5 Ton Evap with a 3.5 ton Condenser

[steelerss]

Friend of mine has a 5 Ton Evap. with a 3.5 ton condenser.The house is 2800 sq. Ft. with two T-stats driving two dampers. One damper is for the upstairs and the other is for the downstairs. there's not a problem with heating the house in the winter months, but in the summer on days above 90 F the condenser runs all the time he can't get the temp below 80 F. The way this unit works is if the temp is warmer upstairs the damper will close for the downstairs so you will not have any condition air flow to the downstairs until the temp of the upstairs is lower. Then the downstairs damper will open and the upstairs will close its damper so basically means only one damper can be open at a time which bring me to my question is that why they have a 3.5 ton condenser because of lack of air flow across the coil? so they under sized the condenser with refrigerant less volumn? IF I would put a 5 ton condenser in would the evap freeze up because of choked supply? The furnace has a 20" return Need help Thanks

[Toolpusher]

First answere to your last question,,,Yes

Having a 5 ton indoor coil supplied by a 3.5 ton condenser.
The indoor coil is being starved for refrigerant.

During the cooling season it's only working at half capacity. They need a load calc. done to determine what the actual load is, and then see if the ductwork is capable of providing that amount of air.

Then have the proper size equipment installed, to match the load and ductwork.

Life long Steerler fan,

[Edited by Toolpusher on 01-25-2006 at 10:03 PM]

[a\c don]

Sounds like a really sucky zoning system.

As far as the sizing goes you would have to do a heat load on the home.

A 5 ton air handler with a 3 1/2 ton condenser is not that uncommon.

Check ARI ratings to see if you have a matched system.

If its a match and the evaporator has a TXV you should be ok but if its a fixed metering device it must be sized to match the condenser.

Hope this helps.

[RoBoTeq]

There is technically no such thing as a 5 ton evap or any specific capacity evap for that matter. Capacity is only determined by the condensing unit or heat pump capacity.

[Toolpusher]

Then why do the Mfg's make so many coils to match their own condensers ?

With your statement they would only need 1 coil for all units.

Did I mis-read something again ?

[RoBoTeq]

Originally posted by Toolpusher
Then why do the Mfg's make so many coils to match their own condensers ?

With your statement they would only need 1 coil for all units.

Did I mis-read something again ?

I didn't state that the coils don't need to be different sizes depending on capacity and efficiency of the outdoor unit, just that the coil itself does not dictate capacity.

[Toolpusher]

just that the coil itself does not dictate capacity. [/B][/QUOTE]


I'd agree with that,
But it read different from this side of the screen. Sorry.

[walterc]

A bit of a trick answer. The total capacity comes from the OD unit, however the ability to regulate that capacity can be done with the evaporator in relation to sens terms.
In my opinion a 5 ton evaporator should not be used with a 3.5 ton outdoor unit due to the fine tuning envolved and exact and consistant operating conditions.
The upstairs/downstairs dampining should be 80%/20% in my opinion for the best adjustable cfm per duct capacity usage.
I had only one system similar to this and I had to re- meter the indoor coil and reduce the blower speed to get the system to dry out the damp cave like atomosphere in the home. This was with a Trane system and their 5 ton coils as some of you know are humongous. :)
Getting with a contractor that deals with that system and can give you figures would help. Maybe they have design differences with their equipment.

[beenthere]

That could be a matched system, depending on the seer rating of the OD unit.

The system may have been designed for an 80° indoor temp.

What drive blower does it have.

Check your air flow.

[RoBoTeq]

Everyone is basically correct here. It is the manufacturing decision to put numbers in the nomenclature of the coils that messes us up in the field.

Some manufacturers use different nomenclature for their model numbers even though, aside from the metering, the coils are identical. For example; a coil rated with a 3 ton 10 SEER system may have a 36 in the model nomenclature while that same identical coil may have a 24 in the nomenclature when matched to a two ton 13 SEER system. Of course you could use the one with the 36 in the model on the 2 ton 13 SEER system, but then it would appear that you have used a 3 ton coil with a 2 ton system.

I would really like to see indoor coil model nomenclature go to alphabetical designation. That way you just match up an "A" "B" "C" etc. coil with whatever outdoor unit you are using and no one gets all bent out of shape over thinking the coil is the wrong size.

