mixing 13 seer

Eugene Silberstein 3

Once or 10 times in a pinch.

bill phillips sr_2

What are the ramifications of mixing 13 seer condensing units with older 10 seer or less evap. coils?

don_182

The one

biggest issue for me is its not ari rated.

The other is...most company that make the equipment will
no longer stand behind the warranty if they know its a mixmatch.

And with today newer technology when it comes to surface area,variable speed blowers,two stage equipment it would be
a disservice to your customer to leave the 10 seer in place.

Now the question will it work..sure if its stright ac and
you add a expansion valve...And I'll bet you could dail in the refrigerant to be in the safe zone as well.
But...would you still be willin to go it alone when you write down that it has a 10/10 warranty on the system.

Change it all Bill..and save yourself the hassle.

Empire_2

Lower head pressure

I don't know about you men, but I am seeing lower head pressures than with a 10/10 evap and cond with fixed restrictor. Any comments?

Mike T.

don_182

Hello Mike

Me too.I guess we can throw the 30 to 35 above amb in the
same bag with the beer can cold rule of thumb.

If I may...do you have any knowledge with the honeywell T7300 thermostats on a lonworks network system?

The tstat is staying in recovery mode and I'm getting beatup
trying to figure it out.

TIA.

Jeff Lawrence_25

I saw the feild tech guy the other day

And he was commenting on 13 SEER 'problems.'

It seems that there are people out there that have problems with getting the charge right on 13 SEER equipment. I didn't beleive him. (He recommended that we charge the units and come come back the next day to verify the charge.)

I ate those words yesterday.

Gent calls me and says the installer won't come back out to fix the problems with the new unit and asks if I would. It's hot inside and out.

I get there and the condenser is making some funny noses. It's almost whistling (Kinda hard to describe the sonds it was making). I hook the guage manifold up. I don't remember the exact haed pressure, but it was about 400 plus pounds on an R22 unit. The suction pressure was about 105-110.

Attached is are a couple of full sized pictures of the recovery drum I used to get the pressures down. I had to put the drum in a bucket of ice and this is what I saw when I pulled it out. The drum was empty when I started.

Empire_2

T-7300

Don, yes on the T-7300 w Q-7300 subbase. What is the t-stat actually reading? What are the Dip-switched set for and what application are you using, exm:2sth heat/cool- Heat pump etc...If energy management is added, the t-stat can still only perform so many functions. Ultimatly the EMS decides what it want's to do.

Mike T.

Charles G.

13 S.E.E.R.

Why TXVs?
Most manufacturers recommend thermostatic expansion values (TXVs) be used with all of the new 13+ SEER systems. Why? It’s not just for efficiency. The primary reason is reliability. TXVs offer better refrigerant control that boost efficiency, and more importantly, it helps prevent flood-back of refrigerant to the compressor. Consider a properly charged AC system with a piston metering device-what happens when the indoor air filter becomes full of dirt? Airflow in the system drops resulting in colder indoor coil temperatures and a lower suction pressure.
When the suction pressure drops, a larger pressure differential is exhibited
across the fixed-orifice piston. This condition also causes more refrigerant to be
pulled through the piston. The extra refrigerant is now entering a colder than
normal indoor coil, and at this point, it’s likely the refrigerant will not gain enough
heat to completely boil off into a vapor. Eventually, this results in liquid refrigerant
flooding back to the compressor.
In that same system, what happens if the outdoor coil is dirty? The system head
pressure rises. If the indoor air filter begins to plug as well, the pressure across
the fixed-orifice piston goes even higher. The compressor now sees BOTH high
head pressure AND flood back.
Some manufacturers specify non-bleed, hard-shut-off TXVs for all of their 2006 and beyond systems. TXVs optimally regulate refrigerant flow and help compensate for pressures and temperatures that can go beyond the “normal” operating range of the system. The hard-shut-off feature helps prevent refrigerant migration to the indoor coil during shut down. If refrigerant were left to migrate, refrigerant flood back would occur at the compressor during start up. This is not a good situation.
Another good reason for using TXVs is that manufacturer’s warranty requires it. However, what’s the best reason for using TXVs? Customer satisfaction. Yes, TXVs help efficiency, but their primary job is to increase system reliability.
Think about this fact, new 13 SEER systems that do use 3/8” tubing in the
outdoor coil require up to twice as much refrigerant as older systems. Add the
use of a piston as the expansion device then the task of preventing refrigerant
flood back becomes even more difficult. Some systems use less refrigerant and
use TXVs for expansion. Both of those changes help guard against flood back
and increase system life.

don_182

Thanks Mike

It was the stat.It went into a recovery mode and would never come out.I try it on another subbase and it did the same thing.Locked up solid.
I replace it today and all is well.

It was on a two stage heat/two stage cool gas-pac.I was under pressure because this is one of our biggest account and they're having a wedding tomorrow.

The commons area is now in chill mode.

Thanks again.

Empire_2

Don, in the past

I have installed a temporary stat in the return if the problem was in the existing stat and time constraints or availability of parts was an issue. I know you were under pressure, but YA GOTTA LOVE IT! That's why they call you:-)

Mike T.

Mark_46

Mike

may ask what do you mean by 10/10?

Empire_2

Hey Mark:

10 seer Cond and "A" coil ratings.......

Mike T.

clammy

promblems i,ve seen

The promblems i have seen with using 12 /13 seer stuff with older 10 and less seer stuff is the compressors often develope promblem within a year or two and go into bypass ,mostly on scroll compressors but i have seen recro compressors also do it to but not on such a steady diet .Non of the newer 12 /13 seer stuff works with older stuff it's just the way it is you have to end up replacing everything and start all over but there arer many who take the short cut and in a year or so there shot again .As for me just tossing a new condenser on some 20 or 30 year old coils or a/h is just asking for service proimblems and is not worth even touching i let some one else do it it's not my bag just do it right the first time or don,t do it peace and good luck clammy