Understand your building's systems
Plain explanations of the mechanics behind commercial and residential HVAC in the Eastern Sierra — 41 guides, organised by what you are trying to do, plus a glossary of the terms technicians use.
Commercial & Central Plant
The equipment that keeps hotels, lodges, schools and municipal buildings running across the Eastern Sierra.
How Systems Work
Plain explanations of the mechanics behind the equipment in your building.
Diagnose a Problem
Start here when equipment is behaving badly and you want to understand why.
Compare & Decide
Trade-offs laid out, including the cases where repair is the better answer.
Plan & Maintain
The failures that shut a building down in January are usually visible in October. These are the checks that find them.
Speak the same language as the technician
Standard industry terms, defined plainly — so a quote, a service report or a combustion reading makes sense when you read it.
- AFUE
- Annual Fuel Utilization Efficiency — the share of fuel energy a heating appliance delivers as usable heat across a season, expressed as a percentage.
- Air separator
- A device in a hydronic loop that collects entrained air so it can be vented, preventing pockets that block circulation at the high points of a system.
- Altitude derating
- The manufacturer-specified reduction in a burner's rated input at elevation, because thinner air supplies less oxygen per unit volume for combustion.
- Building automation system (BAS)
- Centralised controls that sequence heating, cooling, ventilation and pumps across a building, often reported as an EMS or energy management system.
- Chiller
- Equipment that removes heat from water or a water/glycol mix, producing chilled water that is circulated to coils for cooling.
- Combustion analysis
- Measuring flue-gas composition and temperature on a firing appliance to verify the burner is set to the manufacturer's specification for its installed conditions.
- Condensing boiler
- A boiler that extracts additional heat by condensing water vapour out of its flue gas, which requires low return-water temperatures and acidic condensate drainage.
- Cooling tower approach
- The difference between the temperature of water leaving a cooling tower and the ambient wet-bulb temperature — a direct measure of tower performance.
- Delta-T
- The temperature difference across a coil, heat exchanger or loop. Comparing measured delta-T against design reveals flow and heat-transfer problems.
- Economizer
- A control strategy that uses suitable outdoor air for cooling instead of running mechanical refrigeration, sometimes called free cooling.
- Expansion tank
- A vessel that absorbs the volume change of water as a closed loop heats. A waterlogged tank causes pressure spikes and relief-valve discharge.
- Heat exchanger
- The component that transfers heat between two media without mixing them — combustion gas to water in a boiler, or water to air in a coil.
- Hydronic system
- A system that distributes heating or cooling using water rather than air, through radiators, panels, coils or slab loops.
- Kettling
- Knocking or rumbling as a boiler fires, usually caused by scale on heat-exchanger surfaces letting water flash to steam against a hot spot.
- Make-up air
- Outdoor air deliberately introduced to replace air removed by exhaust equipment, keeping building pressure and combustion air supply correct.
- MERV
- Minimum Efficiency Reporting Value — a 1-to-16 scale rating how effectively a filter captures particles of given sizes. Higher ratings cost more pressure drop.
- Outdoor reset
- A control curve that lowers supply-water temperature as outdoor temperature rises, so a loop runs no hotter than the building currently needs.
- Short-cycling
- Equipment starting and stopping repeatedly without reaching a stable operating condition, which wastes fuel and wears ignition and heat-exchanger components.
- Snowmelt system
- A hydronic or electric loop embedded in a slab to melt snow and ice, which sits idle for months and is then asked to perform on the worst night of the year.
- Zone valve
- A valve that opens or closes flow to one part of a hydronic loop so areas of a building can be controlled independently.
Not finding the answer you need? Our technicians would rather explain the problem than quote around it — call and describe what the equipment is doing.
(760) 210-0873Ready to Put It Into Practice?
Describe what your system is doing and we'll tell you what we'd check first — call (760) 210-0873 or request service online.