Hydronic Heating Flashcards
What are the four main hydronic heating piping layouts that are commonly installed?
1)One pipe - series loop. AKA A perimeter heating system. 2) One pipe - monoflow or diversion tee. 3) Two pipe - Direct return. 4)Two pipe - Reverse return.
What’s the purpose of an expansion tank in a hot water heating system and where should it be located?
It prevents the pressure relief valve from going off when the boiler fires up - in the end it prevents more water from getting into the system and causing corrosion. The expansion tank should be located upstream from the system pump. The place where the expansion tank is attached is commonly known as the point of no pressure change.
Where’s the best location for the circulator to be installed on a hydronic heating system?
Downstream of the expansion tank. Another possible location would be on the return piping into the boiler. In some cases a circulator can be placed on both the supply and the return piping. This would be more likely in a situation that requires a constant and steady flow, such as a radiant floor heating system.
What’s the pressure relief valve in a residential boiler usually set to?
30 psig.
Where is the pressure relief valve usually located?
On the boiler.
How much should a pressure relief valve be able to relieve?
100% of the rating of the boiler.
What would cause a pressure relief valve to start dripping?
A waterlogged expansion tank.
What is make-up water on a hydronic heating system?
Make up water is water that’s introduced into the closed hydronic system when water either leaks out through a break in the system or more commonly when the relief valve kicks off.
What’s another name for a pressure reducing valve that reduces the pressure before it gets into the system?
The pressure reducing valve is also known as the feed water valve.
What’s the pressure in a hydronic heating system usually set to?
12-20 psig.
What is a flow check valve and where’s it located?
A flow check valve is a valve that prevents the unwanted flow of water through a system when the burner isn’t on. It’s located on the supply leaving a boiler.
What’s the difference between a flow check valve and a flow switch?
A flow switch ensures flow through the system before the burner will kick on.
Where would you install the backflow preventer in a boiler system?
A backflow preventer’s installed in the make-up water line on the boiler.
What’s the typical backflow preventer installed in a residential boiler?
The Watts 9D.
Where would the PRV be installed in relation to the boiler?
The PRV’s installed on the make-up water line.
What’s the PRV set at in a typical residential application?
Between 12-20 psig.
What’s an air scoop? Where’s it located?
An air scoop is a water / air seperator. It’s attached to the expansion tank which will be located upstream of the system pump. This would be where the temperatures highest and the pressure’s the lowest in the system.
What is the “R” value of a material? What’s the “U” value of a material? What’s the DTD (Design Temperature Difference refer to when calculating heat loss from a building?
“R” value = #Hours / BTU / Degrees F / ft2
“U” Value = #BTU’s / Hour / Degrees F / ft2
“U” Value = 1 / R Value.
DTD = IDT - ODT.
Note: IDT means inside diameter temperature. ODT means outside diameter temperature. The DTD is the difference in temperature from the inside of the building in relation to the outside of the building during the coldest times of the year. This difference in temperature is used to calculate heat loss.
How would you calculate the flow rate required in a hydronic heating system?
GPM (Gallons Per Minute) = BTUH / (Change in temp. x 500).
Note: The normal temp. drop across a system is 20 Degrees F, but for infloor systems its 10 Degrees F.
What’s a “fire tube,” and what’s a “water tube” in relation to boilers?
A fire tube is where hot gases from a fire run through tubes that are surrounded by water. A water tube is filled with water and heated externally by fire.
What’s a conventional boiler? Is it more or less efficient than a condesing boiler?
A conventional boiler is one that’s products of combustion remain relatively hot and do not condense. They’re vented through the flue. Not as efficient as a condensing boiler.
What’s a condensing boiler? Is it more or less efficient than a conventional boiler?
A condensing boiler is one in which most of the heat is removed and reused from the products of combustion. and the products of combustion cool down enough to condense. It’s more efficient than a conventional boiler.
What extra component would you require if you used boiler water to heat domestic hot water?
A heat exchanger (an indirect connection.)
What’s the difference between a gravity hot water heating system and a closed loop hydronic system containing a circulator?
