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Summary of Contents for PrecisionTemp TWINTEMP JR.
- Page 1 TWINTEMP JR. HYDRONIC SYSTEM 2/2013 ...
- Page 2 TwinTemp Description of Operation and Sequence of Operation Technical Description of Operation‐ The TwinTemp systems provide quiet space heating utilizing liquid to air blowers or radiant devices, while producing a continuous supply of hot water. Its Variflame gas modulation enables it to use a very small tank and still maintain efficiency without rapid burner cycling. This greatly reduces startup time and standby heat loss. Unlike its diesel counterparts the TwinTemp has an instant on burner and modulates the gas flow on a 4‐1 ratio. A copper heat exchanger inside the tank of heated antifreeze in used to indirectly heat the potable water. This method is not only efficient, but will extend the life of the critical heat exchange elements, tank and circulating pumps. Sequence of Operation The power and propane are turned on to the TwinTemp. If the Tank thermostat senses low tank temperature (below 190° F), it will send 12 vdc power to the green control board and Pump 1 (rear) pump. Note‐ the Junior has one zone pump and the TwinTemp‐2 has 2 zone pumps. Anti‐freeze starts to circulate from the bottom of the tank, through Pump 1, to the burner heat exchanger, out to Zone 1 blowers and back to tank. Simultaneously, the control board powers the power vent relay which activates the power vent and fluing is proofed by the pressure switch via the ¼” hose. The pressure switch sends 12 VDC to the ignition board (if flue is blocked, burner will not light). The solenoid gas valve is energized and a spark is effected to the igniter probe over burner via the yellow ignition wire. The flame is proofed via the same igniter element and yellow wire. Gas flow is adjusted by the gas modulating valve based on antifreeze temperature. Temperature readings are taken twice per second by the T‐Mid Thermistor. As set temperature (about 190° F) is approached, the gas flow is reduced as much as 70% by reducing the voltage to the gas modulating valve until set temperature is achieved and the burner goes off. When a hot water tap is opened, cold water enters the copper tank heat exchanger imbedded in the tank and the heat transfer takes place. The hot water exits the tank coil through a tempering valve that can be set to any temperature between 100°‐145°. As the tank cools, the burner cycle starts again when the tank thermostat senses the tank is getting cold. If the zone 1 room thermostat senses low room temperature, it sends power to the zone’s relay that then powers pump 1, control board and the zone blowers through the 160 degree tank switch. When the zone 2 (TwinTemp‐2 only) thermostat calls for heat the zone 2 relay sends power to the pump 2 and the blowers in zone 2 are activated. The burner will be activated by the tank thermostat as above if the antifreeze temperature falls below set temperature. ...
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- Page 5 TwinTemp Preventive Maintenance Schedule It is recommended that the TwinTemp be inspected by a qualified service technician at least once a year. Clean interior of TwinTemp cabinet including combustion air intake grill. Inspect all wiring connectors for corrosion and looseness.
- Page 6 TwinTemp 2/ Jr. Diagnostics & Trouble Shooting A. Use Rhogard Boiler antifreeze with Protek 922 additive or equivalent with Aluminum tank. Camco is acceptable with stainless steel tank. 1. Mix antifreeze 50/50 with distilled water 2. Total amount of antifreeze held in hydronic system of a Newmar coach is approximately 5.5 gal. 3. Always check fluid level and condition. 4. Common cause of contamination; a. Repeated introduction of air in closed system causing fluid contamination. b. Plumbing leaks, radiator cap, etc. c. Do not mix winterizing afrz. or ethylene glycol afrz. with propylene glycol boiler antifreeze. d. Effects of contamination, sludge, metal corrosion. B. Starting diagnostics check basics; power, fault codes, etc. then use the sequence of operation to aid diagnostics. 1. Two calls for ignition, Antifreeze temperature (tank thermostat switch) and interior thermostat. C. Causes and symptoms of restricted flow. 1. Sludge/restriction in plumbing loop. 2. Kinked plumbing lines or connections. 3. Sounds associated with restricted flow are rattling knocking noise during propane ignition with ignition only ...
