Iv`e got a different guy coming out to test.
Please reply with all the questions I should ask him
Before he comes out,ask If he can test/measure the ESP(external static pressure) of the furnace.
Many can't and if you say ESP,and he's not sure what you mean,he's one of them.
He may not have the fan data for Carrier,best to ask about that as well.
The chart includes .1 for a factory type filter,he will need to adjust for this ,if it has a different filter.
Test points are entering and exiting of the furnace,The exiting point is between the furnace and the coil.A/C needs to be running(wet coil) during the test.
I am just giving him the benefit of the dought his duct system is half way decent.
Originally posted by dash
Testing Total external static of the furnace ,is the only way to know .If it's .8 or above ,the -12 is the better choice,.7 or below the -08 is the better choice.
If he has a TESP of up around .8, he might have heat rise problems on top of his other problems.
We will not know until he has a competent contractor who can evaluate his sytem correctly, and report their findings.
Just for air flow sake I have 7-6inch and 1-8inch (8inch heats basement in winter any other time it is closed) flex duct coming off of the trunk.
If I were to have the installer put the matching 2ton inside unit in would it be able to feed all of my ducts?
BTW - If I have hime put in the correct unit what is the model # of the unit?
7/ 6 inch ducts is only going to give you about 560 CFM. You need 750-800 CFM. If you keep your 8 inch duct open, you will gain another 180 CFM which will give you a 740 CFM capacity. This will barely get you there. This is assuming you have a TESP of .5 in your system.
The correct furnace would have a -08 designating a 2 ton blower. Whether you need a 45,000 BTU or a 70, 000 BTU can only be determined with a load calculation.
Wouldn't a setup like this totally kill any latent removal?
High cfm greatly reduces latent capacity.
The only way to tell what cfms you have today,is to test and/or measure.Then you'll know which furnace is the better choice.
should I have the guy put in the correct unit
I had mentioned earlier that I have 7/6inch ducts and 1/8inch duct. I am able to disconnect the 1/8inch duct and remove it. It is not necessary since I added it to heat my basement (which really doesn`t work anyway)
With only 7/6inch flexy duct to feed ,the longest being about 20ft.. from the trunk. Should I have the installer put in the 2ton rated inside unit and be done with it?
...or could there be some advantages of having an oversized inside unit.
One disadvantage of having the larger inside unitis is that the system is loud and the air blows pretty hard out of the registers ...even when jumpering the blower to the lowest speed.
The best HVAC systems that I have seen have been silent and comfortable.
[Edited by eisenberg on 06-30-2005 at 02:44 PM]
You can have a quiet, comfortable system. But, before that happens a few items need to be addressed.
The duct system is woefully inadequate. You have about enough duct for a 1.5 ton system. BTW, I'll bet your present system sounds like a jet.
If you stay with 6" flex you should be seeing about 9-10 runs.
Get the system reconfigured with matching components.
Best of luck...
made an appointment
I would prefer to have the guy install the correct system.
I have scheduled to have someone come by Tuesday afternoon and will update this thread with his findings
so on the unit he has, whats the airflow on low and medium low at .5"? Can he not get that down to 800 or even 850 cfm? I better look it up.
Oops I see madinusa already looked up medium low. How about low?
If you could look it up for me that would be great.... let me know if you need any info about the house or HVAC equipment
edit I do not know for low
...all I know is that there are three settings
red - low
blue - low-medium
black - high
...as far as cfms...i don`t know and do not have the manual w/ me
[Edited by eisenberg on 06-30-2005 at 03:07 PM]
I cant find it.... Made or Dash can post the low speed tap info. I'm betting not only the drive is oversized but the heating capcity is probably to much also. I cant imagine much over 50,000 for that house. Obviously we need to know the true load calcs.
oops, maybe that furnace only has 3 speeds. sorry for not knowing that model number, must be a basic 80%.