Hi effieciency dx units

[Hileg]

Could someone please explain how a hi effieciency dx split system is designed? Does a 4 ton 10 seer remove the same amount of latent and sensible as a 4 ton 13 seer? Is the volume of air the same for both units (2000 cfm).If I am considering replaceing my 4 ton unit with a higher efficiency unit will I have humidity problems? I know higher efficiency means the same 4 tons cost less to operate, but what is the sacrifice or is there any?

Thank you

 

[quark]

All parameters remain same except the energy consumption. What you are sacrifying is your wallet thickness, initially, but law of conservation holds good and you can again thicken your purse over a period of time.

Generally scroll compressors consume less power when compared to recips and most of the high EER(or SEER) units have these. Further, a 4 row coil condenser unit gives better performance at higher ambient temperatures and the compressor discharge pressures are lower when compared to a 2 row coil.

Happy Independence Day to all fellow Indians

 

[Hileg]

Thank You

 

[Rodale]

The total cooling capacity of a 4 ton system should be the same 10 SEER or 15 SEER. You have to look at the coil capacity to see the Sensible/Total ratio. Air flow should be 350 CFM per ton minimum. The lower the airflow the greater the moisture removal. Till you freeze the coil.

 

[sterl]

Scrolls aot recips and larger (deeper) condensers all contribute to the higher SEER. Without consideration of operating charge and certain transients of operation, on an AC system, as it applies to condensing surface: If some's good, more's better and too much is just enough.

Not so the evaporator side...Humidity is going to be effected, a large evaporator will operate at a higher suction with the same airflow, which without getting into copious detail will be accompanied by a lower dew point depression and that is largely the need in a HH A/C System

There are some who opt for 6-ton units on a 3-ton load...Effectively, the unit cycles such that it only operates 50% of the time even when its hot & humid...The interior space then goes from humid, to just a little less humid, and back to humid...And people then set the T-Stat for 64 so the damn thing has a chance to dry out the space.

And you SEER don't mean much if your unit is running 100% of the time and your living room is cold enough to age steaks...

 

[Hileg]

Sterl, I think this is more along the lines of what I have heard about Hi effiency units. I don't quite understand everything your saying, but it sounds like the higher eff. units do more sensible heat removal versus latent. And this is why the t-stat must be lowered to compensate for the higher humidity, but there goes your efficiency. Would it be safe to say that the higher effiecncy units do not operate at the normal 68# suction pressure and have a higher operating suction pressure when the return air is say 70-72 degrees F.. Would you know what that suction pressure would be? What should the on/ off runtime for a unit that is sized properly be?
Thanks for your help.

 

[Hileg]

Another question is do higher efficiency units have larger evaporators versus lower seer unit evaporators or is the larger eqiupmnet only at the condensor coil?

 

[tsaman]

Higher efficiency units ( both coils, which need to be a matched pair ) the cond unit and evap will be larger.....the higher SEER (14) will be aprox 30% larger in size than a 10 SEER. It goes back to coil surface and other factors such as compressor type, controls etc.