Search:

There are no requirements for agricultural spaces in the IMC. Many indoor grow facilties do not bring in outside air because they don't want contaminants and want to control CO2. That said,...

There are high-end control systems for maintaining the correct pressure relationships in hospitals, but you have to have them installed and programmed by a controls contractor. Other than that, what...

This is it. I worked for a large HVAC manufacturer during the transitions. It is all about the ability to use smaller tubing throughout the system, particularly in the coils.

Legionella can be found in many municipal water systems and that is how it gets introduced. There is not much in the incoming water, and it does not multiply rapidly (if at all) at cooler...

Ah. I missed the words "split-system" in the OP. Sorry. Unfortunately, it does not look like Carrier has a similar split system.

Not quite what you're looking for, but these Carrier units are three-stage. They have two compressors of different sizes. The smaller compressor runs for stage 1, the larger for stage 2, and both for...

One thing to check - make sure that the fan control on your thermostat is not set to "high" and always running. Make sure that it is set on "auto" so the fan shuts off between cycles and does not...

At what speed are the fans set? If they are locked onto high then you will get less dehumidification because you have a higher leaving air temperature from the unit. If they are set to high, then...

RSES.ORG, then click on access to the digital journal on the left side of the screen. You need to register, but it's very easy.

@TechmanTerry - thanks for the pointer!

You also may want to determine whether somebody programmed a top speed in the drive. I recall that at some point in my career I dealt with a low flow issue where the max frequency of the drive was...

The question can't be answered without knowing your weather conditions. Where I live, you can run 100% OA all year long with no energy penalty. In Miami, the penalty is massive.

By the way,...

It's true that the copper fins have much better thermal conductivity, but you quickly run into the limit imposed by the capability of the tube to transfer heat to the internal fluid. Typically...

Yep, another installation with the thermosyphon solar panels installed upside down. At least there will be no heat added to the refrigerant, so the units should run, though at slightly worse...

You are correct that the combination of motor, fan, and cabinet are mapped by the OEM that make the furnace, fan coil, VAV box, or other product that comes with the constant CFM motor. I worked for a...

Just out of curiosity, how thick is the insulation on the line sets? We've been having an internal debate about the value of insulation on the vapor line during heating mode.

Direct sunlight will also give a false high temperature reading.

No, it is correct for water loops. For glycol loops you need to know the type of glycol and mass % of the mix to get the new specific heat of the fluid. It will be something less than the 1 Btu/(lb X...

The 500 is derived from this:

1 Btu/(lb degF) X 8.33 lb/gal X 60 min/hr

I just realized that I may have misunderstood what you are looking for when I said to use a differential pressure transducer. Now I read this as you need to know the pressure in both ducts, but only...

I'm not a controls guy, but it seems to me that you want a differential pressure transducer, like the kind that are used in VAV box controllers. They are designed to tell you exactly what you want to...

A very slight loss in efficiency vs. the cost of ripping off the drywall. I'd bet the house will be torn down before that investment pays off.

Are you referring to where it says "rated at 300 CFM?" That' not a upper velocity limit, but the velocity at which the initial pressure drop was determined.

I worked in air handler manufacturing...

Enclosures cost money. 99.9% of customers will not pay extra for an enclosure. Hence, no enclosure. I worked for an HVAC manufacturer for years. This is the mindset.

Assuming that your filter will be 24" X 24" nominal, you will probably have a clean filter pressure drop of at least 0.2 in. wg at 425 FPM air velocity if all 1700 cfm came though the louver. Of...

Do you have the fan set to run constantly? When you do that condensate left of the fins at the end of the cycle re-evaporates. A good article on the topic here:
...

Do you have the fan set to run constantly? When you do that condensate left of the fins at the end of the cycle re-evaporates. A good article on the topic here:
...

Just curious - what is the reason for running such dry air?

The only advantage is that if you have poor air distribution continuing to run the fan will even out the temperatures in the house, at least to some degree. The disadvantage is that fan motors use a...

First, the answer to your question about ton-hours is that it is 12,000 Btu's of cooling provided for a period of one hour. It is measured with a btu meter, which is a device that measures...

It is not always true that most of the kW input of a fan is converted to mechanical energy. Wire-to-air efficiency of a small motor and fan is very low - 25% is not unusual (eg. a fan coil with a 75%...

In your original example of lifting a weight, it is true that some of the energy is converted to potential energy because the height relative to the center of the Earth increased - the increase is...

EER is the Energy Efficiency Ratio at a defined condition. This is the definition of EER from AHRI 340/360: Energy Efficiency Ratio (EER).A ratio of the Cooling Capacity in Btu/h to the power input...

A very good answer. I was going to write something similar.

The Law of Conservation of Energy https://en.wikipedia.org/wiki/Conservation_of_energy always applies, at least in the physical world in...

Fair enough, as you have already-existing hotels that have a history as you describe. Your plans do make sense in this case.

I should have mentioned this at the same time that I gave you the DOE link:

If your goal is to determine if your client can buy a smaller chiller plant, then you need to rethink that. For offices...

If this unit uses a high percentage of outdoor air, then you want a DX-DOAS unit. Essentially it looks like an RTU but is designed to cool air and reheat as you describe. Some of the brands listed...

The DOE website has all of the prototype buildings used to calculate energy savings of both ASHRAE 90.1 and IECC codes when they are updated. There is both a small and large hotel model. The...

Is it AHRI certified?

Do you mean that the water is not going into the drainpan and blowing downstream? Is the fan still running when the unit shuts off? That is, when you say, 'the unit shuts down,' do you mean the...

Assuming that the point where the water is forming is after the metering device, it's condensation. When the liquid goes through the metering device the pressure drop causes some of the liquid to...

Again, without detailed knowledge of the coil and access to a coil program that handles parallel-flow (few, if any, commercially available programs do) its hard to say. But I can say that if it is a...

These guys are full of it. Their latest claim, that the Mpemba Effect drives the savings is pure bull. The Mpemba Effect, which not all scientists agree even exists, is about the water that was hot...

I was responsible for the engineering of large coils for a large air handler company for many years. There is no simple formula. It depends on your entering water temperature, entering air...

Do an internet search for "thermal coffee carafe." Amazon has a large selection. I have a stainless steel one that keeps my coffee hot at least 8 hours. I do use it only indoors - you might not get...

I believe, but am not 100% sure that mini-split EEV’s are in the outdoor unit. Though I think they still measure superheat st the coil.

If you do this with a TXV, unless you have perfect...

The purpose of dumping hot gas into the evaporator is to put a false load on the compressor to allow the unit to run at very low loads. Normally a unit with a single speed compressor must run at full...

This is not a hot gas bypass coil. It is called a hot gas reheat coil. It is very common to have one in humid climates to do just as BBeerme described. The air is cooled to get the dew point you...

I would be surprised if it not circuited inside/outside. You want the all of the water to touch the tubes in each circuit so that when only one circuit is running all of the water has a chance to...

Assuming that the water is on the outside, I will put in my $0.02. This could be entirely wrong - I am just basing this on what we know.

First, a perfect vacuum would add less than 15 psia to the...

deleted.