New system Old line set Question

[Vanchakis]

Hi there,

I'm a newbie and have yet to find a common answer to this question. I've had three HVAC companies (Palm Desert, CA) out to price out a new HVAC system to replace old unit and I'm getting conflicting answers: Problem: My single level house (just under 2000 sq. ft.) has a 5 ton compressor (R22) but the suction line is an older 3/4" line. One tech says that getting a new 5 ton R410a compressor is perfectly fine with existing 3/4" line set with minimal efficiency loss and no threats to increased damage from line pressure. Another company says that 3/4" is too small for the above reasons, and recommends a 4 ton compressor with a 5 ton coil. I keep reading that the manufacturers recommended pipe sizing for most 5 ton units is 1 1/8", and possibly 7/8". I'm also nervous about voiding a warranty because of installation using improperly recommended existing 3/4" line set.

The problem I have is that the line set goes about 70 feet through concrete slab foundation of house and into my garage. Neither of the 3 contractors mentioned the cost of running a new line set of what I'm assuming is the proper size piping of 1 1/8".

Please let me know who is right, if the new line set is essential, and the best solution. I'm in Palm Desert, CA so I can't afford to have a brand new system that is installed less than efficient or might possibly be susceptible to a voided warranty for improper installation of a 4 or 5 ton 410a system on a 3/4" line set.

Thanks,

Vanchakis

[lynn comstock]

I live in Yuma, AZ, with a 2000 sq ft house built to 1960 standards that has single pane windows. My ductwork is not in the attic and my home does nicely with a 3 ton unit for the past 25 years or so.

Get a manual J heat load, consider improvements and you may do the job with a 3 or 3.5 ton. That will make the piping a non issue and improve the functioning of the ductwork as well. Ductwork is the biggest weakness in most homes.

See the DOE publication: http://apps1.eere.energy.gov/buildin...rica/27630.pdf
Also see: http://www.proctoreng.com/articles/better.html

[beenthere]

A 5 ton R410A on a 3/4" suction line will have more then an 8PSIG pressure loss. And a velocity of around 2,300 FPM or more. A wild guess at capacity loss is in excess of 3,000 BTUs.

Might want a load calc done to see if you really need a 5 ton.

[Vanchakis]

Thanks for the help, the systems I'm being suggested are as follows (for my budget):

American Standard 5 ton 4A7B4 13.75 SEER, American Standard AUD2 Furnace, Benchmark Coil, Honeywell Focus Pro 6000 Thermostat

Lennox XC14 5 ton, 14.5 SEER, Lennox G60UH Furnace, Honeywell Focus Pro 6000 Thermostat, ADP Coil

Kenmore 4 ton 13.5 N4A348 Condenser, Kenmore Furnace C8MPV090

Not sure which is best assuming the prices are all around the same which they are.

Any preferences on the best system would be helpful as I can only find conflicting reviews.

Thanks,

Vanchakis

[big sky hvac]

Thanks for the help, the systems I'm being suggested are as follows (for my budget):

American Standard 5 ton 4A7B4 13.75 SEER, American Standard AUD2 Furnace, Benchmark Coil, Honeywell Focus Pro 6000 Thermostat

Lennox XC14 5 ton, 14.5 SEER, Lennox G60UH Furnace, Honeywell Focus Pro 6000 Thermostat, ADP Coil

Kenmore 4 ton 13.5 N4A348 Condenser, Kenmore Furnace C8MPV090

Not sure which is best assuming the prices are all around the same which they are.

Any preferences on the best system would be helpful as I can only find conflicting reviews.

Thanks,

Vanchakis

I would say that the first thing you need to do is have a load calc done to determine what size A/C your home really needs. Just because it originally had a 5 ton doesn't mean that's what your home really needs. It's possible that a 3 or 3.5 ton will do the job just fine. Of the quotes you received, I only saw one that had a variable speed blower motor, and it was a 90,000 btu furnace for a home in CA? What were the other sizes of furnaces quoted? Find out what your home actually needs for cooling AND heating, then you can decide on a contractor and equipment. My advice for whatever you choose is to get a furnace with a variable speed blower motor. Your overall comfort will be improved along with the efficiency of the system. I would also consider a heat pump over the just straight A/C, your climate is well suited for a heat pump in the winter.

[Vanchakis]

Thanks, I'm getting the updated pricing on the variable speed furnaces as well. Any idea how much it costs to have a load calc performed?