[lucky777]

I just had Trane system installed with RXC061S3HPC0 coil and 2TTR3036A condenser. Does it sound like a matched system or I'll have problems with it in a summer?

[tulsatwisters]

In a normal residential heat cool split system there are four components to consider. The air handler, condensing unit, evaporator coil and metering device. The components used must be compatible with each other, but you have to take a couple of factors into account. The total BTUH capacity and the SEER rating. Considering airflow only, the air handlers manufactured are designed to move a set amount of air in the cooling and heating modes based on a set factor per ton of cooling and heating capacities. The condensing unit BTUH should be sized to match the CFM capacity of the air-handling device. Considering BTUH In residential heating and cooling, the condensing unit should match the evaporator coil and metering device. However, the calculation must take into account the SEER rating of the equipment used. Looking at various SEER ratings for the same BTUH condensing units, there are different volumes of refrigerant for each of the different SEER ratings being moved through the system. This volume of refrigerant must be taken into account in sizing the evaporator coil and metering device. As the SEER rating increases on the condensing unit being used, so does the volume of refrigerant being circulated through the system. In order to properly accommodate this increase in volume of refrigerant, the metering device would need to be sized to supply an additional volume of refrigerant to the evaporator coil. The evaporator coil then would need to have a psychical internal area large enough to hold this increase in volume of refrigerant. We then must consider not just the BTUH rating of the condensing unit, but also the SEER rating of the equipment, in determining the proper size metering device and evaporator coil. At this point we must assume that the type of refrigerant being used is the same for each component as designed by the manufacturer. Normally the manufactures rate condensing units in BTUH or in laymen terms tonnage and in SEER or EER rating, but the Evaporator coils and metering devices are normally rated in tonnage only. This factor means that it would not be unusual to find a condensing units rated BTUH to be different from the rated BTUH of the metering device and evaporator to get the operating SEER of the system to match the manufactures SEER rating of the condensing unit. In addition, you can easily find examples of exceeding the manufactures SEER rating on a condensing unit, by modifying the type and size of the metering device and evaporator coil. Keep in mind the duct system design also plays an important part in determining the performance of the equipment used, but I have chosen to focus on the equipment only in this reply.

[lucky777]

I need word of advice. On the new Trane install I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. I just realized that this system largely mismatched. Should I request a contractor to match the system capacity or this configuration will be just fine?

[tarz]

As previously stated, this is common. Always trust your contractor.

[RoBoTeq]

Originally posted by tulsatwisters
In a normal residential heat cool split system there are four components to consider. The air handler, condensing unit, evaporator coil and metering device. The components used must be compatible with each other, but you have to take a couple of factors into account. The total BTUH capacity and the SEER rating. Considering airflow only, the air handlers manufactured are designed to move a set amount of air in the cooling and heating modes based on a set factor per ton of cooling and heating capacities. The condensing unit BTUH should be sized to match the CFM capacity of the air-handling device. Considering BTUH In residential heating and cooling, the condensing unit should match the evaporator coil and metering device. However, the calculation must take into account the SEER rating of the equipment used. Looking at various SEER ratings for the same BTUH condensing units, there are different volumes of refrigerant for each of the different SEER ratings being moved through the system. This volume of refrigerant must be taken into account in sizing the evaporator coil and metering device. As the SEER rating increases on the condensing unit being used, so does the volume of refrigerant being circulated through the system. In order to properly accommodate this increase in volume of refrigerant, the metering device would need to be sized to supply an additional volume of refrigerant to the evaporator coil. The evaporator coil then would need to have a psychical internal area large enough to hold this increase in volume of refrigerant. We then must consider not just the BTUH rating of the condensing unit, but also the SEER rating of the equipment, in determining the proper size metering device and evaporator coil. At this point we must assume that the type of refrigerant being used is the same for each component as designed by the manufacturer. Normally the manufactures rate condensing units in BTUH or in laymen terms tonnage and in SEER or EER rating, but the Evaporator coils and metering devices are normally rated in tonnage only. This factor means that it would not be unusual to find a condensing units rated BTUH to be different from the rated BTUH of the metering device and evaporator to get the operating SEER of the system to match the manufactures SEER rating of the condensing unit. In addition, you can easily find examples of exceeding the manufactures SEER rating on a condensing unit, by modifying the type and size of the metering device and evaporator coil. Keep in mind the duct system design also plays an important part in determining the performance of the equipment used, but I have chosen to focus on the equipment only in this reply.

