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Sanyo Air Conditioners
Gas Heat Pumps - Technical Background
GHP 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 0.63kW. 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 and 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, 20 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 polyalkylene 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 have a
single fan while the 13, 16, 20 and 25hp contain 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 2.2kW) 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
22kW 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
10,000 hour 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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Technical information associated with:
Sanyo Gas Heat Pumps - Technical Background
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