Need to know: Pool heating requirements for your school

Having a school pool is a privilege many New Zealand schools are fortunate to be able to enjoy.

They provide opportunities for exercise, learning important life skills, and plenty of fun! School pools are also a big responsibility that requires some attentiveness: safety, of course, is critical –not simply in terms of supervision but in terms of water quality and temperature too.  Keeping your pool well-maintained, and well-heated will make sure its well-loved by your students and wider community.

Finding the correct balance of water quality and temperature throughout the year is essential. School pools must meet all the requirements of the New Zealand Standard NZS 5826:2010 – pool water quality. A New Zealand Qualifications Authority (NZQA) qualified person must have the management of the pool’s water quality under their continuous technical supervision, with this person readily available whenever the pool is operating, for example. And a qualified person must test your pool water three times a day to check: pH, alkalinity, calcium hardness, chlorine level, and any other features of the pool chemistry.

Schools must arrange for monthly microbiological monitoring of pool water, requiring water samples be sent to specialist water treatment labs. The pool water quality standard also requires a school’s filtration system must have a two-hour water turnover rate.

We spoke to some professionals this issue, whose very job it is to look after school pools. Speaking from alternate perspectives of solar heating and heat pumps, they each share with us some advice on how schools can suss out their pool water temperature.

Industry expert Justin Watene, owner of Sunbather NZ, specialises in providing and refurbishing solar systems to ensure sufficiently warm swimming conditions. His company prides itself on helping people get into pools for as much of the year as possible and has been doing so for more than 35 years.

According to Justin, “The biggest outcome to solar heating, is the ongoing costs. For schools, we would estimate costs to be below $500 per season to heat a school pool. Compared to diesel, gas or a heat pump, which would push the cost well into the thousands.”

Watene is keen to point out the multiple benefits of having your school pool covered too.

“A cover adds a level of efficiency that heats the pool faster, reduces water loss and helps with water quality.”

A recent case study Watene shares is a project at Titirangi Primary School in Auckland. “The outcome aim was to create a water temperature of between 26-28 degrees, from September to April.

“To do this, we had to remove an old Heliocol system – this was made in Israel out of plastic composite. This system had been installed on timber beams. PVC, Plastic and solar composite materials expand and contract. Timber does not. This caused the solar manifolds to move, while the timber remained rigid, causing the panels to snap and leak.

“We worked with the school to remove and reinstall a system fit for purpose. Once the school had confirmed funding to replace the roofing, we removed the system and then re-installed the solar system with a life expectancy of 15-20 years and a 10-year warranty.”

Watene says having HiPEC PVC composite runs that are very long, means they are very efficient. “So heating a pool can happen within the day, given available sun.”

He recommends systems designed to withstand the harsh NZ sunshine, which are installed by approved providers. “Solar systems that have both not been installed correctly or cannot handle the NZ UV, will break down and cause serious damage to roof areas.”

There are a range of funding options available to New Zealand schools to help with solar system costs, given the environmental benefits. “We work with a range of funding organisations, who can apply for funding throughout NZ for most regions. They work on the best solution and will then facilitate the funding process,” says Watene.

Kevin Trigg of Hot Water Heat Pumps is an expert in the field of heat pump water heaters, working with schools around the country to keep their swimming pools warm. He says, “Pool heat pumps are a very efficient form of water heating. Generally, they are five times cheaper to operate than electric resistance heating and LPG, and half the operating cost of natural gas. It also has the reliability of not being dependant on the sun and doesn’t need extra water pumps as heat pumps use the filtration system for their water flow.

He warns schools to beware of sub-standard offerings:

“Unfortunately, pool heat pumps are an unregulated industry and anyone can say anything and test in any condition to make their machine seem better than another.

Inverters are currently a good example of this. An inverter is not a heating system, but a technology used for some pool heat pumps.

“Space heating heat pumps and inverter washing machines/microwaves, etc., are all highly regulated industries and must meet energy performance standards. This is not the case for pool heat pumps, where most inverters don’t actually ‘invert’, but operate at 100 percent. Inverter heat pumps operating at their maximum capacity can be less efficient than a well-engineered fixed speed heat pump. Heat pump capacity and performance change depending on air and water conditions, it can be hard to compare different pool heat pump products.”

A well-engineered heat pump is a great option for pools. Pools have a large thermal-mass and can hold their temperature for a period of time, allowing the system to completely shut down till the next day saving money on the filter pump operation time.

“We pride ourselves in providing the most suitable technology for a given application. As a New Zealand manufacturer and engineering company, we have spent the last 40 years leading and supporting the industry. There are schools nationwide that still have our heat pumps on their pools from over 20 years ago, all thanks to our quality design, construction and components. Many of our older models can still be repaired as parts are readily available, whereas most imports have less than half the life expectancy and parts are often an issue.”

Keeping your pool covered is key, according to Trigg. “A cover is an essential pool item to inhibit heat  loss and evaporation. They can  literally half the heat loss. It is important to get a good thermal cover to lower the running costs of your heating system,” he says.

Looking ahead, the technology in this field, like every other, will progress, says Trigg. “Technology is an ever-evolving animal, and the industry will be in a time of transition for at least the next few years while refrigerants with different properties continue to be developed and make their way into the mainstream.

“It is important to get the right technology for the job. Inverters, for example, are great and efficient for maintaining low thermal-mass applications like space heating, but not as suitable for high thermal-mass applications. To have an efficient system, it is important to use a reputable company with a long history to avoid costly repairs and maintenance in the longer term.”