New Air Handler

[bill022572]

HI - I have a 4 ton Payne split system (I think 10 seer) and the evaporator coil is in very bad shape. I think my best solution would be to replace the complete system (it is approximately 9 years old). However, due to financial issues, I may have to replace just the air handler. If I could afford to replace the whole system, I would get a 16 seer and a variable speed air handler. My question is this : can I just get an air handler with variable speed fan for now and then at a later date get the matching outdoor unit ? Would this work OK ? Thanks - BILL

[air2spare]

Its not the best scenario but it is what it is. You can upgrade the airhandler only with a variable speed but you'll have to go back with R22 when you replace the outside unless you already have R410a. Replace your t-stat to a digital if you don't already have one. Is this a heatpump?

[bill022572]

No it's not a heat pump. I actually hadn't thought about the R22 and 410a deal. I know it's not ideal - just wondered if it would work. Also - I ultimately need to go to a 5 ton unit - could I put a 5 ton airhandler in and then match it with a 5 ton condensing unit later ?

[Roadhouse]

No it's not a heat pump. I actually hadn't thought about the R22 and 410a deal. I know it's not ideal - just wondered if it would work. Also - I ultimately need to go to a 5 ton unit - could I put a 5 ton airhandler in and then match it with a 5 ton condensing unit later ?

Hi there. Can I ask you what makes you believe that you ultimately need to go with a five ton and on that note, what size system do you currently have?

[beenthere]

No it's not a heat pump. I actually hadn't thought about the R22 and 410a deal. I know it's not ideal - just wondered if it would work. Also - I ultimately need to go to a 5 ton unit - could I put a 5 ton airhandler in and then match it with a 5 ton condensing unit later ?

Don't base needing an increase in size by the performance of your current 4 ton.
Your indoor and or outdoor coils could be so dirty that you are only getting 3 to 3.5 tons of cooling from it.

[air2spare]

Don't base needing an increase in size by the performance of your current 4 ton.
Your indoor and or outdoor coils could be so dirty that you are only getting 3 to 3.5 tons of cooling from it.

:ditto:...and the ductwork has to match the tonnage

[Roadhouse]

Both of these guys are correct. The ONLY way to determine proper system size for a home is to have a heat loss analysis performed on a home, not just believe that since an older 4 ton ancient 10 seer (10 seer is jurassic comparatively and hasn't been made for years now) with a rotten coil that is understandabley under performing is not cutting it any longer so go bigger. And as already said, ducts will have to match that system.

[air2spare]

And as already said, ducts will have to match that system.

and they usually don't

I would rather have a 13 seer properly ducted than an 18 seer out of wack

[bill022572]

I know there are some calc tests for duct work and tonnage size I need to have done. I wouldn't do anything without those but I'm pretty sure based on : where I live (South Florida) - my house positioning (east and west) - the amount of windows facing east and west (about 17) - and my house sq. feet under air is 2300 - I'm thinking a 5 ton. My next problem is finding a competent contractor to do these calcs. But anyway - another question about my evaporator coils. I think they are still dirty inside - even after 2 cleanings. My question is : if you take a 75 watt bulb in a drop light and shine it on one side of the coil : shouldn't you at least see some light through the coil directly on the other side ?

[bill022572]

But the ducts might be a different story. Don't know about the size of those.

[hvaclover]

I know there are some calc tests for duct work and tonnage size I need to have done. I wouldn't do anything without those but I'm pretty sure based on : where I live (South Florida) - my house positioning (east and west) - the amount of windows facing east and west (about 17) - and my house sq. feet under air is 2300 - I'm thinking a 5 ton. My next problem is finding a competent contractor to do these calcs. But anyway - another question about my evaporator coils. I think they are still dirty inside - even after 2 cleanings. My question is : if you take a 75 watt bulb in a drop light and shine it on one side of the coil : shouldn't you at least see some light through the coil directly on the other side ?

that old school technique was great for the 60s and 70s but won't work today.

Coil fins are a lot tighter and thicker these days due to the higher efficiency requirements. You'd have to have to calculate the CFM or the pressure drop across.

Why do you ask> Did you do the cleaning yourself?

[bill022572]

No - I had them cleaned but they still don't visually look clean. I can see them from under the air handler if I stick my head inside. You can still see some dirt on them. But I did watch them being cleaned and he sprayed them with cleaner 3 times and the cleaner foamed like crazy and he rinsed them a lot in between.

[hvaclover]

It's remotely possible there is still some dirt remaining. I clean coils from the inside out. That usually gets it the first time.

If you want to be sure you can have a pro check the pressure drop across the coil.

Should be moving the amount of air equal to the tonnage of ac you have.

[bill022572]

In looking at my evaporator coil more closely (I can actually get my head and upper body up under the underside of my coil - my blower motor is above the coil), I can kind of see why I am probably not getting good airflow from my vents. The coil is deteriorated pretty badly - and some of the fins were bent. I started to make an attempt to straighten them with a fin comb but they actaully started to fall apart - so I quit before I did more damage. My new question / idea is : would it make any sense to just replace the coil with a generic (maybe Aspen or Dayton) - which would probably come with a TXV valve ? I could do this for a pretty reasonable amount. I'm wondering if this would help with my airflow and possibly be a little more efficient (not a lot - but slightly).

[air2spare]

replacing a leaky coil is always good

[air2spare]

:cliff:

[hvaclover]

replacing a leaky coil is always good

for the pro, yeah:grin2::grin2: