background image

Rheos Boiler and Water Heater

Page 45

SECTION 8.

Trouble Shooting

8.1  Sequence of Operation 

The Rheos appliance is a cold start appliance 

that should start only on a call for heat from a tank 

aquastat, room thermostat, zone valve end switch or 

other space temperature control device. 

1.  Upon a call for heat,

 

(a)  The internal pump will start. (Pump is 

optionally mounted on unit.)

 

(b)  The blower will begin a 15 second pre-

purge.

2.  Following the prepurge cycle the hot surface 

ignitor will heat and will begin a 7 second trial 

for ignition. The unit is allowed three attempts 

for ignition.

3.  The gas valve will then be energized and low-

fire (50% of full fire) ignition will occur. The 

unit will remain in a low-fire start-up period for 15 

seconds.

4.  After the low-fire start time is over, the unit 

will be in normal operation firing rate and will 

modulate based on the heating load via the 

temperature controller settings and readings.

5.  When the call for heat is complete, or the unit 

reaches its setpoint temperature, the gas valve 

will close, and the fan will continue to run for 

its 30 second post-purge. If a pump time delay 

is used, the pump will continue to run for the 

specified amount of time (adjustable from 0.1 to 

10 minutes).

8.2  Resolving Lockouts

There are many causes of lockouts. The three 

most common causes are: (1)  inadequate gas supply, 

(2) poor combustion, (3) ignitor failure (4) combustion 

air.

1.  Inadequate gas supply: Before proceeding, ensure 

that the gas supply has not been shutoff or the LP 

tank (LP boilers) is not empty. Then, restart the 

boiler and observe the operational cycle. After 

the pre-purge time, the unit should light. If it 

does not, consult the factory.

2.  Poor Combustion: Poor combustion should be 

suspected if there is a strong flue gas odor. The 

odor may result from an improper gas/air ratio 

(high or low O

2

 or CO

2

). If an improper gas/air 

ratio is suspected, consult the factory.

3.  Ignitor failure: If the boiler goes through a 

normal start cycle but combustion does not 

occur, ignitor failure should be suspected. Check 

the ignitor by unplugging the ignitor plug and 

measuring the ignitor resistance. It should be 

50-80 (

-

) ohms. If the resistance is not 50-80 

ohms (

W

), replace the ignitor. If the resistance is 

correct, reset the boiler and check for 120 VAC 

at the ignitor plug during the start cycle. If there 

is no voltage, replace the faulty ignitor wire 

harness.

4.  Inadequate combustion air:  If the boiler goes 

through a normal ignition cycle, and shuts off 

after the blower ramps up to full speed, an 

abnormal restriction in the air intake or exhaust 

system should be suspected.  Check the air filter 

for buildup of debris and clean filter if necessary. 

Inspect all exhaust venting and intake venting for 

blockages.  Remove any blockages and inspect 

and replace any damaged vent sections.  If the 

unit still continues to lockout after igniting, 

consult the factory.
Once the reason for the lockout has been 

identified and resolved you can reset the unit by 

pressing the manual reset button (see Detail A in 

Figure 30. Control Panel).

8.3  Delayed Ignition - Possible Causes

8.3.1  High Lockup Pressure (LP 

Appliances) - Occurs on Start-up

High lock up pressure is the most common 

cause of delayed ignitions on LP fueled appliances. It 

may result from an improper second stage regulator 

selection or from a faulty regulator.

Lock up can be detected by measuring the gas 

supply pressure to the appliance at the inlet pressure 

port on the gas valve. The gas supply to the appliance 

must be shut off before making any connections. To 

check: use a water manometer or pressure gauge with 

a scale reading of at least 25 in. W.C. or 15 oz/in

2

(6.2kPa). Attach the manometer to the gas valve inlet 

pressure port. Turn on the gas supply. The Rheos 

appliance is designed to operate with supply pressures 

of 4-13 in. W.C. (2.3 - 7.5 oz/ in²) (0.1-3.2kPa). If 

the supply pressure exceeds 13 in. W.C. (7.5 oz/ in²) 

(3.2kPa) (with the appliance off) it is possible that this 

may be the cause of the delayed ignitions and the inlet 

pressure must be reset to between 4-13 in. W.C. (2.3 

– 7.5 oz/in

2

) (0.1-3.2kPa). Restart the appliance and 

then switch it off. If the inlet gas pressure exceeds 13 

in. W.C. (7.5 oz/ in²) (3.2kPa) after the appliance is 

switched off, correct the lock up problem.