Thanks,

Vanchakis

[aircooled53]

Hi there,

I'm a newbie and have yet to find a common answer to this question. I've had three HVAC companies (Palm Desert, CA) out to price out a new HVAC system to replace old unit and I'm getting conflicting answers: Problem: My single level house (just under 2000 sq. ft.) has a 5 ton compressor (R22) but the suction line is an older 3/4" line. One tech says that getting a new 5 ton R410a compressor is perfectly fine with existing 3/4" line set with minimal efficiency loss and no threats to increased damage from line pressure. Another company says that 3/4" is too small for the above reasons, and recommends a 4 ton compressor with a 5 ton coil. I keep reading that the manufacturers recommended pipe sizing for most 5 ton units is 1 1/8", and possibly 7/8". I'm also nervous about voiding a warranty because of installation using improperly recommended existing 3/4" line set.

The problem I have is that the line set goes about 70 feet through concrete slab foundation of house and into my garage. Neither of the 3 contractors mentioned the cost of running a new line set of what I'm assuming is the proper size piping of 1 1/8".

Please let me know who is right, if the new line set is essential, and the best solution. I'm in Palm Desert, CA so I can't afford to have a brand new system that is installed less than efficient or might possibly be susceptible to a voided warranty for improper installation of a 4 or 5 ton 410a system on a 3/4" line set.

Thanks,

Vanchakis

4.0 ton evaporator/condenser - 7/8"~ 3/8" line set
5.0 ton evaporator/ condenser- 1 1/8" ~ 3/8" line set

[Vanchakis]

I was told by a couple of the contractors in Palm Desert that the 1 1/8" suction line is not necessary with the 410a and that they usually deal with 7/8" for 5 tons, but that going with a 5 ton with the existing 3/4" line for the 410a would be very minimal loss in capacity and efficiency. The old existing 5 ton system in place had pretty low blower air circulation so I'm assuming I wouldn't want less than 5 ton?

[aircooled53]

I was told by a couple of the contractors in Palm Desert that the 1 1/8" suction line is not necessary with the 410a and that they usually deal with 7/8" for 5 tons, but that going with a 5 ton with the existing 3/4" line for the 410a would be very minimal loss in capacity and efficiency. The old existing 5 ton system in place had pretty low blower air circulation so I'm assuming I wouldn't want less than 5 ton?

They told you WRONG. 7/8" min..under 50ft. for 5.0 ton:gah:

[big sky hvac]

Thanks, I'm getting the updated pricing on the variable speed furnaces as well. Any idea how much it costs to have a load calc performed?

Thanks,

Vanchakis

In reality, the load calc shouldn't cost you a dime. In order for the contractor to give you an estimate, he would need to know what size equipment he's going to need before figuring the price. Without a load calc, he's guessing at the size, therefore you could be getting an oversized system. If it's a reputable company, they're going to do a load calc and also look at the ductwork to make sure the duct can handle whatever load is required, which they determined by performing a load calc.

[BaldLoonie]

Don't buy from a dealer who won't do a load calc. If he isn't concerned about putting in the right sized equipment, he really doesn't care about your comfort and utility bill! Of course that rules out a lot of dealers!

Minimal airflow from 5 tons? Could be a mess of a duct system :D

I wouldn't put a new 5 ton on 3/4". Not gonna spend all that money and ignore the manufacturers instructions. I would think you'd be fine with most brands at 7/8" however. .

A-S quote is a builder model A/C which is OK, their builder model is comparable to some brands' deluxe units. I don't like the 3rd party Benchmark coil. Rather see it used with a Trane coil.

XC14 Lennox is their better line of A/C. ADP coil is a 3rd party but since Lennox owns them and made in same factory usually, shouldn't be an issue unless there are warranty concerns.

Kenmore A/C is the low end model, the C4A3 is much nicer. Interesting that he is quoting 4 tons. Wonder if he did a calc and found that you could downsize. Most dealers won't go smaller without assuring themselves that the unit can cut it.

[lynn comstock]

Just so there is no confusion, is the 3/4" pipe measured OD (outside diameter)? For refrigeration we talk OD. Plumbers talk ID (inside diameter). Measure it yourself.

[Vanchakis]

The 3/4" pipe is outside diameter. I'll ask about the load calc, two contractors seem pretty definite on the need for a 5 ton without a load calc and I think their basing it on the sq ft of the house (just under 2000). They all have said the ductwork looks good, well insulated and sealed etc (attic crawlspace). I think the air flow is a little less than full because of the old furnace blower but not certain. The Kenmore guy is certain that given the 3/4" piping running into the foundation, a 4 ton would be exactly the same performance as a 5 ton. The other two are certain in their support of the 5 ton and say that the 3/4" piping with 410a is totally fine.

Not an HVAC expert but can't figure out why three major/reputable companies in the Palm Springs area can be so conflicting on their expertise. And now everyone on the forums are telling me 3/4" is useless for 4 and definitely 5 ton condensers. Hard to tell who knows what their talking about.

