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.