8.3.2  Gas Valve Regulation 

Gas valve regulation problems can also cause 

delayed ignitions. If gas valve regulation problems 

are suspected, consult the factory. Do not attempt field 

adjustment or repair.

Summary of Contents for Rheos RHCH

Page 1: ...professional service technician qualified in hot water boiler installation and maintenance Improper installation and or operation could create carbon monoxide gas in flue gases which could cause seri...

Page 2: ...Connections 21 5 3 Temperature Control Boiler 21 5 4 Temperature Control Water Heater 21 5 4 1 Remote Water Heater Temperature Control 21 5 4 2 Internal Water Heater Temperature Control 22 5 5 Tempera...

Page 3: ...be reviewed completely before proceeding with the installation Consult the Laars Heating Systems factory or local factory representative with any problems or questions regarding this equipment Experie...

Page 4: ...ter high efficiency condensing model only 1 3 Warranty Laars Heating Systems Rheos appliances are covered by a limited warranty The owner should fill out the warranty registration card and return it t...

Page 5: ...on nection W Inlet Water Connection Non Pump Mounted P Inlet Water Connection Pump Mounted S Outlet Water Connection All Models inches cm inches cm NPT NPT NPT 1200 6 15 6 15 2 1 2 2 1 2 2 1 2 1600 6...

Page 6: ...ces Consult the factory for assistance 1 9 Locating Appliance for Correct Vent Distance From Outside Wall or Roof Termination The forced draft combustion air blower in the appliance has sufficient pow...

Page 7: ...the outdoors or shall communicate through a vertical or horizontal duct to the outdoors or spaces that directly communicate with the outdoors and shall have a minimum free area of 1square inch per 30...

Page 8: ...pening K Clearance to a mechanical air supply inlet 3 feet 91 cm above if within 10 feet 3 m 6 feet 1 83 m horizontally Vent termination not allowed in this location for Vent termination not allowed i...

Page 9: ...m m from the unit to the vent terminal Up to five elbows can be used with the 50 feet 15 2m of pipe Subtract 10 allowable linear feet for every additional elbow used IMPORTANT NOTE ABOUT COMMON VENTIN...

Page 10: ...fueled equipment installed in every dwelling building or structure used in whole or inpart for residential purposes including those owned or operated by the Commonwealth and where the side wall exhaus...

Page 11: ...website phone number or manufacturer s address where the venting system installation instructions can be obtained and 2 The special venting systems shall be Product Approved by the Board and the inst...

Page 12: ...LEGEND VALVE TEMPERATURE SENSOR 3 WAY VALVE PURGE VALVE SYSTEM RETURN SYSTEM SUPPLY INSTALL AIR VENTS AT HIGH POINTS IN SYSTEM PIPING SIZING OF EXPANSION TANK PER TANK MANUFACTURER S INSTRUCTIONS PRI...

Page 13: ...REQUIREMENTS BOILER CIRC PUMP SYSTEM PUMP C C C 180 F 180 F 140 F 120 F NOTES 1 BOILER LOOP TO BE MAINTAINED AT 180 F 2 ZONE THERMOSTATS TO BE INTERLOCKED WITH BOILER BOILER TO FIRE UPON CALL FOR HEA...

Page 14: ...P MOUNTED UNIT AVALIABLE BOILER CIRC PUMP COLD WATER MAKE UP SYSTEM PUMP SYSTEM RETURN SYSTEM SUPPLY ADJUSTMENT PROCEDURE TO MAINTAIN 130 F INLET TEMP 1 Turn on heater and open valves A B 2 After stea...

Page 15: ...Test for spillage at the draft hood relief opening after 5 minutes of main burner operation Use the flame of a match or candle or smoke from a cigarette cigar or pipe 6 After it has been determined th...

Page 16: ...EXCHANGER 5 TPRV 3 4 2 1 THERMOMETER GLOBE VALVE CHECK VALVE PRESSURE REDUCING VALVE W FAST FILL BYPASS EXPANSION TANK WITH AIR SCOOP AND AUTO AIR VENT PUMP LEGEND VALVE TEMPERATURE SENSOR 3 WAY VALV...

