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Sanyo Air Conditioners
Gas Heat Pumps - Technical Background

GHP Gas Hear Pumps Technical Background:

SANYO’s experience in GHP technology gives them a clear advantage in a market that demands diversification. They are the GHP leaders in Japan with 38.6% market share, where gas powered air conditioning constitutes 44% of the market. In fact Japan is the birthplace of GHP, where it was developed in the early ‘eighties when the demands of Tokyo’s 20-million population meant the national grid threatened to reach breaking point. The Japanese government invited SANYO to help develop an alternative to electrically powered air conditioning and the result was the first ever Gas Heat Pump in 1985. Followed by the only 3 pipe VRF in 2005, and now the ECO G Power in 2008.

GHP – The Facts:

The operating temperature conditions are -20ºC for heating and -10ºC for cooling. No defrost operation is required in the heating mode. Therefore no heating ‘downtime’. Power supply for the GHP is 20A single phase for all models, electrical consumption due to inverters is as low as 0.63 kw. Either natural mains gas or LPG can be used to power the system. All GHP pipe work and communication wiring are as per the SANYO ECO Multi VRF system, allowing the mixing of GHP & ECO on the same “S-Net” configuration. (Communication BUS) The system installation procedure is identical to the current ECO Multi VRF system, although the permitted indoor unit per outdoor unit quantity is increased to a maximum of 32, which applies to all models. The recommended indoor to outdoor capacity ratio is from 50% all the way up to 200%, offering greater flexibility to users.

All GHP models use Nissan built engines and refrigeration compressors produced by Japan based Seiko Industries. There are two engine capacities used. The 1300cc twin overhead cam is used for the 8 and 10hp, which requires one compressor while the 2500cc overhead valve engine is installed to the 13, 16, 20hp and 25hp, which has twin compressors fitted. The 8 and 10hp model includes one condenser fan while the 13, 16, 20hp and 25hp uses two fans. The condenser fan motors are single-phase inverter, driven using DC voltage. The inverter system also controls the single-phase coolant water pump. Waste gas output is minimised in the GHP with the aid of an acid neutralizer, fitted to the engine exhaust system. With regular servicing, the engines offer approximately 13 years hassle free operation. The service requirements of the outdoor units are minimal. Major servicing is suggested at 10,000 running hour intervals. This tends to work out at an average of one service every four years. With 8,800 hours in a full year, even if you run the unit full time servicing would only be required once a year. The facility for Refrigerant Leak Detection is in-built into the GHP just as on the three pipe electrical ECO version. An external refrigerant detector is connected to the CN6 plug on the indoor unit PCB. If the sensor is activated then the system immediately shuts down. A dedicated P14 fault code is then displayed on the system remote controllers.

GHP Outdoor Units - Engine Components:

To achieve long service intervals offered by the GHP its engine requires an oil reserve. Up to 50 litres of oil are stored in a single oil tanks. The oil system has an external oil pump to circulate the oil from the oil tank to the engine sump. The engine also has an internal oil pump as per a normal car engine. Two Air Cooled Water Coolant heat exchangers are positioned before the refrigerant Air Cooled Heat Exchangers, which are of equal size. If the engine water rises above 80ºC then coolant water passes through these. There are two Coolant Water tanks installed. The main tank is installed at high level and the reserve tank is installed below. The coolant water is filled with water/glycol to prevent freezing as low as -45ºC. The system’s Coolant Water Pump is an Inverter driven pump, operating on 240DC voltage full speed = 3200RPM. Its Air Intake Filter is very similar to that found in a car engine.

The GHP uses a special type of spark plug designed for longer life. The same plug is used for all models. Control of the Gas/Air Mixture control valve or Throttle valve is achieved by a step motor operating between 0-480 steps. The control valve can be varied as and when more engine RPM is required. The GHP’s Exhaust/Coolant water heat exchanger is of the Shell and Tube variety, acting as a Condenser to condense the moisture from the exhaust gases. Its Exhaust Gas Drain Neutralizer ensures that the moisture condensed from the exhaust gases is passed to the Drain Neutralizer. Within the Neutralizer there are Calcium Carbonate chippings that absorb any acid produced, maintaining the drain water at a ph level 6.8-7.0. The Stainless Steel Exhaust Muffler normally operates at 80ºC. A high temperature muffler sensor is fitted to ensure that if temperature exceeds 130ºC then the high temperature alarm will be triggered. A gas control valve in the system incorporates three jets: a fixed main jet, a fixed by-pass jet and a variable control jet. The valve also contains an adjustment plate that is used if the GHP is run on LPG.