I'm sure this cleared things right up for the HO :p

[tulsatwisters]

That is exactly why a customer needs to deal with a quality Licensed Mechanical Contracting company. The HVAC-R industry is extremely technical and complicated. Regardless of the amount of experience and training, no person is capable of knowing it all, as humans we just do not have the lifespan that would be needed. The general public for the most part has no idea of the amount of training and knowledge needed to be good at what we do. The customer, all customers need to hire an experienced professional that they trust, if you do not trust your contractor, hire one that you do and please take their advice. Being at the job site, seeing the job and accumulating all the data and being able to talk to the homeowner in detail about the job, means the contractor will know more about the job than anyone else and you should always trust what he tells you. The contractor’s job is to look out for his customer’s best interests and most do and if you choose to do so, you can always get a second on site opinion

[RoBoTeq]

tulsatwisters; I am dyslexic and getting old, please punctuate. Thanks :D

[contactor]

Paraghraphs would be nice as well. :D

[tulsatwisters]

Sorry RoBoTeq , I will try my best to do better.

[lucky777]

You can also try to make it short and to the point. I still don't understand what advantages or disadvantages, if any, for oversized coil. I've been reading that oversized coil can contribute to high humidity in the house, is it right?


[Edited by lucky777 on 01-26-2006 at 11:01 PM]

[tulsatwisters]

It is difficult to make an understandable point on a technically involved and complicated question.

The general public without at least some basic knowledge of physics, psychometrics, electricity, electrical controls, etc., may have trouble understanding, what may by necessity, be an involved answer to what may seem to a layman a simple question.

My point was that the coil might not be oversized, just because the BTUH rating or tonnage is different from the condensing units BTUH or tonnage rating. You have to take the SEER rating of the condensing unit into account.

Even with my short (to me) four-line to the point answer, I have left out a lot of data that would need to be considered. It is not a simple question.

[walterc]

lucky777-
Trane is dragging their feet in providing the new specs on the updated equipment so I haven't those answeres.
I do show the rxco coils made for the 2 stage compressor systems. The ttr units are not 2 stage but that doesn't mean trane hasn't a match for it. I couldn't tell until I get the facts sheets and software.

[Mr Bill]

Originally posted by tulsatwisters
Regardless of the amount of experience and training, no person is capable of knowing it all, as humans we just do not have the lifespan that would be needed.


Some here are not going to like that statement. :D

[RoBoTeq]

Originally posted by tulsatwisters
It is difficult to make an understandable point on a technically involved and complicated question.

The general public without at least some basic knowledge of physics, psychometrics, electricity, electrical controls, etc., may have trouble understanding, what may by necessity, be an involved answer to what may seem to a layman a simple question.

My point was that the coil might not be oversized, just because the BTUH rating or tonnage is different from the condensing units BTUH or tonnage rating. You have to take the SEER rating of the condensing unit into account.

Even with my short (to me) four-line to the point answer, I have left out a lot of data that would need to be considered. It is not a simple question.


I think this states it very well (thanks twister :D )

I keep hearing the term "oversized coil" when in fact, higher efficiency systems simply need "larger" coils to match the larger coil on the outside unit.

[RoBoTeq]

Originally posted by mrbillpro

Originally posted by tulsatwisters
Regardless of the amount of experience and training, no person is capable of knowing it all, as humans we just do not have the lifespan that would be needed.


Some here are not going to like that statement. :D

Stirring crap? Maybe you would be more comfy in a toilet.

[matt8085]

An oversized evap w/txv will certainly run at a high superheat, providing alot less cooling for compressor. Resulting in eventual compressor/system component failure.

[tulsatwisters]

Originally posted by matt8085
An oversized evap w/txv will certainly run at a high superheat, providing alot less cooling for compressor. Resulting in eventual compressor/system component failure.

The above quoted reply is a great example of the type of question or in this case statement that could take pages upon pages to respond to.
I am not necessarily indicating the statement is inaccurate, but it does encompass several different laws of physics that to discuss each in detail would take an enormous amount of time.