Page 17: ...THROUGH 7 5 N NORMAL 7 6 THROUGH 17 H HARD OVER 18 17 1 PARTS PER MILLION 1 GRAIN HARDNESS PER GALLON KEY CAUTION THIS DRAWING SHOWS SUGGESTED PIPING CONFIGURATION AND VALVING CHECK WITH LOCAL CODES A...

Page 18: ...fluid in the piping system As a result no new minerals or oxygen is introduced into the system To ensure a proper operating temperature leading to long boiler life a flow rate has been established bas...

Page 19: ...Hot Water Supply Piping Water Heater Follow the tank manufacturer s guidelines for completion of the hot water system connections feet 9 1m of full sized piping and a normal number of fittings Table...

Page 20: ...pump The headloss shown is for the heater only and the user will need to add the headloss of the piping system to properly size the pump 4B 4 Combined Water potable Heating and Space Heating NOTE The...

Page 21: ...ump to terminal 2 on the pump delay relay and 120V neutral to the 120V neutral circuit of the unit If the pump is 3 phase higher voltage than 120V or higher horsepower than 1hP the pump s starter or a...

Page 22: ...temperature will be 155 F Set the manual reset high limit to 175 F Example Metric units If the heater s temperature control is set to 55 C and the temperature rise through the heater is 14 C the outle...

Page 23: ...Rheos Boiler and Water Heater Page 23 Figure 16 Control Parameter Possible Interference Figure 17 Control Parameter Possible Interference...

Page 24: ...tpoint which is 175 F in this example Therefore the throttling range will cause the Rheos to modulate between 50 and 100 of full fire between 175 F and 165 F Between 175 F and 180 F the unit will rema...

Page 25: ...0 10VDC to indicate which terminal received the hot signal and which terminal receives the common signal from the controller The Rheos unit will modulate between 4 7V and 10V for 50 and 100 respectiv...

Page 26: ...LAARS Heating Systems Page 26 Figure 18 Wiring Diagram Model 1200 Standard and Codes A C D F and G...

Page 27: ...Rheos Boiler and Water Heater Page 27 Figure 19 Wiring Diagram Models 1600 2000 and 2400 Standard and Codes A C D F and G...

Page 28: ...LAARS Heating Systems Page 28 Figure 20 Wiring Diagram Model 1200 Codes B and E...

Page 29: ...Rheos Boiler and Water Heater Page 29 Figure 21 Wiring Diagram Models 1600 2000 and 2400 Codes B and E...

Page 30: ...LAARS Heating Systems Page 30 Figure 22 Wiring Diagram Model 1200 Pump Mounted Standard and Codes A C D F and G...

Page 31: ...Rheos Boiler and Water Heater Page 31 Figure 23 Wiring Diagram Models 1600 2000 and 2400 Pump Mounted Standard and Codes A C D F and G...

Page 32: ...LAARS Heating Systems Page 32 Figure 24 Wiring Diagram Model 1200 Pump Mounted Codes B and E...

Page 33: ...Rheos Boiler and Water Heater Page 33 Figure 25 Wiring Diagram Models 1600 2000 and 2400 Pump Mounted Codes B and E...

Page 34: ...ems Page 34 Figure 26 Wiring Schematic Model 1200 Standard and Codes A C D F and G Figure 27 Wiring Schematic Models 1600 2000 and 2400 Standard and Codes A C D F and G Schematic Wiring Diagram Schema...

Page 35: ...os Boiler and Water Heater Page 35 Figure 29 Wiring Schematic Models 1600 2000 and 2400 Codes B and E Schematic Wiring Diagram Figure 28 Wiring Schematic Model 1200 Codes B and E Schematic Wiring Diag...

Page 36: ...gure 31 Wiring Schematic Models 1600 2000 and 2400 Pump Mounted Standard and Codes A C D F and G Schematic Wiring Diagram Figure 30 Wiring Schematic Model 1200 Pump Mount ed Standard and Codes A C D F...

Page 37: ...Water Heater Page 37 Figure 33 Wiring Schematic Models 1600 2000 and 2400 Pump Mounted Codes B and E Schematic Wiring Diagram Figure 32 Wiring Schematic Model 1200 Pump Mount ed Codes B and E Schemati...

Page 38: ...nstructions as to whether the make up water valve should be left open or closed 15 After placing the unit in operation the ignition system safety shutoff device must be tested First shut off the manua...

Page 39: ...or warm up sequence starts and after all safety devices are verified the gas valve opens 14 Open gas orifice test port valves Check gas orifice differential at full fire and make note of the different...

