What does the term head mean when related to pumps?

 If you point the discharge of a pump straight up into the air it will pump the fluid to a certain height, or head, referred to as the shut off head

Why is the pump on a hydronic system often referred to as a circulator?

How are flow and head related in pump performance?

Head is the mechanical energy.

Stated in foot pounds/pounds of water

When is it appropriate to use a high head pump and when is it best to use a pump with a “flat” pump curve?

High head pumps are used in systems that have aot of head loss (resistance) and a large flow requirement.

ie.... radiant flooring system or ground loop heat pump

High Head pump = steep curve

Flat Head pump = works best where flow varies alot. ie....a system zoned with one pump and zone valves

When a pump is used on a system that has multiple zones, how does the pump performance change as zones are opened and closed?

If only 1 zone is circulating the operating point would be high on the curve

(Low flow, High Head)

You’ll hear the expression “pumping away from the boiler” used for piping hydronic systems. What does that mean?

Having the Pump after the expansion tank

(Usually not on the return side)

Working with the expansion tank, not against

How are steam boilers and hot water boilers different?

 Heating points (ST-212⁰, HWB-180-200⁰), Accessories-HWB requires more parts (such as pumps, flow check valves, circulators and expansion tanks. Water levels-HWB is full and uses pump to circulate, ST is not fall and expands naturally to fill pipes. Efficiency and safety- HWB are considered safer than ST, ST are also less efficient because that don’t uses pumps, Costs-relatively the same.

Steam has to be trapped in a coil on a two-pipe system or it will flow right back into the return

 also used to remove water(condensate) from the steam line                                  

A steam radiator not heating

Occurs when liquid water collects in a section of piping and is propelled down the pipe by steam pressure until it hits an obstacle (usually an elbow or tee).

A feeder, low-water cut off, or combination

What is a

a low water cut-off on a system?

a low water cut-off interrupts power to the burner in the event of a low water condition

a feeder and low water combo combines both functions into one unit

One pipe system, uses special Tee’s known as monoflow tees in order to branch the water to each heat emitter (parallel mini loop connected to the main one), allows for easy control of individual heat emitters

What main advantages does radiant panel heating offer?

                     Radiant heat heats the

                     objects, and occupants

                     of the room, not the air.

Cross linked polyethylene-material is more durable under temperature extremes, chemical attack, and better resists creep deformation, making PEX an excellent material for hot water and other applications

 It prevents O² from the atmosphere from getting in the system.

What are some of the methods used for installing radiant floor heating?

Staple up under floor

In floor panel systems

Why is insulation along the edge of a slab which has in-floor heating in it so critical?

Huge amount of heat loss occurs

*also needed underneath aswell

Is radiant panel heating always found in the floor?

What temperature range does a typical aquastat have?

If an aquastat is being used to control the temperature of the water in a domestic hot water tank, do you want a control that has a wide differential or one with a very narrow differential?

If a system is zoned using individual pumps for each zone, how do the thermostat and pump have to be electrically connected?

Where would you find a secondary high limit on a boiler?

The control uses the conductivity of the water to complete a path between the Probe and the metal of the boiler or piping

The Burner Circuit, it prevents it from firing

As the float chamber fills with air, the float drops, which allows air to exit out the vent. (kind of like a automatic toilet flusher).

Near boiler on supply pipe, on suction side of the circulator, in a horizontal section of pipe

Directional, 1” threaded, used as a thermostatic operator/isolates zones.