Results 92 to 104 of 132
10-06-2012, 07:27 PM #92
Although I had the duct leaks identified and sealed, including my one return directly through the wall under the ahu stand, one contractor who later did a Manual J and further leak testing (in preparation for his new equipment quote) determined there is still a 17CFM leak at the return that needs to be sealed. This space under the ahu is "unfinished", that is, the wall studs below the top of the stand are not covered by drywall. The contractor who sealed the duct leaks attempted to "seal" the space with ductboard, but apparently his efforts were not 100% effective. I would guess the 17CFM of leakage would allow attic air to leak into the return.
With a less restrictive MERV 8 filter, the suction from the return would pull more air in from the conditioned space in the hallway where the return filter grill is. With a more restrictive MERV 10 (Honeywell 4") or MERV 11 (1" pleated) filter, suction from the hallway would be restricted and more air would be pulled in through the "leak" from the hot attic.
Given the poor, but constant, condition of the condenser coil, this added heat load might just be enough to trip the high pressure switch.
Does that make sense?
10-06-2012, 07:41 PM #93
10-06-2012, 10:32 PM #94
I haven't asked what their electric bills are running, but judging from the current reading on their meter, each of their last 4 bills have averaged $95 less than mine. The meters on my street were changed out for Smart Meters, one by one, all on the same day this past June, so my guestimate of their bills is based on the current difference in our two meter readings, representing almost exactly 4 months worth of usage.
I'd love to save $100 a month or so during the hottest 5 or 6 months of the year!
10-07-2012, 01:39 AM #95Regular Guest
- Join Date
- Jun 2001
- Oklahoma City
The 3 ton would be more apt to loose a little ground during the hottest afternoons, but would catch up when the sun went down. It would lead to a long run cycle which is optimum for high efficiency/low power bills. As we discussed before it's doubtful your 3.5ton unit is actually delivering 3.5tons, most AC units do NOT deliver their rated capacity. 75% of rated capacity isn't untypical, especially on the larger units.
10-07-2012, 03:41 AM #96
What do you figure the 12 hour daily cost of A/C alone should be for a 3.5 ton?
10-07-2012, 11:39 AM #97
10-07-2012, 12:39 PM #98
Now connect that concept to equipment size. It's the same concept from a little different orientation. The 4 ton pump is like installing a permanently more restrictive filter.
1600 cfm airflow requirement vs 1200 cfm airflow requirement means a whole lot more pressure on your whole system. Your "system" includes rooms, as well as duct, and all these things leak "liquid air" in humid climates. These are leaks that will never be 100% cured.
Rooms that have more supply than return will be pressurized. Like blowing into a paper bag, they will leak to outside. Blowing harder makes the leakage increase. The opposite effect occurs to areas that are return dominant, air from outside will be sucked in.
Measuring current ESP will help you understand if that increase represents no, little, or catastrophic design flaw. If the 3.5 ton fan is set at 1400 cfm, and has .5 static or above, don't go up on equipment without duct redesign and replacement.Which makes more sense to you?
CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%
DO THE NUMBERS! Step on a HOMESCALE.
What is comfort? Well, it AIN'T just TEMPERATURE!
Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.
10-07-2012, 12:45 PM #99
When I picked up the Honeywell fc40r, I returned the MERV 12's for credit, but I couldn't return the MERV 11, which had been purchased over 3 years ago in VA.
From now on, I'll use MERV 8 or lower until I get a new system with a second return.
10-07-2012, 01:39 PM #100
If you took the filter OUT, you would STILL be pulling air in through a duct leak in the unconditioned space, that difference is not tripping the high pressure switch on the outdoor unit.Always here
10-07-2012, 02:03 PM #101
Are we no longer concerned with the high pressure switch tripping?Government is a disease......masquerading as its own cureEcclesiastes 10:2 NIV
10-07-2012, 02:21 PM #102
Evidently? Kinda just fell off the table.....................Always here
10-07-2012, 02:21 PM #103
No we seem to be more concerned about merv rating on filters and avoiding actually resolving anything.
10-07-2012, 02:28 PM #104