Page 40: ...e assemble 7 2 Appliance Maintenance and Component Description Only genuine Laars replacement parts should be used Caution Label all wires prior to disconnection when servicing controls Wiring errors...

Page 41: ...ve the cover from the control panel Remove the electrical connectors from the ignition control Take out the controller s mounting screws and pull the controller out Replace in reverse order See Figure...

Page 42: ...es of the heat exchanger is caused by one or more of the following incomplete combustion combustion air problems venting problems and heater short cycling Soot buildup or other debris on the heat exch...

Page 43: ...or installations with IRI code requirements The valve opens when power is removed from the safety valves And the valve closes when the safety valves are powered See sections 3 1 Item 4 for installatio...

Page 44: ...sphere To remove a switch remove the screw on the plastic housing and pull the clear cover off Disconnect the two wires from the screw terminals Twist the switch off the pipe nipple Reassemble in reve...

Page 45: ...hould be 50 80 ohms If the resistance is not 50 80 ohms W replace the ignitor If the resistance is correct reset the boiler and check for 120 VAC at the ignitor plug during the start cycle If there is...

Page 46: ...limit it the heating load should be redistributed to control it See Section 5 5 regarding controller setup If short cycling occurs in a water heater application it is probably caused by undersized pip...

Page 47: ...ONENTS See Figures 40 and 41 25 Gas train assembly standard Nat R2011100 R2017400 R2017500 R2003200 25 Gas train assembly standard LP Nat R2011200 R2017600 R2017700 R2010400 25 Gas train assembly cont...

Page 48: ...5 pack Control packs B and E RE2043500 RE2043500 RE2043500 RE2043500 not shown 64 Fuse holder qty of 5 RE2000300 RE2000300 RE2000300 RE2000300 65 Diagnostic lights kit R2005600 R2005600 R2005600 R2005...

Page 49: ...r R2024600 R2024600 R2024600 R2024600 107 Flange pump gaskets hardware R2024700 R2024800 R2024700 R2024800 108 Shims pump bracket 10 ea R2013600 R2013600 R2013600 R2013600 109 Gaskets 10 pk R2013800 R...

Page 50: ...50 Figure 39 Combustion Components 12 13 10 9 17 14 14 20 19 19 19 19 19 19 6 7 8 5 4 18 OR 19 18 OR 19 19 19 1 Complete Combustion Component Assembly 2 ASSEMBLY 3 14 15 16 14 21 18 OR 19 14 11 Hardw...

Page 51: ...Rheos Boiler and Water Heater Page 51 Figure 40 Gas Train Combustion Air Components 47 48 48 55 56 52 48 41 42 43 44 45 46 49 50 54 48 48 51...

Page 52: ...ack C Gas Train 57 53 26 28 OR 30 29 OR 30 31 31 35 36 OR 37 39 38 40 Control Packs B and E Gas Train Control Packs A and D Gas Train 57 53 For sizes 2000 Natural gas and 2400 For sizes 1200 1600 and...

Page 53: ...Rheos Boiler and Water Heater Page 53 Figure 42 Electrical Components...

Page 54: ...LAARS Heating Systems Page 54 Figure 43 Heat Exchanger Water Path Components 93 100 98 103 104 97 101 106 110 94 106 OR 108 107 107 OR 109 95 105 106 106 106 96...

Page 55: ...er Page 55 Figure 44 Jacket Components 116 117 118 119 120 121 122 123 124 125 126 127 128 128 126 129 130 131 131 132 Jacket Hardware Kit 136 Jacket Retro fit Kit standard 137 Jacket Retro fit Kit mo...

Page 56: ...Wiring Diagram Model 1200 Standard and Codes A C E F and G 26 Figure 19 Wiring Diagram Models 1600 2000 and 2400 Standard and Codes A C E F and G 27 Figure 20 Wiring Diagram Model 1200 Codes B and E 2...

Page 57: ...Rheos Boiler and Water Heater Page 57...

Page 58: ...LAARS Heating Systems Page 58...

Page 59: ...Rheos Boiler and Water Heater Page 59...

Page 60: ...rvice Advisors 20 Industrial Way Rochester NH 03867 603 335 6300 Fax 603 335 3355 Applications Engineering 1869 Sismet Road Mississauga Ontario Canada L4W 1W8 905 238 0100 Fax 905 366 0130 www Laars c...

Reviews: