A coil/Condensor sizing

[plummen]

uh they did,look at the differance in coilsizes between a 10 and 13 seer! that 15 seer unit i put in last picture is a 2t [:-slaphap

[Jim Katen]

uh they did,look at the differance in coilsizes between a 10 and 13 seer! that 15 seer unit i put in last picture is a 2t [:-slaphap

Just so I have this straight, you're saying that it's ok -- and even better -- to have an oversized *condensor* coil on an AC system?

- Jim Katen

[plummen]

im saying this is where the factorys are gaining a big chunk of their extra efficiency.l cant make it much simpler than saying park a 10 seer condensor next to a 13 seer then put that next to a 14-15 seer ,notice a pattern in the size ofcoils for same tonage of cooling? [:-magnify

[Jim Katen]

im saying this is where the factorys are gaining a big chunk of their extra efficiency. l cant make it much simpler than saying park a 10 seer condensor next to a 13 seer then put that next to a 14-15 seer ,notice a pattern in the size ofcoils for same tonage of cooling? [:-magnify

And if you look into it more carefully, what you'll see is very deliberate engineering designed to extract as much efficiency as possible out of a delicately matched set of equipment. You will not see greater efficiency when a field tech simply sticks a larger coil onto a system that wasn't designed for it because Carl, down at the warehouse, told him that it would work better that way.

- Jim Katen

[plummen]

ok then explain to me what advantage the factory gains by making the A coil bigger between the 10seer and 13 seer ? im all ears ! ive got my happy face on here so enlighten me! [:-slaphap http://hyetechutilities.com

[Jim Katen]

ok then explain to me what advantage the factory gains by making the A coil bigger between the 10seer and 13 seer ? im all ears ! ive got my happy face on here so enlighten me! [:-slaphap http://hyetechutilities.com

Some manufacturers are using larger coils as part of an overall strategy to improve efficiency. That's not the only change they're making. They're tweaking many things, including fan speeds to squeeze out as much efficiency as they can from the systems. To do this successfully, they have to consider the entire installation, not just coil sizing.

That does't mean that a well-meaning field installer can simply install bigger coils on a system and think that he's making it "more efficient."

In the past, it was common for some HVAC techs to install slightly larger *evaporator* coils to improve dehumidification. This was (generally) done with the manufacturer's blessing because there was very little downside to it.

Nowadays, however, I think it's a poor idea for a heating tech to install anything other than what the manufacturers specs for the system. Maybe that's what you've been saying -- I can't tell -- if so, I'm in complete agreement with you.

However, what you seem to have been saying is, "If I slap on a bigger coil, it'll make the system better." If that's what you're trying to say, then I disagree with you.

- Jim Katen, Oregon

[Marc]

I'm with you, Jim, 100%. All this talk about contractors claiming to improve system cooling efficiency (or latent heat removal) by increasing the condenser capacity in relation to the evaporator capacity is nothing more than an enormous lapse in good judgment. The design of HVAC systems is far more complex than any post on this forum that I've read has suggested. There is no better Rx for home inspectors and contractors to follow than to simply stick with the manufacturer's recommendations and defer any issues with system design to them.

There's good contractors out there and there's bad ones. It's not good for us to stereotype other professions.

Marc

[robert1966]

I had a similar situation with the tonage being different by 1/2 ton. Great post as I have learned a lot on this one......

[rbaake]

I always get a photo of the coil & condenser data plate and try to match them later in my office with a Preston's Guide. Sometimes the numbers don't add up and I state in the report that I could not determine if properly matched.

So yes, I do check because it's easy and because I also include model and serials numbers in all reports.

But as many have said, there's no clear guidelines as to how much mismatch is allowed (I typically mention if off by more than 6000 BTU's).

BTW, the NJ standards specifically state that we do not determine sizing of HVAC systems.

Good Luck...

[plummen]

Johnstone supply catalog #197L pge 800 aspen manufacturing evap coils.

2t outdoor unit Ac3B024F1 with coil:

MVR34 36+X4 13.5 seer(3t coil and matched piston)

MVR34 36 13seer(3t coil matched piston)

MVR24 36+X4 13 seer(3t coil matched piston)

MV124 30+X4 13 seer (2.5t coil matched piston)

MVR24 30+X4 13 seer (2.5t coil matched piston)

2.5t outdoor unit AC3B030F1 with coil:

MVR34 36+X4 13.5 seer(3t coil matched piston)

MV524 42+X4 13.5 seer(3.5t coil matched piston)

MVR24 42X4 13 seer(3.5t coil matched piston)

MVR124 30+X4 13seer(2.5t coil with matched piston)

MVR24 30+X4 13 seer(2.5t coil with matched piston)

now those are just the factory reccomendations for the 2 and 2.5 t condensors from coleman/evcon which happens to manufacturer condensors and coils for many other companys.

