Pump Fan/Overun

Pump Over-run, Fan-Over-run, Anti Scale

Various manufacturers have incorporated varying features in their boilers in order to prolong the lifespan of their appliances. These are mainly designed to cool the appliance down before the next heat cycle for scale prevention, and also to stop nuisance rapid cycling on and off of the main gas burner. Please find below a useful table with the most common features as included by a host of manufacturers. These features are normally controlled by a combination of sensors and/or Printed Circuit Board.

Please note;

Pump Over-Run = Pump continues to run after the demand has finished to cool the appliance down

Fan Over-Run = Fan continues to run after demand has finsihed to cool the appliance down

Frost Protection = Boiler has inbuilt frost protection for when the temperature drops to prevent freezing

Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Alpha 240E, 280E, 240XP 5 mins in ch mode None <5 degC boiler fires to 30 degC
Alpha 240P, 280P, 5 mins in ch mode low speed at rest <5 degC boiler fires to 30 degC
Alpha 240X No low speed at rest none
Alpha 240XE, 240 Eco 5 mins in ch mode low speed at rest <5 degC boiler fires to 30 degC
Alpha CB 25-33 3 mins 30 Secs 8o runs boiler to 30o on Primary Sensor
Alpha CB24,CB24X 30 secs,0 in HW only 20 seconds Activated below 8 deg C Via PCB + CH sensor
Alpha CB28, CB28X 30 secs,0 in HW only 20 seconds Activated below 8 deg C Via PCB + CH sensor
Alpha CD 18R Temperature & Time Temperature & Time 8o runs boiler to 30o on Primary Sensor
Ariston Ariston Clas HE R External Pump overrun – 3 minutes external pump at 3-8 deg if 9 deg not achieved appliance fires -30C
Ariston E Combi internal pump at 3-8 deg diverter alternating for 20 mins if 9deg not achieved appliance fires -30C
Ariston Eurocombi 23MFFI via heating probe + pcb. 5degC boiler fires to 58 Deg C
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Ariston Genus 23 MFFI via heating probe + pcb. 5degC boiler fires to 58 Deg C
Ariston Genus 27 MFFI via heating probe + pcb. 5degC boiler fires to 58 Deg C
Ariston Genus 27BFFI none
Ariston Genus 30 MFFI via heating probe + pcb. 5degC boiler fires to 58 Deg C
Ariston Micro combi 23MFFI Pump – After DHW demand 30 secs – After CH satisfied 3 minutes Fires on min rate @ 3 DegC  and heats to 33 Deg C
Ariston Micro Genus 23MFFI Timed from PCB and controlled by jumper JP 5 (CMP I PCBs have no pump over run features Fan over run after hot water demand Controlled by primary sensor  At 8degC pump runs and off at 15deg If temp drops to 3degC the boiler fires at min gas only until boiler temp is 33degC
Ariston Micro Genus 27MFFI Timed from PCB and controlled by jumper JP 5 (CMP I PCBs have no pump over run features Fan over run after hot water demand Controlled by primary sensor  At 8degC pump runs and off at 15deg If temp drops to 3degC the boiler fires at min gas only until boiler temp is 33degC
Baxi 80e, 105e 30 secs < 5°C boiler fires till 30°C
Baxi Bahama Honeywell 30 seconds
Baxi Bahama Sit 10 seconds No <5°C boiler fires to 30°C
Baxi Combi Instant 105e 30 seconds pre-heat facility
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Baxi Genesis 80, 96 3 mins after a ch demand none
Baxi Maxflow <5°C boiler fires
Baxi Solo 2 & PP3 Series Approx 8 mins Via pcb + sensor
Baxi DUO TEC/Platinum HW – 30sec, CH – 3min 10 sec <5°C boiler fires to 30°C
Biasi Parva M90 24S,  28S Fires @ 4 Deg C via PCB & ch thermistor
Biasi Prisma 24S, 24SE none
Biasi Prisma 28S, 28SE none
Biasi Riva Advance 47-970-29/30/31/32/33/34 Zero to 8.5 minutes Via HW sensor, less than 4 degrees will fire the boiler around HW circuit until 60 degrees, boiler protection only
Boulter Buderus 500-24S -24C Preset to 5mins Flow NTC @8o fires to 17o , less than 2o boiler locks out
British Gas ICC1/Energy saver <7 degC pump runs,<3 fires to 10 degC
Broag Avanta Plus Series Hw on Temp C/h 2-99 minutes less than 7 degrees pump only– less than 3 degrees burner  via primary thermister
Crosslee Trisave FS 80/C 5-10 mins
Ferroli  F 30 B & F 24 B 6 minutes set time If less than 5 minutes then fires until 14 degress
Ferroli 76FF, 77FF, 100FF 6 mins in CH, 10 secsin HW low speed at rest Dedicated stat.