Gravity System: Larger pipe, no pump, may be open at top (no circulator.
Closed loop hydronic system: Smaller pipe, pump, pressurized.
Which two variables determine how a circulator is sized in a hydronic heating system?
Desired flow rate of the system, & pressure.
Where would a baseboard / wall fin be installed? How would you calculate how much you need in order to heat a room? What type of copper is it usually made of?
Usually installed on an exterior wall and if possible below a window. To calculate the amount you need you would take the room heat loss and divide it by the rating of the baseboard.It’s usually made of Type H copper.
What’s the minimum return water temperature for a non-condensing boiler?
140 Degrees F.
What should be installed between the piping at the structure and the fan coil unit itself?
Flex connectors and shut off valves.
What is a low mass boiler? What must be proven to be working on a low mass boiler before the burner will fire?
A low mass boiler doesn’t contain much water in the heat exchanger. Therefore flow must be proven through the system before the burner will kick on.
What is a chiller?
A machine that removes heat from a liquid using the refrigeration cycle.
What type of piping connections do chillers use?
Flange connectors, flexable connectors, and shut off valves.
What is a cooling tower?
Removes waste heat to the atmosphere.
How would the water level be maintained in the reservoir of a cooling tower?
A float switch or an electronic level switch.
Where should the low water cut off (LWCO) be installed in a hot water boiler?
In the supply piping above the boiler.
Where should the low water cut off (LWCO) be installed in a steam boiler?
On the boiler, 1-2 inches above the highest water tubes.
How do you cut glass sight tubes?
Score the entire tube, and then gently tap or slightly heat up.
Where would you install outlets from a ducted cooling system?
In the ceiling.
What steps should you take when replacing an element in a electric hot water tank?
1) Turn off the power. 2) Turn off the water. 3) Replace the element. 4)Turn on the water. 5) Turn on the power.
Where and at what height should you install a thermostat?
At 5 feet (60”) above the ground, it should be installed on a interior wall, away from sunlight and sources of heat, in an area with good air flow.
When doing routine maintenance on a boiler, you notice that the water’s black and smelly. What do you conclude from this? What if the water’s clear?
If the water’s black and smelly (brackish water), this would indicate that everything’s okay. If you notice the water’s clear, it would indicate a leak in the system which would be allowing more clean fresh water in.
A unit heater is installed in a shop and is intended to supply heat to the shop area. The shop has a loading dock with a bay door. In which direction should the unit heat discharge?
The unit heater should discharge across the bay door.
The domestic hot water in a residence is heated by running boiler water through a water to water heat exchanger. What valve is needed on the domestic side in order to ensure the water does not become too hot?
A tempering valve.
A house is fitted with a radiant panel heating system. You are to install balancing valves in the system,. Where would you install them?
On the return header.
What is a wild loop? When installing a wild loop, what component is generally installed in conjunction with it?
It acts like a pressure differential valve, whereby it allows the system to have a continuous route for hot water to travel even when the other zones are closed. The wild loop was generally installed in a crawl space and continuously had hot water running through it. A globe valve was installed in the loop to allow for throttling.
A homeowner decides to heat his domestic hot water using a solar heating system. What does the homeowner need to install in his system in order to prevent contamination of the domestic hot water?
A heat exchanger.
A boiler’s installed in a residence and the domestic heating system includes low-temperature radiant floor heating. What’s required on the low temperature heating side?
A mixing valve.
A direct return heating system is being used in a building. The heat in the rooms isn’t controlled individually but by a central thermostat. It’s noticed that one of the rooms is hotter than the others. How can this issue be solved?
By adjusting the balancing valve.
How many BTU’s is in one cooling ton / hour?
12,000 BTU’s per cooling ton.
What is a triple duty valve?
One valve body that has a check valve, shut off valve, and balancing valve.
How is cooling pipe (refrigeration pipe) put together?
By brazing.
Where would you install the cooling coil in a cooling system in relation to the fan?
The fan must come before (upstream of) the cooling coil.
What is the required safety valve rating for a low pressure steam boiler?
