Search results

  1. rbranco

    HELP vailliant boiler f75 code ever few months

    Have you seen what comes out of the pump? Is it hard black magnitite bits?
  2. rbranco

    VR65/VR66 for HW flow temp control

    I have the VR66 which controls both valves, the boiler controls the pump, (exact setup depends on if you are 4xx/6xx/8xx ecotec, on 4xx you need the VR66 to control both valves idealy). I have the VRC720f as its the newest model and got it cheaper than the older one, but I did use the setup...
  3. rbranco

    Is my Vaillant PCB dying?

    Some people at one time would put the boards in the oven to reflow them (without proper reflow ovens you can kill the board completely) with play stations etc hit and miss , but does not work well with double sided boards. Main thing is to get it above the temp to make the solder flow but not...
  4. rbranco

    Vaillant 831 Intermittently does not reach set flow temp

    Check the status code the boiler is running at when flow temp is not high, it could be s53 (i think) too much differencr in flow temp, then it does not go to full power.
  5. rbranco

    Pressurising vented heating system

    Unless you can be sure of all the piping joints under the floors etc is good, ide leave it as unpressurised as you do not want a weak joint popping.
  6. rbranco

    Vaillant 831 Intermittently does not reach set flow temp

    Have you got Vailant ebus controls ie a VRC?
  7. rbranco

    Conventional gas boiler not fully heating water

    Water is freezing at the moment, how long is you HW on for in the morning?
  8. rbranco

    Heating queries in a 3 storey house

    Setting temp higher will not change how much fuel you use as it will just use it over a longer timeframe vs in the morning. What it will do is heat up quicker to the day temp. Is your system Zoned? If not it might be an idea to get it split into Basement and rest of house, or even 3 zones, then...
  9. rbranco

    Flow & Return Temp issues

    Might be little you can do if your boiler can not modulate any lower vs the heat loss, ie if you need 3kw to maintain temp but boiler can not go below 6kw then the water temp will continue to rise until it cuts out.
  10. rbranco

    Flow & Return Temp issues

    Also you loose less heat in pipes if flow temps are lower, useful if you pipes are, under floors or enclosed etc.
  11. rbranco

    Flow & Return Temp issues

    WC weather compensation If you have you boiler sized too high and its not scaled back then it will heat up the water too quick for the heat lost by radiators. Ie you have a 10kw heating requirement but boiler puts out 18kw etc, it will heat up too much. Without smart controls like WC, room comp...
  12. rbranco

    Flow & Return Temp issues

    Reduce the flow temp first and look if you can get WC controls to dynamically change flow temps, also check if boiler has been scaled correctly with max kw output
  13. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    Using a VRC is slightly different as you do not toggle the boiler trigger as its always bridged and eBus just tells it to not fire. Im sure there is some hysteresis on the VRC controller so it takes a few seconds before it applies your change. The VR66/65 does not know anything about if you...
  14. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    The VR66 does not have any feedback from the valves, it never knows if they are open/closed, it only assumes that they are open when powered. This is in part why a ABV is a requirement as the pump may start before the valve opens and stays running after its closed. If the valve fails closed then...
  15. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    So you keep your HW tank at full temp 24/7 or do you switch the cyl stat wire? VR66 does not need to inhibit CH as it handles both valves, so it just overrides the valves, its an effective inhibit. Remember there is cross over of the VR66 and system boilers. The VR66 is invisible to VRC...
  16. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    d78 does not do anything without VR66 on an regular 4xx boiler, if you have a system boiler then it has the hardware internally to switch between CH/HW and thus VR66 is not needed. The whole point of having HW priority is that there is no need for mixing valves or multiple flow temp sensors for...
  17. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    You connect the 2 or 3 port valves to it and also the CylStat or NTC. You can use it without full eBUS controls (ie manual programmer) but it needs you to wire it in a non-standard way as they do not indicate in the manual how to do it on normal controls. I did it but now ive got full eBUS.
  18. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    You can't without VR66 but then you loose CH control. It has to do this to prevent temp differential across the heat exchanger which causes issues, once flow temp rises it goes full power until flow temp is 80c. It never does low flow temps like CH.
  19. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    To add additional clarification, ebus does not control power output as stated, the boiler does that internally to maintain the target flow temp requested. Even with all the VRC stuff, the boiler is still non the wiser about room/outside temps, that part is handled by VRC. VRC is the commander...
  20. rbranco

    Vaillant VR66 wiring control centre causing heating modulation woes?

    D00 is the max the boiler ever goes to regardless of ebus, there is another setting for max kw for HW when using ebus.
Top