- Page 7 4. Monitor t mid test point (yellow) during ignition for a rapid DC voltage drop i.e. 2.0vDC drop to .5vDC in 10‐30 seconds indicating restricted flow. D. Plumbing restrictions: Supply line hot return line warm/cool while in winter mode. 1. Summer/Winter valve may allow fluid to bleed through if restriction is in the hydronic loop causing the TT to appear to operate normally. E. Newmar uses relays making a single zone system into two zone system by controlling the heat register fans. 1. The TwinTemp thermostat and blower signal goes to the bank of relays and then distributed to the coach wiring. F. Summer / winter valve positions. G. Electric element operation. 1. Used as stand alone for limited hot water or used in conjunction with propane to reduce propane consumption in either summer or winter operation. 2. Overheat reset & electric element ECO 3. Low fluid level in tank will make boiling noise when electric element is in use. H. Hot water production 1. Mixing valve. 2. Summer hot water production, 2.25 gallons of antifreeze heated. 3. Winter hot water production delayed until 5.5 gallons of antifreeze are heated causing short delay in hot water ...
- Page 8 TwinTemp Hydronic Heating/ Water Heating Operating Instructions For maximum heat and hot water output, it is recommended to use the LPG mode of operation in addition to the 120 volt electric element. Electric element operation should be used for minimal hot water demand such as washing hands or dishes. It is not necessary to have the water system filled to use the space heating system, but the heating system must be filled with anti‐freeze. To Start Up System: Turn on the propane supply. Turn on 12 volt power switch on the right side of the TwinTemp cabinet. Turn on 12 volt power switch on coach, if applicable. Burner will start‐up and system will be up to operating temperature in approximately 10‐15 minutes depending on position of Summer/winter valve. Summer Operation Position Summer/Winter valve in Summer position. When the space heating function of the TwinTemp is not needed, the heated anti‐freeze should not be circulated to the blowers. To prevent this circulation, the Summer/Winter by‐pass valve should be turned ¼ turn. When heating is again needed, this valve handle should be turned ¼ quarter turn from the Summer position to the Winter position. This adjustment should only be needed twice a year for summer/ winter operation. Summer Winter For Space Heating: Position Summer/Winter valve in Winter position. Turn on main coach thermostat and set to desired temperature. When the system reaches set temperature the blowers will turn on and heat is delivered. When room reaches set temperature, the pump and blowers for that zone will go off. If tank temperature is below set temperature the burner will stay on until tank reaches set temperature. NOTE: the heat register blowers will not activate if the tank temperature is below 160˚ F. This assures that the hot water function takes priority under heavy usage conditions. Blowers will resume operation when tank returns to operating temperature. ...
- Page 9 For Hot Water TwinTemp unit and water system pump must be turned on or connect to city water system.Turn on hot water tap. Note: During heavy heat and hot water demand, the hot water system takes priority and the heat register blowers may shut off briefly to maintain hot water supply. Hot water temperature is factory set at approximately 120 degrees. To change temperature, consult the operating manual. Once the tank reaches set temperature (5‐15 minutes after system is turned on), continuous hot water is delivered when any tap is opened. Delivery temperature is determined by the setting of tempering valve Warning: this valve is factory set at about 120˚ F. adjusting temperature any higher could result in severe injury due to scalding. Tank thermostat turns pump 1 and burner on automatically when tank temperature starts to drop. Anti‐freeze circulates from burner and back to tank as it heats. Burner remains in high fire and gas modulates burner to low burn until set temperature is attained. When set temperature is reached, burner and pump shut down and system returns to stand‐by mode. Winter Mode Hot Water Production During winter operation if the system has been dormant for more than 20 minutes turn on interior thermostat to call for heat. When the heat register blowers come on turn off thermostat and turn on hot water tap. Preheating the system is required in winter mode for hot water production due to 3 gallons of cold fluid in the hydronic loop suddenly being returned to the TwinTemp tank lowering the fluid (boiler antifreeze) temperature required for hot water production. Once fluid temperature reaches set temperature the system will make continuous hot water. To Use With 110 Volt Heating Element Turn on 110 volt element switch located inside coach. Let the unit heat up for a minimum of 30‐60 minutes. Note: In the 110 volt mode of operation the electric element supplies the heat until demand exceeds its capacity at which time gas burner automatically ignites. The TwinTemp Jr. is equipped with one 110 VAC electric heating element. The element provides limited amounts of hot water or space heating, such as washing hands or dishes. The electric element can be used with or without the propane burner, but for continuous hot water or space heat, the propane burner must be used. To operate, turn the 110 volt switch on in the coach. For small amounts of hot water only, there is no need to turn the 12 volt power on to the TwinTemp. However, if space heat is required in very cold weather, the 12 volt switch should be turned on. If there is a higher demand for heat than the 110 volt element(s) can provide, the propane burner will activate automatically. For best operation, turn the 110 volt element on about 30 minutes before turning 12 volt switch on. This allows the tank to come up to temperature utilizing the electric element before the burner can activate. This will help conserve propane. ...
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