Cold-climate design and operation

Cold-climate design and operation

Freeze protection, draining circuits and restarting after winter

In cold climates, the quality of fountain design is also important during shutdown. A set that works well in the summer may be damaged during the first frost due to water remaining in a valve, fitting, or small chamber.

Winterization should be anticipated from the design stage: drain routes, air intake locations, equipment access, pond condition and system behavior during power outages are all part of this design.

This chapter presents a hypothetical example to explain the review method. The numbers are educational assumptions and are not a substitute for local climate information, equipment instructions, and operational calculations.

52–1. Choosing a winter strategy

For each project, the cold season strategy must be determined before purchasing equipment.

In the example of this chapter, the seasonal stop and discharge of the display circuit are selected. Sections that must remain watertight will have separate protection.

Claiming that a pump is cold-resistant does not mean that the whole set is approved for winter display. The pipe, nozzle, valve, filter and surrounding area should be checked separately.

52–2. Necessary information about the project location

Cold climate design is not limited to minimum air temperature. The following information is also required:

• duration and repetition of glacial periods;

• wind and exposure of equipment to open air;

• Water temperature and behavior of low-circulation sections;

• soil conditions and frost depth for buried lines;

• Possibility of power outage and access time of the maintenance team;

• rain water and snow melting path;

• Condition of underground water around the pond.

This information should be obtained from reliable sources of site and project studies. Choosing burial depth or stopping temperature based on a general number is not reliable for all cities and buildings.

In the project documents, the design temperature of the equipment, the temperature of the control command and the temperature of storage in the warehouse should be recorded with separate titles.

52–3. Why is it not enough to turn off the pump?

After the pump stops, water may remain in the following places:

• the lowest part of the pipes;

• both sides of the one-way valve;

• Inner cavity of valves and collectors;

• pump and filter housing;

• instrumentation connections;

• downed hoses or no-flow plugs;

• Chamber of dry floor nozzles.

Emptying one section does not necessarily empty the other section. A closed valve or lack of an air inlet can stop the drain flow.

In its winter guide, OASE mentions the risk of pipes freezing during power outages and the protection of equipment without certified cold resistance. Action details should be adapted to the instructions of the installed model. OASE Winter Preparation Guide ^[338]

52–4. Winter evacuation map

In addition to the usual piping plan, the project should have a plan for winter conditions. This map shows the final position of the valves and the discharge route of each section.

The slope should be controlled by measuring the level and the actual situation of the installation. Showing an arrow on the map does not prove that the pipe being run is free of burrs.

Figure note from the source manuscript

Figure 52-1: Schematic of winter evacuation

Show the main line, branches, check valves, downspouts and air inlets. Enter ID and winter status for each lion. Possible points of water retention should be identified with signs.

52–5. Calculation of the volume of drainable circuit water

In the hypothetical example, the components of the display circuit are as follows:

The volume of the pipe is obtained from the following equation:

$V=\frac{\pi D_i^2}{4}L$

For the main line:

$V_1=\frac{\pi (0.05{)}^2}{4}\times 60\approx 0.1178m^3$

For branches:

$V_2=\frac{\pi (0.032{)}^2}{4}\times 80\approx 0.0643m^3$

Total volume:

$V_{total}=0.1178+0.0643+0.045+0.030\approx 0.2571m^3$

Therefore, the calculation balance of this circuit is about 257 liters.

The diameters used are internal diameters. Using the nominal diameter instead of the inside diameter can change the calculation.

This volume is the expected amount for discharge planning; The release of approximately the same amount of water alone does not prove that all the small cavities have been emptied.

52–6. Discharge verification method

For each section, a verification method should be determined: exit observation, point visit, measurement, or other method compatible with the equipment.

In this example, the discharge sheet for each circuit includes the following items:

• ID of circuit and connected equipment;

• Status of valves;

• Place of discharge and entry of air;

• Expected approximate volume;

• method of checking detention points;

• The name of the person in charge and the result of the visit.

If gravity discharge is not sufficient, the auxiliary method shall be determined by the equipment designer and manufacturer. Blowing compressed air at arbitrary pressure can damage equipment or connections; For that, a general pressure should not be prescribed to all circuits.

After draining, the possibility of re-entry of water should also be checked. Rain, site wash, or residual compensating valve can refill the prepared circuit.

52–7. The average temperature of the pool and sensitive points of the circuit

A large volume of water may cool more slowly than a narrow tube. To show this difference, we do a simple calculation.

Suppose there are 24 cubic meters of water with an average temperature of five degrees Celsius. Energy required to reduce its average temperature by one degree:

$Q=m{c}_p\Delta T$

With a mass of 24,000 kg and an approximate specific heat of $4.186kJ/(kgK)$:

$Q=24000\times 4.186\times 4=401856kJ$

$Q\approx 111.6kWh$

If, just for example, we assume the net heat loss to be constant and equal to eight kilowatts:

$t=\frac{111.6}{8}\approx 14h$

This result is not a fountain freeze time or an action deadline. The model assumes complete mixing and constant dissipation and does not account for ice formation.

Water in a valve, low-circulation branch, or chamber exposed to wind may reach critical conditions much sooner. Therefore, a sensor in the center of the pond is not enough to protect the entire circuit.

52–8. Insulation and local thermal protection

Insulation reduces the rate of heat transfer; For prolonged cold standing water, it alone is not guaranteed to prevent freezing.

If part of the circuit must remain flooded, local heating may be required. Tube heating systems such as RAYCHEM products are offered for such applications, but their selection depends on design requirements and installation instructions. Introducing pipe protection against freezing from nVent ^[339]

For an educational calculation, we examine an independent line of 40 meters with the following assumptions:

Ignoring the resistance of the pipe wall, the loss per unit length in the stable model:

$q\text{'}=\frac{T_p-T_a}{\frac{\ln (r_2/r_1)}{2\pi k}+\frac{1}{2\pi r_{2}h}}$

Placement of numbers:

$q\text{'}\approx 4.39W/m$

For 40 meters:

$Q_{pipe}\approx 40\times 4.39=176W$

This value is only the loss of the direct part in the calculation assumptions. Valves, supports, insulation moisture, wind variation, commissioning conditions and heating cable design requirements are not yet considered. Therefore, 176 watts cannot be ordered.

52–9. Thermal protection control and power cut

Thermal protection depends on electricity. Consequently, the design must also specify the response to power failure and controller failure.

For the sample high-water line, the documents must specify:

• at which point the temperature is measured;

• How sensor failure is detected;

• How the performance of the heater is monitored;

• What action is necessary when there is a power cut;

• Is alternative evacuation possible;

• What sequence does power return create?

The fact that the panel light is on is not proof of sufficient heat transfer to the entire path. Insulation health and protection points such as valves and fittings should be checked during visits.

Figure note from the source manuscript

Figure 2–52: Detail of protected line

Pipe, heating cable, sensor, insulation and protective coating are displayed. The valve and support should be identified as points that need to be checked separately. Caption: "Executive details are a function of the heater model and project calculations."

52–10. The winter condition of the pond and structure

Complete drainage of the pond should not be issued as a general order without a structural investigation. In a location with groundwater, the empty condition can make the riser pressure critical.

On the other hand, water retention also requires checking the behavior of the ice and the compatibility of the coatings. The decision should be recorded for the same pond and land conditions.

The winter program should clarify the assignment of the following:

• water level or discharge status;

• Path of rain and snow melt water;

• protection of seams and coatings;

• Preventing the accumulation of water in the nozzle chambers;

• Cap capacity against possible loads;

• Public access and services.

The temporary cover shall not, without design, transfer the load of accumulated snow or water to the delicate equipment. Also, the empty pool should be managed against people falling and unwanted access.

52–11. Separation and storage of equipment

The winter maintenance procedure should be taken from the instructions of the same model.

For example, OASE in its guidance for some equipment without cold protection suggests storage in a frost-free location and in specified wet conditions. In Kasco's 2400SF model guide, maintenance above freezing temperature is mentioned and no need to place the engine upside down is also specified. This difference shows the importance of referring to the model document. OASE Manual, Kasco 2400SF Manual ^[340]

For each separated equipment, a label should be prepared including identification, installation location, technical condition and maintenance method. Connectors should be protected according to instructions and important mechanical settings should be recorded before opening.

Antifreeze or maintenance solutions can also be tested only if they are compatible and approved for the same application; Adding them to the public water feature is not the default winter solution.

52–12. Special considerations for floating fountains

In the floating fountain, ice affects the floats and restraints in addition to the water circuit. Continued spraying in cold weather may also cause ice to accumulate on the set.

In the reviewed model manual, Kasco recommends dewatering the fountain in areas with significant frost and explains the effect of spray on ice formation. This command must be adapted to the relevant document for each model and location. Kasco winter maintenance department

The winter plan of the floating fountain should specify the method of exit, the place of lifting, the mass to be carried and the condition of the remaining restraints. The power cable should not be used to pull the assembly.

If the assembly remains in the water, this decision requires specific consideration of structure, buoyancy, ice, and equipment instructions.

52–13. Seasonal control logic

The system should distinguish between "normal display shutdown" and "winter out of service".

Level control is one of the inputs of this logic. GSO has introduced water level control equipment, but winter protection requires circuit status, temperature and dedicated sequences in addition to the level. GSO water level control equipment ^[341]

52–14. Return to service program

The beginning of the new season should be done step by step:

1. Visiting the structure, covers, connections and evacuation routes; 2. Installation of equipment with registered ID and settings; 3. Control of electricity and protections by the responsible person; 4. Cleaning and implementation of water quality management program; 5. Returning the valves to the operational status; 6. Phased dewatering and leakage investigation; 7. Setting up groups and recording flow rate, pressure and spray shape; 8. Confirmation of conditions before public reopening.

In the guide for decorative fountains, the CDC suggests water retention management, cleaning, and control of factors affecting the growth of legionella. Therefore, returning to work after a long break must have a specific plan. CDC decorative water fountain management guide ^[342]

The possibility of ice on the road must be fixed and its cause checked before starting. The pump should not be turned on to clear a suspected ice blockage.

Figure note from the source manuscript

Fig. 3-52: Steps of spring setup

Choose four images from equipment inspection, re-installation, dewatering and display test. For archival images, include the name of the project and the work stage.

52–15. Winter program delivery test

The winter program should be testable and deliverable like the show program.

Error testing must be done under controlled conditions; To prove protection, equipment must not be intentionally exposed to damaging freezing.

The best time to correct drainage weakness is before the first delivery and before the first winter.

Figure note from the source manuscript

Figure 4-52: Map and winter record sheet

An example of the map with the ID of the valves should be displayed next to the discharge confirmation sheet. The columns of the sheet should include circuit, action, result, date and responsible.

52–16. Study results and final documents

The final file should include the evacuation plan, winterization of valves, list of stored equipment, method of protection of flooded sections and restart sequence.

The person responsible for implementation, the time of action and the verification method of each step should also be clear. With these documents, winter preparation becomes a repeatable and verifiable part of water fountain operation from an action dependent on individual experience.