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Your target supply air temperature may be set just high enough where first stage is not achieving it, bringing second stage on and over shooting it. If your limit or DAT range is exceeded it should...

You will need to run new wire or you will more than likely experience communication problems. Each device will need a four conductor cable. Two for power and two for the low voltage communication...

That makes perfect sense and thank you. I was thinking in those terms as well with the only exception of, instead of reducing capacity to achieve constant dehumidification at a lower rate, we operate...

As far as moisture removal alone goes it will vary based on the above info you mentioned and the constantly changing environment. Not much to dispute there. What I was trying to understand was your...

A starved evaporator will also have a minimal to non existent dehumidification ability. Bottom line is you need a flooded coil for optimal dehumidification with some sort of reheat.
As far as...

I'm on the market for one as well. It would be great for testing air proving switches on reheat coils, setting pressures on high/ low static safety switches, testing pressure transducers, etc. My...

I definitely see what you're saying but the compressor (motor) is maintaining a constant rpm whether loaded or unloaded and pumps at full capacity when loaded to nothing when unloaded. There is no...

Response above. Wouldn't let me post if I didn't write something here :)

Any application where one compressor serves multiple evaporators, condensers, etc would require oil return provisions (digital or conventional). This is what they mean when stating "If the system...

That doesn't appear to be accurate either. The 6 degree SH is indicating that even though there is more refrigerant in the evaporator coil, due to metering device over feeding, there is still enough...

That's not true. The evaporator and air exchange heat. The air needs to provide as many BTUs necessary to boil the refrigerant contained in the coil. Flooding the coil means there may not be enough...

As mentioned, oversized metering device. In addition, it's impossible to have a lower than ambient liquid line temperature. Nothing indicates a restriction so you may want to verify your equipments...

I'd say its good :)

That's where I disagree. 5 ohms across a switch is an open to me. This is the reason why I never use continuity on meters, only Ω, ΚΩ, ΜΩ. The video is interesting. The beginning basically describes...

An open on a series circuit can be of a low enough resistance to show voltage at the load but significant enough to not "carry" current.

He reads 27 volts with one lead disconnected not both. None the less there's an open somewhere in the control circuit

If you want to measure positive pressure, say on the supply duct, hook up the + to your pitot tube in the duct and allow - to be open to atmospheric pressure. For return do the opposite. To measure...

To answer your question, none. Understanding the operation and flow of refrigerant is important and there is a misconception it appears of what a TXV does. Although TXVs aren't utilized as a...

Are you sure it's not a 410a system?
(Both lines are pretty much at ambient temperature?)

I wonder what the logic is behind that. It's not adding up in my head how it is recommended on an undercharged system to increase TXV SH setting in order to get subcooling and then magically expect...

Nice real world picture you drew. I personally don't experience that but everyone knows that's not too far fetched.

Friend, neighbor, Craigslist partner....

Are both stages operating? Is there a chance that your second stage is coming on before your first stage or the circuits are reversed? (Bottom of coil should always be first stage)

There's a difference between providing good service and being professional, from tolerating manipulative, abusive, and scam full customers. Just because they're paying doesn't entitle them to to be...

If the customer is always right, are you immediately just adding refrigerant to their systems? Most will tell you that's what their problem is.

I was thinking along the same line. More from a loss capacity aspect though

I wouldn't imagine an airflow restriction based on the 12 degree split (it would be higher, even at the higher humid conditions). Cleaning the evap is a good start as mentioned above. Check your SH...

It almost appears that you weren't at a high enough range on your meter. Sensors/ thermistors are typically in the KΩ range.

The flask would require some btus as well. The formula for anything is
BTU= lbs (per hour) x Δt x Specific Heat
So if you had 1 pound of water in a glass flask weighing 1 pound, you'd need 1 Btu...

Believe it or not the most educational stuff come from the dissection of vague questions. I think most people gain something when everyone throws in their two cents or past experiences, even if it...

Only one person has mentioned airflow so far though. There is no point in taking any of these measurements and using that formula (which doesn't have an air volume factor in it) if you can't...

Thanks, good read. Yeah I knew that, just tried to build off of been there's post. The only way we'd have pure liquid is if we subcooled the liquid to the evaporator saturation temperature prior to...

Agreed. Although I stated otherwise above.

Actually it really is. The refrigerant relies on the conditioned air to give it enough heat as much as the air relies on the refrigerant to "cool" it ( heat exchange). You will have liquid in the...

If you have a 2 pound capacity and 1 of it changes state it becomes a mixture of both throughout the circuit until additional heat can be absorbed to boil of the remaining half. When that occurs you...

So that being said, when we are measuring superheat, at the outlet of the evaporator, that 36 degree liquid would of have to become a 40 degree vapor giving a 4 degree SH and 100% vapor.

If no,...

It was, thank you.

So is it possible at that last portion, lets just say the outlet of the coil, to have 36 degree liquid with a vapor of 40 degrees?

Had to correct the above statement.

Good point, but I think what we see there is the warmer sub cooled liquid out of the condenser absorbing heat from the cooler, saturated liquid in the evaporator. The btus required for it to match...

So are you saying: A 63 psi R-22 coil with a saturation temperature of 36 degrees can have a mixture of 36 degrees liquid and 40 degrees vapor?

I'll have to start adding salt to my R-22 :)

Yes, direct contact. I assumed that was a given but then again we can go around and around on just about anything here :) Funny thing is that everyone, to a certain extent, is right in a way.

How many Btus is required to make10 lbs 32 degree ice to 40 degree water?

Before that 32 degree ice can gain sensible heat to go to 40 it MUST become water in its entirety. It must completely...

And again, that would be the ideal situation IF our pressures were dead on and at a true CONSTANT. Our thermometers were precise, and temperatures accurate.

And that's where I'm coming from. That's how the laws of physics and chemistry are set. We shoot for a "cushion" to play it safe due to all other variables in the field/ real world.

I'm sure you can, but I can only come up with all the wrong reasons. Like thermometer locations/ calibration, pressure fluctuations within the system, flow restrictions, etc.

The refrigerant in the evap coil is pretty much at saturation. It's not gaining heat to work its way up to it. If that was the case the liquid refrigerant would have to be well below the saturation...

Hurtinhvac, that was a fine visualization you gave me :)

Key word is CONSTANT. I agree with the fact that a uniform condition will not exist in a large mass, non the less one in motion, however in order to understand it you must take a uniform sample under...

Negative. Superheat is a sensible temperature measurement compared to a saturation temperature (estimated by an existing constant pressure in a heat exchanger). In order to have a sensible gain of a...