One HVAC guy said that a new line set would run about $1000 extra and I don't necessarily need it. All products, etc have a good warranty and all companies are telling me that they will convert to 7/8" piping as much as possible outside of the house so that it will pass code, etc. They all say that this is totally normal for pre-existing construction.

Not sure would to believe when they're all so called experts. Is there really this many opinions on something that seems pretty straightforward?

Vanchakis

[lynn comstock]

...Lennox XC14 5 ton, 14.5 SEER, Lennox G60UH Furnace, Honeywell Focus Pro 6000 Thermostat, ADP Coil....

http://www.innovation-group.com.ua/downloads/ii/ac/505367b.pdf Page 9 shows recommended piping sizes up to 50 feet for 2 to 5 ton R410A equipment. This is to help sort fact from opinion and sales rot. This is governed by laws of physics and differs little from brand to brand.

[aircooled53]

Model

File Type: pdf 32-3009-03.pdf (259.5 KB, 158 views)

[Vanchakis]

Thanks for the info, I'm told by the American Standard rep that it's okay to go with the existing 3/4" line that is under the house foundation already with a 5 ton condenser and that the only issue would be a 2% loss of performance out of 60,000 BTU's over an approximately 60 ft line. They said there is no additional risk of damage, leaking, loss of performance, with a 5 ton unit on the existing 3/4" line other than the 2% loss as mentioned. This is from two reputable, long running Palm Desert, CA area HVAC companies. The Sears guy is the one who said all of the same except I should do 4 ton condenser strictly because of the existing line size.

Not sure why the American Standard rep would say it's okay (aside from the 2% BTU loss) to go with the existing 3/4" line. The cost difference that they suggested would be to replace the entire copper line for an additional $.

I'm leaning towards the variable speed furnace option instead (SL280UHV).

[lynn comstock]

A 5 ton R410A on a 3/4" suction line will have more then an 8PSIG pressure loss. And a velocity of around 2,300 FPM or more. A wild guess at capacity loss is in excess of 3,000 BTUs.Good Guess. See the attachement by Trane.

Might want a load calc done to see if you really need a 5 ton. I agree 100%. Find a contractor who will willingly do a load calculation. If your ductwork is average, this is the time to make it better. Did you read the information in the links on Post 2?
182312

[aircooled53]

[QUOTE=aircooled53;10086062]Model


5% loss at 100ft of 3/4 and that is straight shot no 90* or bends,so your 60,000 btu H.E. 14.0 SEER unit is now 57,000btu and about 13.1 SEER

[bad install]

Is there a chart that shows the Allowable suction line diameters for Puron or R410A for a variable or two speed HVAC like the 5-Ton Carrier Infinity?
How much BTU's or energy is lost using a 7/8" diametor line compared to the recommended 1-1/8" line?

[beenthere]

Is there a chart that shows the Allowable suction line diameters for Puron or R410A for a variable or two speed HVAC like the 5-Ton Carrier Infinity?
How much BTU's or energy is lost using a 7/8" diametor line compared to the recommended 1-1/8" line?

About 500 BTUs on a 60 foot long line.

[shamgar]

all companies are telling me that they will convert to 7/8" piping as much as possible outside of the house so that it will pass code, etc. They all say that this is totally normal for pre-existing construction.
Hmmm?

[bad install]

Thank you beenthere. Is there a chart that shows that or would the chart for the single speed system be the same for a two speed?

[heaterman]

.

[second opinion]

Thanks for the info, I'm told by the American Standard rep that it's okay to go with the existing 3/4" line that is under the house foundation already with a 5 ton condenser and that the only issue would be a 2% loss of performance out of 60,000 BTU's over an approximately 60 ft line. They said there is no additional risk of damage, leaking, loss of performance, with a 5 ton unit on the existing 3/4" line other than the 2% loss as mentioned. This is from two reputable, long running Palm Desert, CA area HVAC companies. The Sears guy is the one who said all of the same except I should do 4 ton condenser strictly because of the existing line size.

Not sure why the American Standard rep would say it's okay (aside from the 2% BTU loss) to go with the existing 3/4" line. The cost difference that they suggested would be to replace the entire copper line for an additional $.

I'm leaning towards the variable speed furnace option instead (SL280UHV).


The total length of the line set with fittings? I just ran it through the Train/ AS piping program using 70 and 80 feet with 4 long turn 90 units on same level
80 feet not allowed 70 feet change to 7/8th.

If you can provide the data I wil calculate. Now is the time to get it correct, otherwise have them give you a written warranty for no compressor for ten years

[beenthere]

Thank you beenthere. Is there a chart that shows that or would the chart for the single speed system be the same for a two speed?

The piping guide book has it in it. Its not part of he install manual.

[catmanacman]

on the american standard I would not want the cheapo benchmark coil I would want the trane aluminum coil also I agree that you need load calculation, would think 4 tons would large enough , about a new line set