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Ferroli Domina 80e 6 Mins Via primary sensors, fires the boiler at 7 Deg C to 14 Deg C
Ferroli Domina 80N, 80N DGT & 80e timed  (between 1 -20 mins) if less than 5 degrees will fire boiler until 35deg then 6 mins pump o/run
Ferroli Falcon 80 7-14 Deg C via Ch sensor
Ferroli Hawk II Dedicated stat
Ferroli Maxima Set @ 7 mins adjustable between 0-20 mins ……30secs on h/water Less than 5 degrees will fire boiler until 15 degrees
Ferroli Modena 80e,  102 6 mins no Via CH sensor + pcb 7degC boiler fires to 14 degC
Ferroli Optima range 6 mins Fires boiler + runs pump to maintain    4-12Deg C (dedicated stat)
Ferroli Optimax Set @ 7 mins adjustable between 0-20 mins ……30secs on h/water Less than 5 degrees will fire boiler until 15 degrees
Gemini 960E 30 seconds
Glowworm 330 Timed for 5mins then reads from flow/return sensors if still above 60°C Via flow sensor. 3°C burner fires until 10°C. Burner goes out pump runs on for 5 mins
Glowworm Compact system 60ss, 100ss < 10°C pump runs
Glowworm CXI 3mins then checks temp if over 50°C pump continue suntil under 50°C, 20 secs overrun on hot water Via flow sensor, 7°C pump runs, 3°C boiler firesuntil 10°C
Glowworm Energysaver 100,100Mk2 Via flow sensor, <7°C pump runs,  <3°C boiler fires until 10°C
Glowworm Energysaver 80,80Mk2 Via flow sensor, <7°C pump runs,  <3°C boiler fires until 10°C
Glowworm HXI Via flow sensor, 3°C burner fires until 10°C. Burner goes out pump runs on for 5 mins
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Glowworm ICC1/Energy saver <7°C pump runs, <3°C fires to 10°C
Glowworm Jaguar 23, 28 In ch mode only <10°C pump runs, < 8°C boiler fires to 25°C
Glowworm Micron (pump wired to chb) Via PCB + Sensor  Pump runs @ 15°C
Glowworm Micron(Pump wired to syst) Via PCB + sensor when ext controls on and boiler stat off
Glowworm SXI Via flow sensor. 3°C burner fires until 10°C. Burner goes out pump runs on for 5 mins
Glowworm Flexicom HX 5min Yes – only a few sec <8°C runs pump, if still not over 10°C after 30min burner will fire. <5°C burner fires.
Halstead Ace Inbuilt
Halstead Dimplex Timed @ 2 mins Post Purge Below 5 Deg C  boiler fires on minimum until 20 Deg C
Halstead Heat I 20-30-35 30secs Boiler fires on minimum @ 6 degrees until 35 degrees on primary sensor
Halstead Heat I 24-29 C 30secs If over 78 degrees for 30 secs Boiler fires on minimum @ 6 degrees until 35 degrees on primary sensor
Halstead Quatro, gold, Wickes 2000 Dedicated stat Dedicated stat. Lights <5degC
Hermann Eura HE ? ? Primary sensor below 5o runs boiler until above 10o
Hermann Supamicra 24-30 HE ? ? Primary sensor below 5o runs boiler until above 10o
ICI Caldaie Solar 80E, 96E Via sensor + pcb. Fires burner if primary water drops below 5degC
ICI Caldaie Solar twin Via sensor + pcb. Fires burner if primary water drops below 5degC
Ideal Icos No No No
Ideal Icos System 5 mins No No
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Ideal Isar 5 secs HW, 5 mins CH No pre-heat facility
Ideal Logic Code Combi 26,33,38 Approx DHW 60 sec     CH 4 mins DHW & CH 4 min  <5degC fires boiler for short period via flow sensor and pcb
Ideal Response SE No < 7 Deg C pump runs to 10 Deg C. < 3 Deg C boiler fires to 10 Deg C. Via flow sensor + PCB
Johnson & Starley Reno  2 minutes Flow thermistor less than 5 degrees fires boiler until greater than 15 degree
keston 30C DHW 75 sec     CH 4 mins DHW & CH 4min  <5degC fires boiler for short period via flow sensor and pcb
keston C40,C40P,C55,C55P 2min timed off pcb <7 degC pump runs,<3 fires to 10 degC
Main Main HE41-474-01/02/03/04/05 Time = 2 minutes Flow thermister lower than 5 degrees fires boiler until greater than 15 degrees
Myson Midas Si 30 seconds pre-heat facility
Potterton Combi 80, Combi 100 Timed  between 1&3 mins No Fires < 5 Deg C, heats boiler by 10 deg C approx
Potterton Envoy Timed on pcb 3 mins
Potterton Lynx 2 Timed on PCB
Potterton Lynx RS Dedicated stat
Potterton Promax FSB 30 HE None Post purge Less than 5 degrees fires boiler until 15 degrees
Potterton Puma 80, 100 Timed on pcb 4–9 mins <5 deg C boiler fires to give 10 deg C rise
Ravenheat  CSI 120 3 minutes on heating, not HW Less than 7 degrees pump starts, Less than 5 degrees will fire the boiler until temp raised above 7 degrees (boiler protection only )
