These slides explain some of the main components of a heating system and how they work. Parts addressed in this set of slides include boiler, indirect water heater, boiler header, low water cut-off, switching relay, thermostat, circulator, tempering valve, expansion tank, and air eliminator. Other components are explained in "Boiler Part II".

1. Guide to Boiler Heating System
Components: Part I

2. There are many different components to each boiler heating system.
PexSupply.com can work with you to make sure you have all of the parts,
installation equipment, and planning pieces needed for your next DIY project.
Boiler Heating System Components:
1 - Boiler 11 - Zone Valve Controller
2 - Indirect Water Heater 12 - Circulator Flanges
3 - Boiler Header 13 - Zone Valve
4 - Low Water Cut-Off 14 - Ball Valve
5 - Switching Relay 15 - Boiler Drain
6 - Thermostat 16 - Temperature Gauge
7 - Circulator 17 - Fill Valve
8 - Tempering Valve 18 - Backflow Preventer
9 - Expansion Tank 19 - Boiler Reset Control
10 - Air Eliminator 20 - Check Valve

3. Heating System Diagram

4. 1 – Boiler
The first piece of the boiler based heating system
is of course the boiler. Boilers are used to heat
water or make steam. They are either powered by
electricity, natural gas, or oil, which require
different piping systems for each type.
Shop Now:
• Tax Rebate Boilers
• High Efficiency Boilers
• Weil McLain Boilers
Learn More About Boilers

5. 2 – Indirect Water Heater
After water is heated in the boiler, it is passed
through a heat exchanger located in the storage
tank of the indirect water heater. This allows the
boiler or furnace to turn on and off less
frequently, which helps save energy and money.
However, separate water heater is not needed if
you already have one. Not all applications need Shop Now:
the use of water heaters either. • Weil Mclain Indirect Water
Heaters
• Smart Indirect Water Heaters
• Bradford White Indirect Water
Heaters
Learn More About Indirect Water Heaters

6. 3 – Boiler Header
Boiler headers are also known as boiler manifolds,
which function as a hub for heating systems.
Boiler headers come in variety of sizes with
different number of outlets.
Learn More About Boiler Headers

7. 4 – Low Water Cutoff
A low water cutoff detects when water levels in hot
water and steam boilers reach a level lower than
the minimum required for safe operation. It then
turns off the boiler and prevents possible boiler
failure or fire/explosion. Low water cutoffs are one
of the most important parts of a safe hydronic
heating systems. Shop Now:
• Steam/Low Voltage LWCO
• Steam/Line Voltage LWCO
• Water/Line Voltage LWCO
• Water/Low Voltage LWCO
• Mcdonnell & Miller LWCO
Learn More About Low Water Cut-Off Products

8. 5 – Switching Relay
Switching relays are used to control temperatures
of water in a heating system. They are used to
connect thermostats to circulator pumps so that
the circulator pump goes on when the thermostat
calls for heat.
Shop Now:
• Taco Switching Relays
• Honeywell Switching Relays
• Argo Switching Relays
• Erie Switching Relays
Learn More About Switching Relays

9. 6 – Thermostats
Thermostats are used to control the temperature
of specific rooms of your house. This allows you to
adjust temperatures of each room to fit your
comfort. Thermostats come with different
functionalities such as programmability,
application type, stages, user interface, voltage
and changeover type. Shop Now:
• Honeywell Thermostats
• White Rodgers Thermostats
• Tekmar Thermostats
• Robertshaw Thermostats
Learn More About Thermostats

10. 7 – Circulator
Circulators, also known as pumps, help move
water through a heating system at the needed
rate. When choosing a circulator it is important to
know the application, GPM, head range, material,
voltage and horsepower needed.
Shop Now:
• Taco Pumps
• Grundfos Pumps
• Bell & Gossett Pumps
• Wilo Pumps
• Armstrong Pumps
Learn More About Pumps or Circulator Pumps

11. 8 – Tempering Valve
Tempering valves mix hot and cold water to
produce water at a desired temperature. They are
used for variety of radiant heating and domestic
water applications. In domestic water applications,
they ensure steady temperature ranging from
85 F to 150 F and help prevent potential burns.
Shop Now:
• Watts Thermostatic Mixing
Valves
• Watts N170 Commercial
Tempering Valve
• Watts 70A Hot Water
Extender Tempering Valves
Learn More About Tempering (Mixing) Valves

12. 9 – Expansion Tank
Expansion tanks help keep a constant pressure
in potable water and closed heating systems by
providing extra space for excess water to enter.
Expansion tanks can help prevent pipes from
being damaged from increased pressure.
Shop Now:
• Expansion Tanks for Heating
Systems
• Potable Expansion Tanks
• Well Expansion Tanks
Learn More About Expansion Tanks

13. 10 – Air Eliminator
Air eliminators help remove excess air from
hydronic heating systems which will help prevent
pipes and other components from damage
caused by trapped air. Air can also prevent
proper heat distribution. Air is created as
pressure or temperature changes.
Shop Now:
• Spirotherm Combination Air
Eliminators
• PV SuperVent Air Eliminators
• Spirotherm Air Eliminators
Learn More About Air Eliminators

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