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HEAT PUMPS

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HEATPUMPS

Are the Navitron Heat pumps suitable for single phase or 3 phase electricity?
The Navitron 5kW and 9kW heat pumps are suitable for standard 240v single phase input.

What refrigerant type is used in the WRB05 and WRB09 heatpumps?
We use R407c which in an environmentally-friendly refrigerant with zero-ozone depleting coefficient.

Can you provide larger heat pumps?
Yes, we can provide heat pumps up to 16kW. Larger units are available on request

How does a heat pump work?
A heat pump does not create heat, but rather it moves heat from one place to another. Your refrigerator is a heat pump that moves warm air from inside the box to outside making inside the box colder. A ground source heat pump collects heat energy stored in the earth and transfers it inside your home. However, it does so very efficiently - up to 6 times as much heat is produced compared with the electricity required to run it.

I’ve heard heat pumps don’t work very well in cold climates.
Some air source heat pumps, especially the older models, don’t perform well when the outdoor temperature drops below freezing. Ground source heat pumps connect with the earth and are not affected by freezing temperatures.

How is the heat transferred between the earth and my home?
The earth has the ability to absorb and store heat energy. To use that stored energy, heat is extracted from the earth through a liquid medium (groundwater or an anti-freeze solution), and is pumped to the heat exchanger of the heat pump. There it’s converted into usable heat for the home.

Horizontal Loop System

How much can I save?
A ground source heat pump is three to four times more efficient than a conventional furnace. The unit is moving heat- not creating it, so the only electricity being used is to run the compressor and fans. It will cost less to operate than a high efficiency natural gas furnace or wood stove, and much less than a propane or electric furnace.

Can I use the Navitron Ground Source Heat Pump to Cool my house in the summer?
Yes, you can select the cooling function on the control panel to run the system in reverse and provide cooling in the summer. Do not try to cool the house during winter, or damage may occur to the heatpump.

How does the cooling work?
In the cooling mode, a ground source heat pump takes heat from indoors and transfers it to the cooler earth. You can change from heating to cooling with a flick of a switch on the indoor thermostat.

How does it connect with the earth?
The actual connection is made either through groundwater - an open loop system like a well, or an underground, closed loop system. Most installations use a closed loop.The closed loop uses a continuous loop of a plastic pipe, buried to make contact with the ground.

What can I use for the ground source loop?
There are a variety of heat sources you can use:

• A loop or several loops of plastic pipe buried in the ground, at a depth of at least 2m

•  W loop o several loops of plastic pipe suspended in a lake, river or other source of flowing water

• Well water/stream water/river water/sea water pumped directly through the heat pump, using a suitable filter to prevent ingress of dirt and abrasive particles.

• Water pumped directly from a bore hole, and returned to another bore hole at least 10metres away

Where is the buried loop located?
That depends on land availability and terrain. Most closed loops are trenched horizontally in yards adjacent to the house.

How deep and long are the trenches?
Trenches are normally 1 to 3metres deep. Plastic pipe is placed in the trench, often in multiple layers. Trench length will depend on size and insulation levels of the house. Alternatively, the pipe can be laid out as 'slinkies' which reduces the required trench length.

What length of pipe will I need for the ground loop?
Typically for the 9kW unit, you will need approximately 300m of pipe. Standard pipe 20mm diameter is sufficient. This can be purchased as 150m rolls. Typically in warmer climates you should lay 1m of pipe per 40watts of heatpump (heating) rating. In colder climates, 1m of pipe should be laid for each 30watts of heatpump. The pipe should be laid between 2 and 4metres deep. If space is limited, it is possible to lay pipes at different depths in the same trench - eg 4m/3m/2m.

Should I use antifreeze in the groundloop?
Yes, ideally. In case of leakage, it is important to use a non-toxic antifreeze. The cheapest and easiest solution is to use common salt. You should add enough salt to protect to -12C.

Do I need separate ground loops for heating and cooling?
No. The same loop works for both. The only thing that happens when changing from heating to cooling, or vice-versa, is the flow of heat is reversed.

What if there’s no room for a horizontal loop?
Closed loop systems can also be vertical. Holes are bored to about 40 to 60metres. U-shaped loops of pipe are inserted into the holes, and the holes are backfilled with sealing solution.

Vertical Loop System

What is the pipe made of?
Closed loop systems should only be installed using high-density polyethylene or polybutylene plastic. These pipes are inert to chemicals normally found in the soil, and are guaranteed for 50 years. PVC pipe should not be used under any circumstances.

Can I put a loop in a pond or a lake?
Yes, if it’s deep enough and large enough. A minimum of six feet in depth at its lowest level during the year is needed for a pond to be considered. Certain permits may be required to place a loop in a lake.

Can a ground source heat pump also heat water for hot water?
Yes, by using a device called a desuperheater. Desuperheaters are standard on some units, and optional on others. Producing high temperature water can be very inefficient with heat pumps by comparison to the standard COP rating. The WRB series heatpumps do not have a desuperheater facility, as they are designed for high efficiency.

What size water pump should I fit to circulate the ground-loop water?
The circulation pump for the ground loop is not included in the heat pump (however, an internal pump is provided to circulate the heated output water). We recommend that the pump should produce a flow rate of at least 0.25litres/second and be capable of working with a 10m head. Bearing in mind the resistance of the ground loop, this generally requires a circulation pump of at least 250watts electrical consumption.

What is the noise level of the WRB05 and WRB09 heatpumps?
We have not taken accurate noise level measurements, but it is approximately 50dB

Email: sales@navitron.org.uk