15 psig - maximum pressure setting for a low pressure steam boiler.
How do you grade a steam line in a steam heating system?
Down away from the boiler to the steam trap / dirt leg (1” in 20 ft.) in direction of steam flow.
Both elements on a domestic hot water tank are working normally. What would be the cause of no hot water?
Broken dip tube, calcified elements.
If you have a PRV on a boiler system set at 15 psig, and the system pressure is only 7 psig, what is the problem?
The PRV.
How does a steam trap operate?
It senses the difference in density between water and steam.
A low pressure steam boiler has a set operating pressure 5 psig below the maximum allowed by the ASME code. The differential of the pressuretrol is 4 psig. What is the cut in pressure?
6 psig. the maximum allowed by code is 15 psig.
Where should a cooling tower be installed?
Outside in a ventilated area.
What’s the principle cause of water hammer in a steam heating system.
Water allowed to build up in piping that is then carried along the inside of the pipes.
Where is the cooling coil located on a combination heating and cooling furnace system?
In the supply plenum close to the furnace.
What type of components might be installed with all indoor fuel oil tanks?
Liquid level gauge, drain, pump, and vent whistle alarm.
What’s installed on a fuel oil system to remove suspended particles and prevent clogging of the nozzles?
A screen.
What would be the most likely cause if “no heat” complaints were being received from the occupants of the top floor of an apartment building?
Air lock.
What’s the glycol formula?
Volume of system x (required % glycol - current % glycol) / (100 - current % glycol)
Where are the inlet and outlet connections made on a steam radiator? What about on a hot water radiator?
The connections to a steam radiator are top in and bottom out. For hot water radiators, the connections are bottom in, top out.
Where should the relief valve be piped to in a low pressure steam system?
To a safe place.
What’s the minimum size blow down drain in a low pressure steam system?
3/4”.
Heat exchanger is made from cast iron is the definition of?
A cast iron boiler.
What’s the area where combustion occurs?
The combustion chamber.
Water droplets which form from flue gases that have temperatures less than it’s dew point. (Typically 130 Degrees F) is the definition of?
Condensate.
Is condensation from a boiler acidic or neutral?
Acidic.
The heat exchanger is made from copper, this is the definition of a?
Copper tube boiler.
A storage vessel which receives heat from an external heat source is?
Indirect fired.
A boiler whose heat exchanger contains 15 usg or less is a?
Low mass boiler.
What does a heat anticipator do?
It tricks your thermostat into thinking it’s reached it’s set point, by cutting out early so you don’t overshoot your rooms set temperature.
What is latent heat?
Heat required to change the state of a substance from a solid to liquid or liquid to gas. Also referred to as “hidden heat.”
What temperature range do most hydronic heating systems operate?
32 - 250 Degrees F.
What are 5 heat sources used for hydronic systems?
Boilers, heat pumps, geothermal, solar, and electrical resistance.
Are fire tube boilers low mass or high mass boilers?
High mass boilers.
What do we need to be aware of with low mass boilers and how can we protect against that issue?
Low mass boilers need a flow switch downstream of the primary circulator. This ensures that the water is flowing through the heat exchanger of the boiler prior to burner starting.
What temperature ranges do condensing boilers and conventional boilers operate in?
Condensing : Less than 190 degrees F.
Conventional: Greater than 190 degrees F.
Name three methods of removing air from a hydronic sysem:
Microbubblers, automatic / manual air vents, and chemical additives.
How would you meet the demands of different areas with different heating demands within a project:
Zoning
Where’s the point of no pressure change?
The expansion tank.
Define the terms overshoot and undershoot:
The terms refer to the difference between the actual room temp. and the operating differentials.
Why is it important to size the circulator correctly?
Cost, electrical usage, and head pressure added to the system.
What pressure should the expansion tank be set for?
The static pressure of the system.
How do you winterize a ball valve?
Leave it half open.
What is a hose bib called in hydronic heating?
A boiler drain.
What does the term “Delta Triangle” mean?
Difference in temperature between two points in a system.
What is “air lock.”?
