Domestic Hot Water FAQ’s
Q. What is a Ground Source Heat Pump?
A. Ground Source Heat Pumps (GSHP) are similar technology to an air source heat pump (normal airconditioning unit). Instead of having a fan unit outside to take heat from the air, it has a net work of pipes buried under the ground called a captor area. They extract the latent low grade energy in the soil and utilise this energy to produce hot water for washing, baths and showers. Winter air temperatures can vary depending where you live from +15 °C to -15°C, the ground temperature however remains relatively stable allowing high efficiencies and consistent performance.
Q. What is a Captor Area?
A. The Captor Area is the means by which heat is collected from the ground. This consists of buried pipes (captors) used to transfer the energy from the ground to the Geothermal Generator unit. These pipes can be made from either copper or high density polyethylene (HDPE) and use either refrigerant (copper) or a water/glycol mixture (HDPE) to collect and transfer the heat. Captors are generally laid horizontally.
Q. Are a lot of earthworks required?
A. Not necessarily, Next Energy’s Domestic Hot Water unit only requires approximately 35m2 of land to bury the captor in. The horizontal captors are buried at only 50-60cm deep. This allows for minimal earthworks, saves on installation costs and suits the New Zealand climate well, as we don’t have the harsh winter temperatures of Northern Europe / North America.
Q. Where does the captor area go?
A. The captor area needs to be within 5m of the Domestic Hot Water unit and needs to be under permeable ground i.e. not under concrete or tar seal as it is largely the rain which transfers heat back into the ground. It is also the moisture in the soil which helps transfer heat into the captors. Captor areas usually go under lawn or flower beds or even under a stone chip drive way.
Q. Does the captor area have to be square?
A. No not at all, it can be any shape as long as there is sufficient area and the captor pipes are separated apart by the correct distance. One example is it could be in a trench along the fence line approximately 45m long and 50cm wide.
Q. Will the ground freeze and damage my plants?
A. As part of the normal operation of a Ground Source Heat pump, the soil immediately around the Captor pipes does freeze, however as the system completes its cycle the soil draws heat from the surrounding area and the soil thaws naturally. At a depth of 50-60cm the pipes are well away from any plant or grass roots. There are however restrictions on the distance the captor field has to be from large trees, water/ sewer pipes and foundations.
Q. Can energy be taken from the ground when there is frost and snow in winter?
A. Absolutely, unlike Solar, Next Energy Ground Source Heat Pump systems do not require the use of boost elements under normal running. The systems are designed so there is always sufficient energy stored in the ground to be recovered and heat the water
Q. Can I have one unit for hot water for baths & showers etc, and In-floor Heating?
A. In order to maximise efficiencies our manufacturer Avenir Energie have developed separate units for both of these applications. There is a dedicated hot water unit for baths and showers etc. They also have a large range of units for In-floor heating and Radiators including High Temperature units. In some circumstances it may be practical to use just one unit (High Temperature), but in most circumstances it is better and often cheaper to have the separate units.
Q. Can the unit be installed outside?
A. Yes. The Domestic Hot Water unit is what is referred to as a split system whereby the cylinder and the heat pump are separate units. The cylinder is usually located inside the house in a cupboard and the heat pump unit can be located either inside a garage or outside up against a wall. The location of the unit needs to be within 15m (one way pipe length) from the cylinder.
Q. What is the expected life span?
A. The Next Energy Domestic Hot Water unit uses good quality components, Copeland scroll compressors, and has a life expectancy in excess of 20 years.
Q. How much will it save?
A. Next Energy’s Domestic Hot Water unit will give typical savings of up to 60% on a standard electric cylinder and even more against gas.
Q. Can it be run on night rate?
A. Yes it could be run on night rate especial if your current system works adequately like this. With a 300l cylinder there is plenty of stored hot water (depending on your hot water usage). We don’t however generally wire them on the ripple control, due to the lower power consumption there is no need and they are left on a normal supply to run whenever necessary.
Q. What is the payback period?
A. This depends on the water usage in the house and what system you are comparing it with, a typical 4 person family would expect payback in 5-7years compared to a standard electric cylinder installation.
Q. What is the warranty?
A. There is 5 yrs on the compressor and captor (cylinder manufactures warranty and T&C’s apply) 2 years on other components, 12 month on installation. The captor pipe in the ground has an expected life of 50+ years
Q. How long does it take to heat the cylinder?
A. It will take a similar amount of time to heat the cylinder as the standard elements, so approximately 4-5 hours to heat 300l from 15°C to 60°C.
Q. Will I need to boost the hot water with electric elements as with Solar?
A. No, the Next Energy DHW60 unit is capable of supplying 60°C hot water for a 300L mains pressure cylinder, suitable for a family of 4-6, without the need for boost elements, day or night, summer or winter irrespective of the weather conditions. The cylinder does however include heating elements that are wired up as normal during installation. These are left turned off as a redundancy and can be switched on in the unlikely event the geothermal system is out of service or for maintenance.
Q. Can I use my standard cylinder?
A. In some circumstances yes, usually if it is a reasonably new well insulated cylinder which has an extra fitting for the recirculation of the water through the Domestic Hot Water unit (solar/ heat pump ready). The Next Energy DHW60 is however usually supplied with a “Heat Pump Ready” 300 litre, stainless steel, mains pressure cylinder to best optimise the efficiencies to be had. We are happy to advise on your present cylinder.
Q. If this is new technology, will it work here in New Zealand?
A. The technology has been available in Europe and North America for over 20 years and has proven itself in the harsher climatic conditions of Scandinavia and Europe. Next Energy GSHP’s are made by Avenir Energie a French company (part of the Danfoss group) with many systems installed in Switzerland and Germany amongst other countries. By comparison, New Zealand has a much warmer winter climate and ground source heat pumps therefore, are very effective here.
Q. How do I go about obtaining more information and receiving a quote?
A. Next Energy Ltd is part of the Enersave Group established in 1996. Next Energy will provide an obligation free quote or estimate. Please either contact us directly or fill in our online enquiry form here.
