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Lydmera · thermal-phase1-v2

Methodology and worked examples

See how the calculations are built, what the results cover and how the published examples compare with separate reference arithmetic.

Calculation basis and scope

Pool-water thermal sizing

The current method is thermal-phase1-v2. It separates water heat-up, convection, evaporation, pipework, solar, radiation and wall/floor transfer. Indoor ventilation duty is reported separately from pool-water duty. Named components use cited relations; the combined method also contains Lydmera assumptions.

Outdoor and indoor assumptions

Indoor evaporation uses the simplified ASHRAE low-air-speed relation. Outdoor evaporation uses an adapted historical wind correlation; it has not been validated against the current ASHRAE natural/forced method. Convection is forced-flow only. The outdoor sky temperature uses a fixed 12 K offset; cooling ground transfer is not calculated. Cover and material defaults need project-specific evidence.

Climate conditions

Fetched conditions come from NASA POWER historical gridded data, with recorded period, selection and source. They are archive estimates, not ASHRAE design-weather tables or a weather station at the pool. Site exposure and the required project design conditions still determine the appropriate inputs.

Circulation and equipment

Circulation calculations include pipe and device losses, clean/dirty filter head and available suction head. Automatic pump selection is bounded to fixed-speed identical parallel pumps and the supplied curve range. Filtration presets are internal screening assumptions, not complete PWTAG, DIN, PHTA or EN compliance checks. Manufacturer performance and missing evidence remain visible in equipment review.

The wider design

The workflow supports pool-plant technical proposals. Detailed pool-hall dehumidification and duct design, electrical protection/bonding, structure, water chemistry, suction-entrapment safety and surge/overflow design need their own specialist design and coordination.

What the evidence establishes

Current internal checks

The three cases below compare the current implementation with separate arithmetic using disclosed equations and fixed inputs. Agreement checks implementation consistency; it does not establish field accuracy or suitability for every project.

Legacy compatibility

The older spreadsheet oracle explicitly exercises legacy-v1. Those regression cases preserve historical behaviour and are separate from current-method numerical checks. They are not an independent validation of thermal-phase1-v2.

Independent professional review

The published case pack is internally prepared. Independent professional review of this pack is not yet complete; no third-party approval or certification is claimed.

Three reproducible worked examples

Synthetic cases with fixed manual weather inputs. Each difference is actual minus reference. The 0.001 tolerance is an absolute numerical-agreement threshold in the displayed unit, not a claim of physical accuracy. Negative heat components represent heat gains.

Outdoor pool heating

10 × 5 × 1.5 m; water 15 → 28 °C in 48 hours; air 5 °C, 60% RH; pool-surface wind 1.227 m/s; no cover or solar credit. The reference includes the same adapted outdoor evaporation assumption, so agreement does not validate that model.

Method: thermal-phase1-v2

Outdoor pool heating
QuantityReferenceLydmeraDifferenceTolerance
Water heat-up (kW)23.53802723.53802700.001
Convection (kW)2.4843682.48436800.001
Evaporation (kW)30.11511730.11511700.001
Pipework (kW)0.7499250.74992500.001
Solar (kW)0000.001
Radiation (kW)8.6377978.63779700.001
Ventilation in water total (kW)0000.001
Walls and floor (kW)2.731252.7312500.001
Pool-water heating total (kW)68.25648568.25648500.001
Separate ventilation heating (kW)0000.001

All listed numerical comparisons are within tolerance.

Indoor pool-water duty

The same basin and heat-up period; room 30 °C and 60% RH; activity factor 0.8; indoor pipework. The separate ventilation example uses an entered 0.72 L/s/m² and deck factor 1.5, not a code-compliance rate.

Method: thermal-phase1-v2

Indoor pool-water duty
QuantityReferenceLydmeraDifferenceTolerance
Water heat-up (kW)23.53802723.53802700.001
Convection (kW)-0.056914-0.05691400.001
Evaporation (kW)5.0311445.03114400.001
Pipework (kW)-0.108375-0.10837500.001
Solar (kW)0000.001
Radiation (kW)-0.594346-0.59434600.001
Ventilation in water total (kW)0000.001
Walls and floor (kW)2.731252.7312500.001
Pool-water heating total (kW)30.54078630.54078600.001
Separate ventilation heating (kW)1.621.6200.001

All listed numerical comparisons are within tolerance.

Circulation head and suction check

171.4 m³/h; 200 mm suction and 160 mm discharge bores; 30/70 kPa clean/dirty filter losses. The arithmetic can agree while selection remains indeterminate: no manufacturer curve or complete assurance evidence is supplied. Filter velocity is 42.85 m/h and also needs resolution against the applicable limit.

Method: hazen-williams-fixed-duty-internal-v1

Circulation head and suction check
QuantityReferenceLydmeraDifferenceTolerance
Suction velocity (m/s)1.5155091.51550900.001
Discharge velocity (m/s)2.3679822.367982-00.001
Suction loss (m)1.8966371.89663700.001
Discharge loss (m)3.7892873.78928700.001
Clean-filter total head (m)13.34650413.346504-00.001
Dirty-filter total head (m)17.43214817.43214800.001
Head including 10% allowance (m)19.17536219.17536200.001
Available suction head (NPSHa) (m)9.0641819.06418100.001
NPSH margin over entered 3 m (m)6.0641816.06418100.001
Backwash flow (m³/h)14814800.001
Governing flow (m³/h)171.4171.400.001

All listed numerical comparisons are within tolerance.

Hydraulic selection: INDETERMINATE. This case does not recommend a pump.

Sources and further detail

These sources support the named components and climate provenance. They do not endorse or certify Lydmera’s combined method.