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How does the BoilerMate 2000 work?
A conventional central heating boiler heats the water in the BoilerMate 2000 directly. The stored water is pumped to the boiler for heating and back again by the left-hand of the three pumps behind the front panel of the unit whenever the stored water temperature drops below a specific temperature set in the factory. The centre pump pumps water around the radiator circuits when central heating is required.
The BoilerMate 2000 delivers hot water to the hot taps in a similar way to the previous BoilerMate III, but without the user-adjustable thermostatic blender valve. The right-hand pump starts when a hot tap is turned on and pumps hot store water through the plate heat exchanger, thus heating the cold mains water very effectively on it's way to the hot taps or showers.
The two separate circuit boards behind the cover panel of the BoilerMate III are now replaced by a single combined control board controlling every function. The appliance Control Board (ACB). There are no user-controllable parameters.
Faults known to occur in the BoilerMate 2000:
1) Depleted water in the thermal store.
BoilerMate 2000s have a filling cistern fitted above them, which is there to fill the unit with water. This may or may not have a float valve connected to the mains water supply to fill it. When there is NO mains connection, there is usually provision for manual filling by the user by means of a tap on the wall nearby. When the user doesn't realise this, water lost from the thermal store through evaporation and/or leaks can prevent the unit from working. If the water level falls too low, eventually there s too little water for the pumps to pump, the unit will make gurgling noises and stop delivering hot water. The answer is to check the water level in the top-up cistern and top it up.
2) Circulating pump failure
BoilerMate 2000s sometimes fail to deliver ANY hot water to the taps at all. After a random amount of time the hot taps start working again. This is usually a sticking hot water circulating pump. The quick fix is to fit a new one, but the underlying cause is usually system corrosion caused by absence of corrosion inhibitor in the initial fill of system water. A powerflush is necessary to prevent the problem re-occurring.
3) Water scale-contamination of the plate heat exchanger.
The plate heat exchanger was hailed by manufacturers as the answer to water scaling, but this has proved not to be the case. Hard water in certain areas still seems capable of blocking a plate heat exchanger with calcium deposits causing restricted hot water flow from the taps and warm (instead of hot) temperatures. When the problem becomes acute the water flow slows to a trickle and the temperature swings wildly from scalding hot to stone cold. The answer is to fit a replacement plate heat exchanger, which takes around an hour (instead of several hours to de-scale the copper coil heat exchanger in early versions of the BoilerMate)..
4) Heat sensor failure.
Hot water temperature from the taps and/or shower becomes unreliable and unpredictable. The hot water temperature sensor delivers a signal to the ACB board and this controls the pump speed. They seem to fail with age (after three or four years) and replacement restores reliable hot water performance. I believe they are thermistors but there is more to them than that as there are three conductors in the leads. Their true nature is shrouded in secrecy. No-one at Gledhill gives anything away when I ask questions... quite frustrating really but I'll get to the bottom of them eventually....!
5) Control board failure.
Either the central heating runs continuously, refusing to respond to the room thermostat being turned down or the timer being turned OFF, or there is no heating or hot water at all, with the control board display being either blank or locked and refusing to respond to either the S1 or S2 buttons being pressed. When the display is blank this can sometimes be a blown fuse on the PCB but don’t just replace the fuse, this fault is usually caused by a failed pump and you risk damaging the board if the failing pump is not
Identified and replaced first. Sometimes a failing pump destroys the control board instead of blowing the fuse. The pumps usually fail from water ingress from a leaking pump isolator valve, in which case a drain-down is necessary and new pump and valves fitted, along with a new PCB if also damaged. This is massively expensive and companies maintaining Boilermates on an insurance type of maintenance plan will usually refuse to carry out this repair. They will generally classify the appliance as “Beyond Economic Repair” (BER) and tell you bluntly you have to replace it with a new one, at your expense not theirs.
If your Boilermate 2000 has stopped working, do call or text me to discuss a repair on 07866 766364. Sometimes I get rather snowed under so feel free to nag if I don’t answer quickly!
Copyright Michael Bryant 2021
Site first created 21st January 2007
Site last updated Friday 13th May 2021
Gas Safe Register 197499. CIPHE reg no 56207