The open loops passive cooling series heat pumps contain both compressor and blower sections of the heat pump in one cabinet. Optional desuperheater coils for production of domestic hot water are also available. Units are intended to pump water from an open well and discharge the water either to a return well, pond, leaching field or other suitable method. Units are available in either horizontal or vertical configuration. All units supplied with Electronic 2-stage heat 1-stage cool thermostat.

The refrigeration circuit is only operated in the heating mode while cooling is provided directly by pumping cold well water to the special section of the air coil. Domestic hot water is produced only during the heating mode. "O" style units are particularly suited to areas where the temperature of water supplies is below 50°F.

Typical Disposal Methods

	Water pumped from a well to disposal in pond, lake or stream etc.
	Water returned to a second well.
	Water pumped to a leaching field.

"O" series units are available in 45 - 55 - and 65,000 Btu output in heating mode. Cupro-nickel heat exchangers are available upon special order. Units available with or without domestic hot water generator.

Open Loop Geothermal Heat Cycle

Open Loop Heat Pump System Prerequisites

Water Well

	DRILLED well of 5'' diameter or larger.
	Well casing properly sealed or grouted into rock.
	Water flow preferably entering well at a depth of 75 ft. or more.
	Temperature of well at least 40° F.(Normally 45+ °F.)
	Well must be able to supply requirements of BOTH heat pump and residence usage at the same time with maximum drawdown from static level of 30 ft.

Note: These are minimum water requirements based on an entering water temperature of 46° F

Water Pump System

	A submersible pump is generally required.
	Must be able to pump the required water flow listed above at a minimum of 30 psig. at the dynamic pumping depth of your well.
	Make sure you select the pump using the pump manufacturers pump chart.
	Use a minimum of 30 gal. equivalent air bladder tank.

A heat pump with Btu output capable of heating the home in all winter weather conditions should be selected as follows:

Duct Systems

	A duct system capable of supplying the required air flow is of utmost importance.
	Generally allow 100 cfm for each floor grill.
	All leads to the grills should be 6'' in diameter (28 sq.in)
	Your main hot air trunks should be at least 75% of the square surface area of leads being fed at any given point.
	Return air grills should have the same total square surface area as the total of your supply grills. (minimum)
	The square surface area of your return trunks should be 1.5 times the square surface area of the grills being handled at any given point along the trunk.
	It is VERY IMPORTANT that all turns in both the supply trunks and the return trunks be made with TURNING RADII. Remember that air is a fluid and, just like water, it does not like to go around a SQUARE corner.

Discharge Water Methods

	You do NOT necessarily have to have a return well.
	Some of our customers do one of the following with their return or waste water:    Run it into a drain or ditch.  Leaching field

In most instances if you run the water right out on top of the ground it will soak back into the ground in less than 50 ft. of travel. If suitable care is taken to insure that the drain pipe runs downhill and the end of the pipe is protected by a bale of hay

or spruce bows ect. the end of the pipe will not freeze. When snow comes it will usually cover the entire process much like a small spring. The above information is intended to give the prospective user/purchaser some insight as to the general

requirements for a successful application of the NORDIC heat pump.

Optimum Placement

The NORDIC heat pump has an air-filter rack which can be removed for easy entry through a doorway or to facilitate moving the unit with a furniture cart. Simply remove the two screws which hold the end cap in place, slide the cap off and push the rack back off it's rails. When the heat pump is in place the filter rack can be reinstalled with the removable end (where the filter is removed) facing the direction that allows easiest access for changing the filter. To achieve the greatest efficiency, the heat pump should be centrally located in the home with respect to the the conditioned space. This design provides the utmost in economy and comfort and usually can be accomplished in harmony with the design of the home. A heating system cannot be expected to produce an even warmth throughout the household when it is located at one end of the structure and the warm air is transmitted with uninsulated metal ductwork.

If possible the three main service doors should remain clear of obstruction for a distance of (2) two ft. so that servicing and general maintenance can be carried out with a minimum of difficulty. Raising the heat pump off the floor a few inches is generally a good practice since this will prevent unnecessary rusting of the bottom panel of the unit. We recommend that the heat pump be placed on a piece of 2'' styrofoam covered with 1/4'' plywood. The styrofoam will smooth out any irregularities in the cement floor while the plywood will distribute the weight of the NORDIC unit evenly over the styrofoam. This process will also deaden the compressor noise emitted from the bottom of the cabinet. As an alternative, several pieces of 2''x4'' lumber can be placed under the unit running from the electrical connection side to the filter rack side of the heat pump. Laying the 2''x4'''s in this manner will give the best support since they will be at right angles with the internal steel compressor and heat exchanger support.