Just a few short examples:
1. Proper sizing of equipment
2. Type and size of the TXV
3. Latent & Sensible Heat
4. Refrigerant saturation point and change of state
5. The amount of heat loss/gain required in the Change of State
6. The amount of heat required to change the sensible heat of a Superheated vapor
7. The amount of CFM across the evaporator (As to how it effects the Sensible and Latent heat absorption of the refrigerant
8. General maintenance habits of consumers (here are just two of the items that would relate here as examples: 1. Air Filter type and replacement
2. Condenser coil maintenance
9. Compressor design and construction
10. Minimum and maximum operating conditions of a particular design of compressor

I am going to stop at ten; to the relief of anyone reading this I am sure.

A couple of other discussions could be had:
1. On what is meant by “oversized” and the amount of over sizing?
2. What is exactly meant by “a lot of Superheat”?

Again I am not taking issue with the statement, just saying it is a very good example of how what could seem to be a simple question or statement, could in fact be very complex and take time to properly discuss.
What I really like about the question is how well it points out the need for highly trained and experienced professionals.
I have always felt that the vast amount of knowledge, training and experience we must acquire to be skilled at our profession is lost on the general public.

Who would ever think it would be good ideas for NASA go down to the local fast food restaurant to hire mechanical or electrical engineers? How about a neighbor, friend, relative?

Answer: No reasonable thinking person that I know of

Who would ever think it would be a good idea for the homeowner to go down to the local fast food restaurant to hire HVAC-R engineers? How about a neighbor, friend, relative?

Answer: A large percentage of the general public

[lucky777]

I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf

I have electronic air filter. Assume that equiment will be well maintained and cleaned. All I need to know if with this type installation will perform well and last.

[tulsatwisters]

Originally posted by lucky777
I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf

I have electronic air filter. Assume that equiment will be well maintained and cleaned. All I need to know if with this type installation will perform well and last.

I do not know how many ways there are to say…….. Not enough information to give an accurate opinion.
In reading it the above, it may seem somewhat rude, but that by no means is my intention.

Providing the information below would be a start in analyzing the situation and determining if any corrective action is needed, but only a start.

Model number of the air handling equipment
Indoor and out door wet and dry bulb temperatures
High and low side pressures
Amount of Superheat
Amount of Subcooling
Total CFM from all supply registers
Supply Air temperature
Delta T across condenser
Delta T across evaporator

It is a cat chasing it’s own tail situation:

If you could provide the above information ….. That would make you to at least some degree, an experienced technician.

However,

If you were an experienced technician you would not need any assistance

The only way to resolve the matter, would be to contact a quality with references, licensed mechanical contractor for an on site evaluation.

[RoBoTeq]

Originally posted by lucky777
I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf

I have electronic air filter. Assume that equiment will be well maintained and cleaned. All I need to know if with this type installation will perform well and last.

PLEASE!!!!!! STOP stating that a coil has a capacity that is greater then what the outdoor unit capacity is. This cannot happen. What you have is a 3 ton system using a coil that is capable of handling 5 ton of nominal cooling when used with a less efficient system. IT IS NOT A 5 TON COIL!

Now that twister is posting on this subject I too feel compelled to put this issue to bed. Twister is much better at organizing the specific details of the physical data then I am so my posting here is hopefully to aide what twister is stating.

Twister; slap me fast if I misconstrue what you are stating because I like the way you put things.

[RoBoTeq]

Originally posted by matt8085
An oversized evap w/txv will certainly run at a high superheat,providing alot less cooling for compressor. Resulting in eventual compressor/system component failure.
Why would the proper TXV not control the intended superheat as a TXV is intended to do? Under what conditions would the TXV not allow more refrigerant to pass into the coil causing the superheat to increase? If the TXV sensing bulb is maintaining a specific superheat based on the temperature of the suction line out of the coil, why would superheat increase?

[lucky777]

Originally posted by RoBoTeq

Originally posted by lucky777
I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf

I have electronic air filter. Assume that equiment will be well maintained and cleaned. All I need to know if with this type installation will perform well and last.

PLEASE!!!!!! STOP stating that a coil has a capacity that is greater then what the outdoor unit capacity is. This cannot happen. What you have is a 3 ton system using a coil that is capable of handling 5 ton of nominal cooling when used with a less efficient system. IT IS NOT A 5 TON COIL!

Now that twister is posting on this subject I too feel compelled to put this issue to bed. Twister is much better at organizing the specific details of the physical data then I am so my posting here is hopefully to aide what twister is stating.

Twister; slap me fast if I misconstrue what you are stating because I like the way you put things.

Thanks RoBoTeq! This was kind of an answer I was looking for! We can put this issue to rest now.

[RoBoTeq]

This whole issue really is created by the way manufacturers designate their coils with capacity numbers. I have been fighting this for decades, to no avail. Maybe someday we will have only letter designated indoor coils. Then I can work harder on getting thermostat manufacturers to stop putting numbers on t-stats and only refer to the temperature as "Cool" (less then 65º), "Comfy" (66º-72º) and "A bit warmish" (over 72º) :D

[Edited by RoBoTeq on 01-28-2006 at 10:18 AM]

[tulsatwisters]

Yes RoBoTeq one of my points was related to the TXV as to it would relate to superheat, another was evaporator pressure, as it would relate to humidity or latent heat removal within the structure.

You are a lot better at quickly getting to the point than I am…. I am just too darn long winded and can’t seem to help it. Too old and set in my ways I guess LOL.

[BaldLoonie]

Originally posted by lucky777
I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf


The RXC line was designed for R410a outdoor units. Why is it being used on a R22 unit? Is the TXV being changed?

Looking at the spec sheet for the 3036 outdoor unit, NO R410a coil is matched nor is any "5 ton" or 060+ coil matched. We can argue all day long about using oversized coils but if Trane doesn't approve it, who knows what performance you'll get and with the improper TXV especially.

There's just so much cooling out of a 3 ton system. If someone decides to put it on a much larger coil, that coil will run warm, TXV or not. Fine in the desert but not in a humid climate.

[BaldLoonie]

Originally posted by RoBoTeq
[QUOTE]
Why would the proper TXV not control the intended superheat as a TXV is intended to do? Under what conditions would the TXV not allow more refrigerant to pass into the coil causing the superheat to increase? If the TXV sensing bulb is maintaining a specific superheat based on the temperature of the suction line out of the coil, why would superheat increase?

TXV will help when using a big coil but at some point, the surface area and load of the large coil be so great that the TXV will be wide open and still not provide a cold coil. Cool out, warm in on a big piston coil will provide outrageously high superheat. But if you have a huge coil on a TXV, that can be avoided to a point. But with the large surface area, I still can see times when there could be a superheat above what the TXV can control.

[lucky777]

Originally posted by BaldLoonie

Originally posted by lucky777
I already stated that I got 5 ton RXC061S3HPC0 coil and 3 ton 2TTR3036A condenser. RXC061S3HPC0 has High Efficiency Bleed TXV, coil specs are here http://www.aireng.com/clientuploads/Coils_etc/rxc.pdf


The RXC line was designed for R410a outdoor units. Why is it being used on a R22 unit? Is the TXV being changed?

Looking at the spec sheet for the 3036 outdoor unit, NO R410a coil is matched nor is any "5 ton" or 060+ coil matched. We can argue all day long about using oversized coils but if Trane doesn't approve it, who knows what performance you'll get and with the improper TXV especially.

There's just so much cooling out of a 3 ton system. If someone decides to put it on a much larger coil, that coil will run warm, TXV or not. Fine in the desert but not in a humid climate.

I was told that 3036 is R410a. Isn't it?

[lucky777]

This doesn't look good. According to Trane 2TTR stands for R22 and 4TTR stands for R410A. RX in coil name means that it is R410A. So much about "Always trust your contractor". At estimate time I specifically asked about R410a system and was quoted one.

[RoBoTeq]

Whoopsie...

Not being familiar with Trane nomenclature I did not even think about the metering on the coil not being compatible with the outdoor unit.

Baldy; thanks for the TXV/large coil clarification. I did put that out there as a rhetorical question. Like you stated; large coils with light capacity, high efficiency systems are fine in arid conditions but not if you need humidity control

[tulsatwisters]

People should trust their mechanical contractor and before they pick one, they should do a bit of background checking. References, licensing the BBB, etc, make sure the job includes an inspection by the city or state agency covering mechanical work.

The customer has to take on the responsibility of doing a bit of homework in picking a quality mechanical contractor.

You can find (online) more research on which coffee maker to buy, before the purchase is made, than on which contractor to use.

In the case of mechanical contractors, most of the research is done after the purchase was made, not before.

