Danfoss BEM 5000 Boiler Energy Manager

[fixer-AL]

Hi folks - I have one of these controlling my boiler and have found it to be an effective piece of kit for keeping my property at an even temperature through the seasons. It has now developed a fault on the CH channel (no longer powers the pump or boiler) but still functions on the HW channel. Now obsolete and unsupported by Danfoss has anyone with any experience of these any ideas on what the problem may be? I'm guessing it may be one of the onboard components as I can't see any bad joints on the pcb. It would be a shame to have to bin it.

 

[cross thread]

Maybe a issue with the clock rather than the 5000

 

[Deleted member 267285]

Does it still operate when pressed? I’m thinking it could be a motorised valve.

 

[ianmcd]

As @CBW says check the CH motorised valve, far more likely to be that than the BEM

 

[fixer-AL]

Thanks for the replies so far but it is definitely none of the above. All motorized valves functioning as they should. Timeclock is almost new and not the issue. The problem IS the BEM 5000 unit. If I bypass the BEM unit the CH works perfectly. The problem is on the pcb but I haven't the testing equipment or knowledge to identify the failed component. Guessing that it may be the onboard amp chip or the phototransistor.

 

[ianmcd]

It has now developed a fault on the CH channel (no longer powers the pump or boiler)

It never did in the first place, it powers the motorised valve, the valve powers the boiler and pump

 

[fixer-AL]

It never did in the first place, it powers the motorised valve, the valve powers the boiler and pump

The Danfoss installation diagrams show the switched lives from the CH/HW programmer powering the motorized valves. They, in turn feed the BEM - the pump and boiler are then controlled by the BEM. If the pump and boiler were fed from the motorized valve then the BEM wouldn't do its job! I can understand that the motorized valve would be the first item to check but I can confirm that it is functioning as it should. The problem is, without doubt somewhere on the BEM control circuit board.

 

[Johntheo5]

Looks like problem with the PCb but mabe worth swapping the CH M.valve end switch orange wire (or vica versa) into HW terminal in the BEM 5000.

 

[fixer-AL]

Looks like problem with the PCb but mabe worth swapping the CH M.valve end switch orange wire (or vica versa) into HW terminal in the BEM 5000.

View attachment 309081

I have checked the feed from the motorized valves with a multimeter - they both provide the mains feed to the BEM when called to do so without issue - the problem is on the BEM pcb. However, to confirm this and to remove any doubt whatsoever, I have swapped the leads of the two valves as suggested by Johntheo5 and the CH channel still fails to run the pump or boiler. As mentioned previously, if I bridge across the BEM terminals in order that the CH valve feeds the pump and boiler directly, everything works as it should.