GHP Refrigeration System:

The compressor used in the refrigeration system is a Belt driven Multi-Vane Rotary compressor incorporating five Vanes, two Suction and two Discharge ports. The lubrication oil used is a Poly Alkaline type unique to the GHP. The 8 and 10hp model contains a single compressor with on/off magnetic clutch control.

The 13, 16, 20 and 25hp (2 and 3 pipe) models, feature a twin compressor arrangement, one with on/off control and one at a constant operation. Its Oil Separator is the same as the Eco-Multi, as is its Four Way Reversing Valve. The Condenser fan motor is a 240V DC Inverter driven type. The 8 and 10hp has a single fan while the 13, 16, 20 and 25hp contains two fans, which are both inverter driven. Two outdoor heat exchangers are incorporated in the refrigeration system, both equal in size similar to the ECOi System. The Suction/Coolant Water Heat Exchanger used in the system is a Plate type Suction Gas/Coolant Water Heat exchanger that is used in the Heating mode. Coolant water is passed through the exchanger to allow Suction gas to absorb heat transferred from the engine. The water flow is regulated via a 3 Way control valve. A Hot Gas Bypass Valve is in place to unload the compressor at starting. It is also used to prevent low-pressure gas situations occurring. Two standard Pressure Transducers are fitted, one to the Discharge gas line for high pressure control and one to the Suction line. These sensors enable the actual operating pressures to be viewed via the outdoor PCB.

General Mode of Operation:

Engine Operation:

When there is a requirement for ‘Thermo-On’ from a single fan coil (the minimum size is 2.2 kw) or multiple fan coils, then the engine is started. At this point the engine RPM is governed by the difference between the temperature set point and actual current operating temperature. Therefore the greater the temperature difference, the higher the engine RPM. The minimum operating engine RPM is 800 and the maximum RPM is 2200. If all indoor units are at ‘Thermo-off’ then the engine stops. The engine has been designed to operate within 10,000 hour service intervals. The engines are expected to use oil at a rate of 3cl/h.

Additional Features:

Water Chiller:

To increase the flexibility and usage of the GHP, a water chiller can be installed. The chiller is available in two sizes offering cooling capacities of 25 kw and 50 kw. The chiller can be positioned up to 120 metres from the outdoor unit, therefore internal chiller location is made possible. The operating water range for the chiller is +5ºC to +15ºC as standard. If required the temperature range can be altered to offer low temperature usage from -15ºC to +5ºC albeit anti-freeze additives are required for the water system. Simple local control at the water chiller is a standard feature. Also a remote control option is available, allowing remote stop/start and alarm capabilities.

Internal Hot Water Heat Exchanger:

The 13-25hp GHP outdoor units are fitted with an internal additional heat exchanger. This allows for external hot water to be obtained whenever the GHP unit operates in the cooling cycle. Instead of dissipating the engine heat to the atmosphere, the engine cooling water is passed through the internal heat exchanger and this heat is then passed into a secondary water system. Up to 22 kw of heat can be produced at 75ºC making this option a viable means to boost any hot water system.

Commissioning:

To make commissioning as hassle-free as possible all GHP outdoor units after final production are passed to the test run bay for a minimum one hour trial run. Extensive testing and operation checks are carried out. Only after passing all the stringent testing are the GHP systems passed for export. Site commissioning for the GHP is similar to the electric ECO Multi VRF system. After completing all field wiring and piping, the GHP utilises a simple ‘Automatic Address’ procedure for the indoor and outdoor units (no need for any DIP switch settings) which allows for quick system set-up. On completion of the ‘Auto Address’ procedure system operation is now possible. Operation of the GHP is then monitored, ensuring all run conditions are within normal operating parameters. To assist in collating the run information, the SANYO service checker can be connected. After recording the running conditions this information can then be stored and printed for insertion into the commissioning documentation. With SANYO offering to commission all GHP systems and offer the relevant gas certification and subsequent maintenance training on-site, any concerns arising from this new technology are instantly dealt with.

Service/Maintenance Requirement:

The following are required when carrying out a 10,000hr service.
1) Change all oil
2) Change oil filter and oil blow by filter (only installed on 8 &10hp)
3) Change Air Intake filter
4) Change spark plugs
5) Clean Drain Neutralizer crystals
6) Engine inspection including compressor drive belt.

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Sanyo Air Conditioners
ECOi House
9 Whyteleafe Business Village
Whyteleafe
Surrey
CR3 0AT

Tel: 0845 6126364
Fax: 0845 6126365