The HVAC Air Handler Freeze Stat is a low temperature limit control and it is used mainly in commercial systems in the duct work on economizers or in air handlers just before any coil especially water coils. It is a safety and protection control to prevent extremely cold air from reaching the hot water or chilled water coils inside the air handler where the air enters from the economizer. Under ideal control set up if the freeze stat trips the economizer dampers close and the blower fan stops. This prevents coils from freezing. A frozen coil can bust open and will need to be replaced if it freezes thus the purpose of thefreeze stat in HVAC air handler applications which utilize economizers for free cooling.
This is a secondary chilled water pump in a large pump room designated for pumps and piping in a data center. After a few minor tweaks and corrections these pumps all operated flawlessly. There was very little issues with the secondary pump start-ups unlike the primary pumps where cavitation was encountered on the primary chilled water pumps and the condenser water pumps for the chiller. The diagnosis for the cavitation of the primary pumps and the condenser water pumps was that the loops were not properly purged of air and this caused those pumps to cavitate. The secondary pumps, pictured here, did not have that problem giving kudos to the team that purged the loops on this side of the chilled water system.
Water Heaters with Tanks and Tankless Water Heaters
Tankless Water Heater
I have been transformed into a believer of tankless water heater systems. Anyone who has read the About Us page at High Performance HVAC along with my friends and family and some fans of the site know that I moved to Ukraine about a year ago for professional reasons. When I first arrived in Ukraine it took a while for me to adapt to the culture, language, services, and way they do things here. Power failures, water outages, and occasionally the natural gas outages are quite frequent here although it is tolerable and a minor inconvenience. Many of the outages occur at night when many people are sleeping but occasionally during the day when you need it. I must include that this has been a big adventure and I have learned much and to tell you if you are living in the States or Western Europe you have it good but that doesn’t mean Ukraine is bad it just means they are little behind and hopefully will quickly catch up. I have not seen a standard water heater here like the common water heaters with tanks in the States. All the systems I have seen here are tankless including the water heaters in the apartment I rented and now in the house where I live. I am sure there are tank-type water heaters here like in the States but I have not seen them yet.
Water towers maintain a ready limited supply of water for communities in the event the water main goes down. Many water towers are used for emergency situations for the fire department to have water for fighting fires and for water fire suppression systems to have a supply of water for the emergency if it should arise.
This domestic hot water mixing valve offers a way to temper the hot water coming from a hot water loop and boiler. It is very important to maintain the appropriate and desirable temperatures of water used for domestic water use. First you want to maintain a safe temperature so people are scolded by extremely hot water temperatures. Hot water boiler loops generally work on a temperature of 180 degrees Fahrenheit and this temperature is too hot for human contact without scolding or seriously burning the skin. A mixing valve is used in the loop to maintain a safe temperature for human comfort. The hot water is mixed with cold water at the mixing valve and the result is the temperature dialed into the mixing control valve which has a range of 120 degrees to 140 degrees if used for domestic hot water applications. Other mixing valves can be purchased that will give a whole range of temperatures including mixing valves that can be controlled by PLCs or DDC to maintain specific temperature ranges for whatever the desired temperature is for the application.