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Ravenheat CSI 85 Range 3 Mins on c/h Below 5 deg  will fire boiler until 7 deg
Ravenheat LSF 100 Range 3 Mins on c/h Below 5 deg  will fire boiler until 7 deg
Ravenheat RSF 82ET 3 Mins on c/h Below 5 deg  will fire boiler until 7 deg
Saunier Duval Ecosy 24E, 28E 3 mins on CH, 30 secs on HW < 3 Deg C boiler fire to 10 Deg C
Saunier Duval Isofast F28E/1,  F35E/1 <6 degC boiler fires to 16 degC  *
Saunier Duval Protherm 100 EC < 10 Deg C pump runs, < 8 Deg C boiler fires to 25 Deg C
Saunier Duval Protherm 80E < 10 Deg C pump runs, < 8 Deg C boiler fires to 25 Deg C
Sime Format Combi 30HE On temperature 6o fires boiler until 15o (boiler only)
Sime Format System 25HE On temperature 6o fires boiler until 15o (boiler only)
Sime Friendly Format Series Dedicated stat
Sime Murelle HE pump overun 30 seconds after both demands Adjustable in parameter 23  -5  to  5 degrees factory set at 3    pump and boiler
Vaillant eco TEC plus 612, 615, 618, 624 & 630 (System Boilers)
Vaillant eco TEC pro 28, plus 824 & 831 (Combi Boilers) Yes <5°C boiler fires unltill flow temp 30°C
Vaillant Ecomax 286 20-80 secs HW 20s-5min CH 5 secs Inbuilt
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Vaillant Ecomax/2E range Yes < 8°C pump runs, < 5°C boiler fires via PCB + flow thermistor
Vaillant VCW 242 E  * ch mode only 5 mins hybrid, 20 secs non 20 Secs(both modes) No
Viessmann Vitodends 100 WB1A Yes Yes Below 5o fires until above 15o
Viessmann Vitodends 200 WB2A Yes Yes Below 5o fires until above 15o
Vokera Compact Combi <7 Degc pump runs. If temp continues to drop then burner fires to 30 Deg C
Vokera Linea range Above 80 Deg C° Above 80 Deg C at 7degC pump runs until 10 DegC. At 3 degC boiler fires to 30 degC
Vokera Linear 25-30-35 HE Yes (See Instructions) Yes (See Instructions) Primary Thermister (see instructions)
Vokera Maxin 24E, 28E Dedicated stat
Vokera ProCombi A Yes – Min 20sec but can be longer depending on boiler temp. Yes – 10sec post purge if burner lit when demand ends <6degC boiler fires on min until 35degC, checked by primary flow thermistor
Vokera Compact HE 25/29 Yes – Min 20sec but can be longer depending on boiler temp. Yes <6degC boiler fires on min until 35degC, checked by primary flow thermistor
Worcester / Bosch 230 RSF Temperature related no none
Worcester / Bosch 240 Combi BF Dedicated stat No fan none
Worcester / Bosch 240 RSF Dedicated stat, >60 Deg C No none
Worcester / Bosch 24CDi 4 minutes on C/h then Via CH sensor runs above 80 degrees 15 Seconds unless heat demand has NOT occurred within 30 mins then funs until drops to 80 Deg C <8 DegC Pump runs 4 Mins then monitors temp.  <5 deC boiler fires 30DegC
Manufacturer Model/Range Pump Overrun Fan Overrun Frost Protection
Worcester / Bosch 24i Via CH sensor runs 60-70DegC 4 mins < 6 DegC pump runs to 8 DegC, <4 deg C boiler fires to 20 Deg C
Worcester / Bosch 24si 2, 28si 2 Upto 4 mins on c/htg or fan overrun only depending on temp at primary sensor. No pump overrun on H.Wtr 15 seconds
Worcester / Bosch 280 RSF Pump over-run only if primary water sensor temperature above 70deg C. No Controlled by primary sensor. Pump runs for 4minutes if temperature less than 8deg C, if below 5deg C boiler fires until temperature reaches 30deg C
Worcester / Bosch 28CDi 5 minutes on C/h then Via CH sensor runs above 80 degrees 15 Seconds unless heat demand has NOT occurred within 30 mins then funs until drops to 80 Deg C <8 DegC Pump runs 4 Mins then monitors temp.  <5 deC boiler fires 30DegC
Worcester / Bosch Both versions of 350 None >75C  to 65C none
Worcester / Bosch Cdi range, Ci range, Si range & C1 ICC1 etc Temperature related Temp related via primary sensor. 8degC pump runs for 4 mins every 30 mins. @  4degC burner fires to 20degC
Worcester / Bosch Greenstar (all models incl ICC2 etc) Timed on PCB via primary sensor. 8degC pump runs. 4degC burner fires to 20degC
Worcester / Bosch Greenstar Cdi 3 mins 30secs (adjustable ) If below  8°C pump runs untill flow reaches 12°C, if below 5°C boiler fires until 30°C
Worcester / Bosch Highflow 400 2 versions, dedicated stat or
Worcester / Bosch Highflow 400 Timed on pcb

 

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