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Relative humidity as a metric is more valuable for its effect on materials than regarding indoor human comfort, although it has its uses for the latter. That said, dew point and wet bulb are...
Type: Posts; User: Shophound
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Relative humidity as a metric is more valuable for its effect on materials than regarding indoor human comfort, although it has its uses for the latter. That said, dew point and wet bulb are...
Yes, thanks for the clarification, and good to be around here again, Teddy. :)
I had indoor target dewpoint transposed for supply air dewpoint. Ideally supply air dewpoint should be <50°F.
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Here's what I'd do if I were your tech analyzing your HVAC system's performance within a dehumidification context. With the system running (ideally for some time) I would measure the temperature and...
A dehumidifier that first chills the air to dehumidify it, then reheats the air before sending it onto the house, could potentially raise interior air temperatures higher than desired. There are...
The sling psychrometer is only accurate if used the correct way, which few folks know how to do. There's a time element as to how long it should be swung around, as well as a speed factor as to how...
"Add alcohol to and spin around"? The tech used a sling psychrometer? There's a large margin of error with those things; and if he added alcohol to the wet sock vs. distilled water, he won't get good...
That only confirms what I said in my previous post. Short of forced air ventilation, natural convection ventilation will not lower attic air and surface temperatures very much. There simply is too...
Ventilating an attic via natural convection on a hot, sunny day while dark colored composition shingles remain on the roof will never significantly lower attic air temperatures, nor attic structural...
Do you have a drywall ceiling below the attic over the garage? If so, consider insulating above the ceiling. And if that west facing brick wall is exposed to the garage, consider insulating that as...
Atlanta, Georgia? New house? I'd do two things: pay a LOT of attention to detail on the house building envelope. You want minimal air leakage through the shell and you want consistently applied...
Since the capacity and amp draw decrease occurred on the hottest two days of the year, and although you did not hear a "hiss" at the compressor but rather a "growling" sound, I still think there's...
If your upstairs system handled the humidity just fine last year, but not this year, your upstairs a/c system may need service.
Apartments can be notorious for pulling air in from adjacent units, especially when building cavities are used for the return air path. I once had an apartment where every time the neighbor cooked or...
I agree with Teddy Bear in that it would be helpful if you post temperature and humidity levels in your house.
What also might help is if you can somehow measure how long the system runs. Due to...
Link to my article: https://www.rses.org/assets/rses_journal/0718_Psychrometrics_022_025.pdf
When a compressor goes into "bypass", it recirculates some of its discharge into the suction in order...
How can the tech not catch the blower not moving any or too little of air? Oh...wait...because too many techs don't have enough of a good understanding of proper air flow. Silly me for even asking...
Thanks re: avatar. I teach psychrometrics part time and I published an article in RSES Journal this month on how to use it on service calls. I've found knowing psychrometric principles to be a huge...
On the two days of your upstairs unit with anomalous kW readings, the compressor may have been going into bypass due to excessive head pressure (dirty outdoor condenser coil and/or excessive outdoor...
If TESP is too high it is usually due to restrictive duct work on the supply or return sides, or both. Supply runs tend to be the worse of the two potential culprits, due to the amount of ducting...
A cardboard box slows down the ability of a capacitor to reject heat, as the cardboard material itself does not conduct heat nearly as well as the metal shell of the capacitor. Leaving the capacitor...
Hate to say this, but going by your description, they did not measure static pressure correctly. In a furnace, the probes should be placed after the filter in the bottom and BEFORE the evaporator...
OP said his EEV is disabled (which I find incredibly strange why a tech would do that), which if true means it's likely flooding the coil with refrigerant. Air flow is likely below nominal in his...
The first thing I would want established is how much air the blower is actually pushing through the cooling coil. Without that information, all diagnostic efforts are not much better than taking...
I generally do not recommend blower speed changes without a simultaneous evaluation of the refrigeration system to ensure it is optimized for the new blower speed. This circles back to my last post,...