Plumbing the Heat Pump

The NORDIC heat pump must be supplied with an adequate water supply, since in essence, water is the fuel for the unit. It is imperative that the flow requirements listed in the engineering section be closely adhered to. Maritime Geothermal Ltd. recommends the installation of a water flow meter on the discharge line so that the exact amount of water flowing can be determined at a glance. Plumbing lines, both supply and discharge, must be of adequate size to handle the water flow necessary for the heat pump. For distances less than 40 ft. from the pressure tank, 3/4'' copper lines should be run while for longer distances we recommend that 1'' plastic or copper lines should be run to the heat exchanger. Similarly, a 1'' line should be run from the discharge pipe to the method if disposal. Ideally there will be water flow available in excess of the requirement of the heat pump. In such a situation the proper pump can be selected to maintain a pressure of 30 to 40 psig. on the lines when the heat pump is operating. However in some cases a well can supply a heat pump only if the minimum requirement for water is used.

Water flow to the heat pump can be controlled very accurately by the installation of a reverse action pressure valve in the discharge line of the unit. Another method of regulating the flow is by the use of a ``DOLE'' valve. This valve will automatically control the amount of water flowing through it by varying the diameter of a flexible rubber orifice through which the water passes. If either of such valves is needed they can be supplied and installed by your dealer. All water line valves on both the supply and discharge lines should be either ball or gate valves since a GLOBE valve will create too much restriction across the line possibly causing the heat pump to trip out on it's low pressure safety cutout control as a result of insufficient water flow. Exposed water lines will have a tendency to sweat when the heat pump is in operation, therefore it is recommended that both the water supply and discharge lines be insulated with suitable insulation.

Typical Plumbing & Piping "O series"

Hot Water Connections

Connection to the hot water generator feature of the heat pump is accomplished by teeing into an electric or oil fired hot water tank with a capacity of 40 gal. minimum. A typical piping diagram is shown elsewhere in this manual. Be sure to note the position of the check valve and the direction of water flow. One should be sure the tank is filled with water and is under pressure before activating the heat pump. Slightly loosen the copper union on the hot water discharge pipe to allow air to escape from the system before the unit is started. This step will make certain that the water circulator is flooded with water when it is started. Since the pump is water lubricated, damage will occur to the pump if it is run dry for even a short period. The union on the discharge water line may have to be purged of air several times before good circulation is obtained. A hand placed several feet down the line will sense when the water is flowing. The thermostats on the hot water tank should be set to 120 deg.F. since the heat pump has an internal thermostat set at a low of 130 deg.F. By setting the tank thermostats as described, the heat pump will try to keep the tank above the cut-in point of the electric element settings thus generating hot water from the heat pump only. During summer, or periods of high demand, the electric elements will energize to help make hot water.

Condensate Drain

You will notice in the piping diagram that there is a small drain pipe to the left of the front door. This drain allows the condensed water vapor which forms during the air-conditioning cycle to escape to a suitable area of your selection. On a very humid day there could be as much as 10 gallons of water formed. Care should be taken in the spring to insure that this pipe is not plugged with dust that has formed during the winter since the water formed will overflow into the bottom of the heat pump.

Water Disposal Methods

Water disposal methods vary from area to area however some consideration should be made to prevent the cooled discharge water from immediately coming in contact with the supply source. Generally speaking, returning water to a second well, pond lake or stream is acceptable while returning water to the same well will usually cool the water so much that the heat pump will shut off on it's low pressure safety control. A return well should be a minimum of 80 ft. from the supply well for residential applications. The water returned to the well will not be necessarily be pumped into the same aquifer, depending on underground conditions, but the return well does have to be able to supply the same quantity of water as the amount you wish to recharge into it. If the static level (level when not being pumped) of a well is high (10 to 20 ft. from the surface) it may be necessary to place a well cap on the well to keep the return water from flowing out the top of the well. This cap is commonly required since a certain amount of pressure is needed to force the return water back down the well if the static level is high. Return wells are not always the answer and to some it may be more satisfactory to pump the water to a pond or away into the woods. Water recharged naturally through percolation into the soil is an alternative to a recharge well. The water discharged will generally soak into the ground within a distance of 50 to 100 ft. If care is taken to make sure the end of the pipe does not freeze then this method of disposal works well.

Safety Controls

The NORDIC heat pump has two built in safety controls which are designed to protect the unit from situations which could damage it.

1. LOW PRESSURE CONTROL is designed to shut the unit down if the refrigerant evaporating pressure becomes too low thus risking the danger of freezing conditions in the evaporator. There are only (4) reasons why this control would activate and they are:

	Low water flow. (See requirements for each model)
	Low water temperature. (Below 40 deg.F.)
	Dirty or fouled heat exchanger.
	Low refrigerant charge.

2. HIGH PRESSURE CONTROL is a high pressure safety limit which monitors compressor discharge pressure. This device will not normally trip unless there is an interruption in air flow. Such a situation could occur if the blower motor or fan belt failed or if the heat pump had an extremely dirty air filter. If either of these controls trips it will activate a LOCK-OUT RELAY which prevents the unit from restarting until power to the control circuit is broken (by turning the thermostat to the OFF position and then back on again) or the electrical supply to the unit is broken by opening the heat pump breaker and then closing it again. If one of these controls trips there is a serious problem with the system and it must be rectified if the unit is to maintain good service.

NOTE:Under no circumstances should the heat pump lock-out relay be reset more than twice in an hour. If the the heat pump is shutting off because of LOW or NO water flow then repeated resetting of the unit could cause the heat exchanger to freeze and rupture destroying the heat pump.

