Heating Help

envelope 2

@ February 6, 2012 5:17 PM in heat pump vs. warm air furnace

As previously mentioned, the cause of dry air on forced air systems is because of the increased infiltration that is caused by the pressure differentials created by moving the air.
It has nothing to do with the heating air temperature-heat does not rid air of it's moisture content, only the ability to absorb it. The other factor-one that directly affects comfort is the influence of MRT (mean radiant temperature). In a forced air system the walls and ceiling stay fairly cool and absorb additional heat from the air during the off cycle, thus requiring an elevated thermostat setting to maintain the same feeling of comfort. The less cycling that is going on will result in better comfort, and the newer heat pumps with variable capacity do a good job of this.

Flash bulbs

@ July 20, 2011 9:34 AM in Tale Tale

Another trick is to use an old fashioned flash bulb-remember those? I used to keep a supply with wire leads soldered on for those systems where the culprit is elusive, such as older Carrier chillers.

Dye

@ July 14, 2011 6:04 PM in Finding a leak in chiller system

Yes, your water treatment contractor would know what to use. Plain old food coloring would work for a small system.

Bunk also

@ July 2, 2011 11:05 PM in hype, bunk, or for real?

This is a simple "duty cycler" device that turns the compressor on and off during the unit's normal on cycle. These devices were popular among shysters during the Jimmy Carter years. Destroyed a lot of equipment. Even saw the aftermath of having one applied to a 500 ton centrifugal chiller-broke the slot insulators in the motor rotor. Of course, the individual responsible for destroying a $150,000 piece of equipment had arranged to have no liability. Unfortunately we will see more of this as energy costs rise. To put it in simple terms, energy efficiency is the practice of moving BTU's from point a to point b using the least amount of energy. Nothing magic about this.

overcharge

@ July 2, 2011 10:51 PM in Goodman 410 Problem

Sounds like an overcharge condition. When the TXV goes full open some of the charge is in the evaporator, thus reducing the overcharge in the condenser. The best way on these small systems is to weigh in the charge.

Subcooling

@ June 24, 2011 10:12 AM in Trane chiller issues

Be careful with taking too much stock in liquid subcooling readings. Water cooled equipment has limited capacity for subcooling the liquid, because the amount of subcooling can never exceed the condenser approach temperature. Water cooled equipment will normally operate between 5 and 10 degrees approach on the condenser at full load; even less at part load. Charging should clear up the sight glass plus a few pounds for a chiller of this size. Your numbers point to an overcharge. Head pressure should be the saturation pressure of the leaving cooling water, plus a little for approach.

Wastewater

@ June 22, 2011 4:47 PM in high volume air vents?

Golden-Anderson makes air vents up to above 4" size. We use them on large chilled and process water systems.

Heat recovery

@ June 13, 2011 8:29 PM in waste heat recovery

There are many ways to recover waste heat from a refrigeration system. Heat exchangers on the hot gas leaving the compressor would be first choice. A heat exchanger on the spray water could be used for low grade heat. All of these are standard devices-not normally used because energy has been too cheap and the first cost usually rules.

Research

@ June 1, 2011 7:23 AM in Is "Stoichiometric" combustion possible?

All joking aside, it's theoretically possible, but not even in a lab can it be done. To have a purely stoichometric burn, it would require each fuel molecule to combine with an oxygen molecule. Not going to happen in "real life". The closest I have seen on large boilers is O2 at 2.5%, before making copious amounts of CO. The new Miura burner design comes close, with mixing vanes in the gas/air duct ahead of the combustion zone. Oddly enough, duct burners utilizing fresh air firing with O2 at more than 10% make lots of CO because of flame cooling caused by too much excess air. I have learned that it's best to leave the setup on the lean side, so changes over time don't cause a dangerous condition. The old fan/premix burners should have come close, but again suffered from flame conditions and required much excess air to burn without making CO. All that being said-much progress has been made for efficiency. The trade-off is higher complexity and shorter lifespan.

Dielectric

@ May 19, 2011 1:41 PM in Dielectric nipples

The dialectric nipples are simply nipples that have an interior non-corrosive liner. The premise here is that they prevent any erosion/deposition from the area closest to the difference in chemical potential. Dialectric couplings and other insulated assemblies do not prevent the action of electrolysis, because both sides of the assembly are grounded to the building structure. We use copper to brass or bronze valves all the time and have never had a problem. Don't see a down side for using dialectric nipples, except for the expense, and another threaded joint to leak.

Odorant

@ May 19, 2011 12:08 PM in Why is LNG getting such a bad deal?

Forgot about that-the gas in cross-country pipelines and that derived from LNG has no odorant. The Mercaptan is injected before the gas travels into the local distribution system. Perhaps one of our readers can chime in and educate us about this process. The company I used to work for blew up a penthouse on a hospital in Kentucky by purging a gas line while waiting for the odorant to appear-problem was that the utility had run out of mercaptan and were not adding it at that time...they even admitted that fact in court.

Dry

@ May 18, 2011 5:31 PM in Why is LNG getting such a bad deal?

As Tim said, LNG is simply liquified methane, which is a cryogenic. It is stored as a low pressure liquid at about 15 psi, the vapor that boils off due to heat absorption is drawn off to keep the pressure at this level. The only problem I know of, aside from having to deal with the extremely cold temperatures of the liquid, is that the liquefication process leaves only pure methane, and all of the hydrates, oils and other impurities are removed. A lot of dresser couplings are used as repair devices for underground pipes, and the use of methane that does not contain the oils causes the gasket material to dry out and shrink. This has caused several high profile gas explosions in the last few years. As far as safety goes, the release of methane into the atmosphere is no different than a normal gas leak-it will dissipate since it is lighter than air. I went to an LNG school when I was a firefighter, and one of the training aids was to release 3,000 gallons of LNG into a pit and light it, quite a fire but no explosion. We actually put it out using dry chemical. We transport liquid nitrogen and other gasses as a cryogenic all the time with little problem. No reason LNG should be any different.

