new 13seer cond unit on older indoor unit not cooling.

[carln2591]

recently changed out straight AC unit from unit installed in '88. compressor locked up on old one, no burn out, had oil, no leaks etc..

installed new goodman 1.5 ton 13 seer unit and adjusted to correct superheat according to installation book.. checking indoor delta T was only getting 11-12 degs over the coil.. figured humidity in house was cause and let it ride.

get call back from house it not keep cool. running for hrs and house temp set at 72 and only going to 78... indoor coil is cap tube type, cleaned indoor coil before charging.. triple pumped it down with vacuum pump..

no idea what is problem.. at ODT temp and INT setting it was telling me I should have 5deg super heat.. that was giving me only 20 degrees above out side sat temp on head pressure. ODT 90 usually go with ODT + 35 for good head pressure.. on this the head is only 20 degrees above ODT.. not sure what to do..

one thing the suction and liquid lines are smaller that fitting on compressor. we did not change out line set. could line set be under sized..


thanks
carl
confused and dazed on this one.

[classical]

You need to get your post count up and apply for pre status, we cannot discuss technical issues in open forums.

For now if this is a cap tube it will not work, if it has a piston what size is the piston. It would be best to install a TXV.

[carln2591]

so a cap tube coil will not work with the new 13 seer cond. no way to install a TXV with out a lot of re piping.. maybe better to put new indoor unit/coil with TXV installed already..

thanks for your response.. not sure what a pre status is ..

[davefr]

[QUOTE=carln2591;3750172]maybe better to put new indoor unit/coil with TXV installed already..QUOTE]

You installed a brand new condensor and used a 21 year old existing evaporator coil??

[beenthere]

Need to install a new indoor cooil that is ARHI matched to the outdoor unit.

You need to get your post count ot 15 and apply for pro membership as was stated earlier.

Do it quick.

[udarrell]

A cap tube metering device on an old coil will not work.

Though it'd be better than a cap-tube feed, I wouldn't spend a penny putting a TXV on that old coil; pull it & install a new matching TXV coil with the proper airflow through it.

We should always check the indoor humidity level before making judgments about the indoor temp-split. - Darrell

[carln2591]

they did not want to replace the indoor unit as it worked fine.. suggested we give it a try and see. i mainly deal with new unit start ups and was put out during heat wave to do this replacement.

no problem I can change out the indoor unit with newer hydronic unit and take care of the problem..

this is rental property and they needed cooling asap..

any suggestions on units.. this one is apollo unit, how about first company or comfort aire.. units..

thanks for the update on pro side.. :)

carl

edit
i can just replace coil with txv type and speed up fan ?? or completely replace indoor unit.. ?

[beenthere]

You can just replace the coil.

[carln2591]

beenthere:

thanks for your help. I will check into a new coil.. this sound like FUN... thankfully the crawlspace is nice and tall and with plastic..
carl

[Willserve]

If using a coil with a txv you might have to put a hard start on that Goodman

[carln2591]

good to know..
how about if changing out the air handler with new one rated for 13 seer.. i believe they are still cap tube systems.. i see some in my johnstone supply cat..

[Willserve]

Just like Beenthere said earlier get an AHRI match. If ur going to replace the air handler stay with Goodman for compatability and warranty purposes. I think it's 10 year wty for parts if u register it. BTW replacing and matching is the best way to go and refer to install guide for line size if in doubt.

[carln2591]

i don't think goodman makes a hydronic air handler do they.. have to stay with the same system or that makes for more problems.

anywho thansk
carl

[beenthere]

First company does, so does ADP, and they have new ones rated to work with 13 SEER Goodman condensers.

[Willserve]

Sorry missed the hydronic part, may be easier just to change coil to get them cooling quick if air handler is in good shape. U should be able to use new coil later when u do switch air handler.

[carln2591]

good deal I like the first company stuff.. kinda like the apollo units, which i think first company bought the rights or something like that..

I see the use of hydronics coming back as we transation to clean energy.. they are just the thing for solar hot water systems..

again thank to all
carl

[Rhizzlebop]

Can someone explain exactly why you can't put a new condenser on an old coil? My reps seem to have trouble explaining this. I know its the case, and been so for a while, but they can't seem to verbally nail it down.

I've assumed it was due to the coil surface area not being large enough for the new coolant to get enouh heat transfer, but what is this "tube top" or whatever coil type you guys speak of? I'm just alowly engineer. We don't hear about the "type of tube" coil.

Thanks :)

[beenthere]

Most older coils designed for 10SEER systems have fewer fins per inch, so less heat transfer surface area.

Some manufacturers switched over to rifled tubing in the coil also for better heat transfer. And many older coils don't have that either.

With lower heat transfer, you end up with symptoms of a low air flow.
And you have a loss of capacity.

[carln2591]

that splains it in a nut shell. was wondering my self...

speaking of air flow.. in the new coils do you need to up fan speed as well.. I am not sure this one is running on high for AC or not.. it most likly need the fan blades cleaned as well as they get full of crap over time and push less air..

I like to power wash them at the local car wash bay :) put a plastic baggie on motor and spray like a big dog..

carl

[classical]

that splains it in a nut shell. was wondering my self...

speaking of air flow.. in the new coils do you need to up fan speed as well.. I am not sure this one is running on high for AC or not.. it most likly need the fan blades cleaned as well as they get full of crap over time and push less air..

I like to power wash them at the local car wash bay :) put a plastic baggie on motor and spray like a big dog..

carl

Airflow is always critical and if you have a coil nominally sized lower than rated capacity airflow is even more critical.

BTW you do not need to bag that motor just dry it out, a ride in the back of the truck with the wind turning the wheel is usually sufficient.

[beenthere]

Don't need to up the air flow per say.
Just need proper air flow.

[heaterman]

Warranty or lack of it ought to be more than enough reason to install a matched system not to mention efficiency ratings.

[carln2591]

that all sounds good on paper.. does goodman make a hydronic air handler you know of..??

[carbonguy]

Dont know about your area but supply houses will not warranty claims on the condenser without model and serial of coil or AHU. no match means no warranty