Nine extra weeks · No running cost

Solar Heating That Makes a Pool Usable From April

An unheated outdoor pool is comfortable for about eight weeks a year. A correctly sized solar array typically doubles that, holding the water four to six degrees warmer from April to October, and it costs nothing to run beyond the pump that is already circulating. We size the collector area against the pool's surface, orientation, exposure and how it is covered, install the plumbing and differential control properly, and tell owners honestly what the system will and will not achieve before anything is ordered.

Systems & Installation Request a Calculation

Bright blue swimming pool in a subtropical garden

Evacuated tube solar collector mounted on a tiled roof

About us

Installers Who Do the Arithmetic First

The business was started by a pool engineer and a heating installer who kept being called to solar systems that had been sold by area of available roof rather than by the heat the pool actually loses. A pool loses most of its heat from the water surface, chiefly by evaporation, and the losses depend on wind exposure, night temperatures and whether a cover is used. Until those numbers are known, no collector area is meaningful. We start every project with the calculation and show it to the client.

The result of that arithmetic is frequently that a smaller array plus a proper cover outperforms a larger array without one, at half the cost. It is also sometimes that solar alone will not reach the temperature the family wants, in which case we say so and either propose a hybrid with a heat pump or advise against the project entirely. We have talked perhaps one enquiry in six out of buying anything, which costs us work and produces most of our recommendations.

Installation quality decides whether a system lasts fifteen years or five. Collectors are mounted with correct expansion allowance, plumbed in the right pipe size with full-bore isolation and drain-down, controlled by a differential thermostat with sensors in the right places, and integrated with the existing filtration so the pump is not fighting the array. Every installation is commissioned with measured flow rates and a temperature rise across the collectors, and the figures are written on the commissioning sheet.

Advantages

Why These Systems Actually Work

Six things that separate a working solar pool system from an expensive roof ornament.

Sized From Heat Loss, Not Roof Area

We calculate the pool's losses — evaporation, radiation, convection and conduction — from its surface area, shelter, prevailing wind, typical night temperatures and how many hours a cover is on, then size the collector area to match the target temperature rise. That number is usually between half and eighty per cent of the water surface, and it is often smaller than the array a salesperson would like to fit. The calculation is handed to the client with the quotation so the reasoning can be checked rather than taken on trust.

The Cover Comes First

Evaporation accounts for the majority of heat lost from an outdoor pool, and a floating cover cuts it dramatically for a fraction of the cost of any heating system. We specify the cover before the collectors, and where a client already has one we check that it is the right type and actually used. Several projects end there: the owner buys a cover and a roller, gains three degrees, and decides that is enough. We would rather lose the installation than fit an array that is mostly compensating for an uncovered pool.

Plumbed for Flow, Not Convenience

Solar collectors need a specific flow rate per square metre to work at their rated efficiency. Undersized pipework, too many bends, a bypass in the wrong place or a pump already at its limit will quietly halve the output of a perfectly good array. We size pipe runs properly, fit full-bore valves, arrange automatic drain-down against frost, balance multi-bank arrays and verify the actual flow at commissioning rather than assuming the design figure was achieved.

Controls That Do Not Cook the Water

A differential controller compares collector and pool temperatures and runs the circulation only when there is genuine heat to collect, with a maximum pool temperature, a frost routine and an overheat protection that dumps or stagnates the array safely. Sensors are positioned where they measure what they claim to. Owners get a simple display, a written explanation and, in most cases, a system they never touch. Badly controlled arrays cool pools at night, which is the most common fault we are called to correct.

Honest Expectations in Writing

The quotation states the expected average temperature rise month by month, the expected extension to the swimming season, and the conditions under which those figures hold — including the assumption about cover use, which is the single largest variable. If the family wants twenty-nine degrees in April, we say plainly that solar will not do it alone. Clients can then decide between a hybrid system, a longer season at a lower temperature, or nothing at all, on the basis of real numbers.

Nothing to Run, Little to Maintain

Once installed, an unglazed pool array uses no energy beyond the filtration pump that runs anyway, and the annual maintenance is a visual check, a sensor test and a drain-down before winter. Panels carry ten to fifteen year warranties, and the plumbing is arranged so that a single damaged panel can be isolated and replaced without draining the array. Running costs are effectively zero, which is why most systems pay for themselves against a heat pump within four to seven seasons.

Outdoor swimming pool beside a hotel terrace

Services

What We Install and Service

Calculations, collector arrays, covers, controls, hybrid systems, servicing and repairs to other installers' work.

Site Survey and Heat Calculation

A visit to measure the pool, assess shelter and shading through the day, check the existing filtration and pump curve, examine roof or ground space for collectors, and record how the pool is used and covered. The output is a written calculation of heat loss and required collector area, with expected temperatures month by month and a clear statement of what the system will not do. Charged as a fixed fee and credited in full against any installation.

Collector Supply and Installation

Unglazed polymer arrays for pool heating and glazed or evacuated tube collectors where a pool shares a system with domestic hot water, mounted on roofs, ground frames, pergolas or pool house walls with proper fixings, expansion allowance and lightning considerations. Installation covers all plumbing, isolation and drain-down, integration with existing filtration, and commissioning with measured flow and temperature rise recorded on a certificate.

Covers and Rollers

Floating bubble covers, insulating foam covers, slatted automatic covers and safety covers, with manual or motorised rollers sized to the pool and installed so that one person can operate them in under a minute. A cover that is difficult to use does not get used, which is why the roller matters as much as the cover. We supply covers as a standalone job as often as part of a heating project, and we say plainly when that alone is the right purchase.

Controls, Sensors and Automation

Differential controllers with correctly located collector and pool sensors, motorised valves, frost protection, maximum temperature limits and integration with existing pool automation or a home system where one exists. Owners receive a display that shows what the array is doing, a written explanation, and remote access where they want it. We also retrofit proper controls to existing arrays that were installed with a simple timer, which usually improves output immediately.

Hybrid and Heat Pump Systems

Where solar alone cannot reach the required temperature, a small heat pump sequenced behind the array gives the season length of solar with a guaranteed minimum temperature, at a running cost far below a heat pump working alone. We size and install both, set the control strategy so the pump only runs when the array cannot deliver, and show measured consumption after the first season so the owner can see what the combination actually costs.

Servicing, Repairs and Second Opinions

Annual servicing with sensor testing, flow verification, panel inspection and winter drain-down, plus repairs to arrays installed by others — leaking headers, failed controllers, sensors in the wrong place, arrays plumbed to fight the filtration. Second opinions on quotations from other companies are given free of charge, and we frequently confirm that a competitor's proposal is sound, because the alternative reputation is not worth having.

Contacts

Calculations and Bookings

Send the pool dimensions, whether it is covered, how sheltered the garden is, what temperature you would like and when you want to swim from. We will give a realistic answer before visiting, including when the honest recommendation is simply a better cover.

Servicing, repairs to existing arrays and second opinions are arranged through the same office.

Office40 Rue Sainte-Catherine, 33000 Bordeaux, France

Phone+33 5 56 44 19 72

Emailsunwarmpool@gmx.com

SeasonInstallations February–September; servicing all year