Excellent idea

@ May 11, 2011 7:44 AM in Capture AC heat for DWH

I have used a homemade hx for domestic water preheat for over 20 years. Most of the time it provides 100% of our domestic hot water heat. The only caveat is that you must have a preheat tank rather than using the existing water heater-it's hard to add heat to already hot water. For best results use a small circulator to pump a loop through the hx and preheat tank, controlled so that it operates when the ac is in operation.

Pressure drop

@ May 11, 2011 7:21 AM in Water heater problem

The domestic water pressure is probably falling when water is released, causing the contents of the expansion tank to backflow through the water heater and back up the cold water inlet. You could install a check valve in the cold feed to the water heater to stop this.

Drum level

@ May 1, 2011 12:22 PM in water thermal expansion & pressure

In large boilers the drum level will rise on a drop in pressure-not because the water has expanded, but because steam bubbles in the tubes expand and displace the water. This is why process boilers are so prone to trips on low water. When there is a large draw of steam, the pressure will fall and the drum level will rise-then the combustion controls catch up and the pressure rises again and away the drum level goes. Water in a closed non-expandible vessel will exert infinite pressure when it expands due to temperature rise. Of course there is no such thing as an infinitely rigid pressure vessel. Synthetic quartz is made in just such vessels and the expansion of heated water drives the pressure up above 80,000 psig. In most cases in hydronics, there is enough air trapped in nooks and crannies to limit hydraulic pressure to more reasonable levels.

Fans

@ April 24, 2011 2:40 PM in It must have been that way for YEARS!!

I have , on more than one occasion, after being called in to see why an area is too hot in the summer, found the AHU fan running backwards. One instance, on an Army base had been that way for 15 years. Another favorite is swapped zone thermostats, and in one case found the temperature controllers for a hot/cold deck multizone unit swapped. Some of the worst are when the facility contracts with the temperature controls vendor for a lump sum service contract. In this scenario, any work that gets done costs the contractor money-so they just don't maintain anything. I fear that troubleshooting skills are going to die with my generation....

capacity modifiers

@ April 20, 2011 4:47 PM in TXV capacity

1. Differential pressure across the TXV.
2. Subcooling of the liquid.
3. Superheat at the coil outlet.0

ideal gas

@ April 15, 2011 9:52 PM in expands

Refrigerant gasses behave as an ideal gas, i believe; that is they will expand to the ratio of the absolute temperature ratio. The gas leaving the compressor is heated by the heat of compression and by the motor in a hermetic compressor. In a condenser coil, the pressure is that point at which the gas turns into a liquid. This would be the condensing temperature, and the pressure would correspond to the saturation temperature of the refrigerant. If non-condensables are present, then the pressure will be higher than the saturation point, but this would be evident only if accurate temperatures are known. The amount of charge in the system determines how much of the condenser coil is filled up with liquid and can be measured by the amount of liquid subcooling. If the coil had no stored liquid, then the liquid temperature would be the same as the condensing temperature. The amount of liquid subcooling has a great effect in the capacity of the metering device, particularly capillary tubes. My apology for the rambling nature of this post-just tying strings of thought togrther.

Pipe size

@ April 15, 2011 9:34 PM in epa ruling

If the current refrigerant piping is not type M, and sizing is correct for R-410A, then the piping could be reused. The evaporator coil will more than likely need replacement if converting refrigerants because of the higher pressure rating required. Don't know of a source for a 50 ton condensing unit R-22 at present. A major manufacturer has pulled a fast one lately-their units that have been changed to R-410A carry the catalogued ratings, but in the fine print at the end of the submittal it states that the unit has been de-rated-in the case of a 40 ton rooftop-by almost 7%. Luckily we are a design -build contractor and didn't get caught in this one.

Builders

@ April 12, 2011 6:06 PM in Are boilers next?

An answer to the question "Who buys a...." is in simple terms builders. Particularly in the southern states the builder buys the cheapest and most inefficient equipment allowed by law. Hence the "Builder's model" offered by various manufacturer's. It's going to take a paradigm shift in the way business is done. Perhaps some type of "energy report card" or a simple btu/sq ft/degree day for building envelopes would put all on an equal footing. Financial institutions are the cause of a lot of this, by not allowing financing for anything over and above the minimum code. As much as I hate to say it, what the industry needs to reduce energy is sustained higher energy prices-that will drive the push for efficiency.

Brand

@ April 4, 2011 4:34 PM in 2.5 inch Kunkle reilf valve

That is not uncommon for Kunckle relief's. Have you tried manually lifting them to see if they will re-seat? Otherwise, either 2 new valves or try another manufacturer, such as consolidated. I feel your pain...

Cryogenic Vaporizer

@ March 30, 2011 9:07 AM in Nitrogen Powered Air Conditioning Anyone?

Absolutely;  used a Cryogenic Vaporizer to produce 30 degree brine on a solvent recovery system some years ago.  The only problem is that the device is rather pricey.  It would normally be set up in series with the finned vaporizer as a 1st stage.  The vaporizer is set up internally such that the brine solution or chilled water will nor freeze during operation.  This is an excellent application if you use a large amount of nitrogen and have use for process or even comfort cooling chilled water.