In addition you can always get a second professional onsite opinion.

There are not enough facts known.
It is like asking how much is 2+2+3+?+?+?

Answer unknown, without knowing the value of each of the ?

The only way to get the value of each of the ? Is by an onsite evaluation by a professional.

There are a lot of different issues that could be addressed in this particular thread. The discussion can be fun and interesting and maybe somewhat informative, but no final accurate diagnosis can be made though this forum on this question, hence the reason I stated more than once.

To diagnosis any possible problems, get a professional onsite (onsite) evaluation.

[lucky777]

I did the homework. This is supposed to be one of the best contractors in the area. They claim to have 2000 installs a year, been in business for 50 years, and have only 1 complaint in BBB for last 3 years. This complaint is for advertisement. Their salesmen was looking professional and knowledgeable. I'll call on Monday and try to resolve everything peacefully.

[RoBoTeq]

It is always possible that someone simply made a mistake. It happens.

[matt8085]

[QUOTE]Originally posted by RoBoTeq
There is technically no such thing as a 5 ton evap or any specific capacity evap for that matter. Capacity is only determined by the condensing unit or heat pump capacity. [/QUOTE


Every evap has a btu capcity, no? I mean I certainly wouldn't be able to use any size coil in any application.
There are btu limits on every coil<----FACT.
If the situation was reversed, and he had a 5-ton cond. unit and evap rated for 42,000 btu's he might have a more serious issue. This situation all depends on the metering device. If he has a txv rated at 42,000 btu's in a coil rated for 60,000 btu's, there's a good chance that the coil will be starved, especially under a heavy load. I agree that this depends on numerous factors. The system capacity certainly isn't determined by the evap coil, but there IS, in fact a such thing as a 5-ton coil. 5-ton, meaning the coil can handle 60,000 btu's.

[RoBoTeq]

Try to keep up Matt. That issue has been gone over every which way possible. An indoor coil is simply a container that depends on the capacity of the outdoor unit to determine what the capacity of the system is.

There are applications where a coil designated for a nominal 42,000 Btu will be compatible with a 5 ton outdoor unit. It all depends on how the manufacturer decides to designate each indoor coil. The numbers are a very basic guideline that only pertain to the nominal capacity of whatever outdoor unit each indoor coil is being designated to match and can change dramatically up or down depending on the efficiency of the outdoor unit.

[techdaddy]

Originally posted by steelerss
Friend of mine has a 5 Ton Evap. with a 3.5 ton condenser.The house is 2800 sq. Ft. with two T-stats driving two dampers. One damper is for the upstairs and the other is for the downstairs. there's not a problem with heating the house in the winter months, but in the summer on days above 90 F the condenser runs all the time he can't get the temp below 80 F. The way this unit works is if the temp is warmer upstairs the damper will close for the downstairs so you will not have any condition air flow to the downstairs until the temp of the upstairs is lower. Then the downstairs damper will open and the upstairs will close its damper so basically means only one damper can be open at a time which bring me to my question is that why they have a 3.5 ton condenser because of lack of air flow across the coil? so they under sized the condenser with refrigerant less volumn? IF I would put a 5 ton condenser in would the evap freeze up because of choked supply? The furnace has a 20" return Need help Thanks yes putting a 5 ton condenser would freeze up the coil need at least 10x 24 return duct if not more

[lucky777]

Originally posted by RoBoTeq
It is always possible that someone simply made a mistake. It happens.

Contractor will replace 2TTR3036 condenser with R410A unit. Is anything special needs to be done to the coil since it was pressurized with R22?

[walterc]

lucky777- No, according to my books,the indoor coil is a R410a coil.
The oil in a r22 system is not compatible with the oil in a r410 system.
I really hate to dig this up, but if the system was run, there is residual oil in the coil and lines from the r22 unit. Too much can shorten the systems life. Get a good parts and labor warranty on the system or ask about the possible problems to the contractor.

[RoBoTeq]

You are correct; the oil is a problem.

[lucky777]

This sucks... I'll ask for new coil and lines. Guess when I had this system installed? 1/13 and it was Friday. Tell me about bad luck...

[andserco]

IMO--On the evaporater issue, The sensible heat ratio is the only thing you are changing if you have a cond unit with one size coil vs the same cond unit with another size coil..The total capacity is the same...