Electrical

The NORDIC unit is supplied with an opening for 3/4'' conduit nipple on the right blank side of the unit. Above this is another 3/8'' hole for the thermostat wire. A wiring diagram is located on the electrical box cover for quick reference and although the connections to be made are quite simple, Maritime Geothermal Ltd. recommends that a properly qualified electrician be retained to make the connections and wire the thermostat. The NORDIC unit comes supplied with a thermostat and connections are clearly marked on the control box.

Ductwork

Ductwork layout for a NORDIC heat pump will differ from normal design in the number of leads and size of main trunks required. Air temperature leaving the heat pump is normally 95 to 105 deg. F., much cooler than that of a conventional warm air furnace. To compensate for this, larger volumes of lower temperature air must be moved and consequently duct sizing must be able to accommodate the greater air flow without creating a higher static pressure or high velocity at the floor diffusers. Maritime Geothermal Ltd. recommends that the static pressure be kept below .15 inches of External Static Pressure total. Return ducts should ideally be placed in every room and be sized 50% larger than corresponding supplies. In some instances the number of floor diffusers will actually double when compared to the number that would normally be used for a warm air oil-fired furnace.

Starting the Heat Pump

BEFORE starting the heat pump the following areas should be rechecked to assure proper operation.

	Check all high voltage field wiring and electrical connections inside the control box for good connection.
	Check all low voltage thermostat to make sure they are connected properly. Place thermostat HEAT-OFF-COOL switch in the OFF position.
	Turn on the main power switch. Allow the power to remain ON without starting the unit for a period of 4 hours. Refrigerant migrates to the compressor oil when the compressor is unheated. A crankcase heater is standard equipment on your heat pump and it will warm the compressor, dispelling the liquid refrigerant. Compressor damage can occur if the heat pump has been brought in from a cold location and immediately started up.
	Turn on the water supply and check all plumbing for leaks.
	Check the hot water tank to be sure it is filled with water before energizing the circuit.

NOTE: In a low ambient air start-up the hot water tank should be energized for at least 4 hours before the heat pump is started. A combination of low air temperature and 45 deg.F. water in the hot water tank can sometimes cause the unit to shut down on it's low pressure control. If this happens close ONE valve in the hot water circuit to temporarily shut off the flow to the hot water generator. Do not shut off both valves since water expanding in the hot water generator loop will burst the plastic circulator pump housing. When the home has come up to temperature open the valve for normal hot water operation. Crack the union on the hot water discharge pipe to make sure that all air is out of the system and the circulator pump is flooded with water.

	Make sure the air filter is clean and in place.
	Vacuum out any dust and debris that may have collected in the unit during installation. · Check the condensate drain to be sure that it is free of obstruction.
	Make sure the unit is sitting level so that condensate water will not overflow the catch pan.
	Make sure the proper time-delay fuse has been installed in the fuse box.
	Have the following tools on hand and know how to use them.    A. A refrigeration guage set.  B. An electronic or other accurate thermometer.  C. An amprobe.  D. A water flow meter.
	Connect your refrigeration guage set.
	After the 4 hour warm-up period place the thermostat function switch in the HEAT position, turn up the thermostat. The compressor, blower and hot water circulator will start. NOTE: If your unit is equipped with an electronic thermostat there may be a short delay before the heat pump starts. Some models may also experience a 10 to 15 second time delay before the blower starts.
	Observe the readings on the high and low pressure guage set. When the home reaches a temperature of 65 to 70 deg.F. the suction pressure (blue guage) should be approximately 54 to 58 psig. while the head or discharge pressure (red guage) should be in the area of 225 to 275 psig. Record this information on the warranty test card.
	Using an electronic thermometer or other accurate thermometer, record the supply water temp.''IN'' and the water temperature ``OUT''. The outlet water temperature should be from 5 to 9 degrees cooler than the inlet water temperature.
	Record the supply water flow in gpm.
	Record the return air temperature by drilling a small hole in the return air plenum approximately 2 ft. from the filter rack and inserting the thermometer's sensing device.
	Similarly record the discharge air temp. There should be a rise across the air exchanger of from 25 to 35 deg.F.
	At the electrical disconnect switch place the amprobe jaws around the supply wires and record the current in each.
	Place the thermostat function selector in the COOL position and turn down the stat to a temperature that will cause the air-conditioning to begin. The blower and cooling solenoid should operate. The outlet temperature will be approx. 10 to 20 deg.F. cooler than the return air temp.

General Maintenance

As with any piece of equipment there will eventually be some maintenance to be done on the heat pump. Only three areas will need attention and they are as follows:

	1. Change the air filter when required.
	2. Oil the blower motor once a year.
	3. Clean the groundwater heat exchanger. Since the NORDIC heat pump is always in the heating mode, the groundwater heat exchanger will experience very little scaling because it is always cooling the water that is passing through it. However if a situation should occur where the heat exchanger becomes fouled with sand or mud ect. the end of the heat exchanger can be easily removed and the tubes inside cleaned with a 45 caliber

Photo of "O" unit with front door open. (111K)