I can type out pages and pages of which coils they say to use with their condensors to get differant efficiency ratings BY USING LARGER COILS WITH THEIR CONDENSING UNITS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

By all means feel free to contact an actual supply hose such as johnstone supply and tell them their catalog is wrong,and they couldnt possibly know what theyre talking about because their on in the business of supplying contractors who actually install and work on this equipment,they need to go take home inspector clases.[:-party]

[plummen]

I'm with you, Jim, 100%. All this talk about contractors claiming to improve system cooling efficiency (or latent heat removal) by increasing the condenser capacity in relation to the evaporator capacity is nothing more than an enormous lapse in good judgment. The design of HVAC systems is far more complex than any post on this forum that I've read has suggested. There is no better Rx for home inspectors and contractors to follow than to simply stick with the manufacturer's recommendations and defer any issues with system design to them.

There's good contractors out there and there's bad ones. It's not good for us to stereotype other professions.

Marc

maybe you should stop by an actual supply house and have them show you the factory reccomendations also mark instead of just talking about things you have know real experiance in.

here call johnstone supply 402-344-8900 and ask for rich,frank or jim franco and tell them i dont know what im talking about!

[plummen]

johnstone supply catalog 197L page 816 cased upflow/downflow coils:

CAPF1824A6A 1.5-2t coil

CAPF3642C6A 3-3.5t coil

GOODMAN COIL/CONDENSING UNIT MATCHUP CHART pge 826 same catalog

Condensor CKL18-1C use with coils:

CAUF018,CACF018,CAPF018 1.5t coils 10 seer

CAUF024,CACF024 2t coils 10 seer

CAUF030,CACF030,CAPF030 2.5t coils10.5 seer

CHPF024A2A+EEP 2t coil 10 seer

CHPF030A2A+EEP 2.5t coil 10.5 seer

Condensor CKL24-1H

CAUF024,CACF024 2t coils 10 seer

CAUF030,CACF030,CAPF030 2.5t coil 10.5 seer

CAUF036,CACF036,CAPF036 3t coil 10.5 seer

they list which size coils to use all the way up to a 5t in the 10 seer condensors to boost the seer ratings up to 10.5 in some cases.

yeah i know what youre thinking goodman is just a manufacturer,not home inspectors.

dont worry guys monday ill call the oconner co,theyre the trane/american standard supply house in omaha and get a sizing chart from them for ya also.[:-monkeyd[:-party]

[Jim Katen]

Johnstone supply catalog #197L pge 800 aspen manufacturing evap coils.

2t outdoor unit Ac3B024F1 with coil:

MVR34 36+X4 13.5 seer(3t coil and matched piston)

MVR34 36 13seer(3t coil matched piston)

MVR24 36+X4 13 seer(3t coil matched piston)

MV124 30+X4 13 seer (2.5t coil matched piston)

MVR24 30+X4 13 seer (2.5t coil matched piston)

2.5t outdoor unit AC3B030F1 with coil:

MVR34 36+X4 13.5 seer(3t coil matched piston)

MV524 42+X4 13.5 seer(3.5t coil matched piston)

MVR24 42X4 13 seer(3.5t coil matched piston)

MVR124 30+X4 13seer(2.5t coil with matched piston)

MVR24 30+X4 13 seer(2.5t coil with matched piston)

now those are just the factory reccomendations for the 2 and 2.5 t condensors from coleman/evcon which happens to manufacturer condensors and coils for many other companys.

I can type out pages and pages of which coils they say to use with their condensors to get differant efficiency ratings BY USING LARGER COILS WITH THEIR CONDENSING UNITS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I'm trying to figure out what point you're trying to make. No one has disputed that installing systems as specified by the manufacturer is a good thing. No one here would argue that those are not perfectly acceptable matches. The discussion has centered around the idea that a tech can simply install a larger coil that's *not* specified by the manufacturer and imagine that he's making the system more efficient.

Also, I've got to point out that in each case you cite, the manufactuer is specifying evaporator coils that are larger than the condenser coils. Earlier, you maintained that it was more efficient to install an oversized condenser. The information you just posted contridicts that.