It makes perfect sense. I never have a problem with owners of equipment and systems wanting to more deeply understand how they function. The caution is when you do hire someone after you've done a...
Aside from heat gain into ducts running through attics or crawl spaces, other ways you can have uneven supply temperatures room to room is if there is an uneven mixing of air leaving the cooling...
Blower door folks come under two possible titles: energy rater or auditor, and home performance specialist. Some HVAC contractors also do blower door testing, but not many. It's worth investigating...
You're the man...evaluating psychrometric matters via dew point! I wish every HVAC service tech would learn its value as you have.
What you're likely witnessing with your house is what's called...
Whenever I run trends like this I like to compare the actual performance to a set point. I notice you had temp and humidity set points toggled off. It took me a bit to decipher those graphics to see...
Why the high temperature set point (82 degrees)? Your system won't run long enough at that high of a set point to dehumidifiy the house. Extended run times dehumidify, short run times do not....
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These graphs are from my own system a few years ago during a four hour pull down on a greater than design day. Note on the graph where total, sensible, and latent BTUH are...
If you're asking me how I'd attempt to make that mess a bit less of a disaster, the first thing I'd do on the return side is remove that dinky plenum with three return flex ducts diving into it. I'd...
Good catch. Thank you. In general, what I stated above I've found to be true, but leave it to an OEM to change things up! :gah:
That model of supply grill is better than the two way stamped steel version. If you have a two stage system, there's a trick to charging them properly. The system should be in second stage when...
There's a shipload of wrong with that duct system. And to think I was under the impression that ductopusses only lived in attics. No, apparently they also like comfy, roomy mechanical rooms! :eek2:
In my experience, efficiency and comfort need to strike a balance. Too often I've seen efficiency reign supreme at the expense of comfort, which in reality means you run the a/c into the ground to...
You haven't really said what ducts are sweating, or where they are located. Photos might help.
When the compressor is off, is the indoor blower also off?
Assuming that is the case, is the living room on the same floor as the master bedroom?
Assuming that is also true, the bedroom has...
Floor based supply diffusers are often poorly placed and chosen. I prefer a bar grill type that will throw the air mostly up with a slight spread vs. the very common stamped steel type that divert...
You are correct on paper. There's always a bit of slop in the real world to our paper ideals. I extensively data logged my own system earlier this week: had 54 degree dew point at the return, 52...
With the boots along an interior wall vs. exterior you will have a shorter duct run, which equates to lower pressure drop.
Aiming supply jet to throw along ceiling assures a longer throw, and...
The only way to eliminate the a/c as a culprit is to have its performance evaluated. If I were to stick one of my psychrometric probes into the supply plenum of the unit and find it delivering a dew...
If your master bedroom ceiling is flat (at 8' height), and you want to use adjustable curved blade one way ceiling supply registers, you could consider using two boots along an inside wall throwing...
With all ducts in conditioned space yet warmer supply air temps at outlets further away from air handler, if I was on site at your place, and if having ruled out duct leakage as a significant factor,...
You may be right that the return ducting is sucking in hot, humid air. Many times this can be the culprit for poor humidity control from the a/c. There are other causes, also, but that's a good place...
You need to fix the house. No silver bullet with hvac controls and systems. House and hvac must cooperate, not obfuscate. Check out http://energysmartohio.com/ for more information and free chapter...
We have rodent, amphibian, and reptile rooms at our campus where I work. All of them use 100% outdoor air systems.
If you're serious about getting this right, take your needs to a mechanical...
Sounds like compressor surging brought on by lower evap temp due to lowering chilled water set point but not lowering tower water temp. Run tower water colder if you can to see if unhappy noise goes...
Metal adjustable curved blade for ceiling registers and adjustable vertical bar registers for walls is what I prefer. For flat ceiling applications I will adjust the blades to throw the air along the...
I wouldn't accept that work. I would specify the return trunk be as close in dimension to the grill dimensions as possible. At minimum, if the duct must be round, there should be a transition from...