A large volume of air trapped in a heating system which prevents circulation of water through a particular partition or zone.
The pressure required to keeo entrained air bubbles small enough to travel with the water in a heating system is the definition of?
Vapour pressure.
What utilizes a mechanical means (fan) to force the movement of air across a fin or coil.
A forced convection heater.
Which piping system is most associated with manifolds?
Home run systems.
What type of heat source utilizes “gasification.”?
Solid fuel (wood.)
What’s the maximum temperature of a low-temperature boiler?
250 Degrees F.
What two things does a combination gauge indicate?
Temperature and pressure.
Describe “head pressure.”:
The pressure available at the outlet side of a pump or circulator within the system. Expressed in ft. of head.
What is static pressure?
The pressure of the system under a no flow condition. Also the pressure exerted by a column of liquid.
Which type of reducing couplings should be used in a hydronic heating system?
Eccentric.
What’s a disadvantage of a series loop?
Imbalanced heating.
What are some disadvantages of a direct return system?
You need balancing valves in all the loops.
What type of valve should be used to prevent tampering with the hydronic system?
A leak shield balancing valve.
Which type of circulator requires yearly maintenance?
A three piece circulator.
What’s the main advantage of a boiler feed valve over a PRV?
Fast-fill ability to bypass the reducing valve diapgragm within the piece of equipment.
Can you regulate flow with a gate valve?
Never.
What’s the best valve for regulating flow?
A needle valve.
What is boiler short cycling?
An undesirable condition during which the burner operates for a very short period of time.
What is hydraulic seperation?
A method of coupling two or more circuits so that the effect of one operating circulator does not influence the effect of another operating circulator in another circuit.
If you connect two circulators in parallel, what would be the result?
More GPM.
If you connect two circulators in series, what would be the result?
More pressure.
1 in squared of water 12 inches high generates how much psi?
.433 psi.
What’s circulation caused by in a gravity system?
The different weight of hot to cold water.
The gravity circulation of water between a boiler and a heat transfer unit is called?
Convection.
What make the best radiators?
Rough, black materials.
Which system is unsuitable for heat transfer units that have a high pressure drop?
Diversion tee.
Which system can best balance the heat transfer between circuits of different lengths?
A reverse return system.
Which system is a one pipe system in which flow can be diverted to individual heat transfer units?
Diversion tee.
Which system is the most balanced system that uses heat transfer units?
Reverse return.
Which system is also known as a first fed first return system?
Direct return.
A diversion tee induces the flow in the branch by the use of a?
Venturi.
A series loop system must be used with?
Forced circulation.
The diversion tee layout must be used with?
Forced circulation.
The direct return layout must be used with?
Either gravity or forced circulation.
Piping runs in a hot water system should be:
Almost level or have an upward grade of 4mm / m. (1/2” / 10ft.)
Piping runs should not be placed in outside walls. True or false?
True.
Pump circulation can be stopped by air bubbles accumulating at a high point. True or false?
True.
Drops from the downfeed heat transfer should connect from the ____ of the supply pipe.
Bottom.
What are fire tube boilers well suited for?
Hot water heating or steam heating.
What are sections of a cast iron boiler connected with?
Push nipples.
What temperature do boilers in hot water heating systems usually operate at?
82 Degrees C (180 degrees f.)
What are high pressure boilers usually made of?
Steel tube.
What’s the water make up system to the boiler also called?
The water supply.
What do high efficiency boilers require?
A venting permit.
What are convector cabinets usually made of?
Steel.
Where should convectors be installed?
Underneath windows.
What’s the heating element of a convector usually made of?
Finned pipe.
What’s the amount of heat given off by a hot gravity circulation convector usually regulated by?
An adjustable louver.
What are the two types of unit heaters?
Vertical and horizontal.
On the same circuit, do not mix convectors with:
Free standing cast iron radiators.
What do eccentric reducers prevent?
Air pockets.
What type of fitting would you use to prevent electrolysis?
Dialectric fittings.
Radiant panel tubing should not be installed within what distance of any gas appliance vents?
6” (15 cm.)
