50 pounds can legally loose a lot of the charge, fill it up and just document the unit was serviced with 20 pounds more charge added. Perhaps this is because government owns many of these large systems?

Anyway, my thought was to replace this undersized and aging condensor unit with another hermetic system that uses HCFC22. These will be available until 2010 and parts or refrigerant will be around even longer. It's my belief that the evaporator coil, blower and the metal plenum box don't wear out nearly as quickly as the compressor and it's control bits. A larger fresh condensor would correct my undersize issue and keep me going until perhaps 2025, at which time it would be time to scrap it all. If the gas doesn't leak out because of proper soldering connections and it is reclaimed in the end, does it really present any environmental issue? Perhaps less of an issue than scrapping servicable gear.

My thinking is that a new R22 four ton condensor would connect to the 1992 or so dated R22 coil and blower and work without complaint. It may not stack up at an energy rating of 13, but the old system was EER 10, so it should be somewhere between.

I think the cost will be around $1500 for a fresh condensor. A system rebuild would involve ceiling and wall repairs, associated painting, sheet metal work from a mechanic who fabricates plenums, and perhaps new pipes to be absolutely sure no oil contamination remains behind. I bet that will cost me more than $5000 if the pipes are exchanged too.

I'm also thinking about how forgiving R22 gear is for cleanliness and workmanship. The R410 systems need to be soldered with inert gas, properly vacuumed out, and keep hospital clean or the owner encounters early failure without ever knowing someone is to blame. I've seen many R22 systems go for fifteen or twenty years with no evacuation, when a quick tank purge through the lines was standard permitted practice during comissioning.

[The MG Pony]

R-290 is nearly identicle to R-22 with better discharge temps and nicer head pressure ;)