By all means feel free to contact an actual supply hose such as johnstone supply and tell them their catalog is wrong,and they couldnt possibly know what theyre talking about because their on in the business of supplying contractors who actually install and work on this equipment,they need to go take home inspector clases.[:-party]

No one here has said that installers shouldn't follow the manufacturer's specs. They've said that it's a bad idea to use mismatched coils that the manufacturer does *not* spec.

[Marc]

Johnstone supply catalog #197L pge 800 aspen manufacturing evap coils.

2t outdoor unit Ac3B024F1 with coil:

MVR34 36+X4 13.5 seer(3t coil and matched piston)

MVR34 36 13seer(3t coil matched piston)

MVR24 36+X4 13 seer(3t coil matched piston)

MV124 30+X4 13 seer (2.5t coil matched piston)

MVR24 30+X4 13 seer (2.5t coil matched piston)

2.5t outdoor unit AC3B030F1 with coil:

MVR34 36+X4 13.5 seer(3t coil matched piston)

MV524 42+X4 13.5 seer(3.5t coil matched piston)

MVR24 42X4 13 seer(3.5t coil matched piston)

MVR124 30+X4 13seer(2.5t coil with matched piston)

MVR24 30+X4 13 seer(2.5t coil with matched piston)

now those are just the factory reccomendations for the 2 and 2.5 t condensors from coleman/evcon which happens to manufacturer condensors and coils for many other companys.

I can type out pages and pages of which coils they say to use with their condensors to get differant efficiency ratings BY USING LARGER COILS WITH THEIR CONDENSING UNITS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

By all means feel free to contact an actual supply hose such as johnstone supply and tell them their catalog is wrong,and they couldnt possibly know what theyre talking about because their on in the business of supplying contractors who actually install and work on this equipment,they need to go take home inspector clases.[:-party]

Plummen makes a point. But the point is not that a contractor can field engineer a coil size for a given condenser tonnage. It's that there's a misunderstanding in this thread. Noticed in the quoted table where the manufacturer consistently specifies 'matched piston'. When the piston matches and the coil is specified by the manufacturer, it's not a mismatch.

What some fellas are referring to in this thread is where a contractor has chosen to oversize an evap coil without considering the piston and what the manufacturer allows and I've known that to happen often Plummen, where I was the serviceman in the picture instead of the home inspector and, during the course of the service work, learned of the mismatched piston. I check them when I open the refrig lines in the vicinity of the evap coil because experience has shown to me that low-down, cotton pickin' contractors make that mistake often and I'm there to fix the thing for my customer.

Marc

[plummen]

matching the piston is the easy part,its listed right on the side of the condensing unit in most cases.

can everybody live with this now?

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[crandall002]

I'm trying to find specked info fro an old ruud oil fired furnace model#uobb-0950,serial# ef114 m2786 5414, can you please inform.

[crandall002]

ok how would I obtain information from the Ruud information the model# is uobb-0950 how would I get any Idea from that, in regards to the what size condensing unit I will need, the serial number is ef114 m2786 5414, and the furnace input rating is 119000, with a bonnet capacity of 9500

[Marc]

ok how would I obtain information from the Ruud information the model# is uobb-0950 how would I get any Idea from that, in regards to the what size condensing unit I will need, the serial number is ef114 m2786 5414, and the furnace input rating is 119000, with a bonnet capacity of 9500

If you're replacing the condenser and evap sections, perhaps you should look to the house and complete a J calc to figure an appropriate tonnage.

I can't tell from those numbers.

Marc

[Jim Katen]

ok how would I obtain information from the Ruud information the model# is uobb-0950 how would I get any Idea from that, in regards to the what size condensing unit I will need, the serial number is ef114 m2786 5414, and the furnace input rating is 119000, with a bonnet capacity of 9500

Don't attempt to base the sized of an air conditioner on the size of the furnace. Especially a furnace from 1986.

[Dale McNutt]

This thread reminds me of a recurring defect down here in Southern California. I'll call it 50/50 dilemma. Let's say you are inspecting a 3700 sq. ft. "McMansion from say like 2000 to 2007. Most of these have two separate HVAC systems. Most of the time, the smaller system, (let's say 3 tons) is for the upstairs. The larger system, (usually 4 tons) is downstairs. When it comes time to install the condenser-compressor units, they drop off a 3 ton and 4 ton and proceed to install. There are two pads, two pair of copper lines and two shut off boxes ready to be hooked up.

eeny, meeny, miney, moe.......The result on a number of occasions has been a criss-cross. One unit is going to end up with a smaller coil than condenser. That is why I check the systems separately. The shut-off boxes seldom have fuses lately, so the max circuit breaker size needs to be checked. If you have criss-crossed units, there can be a mis-match there as well at the main panel.