The minimum bend radius should be __ times the diameter of the tube?
10.
What’s the ideal location for a pump?
Immediately downstream of the point of no pressure change (expansion tank.)
Should a strainer be installed upstream of the pump?
Yes.
Some circulators have water cooled and lubricated motors. True or false?
True.
A circulator that’s over sized will be?
Be noisy when it’s operating.
Are expansion tanks for open or closed systems?
Open systems.
Are compression tanks for open or closed systems?
Closed systems.
What does a boiler fitting do?
Routes air to the compression tank.
High points on a heating system should be:
Vented.
High volume locations such as mains and unit heaters should have:
An automatic float air vent.
A pot feeder is not used to add:
Glycol.
What does a diverting valve do?
Diverts supply water to the return piping.
State the number of times water expands when it’s changed to steam:
1700 times.
What are the three types of steam?
Wet saturated, dry saturated, and super heated.
State the location in the system where wet saturated steam can be found:
Steam space of the boiler.
State the location in the system where dry saturated steam can be found:
In the pipes.
State the type of system in which super heated steam will usually be found:
In mechanical applications.
Why does super heated steam behaves like a true gas?
Because it has no water vapour in it.
State the reason why dry saturated steam is used for steam heating systems:
It’s better at transferring latent heat.
What’s the operating pressure of most low pressure steam heating systems?
5 psig.
State the operating pressure used in vacuum type systems:
Below atmospheric pressure.
What does HRT stand for?
Horizontal Return Tubular Boiler.
What are two other names for an equalizing line?
Balancing and bleeder.
What’s the purpose of an equalizing line?
Returns water droplets to the boiler.
What does a steam trap do?
Collects condensate and sends back to boiler.
On a low pressure steam boiler, where is a common point at which to introduce make up water?
Condensate return pump.
What are the two types of expansion joints?
Slip & corrugated.
What’s the maximum size for a single safety valve installed on a steam boiler?
3 1/2 inches.
What’s the maximum size safety valve fitted on a steam boiler when two or more safety valves are required?
4 1/2 inches.
Explain the reason for cutting off the end of a discharge pipe at a 60 degree angle.
Prevent build up of back pressure.
Difference of opening and closing pressure of the safety valve is the definition of?
Blowdown.
What’s the name given to the dial gauge that records pressure above and below atmospheric pressure?
Compound gauge.
How do you prevent steam from entering the gauge?
By installing a siphon between the gauge and the steam boiler.
What type of valve is used in the pipelines between the boiler and the water column.
O.S. & Y.
What’s the minimum size piping required for the connection between the water column and the boiler?
1”.
What’s the minimum size piping required for the drain pipe from the water column?
3/4”.
State the size of pipe used to connect the LWCO with the steam boiler”
1”.
What is the name of the piping system in which the heating transfer units are part of the piping?
A series loop.
What is the name of the piping system in which the heating transfer units are supplied by specialty tees?
One pipe.
What is the name of the piping system in which the first heat transfer unit supply is also first returned?
Two pipe direct return.
What is the name of the piping system in which the water has approximately the same distance to travel for each heat transfer unit?
Two pipe reverse return.
What is the major disadvantage of the series loop piping system?
Limited heating capacity for each circuit.
What is the major disadvantage of a one pipe system?
End heat transfer units receive cooler water.
What is the major disadvantage of a two pipe direct return piping system?
Hard to balance flow to each heat transfer.
What’s the purpose of a wild loop?
To prevent the pump from dead heading.
What type of radiator valve is used to prevent unauthorized use?
A lockshield radiator valve.
What are two primary considerations when locating air elimination devices?
Temp. and pressure.
Why is it important to remove gases from a hot water heating system?
To prevent air binding in the system.
What device removes gases directly from the boiler?
The boiler scoop.
What’s required on a coil type boiler over 400 MBH?
A flow switch.
What would indicate you’re looking at a hot water boiler and not a steam boiler?
A pressure reducing valve.
What would you find on a steam boiler?
A sight glass.
At what temperature do fusible plugs melt?
210 degrees F/
