Posted by: @vlp2024

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I installed Vaillant Arotherm Plus as per diagram, replaced gas boiler:Appliances: aroTHERM plus VWL < 10 kW, VWZ MEH 97 , VWZ MWT 150 Controls: VRC720, VR71, underfloor heating.

VRC720 shows now HP control module fault: anyone knows what is this about and which control module is this? Vaillant seems got no idea how to find the source of this fault. On top of it, getting F.1100 fault whenever VWZ MEH 97 gets switched on. I am in the middle of nowhere in france, getting someone to help going to be a nightmare and will cost me a fortune. ( i should have bought reliable asian appliances, grm made now looks like crap, sorry for my french). i checked all ebus cables, connections all setup correctly. do i miss smtg, like do i need to get another control installed, like vwz-ai vwl control module? thanks in advance

I would suggest that you read through the attached guide and see if it throws any light onto your problems.

Posted by: @vlp2024

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I installed Vaillant Arotherm Plus as per diagram, replaced gas boiler:Appliances: aroTHERM plus VWL < 10 kW, VWZ MEH 97 , VWZ MWT 150 Controls: VRC720, VR71, underfloor heating.

VRC720 shows now HP control module fault: anyone knows what is this about and which control module is this? Vaillant seems got no idea how to find the source of this fault. On top of it, getting F.1100 fault whenever VWZ MEH 97 gets switched on. I am in the middle of nowhere in france, getting someone to help going to be a nightmare and will cost me a fortune. ( i should have bought reliable asian appliances, grm made now looks like crap, sorry for my french). i checked all ebus cables, connections all setup correctly. do i miss smtg, like do i need to get another control installed, like vwz-ai vwl control module? thanks in advance

Did you resolve your problem?

Feedback is required to prevent wasted effort.

@derek-m thank you for a wonderful guide, i know it i think by now by heart :).  HP control module fault i found is due to bended cable. F.1100 i could not solve, just will not go away unless i set heater to external type. But now i got a new challenge: it will not run DHW and Heating same time, wonderful engineering, very clever. so, i am struggling now to solve this puzzle. for f1100 i probably have ot purchase new cut off thermostat. it costs around 110euros. I tried different circuits to get both heating and DHW same time with no success, ( heating goes via HEX) and tried circuits from 8 to 16. why engineers did come up with that idea. vaillant reminds me expensive but useless skin care for ladies: lots of marketing with horsesht but in reality suppose to heat only.

Posted by: @vlp2024

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@derek-m thank you for a wonderful guide, i know it i think by now by heart :).  HP control module fault i found is due to bended cable. F.1100 i could not solve, just will not go away unless i set heater to external type. But now i got a new challenge: it will not run DHW and Heating same time, wonderful engineering, very clever. so, i am struggling now to solve this puzzle. for f1100 i probably have ot purchase new cut off thermostat. it costs around 110euros. I tried different circuits to get both heating and DHW same time with no success, ( heating goes via HEX) and tried circuits from 8 to 16. why engineers did come up with that idea. vaillant reminds me expensive but useless skin care for ladies: lots of marketing with horsesht but in reality suppose to heat only.

Heat pumps are not designed to provide central heating and DHW heating at the same time.

DHW heating requires a much higher leaving water temperature than central heating would normally need. The heat pump therefore cannot do both at the same time.

It would appear that the safety cut-out has operated, which is causing the F.1100 fault to appear. I would suggest you check to see if the fuse has blown, also see if there is a reset pushbutton that may need to be pressed.

@derek-m thanks Derek, any idea where that magic fuse i located? i imagine engineers did design this system with fuse in mind, but i could not find it (for cut-off thermostat). reset is clear, it was pressed with no luck.

Posted by: @vlp2024

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@derek-m thanks Derek, any idea where that magic fuse i located? i imagine engineers did design this system with fuse in mind, but i could not find it (for cut-off thermostat). reset is clear, it was pressed with no luck.

All that I can suggest is that you trace back along the cable to the place from which the heater is supplied.

Is this heater the DHW cylinder immersion heater or the back-up heater used to help out the heat pump in very cold weather? If it is the latter, do you actually need it?

Download and read through this document.

@derek-m have you seen built in immersion heater in 97/6?

Posted by: @vlp2024

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@derek-m have you seen built in immersion heater in 97/6?

It is actually called a 'back-up heater' and is in addition to the immersion heater, which would be located in the hot water cylinder. The purpose of the back-up heater is to provide addition thermal energy if the outside heat pump cannot provide sufficient thermal energy. Obviously, it is direct electrical heating with a COP of 1, so should only be used when absolutely necessary.

It would appear that you probably have the choice of disabling the back-up heater by deselecting it, as I think you have already done, or replace the cut-out unit which would then make the back-up heater available for use once more.

The choice is yours to make.

@derek-m you just made entire arotherm plus technology useless, by notion it should heat both DHW and UFH in parallel. what i have so far achieved is having hydraulic stations to  up cylinder and then auto  switch to heating and so on, unfortunately no parallel operation. i am going to phone vaillant to clarify if this thing will ever work in parallel. (don't tell me this is not possible, mitsubishi, daikin and samsung do it). my cop so far is above 4.32, electrical heating? i got PV for electricity and solar to water to cylinder

Good morning,

Arotherm owner for 18 months here. 

@Derek-m is indeed correct. Arotherm will do one, or the other, not both together.  Ours is set for hot water priority so kicks the heating off for the time it takes for the water tank to heat.

its all about planning when is best.  We heat our water in the early morning, cheap electricity, and in the afternoon when we get the highest solar gain.  

atb

Drew 

Posted by: @vlp2024

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@derek-m you just made entire arotherm plus technology useless, by notion it should heat both DHW and UFH in parallel. what i have so far achieved is having hydraulic stations to  up cylinder and then auto  switch to heating and so on, unfortunately no parallel operation. i am going to phone vaillant to clarify if this thing will ever work in parallel. (don't tell me this is not possible, mitsubishi, daikin and samsung do it). my cop so far is above 4.32, electrical heating? i got PV for electricity and solar to water to cylinder

If you wish to supply your central heating and DHW heating from one heat pump at the same time then please feel free to do so.