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VRC 470F - Cylinder Boost

Discussion in 'Plumbing and Central Heating' started by Harry Bloomfield, 11 Feb 2019.

  1. Harry Bloomfield

    Harry Bloomfield

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    Vaillant ECOfit Pure 418 18Kw, VR 65 Control Module & VR10 cylinder sensor, VRC 470F Controller + VR 21 Outdoor sensor/DCF77 receiver + Radio Receiver in boiler.

    Sunvic SDM 1901 3-port

    Hercol 117L 0.44 Sq M cylinder.

    Grunfos Alpha + Circulation pump, variable speed

    I wonder if anyone can explain the what seems to be, weird behaviour of Cylinder Boost on the 470F?

    I it for Cylinder Boost (CB), then CB remains on the 470F's display for simply ages and it seems though the cylinder has been brought up to temperature, there seems to be no CH until it goes off or is cancelled. The only way to know it is up to temperature, is to cancel CB to check the current cylinder temperature. I have it set to 60C for HW, 80C boiler flow. I think I read somewhere it keeps CB active for 45 minutes. Is that 45 minutes after it has reached cylinder temperature, or 45 minutes in total?

    Is it supposed to need manually cancelling, to restore CH?
     
  2. ScottishGasMan

    ScottishGasMan

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    Remember its a weather compensated system so no heating at all while the cylinder is heating.

    The Cylinder boost raises the cylinder temp by 25*c, It will automatically revert to heating if the cylinder gets to that temp. So your not going to manage that anytime quickly on the set up you have and would put the cylinder temp up too high to be really usable.

    In the system config menu, under domestic hot water there is cylinder boost offset. it should be at 25. change it to something more usable like 5 or 10 degrees.
     
  3. ScottishGasMan

    ScottishGasMan

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    Sorry Im wrong. The offset raises the flow temp of the boiler by that much during cylinder boost so forget turning it down.
     
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  4. ScottishGasMan

    ScottishGasMan

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    Its an odd one actually as the heating should come back on once the cylinder hits temperature even on the boost function im sure (never actually used the cylinder boost before as there normally fitted on high recovery unvented units that will have HW 24/7)

    It may even be down to an issue with the set up of the system, the 470 was designed for use with the VR61 wiring center not the 65 or the 66. And your boiler wasnt even in production at the time they stopped making the 470 kit so there 3 seperate bits of equipment that were never "meant" to be used together, obviously ebus is ebus and most functionality will cross from one set of equipment to the other but not possibly without the odd issue.
     
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  5. Bill1958

    Bill1958

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    We have an Ecotec 428 with a VR66 and VRC470 (now has been replaced with a VRC700). When Cylinder Boost activated, heating goes off, flow temperature increases to between 70 and 80º, and it is usually only active for about 30 - 40 mins, then heating comes on again. Wasn't aware that it was timed, assumed it only stayed on till water was at temp.
     
  6. Harry Bloomfield

    Harry Bloomfield

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    It certainly seems to be timed and I thought I had it somewhere. It just seemed silly to my mind - the boiler would replace a bath full of water in 20 minutes before I fitted the 470 and keep the heating ticking over with mid-position, but with the 470 it seems to get the cylinder up to temperature, but continue to show 'Cylinder Boost' in the display until it time out (?) or someone guess it has done the job and presses 'cancel'.
     
  7. Bill1958

    Bill1958

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    We don't use cylinder boost a great deal so couldn't say for certain if its timed, however reading the manual would imply it only remains on as required.
    …heats the water in the domestic hot water cylinder until the desired domestic hot water temperature is reached or until you cancel the advanced function early”.

    Having said that Vaillant manuals are notoriously bad. Next time I use Boost I'll monitor it and see how long it is on for.
     
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  8. Bill1958

    Bill1958

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    Further to cylinder boost question. I have got VRC700 app working. This shows flow temperature and hot water temperature.

    This enabled me to see what happens when boost is activated when heating is on:

    Activate cylinder boost.

    Flow temp rises to 75-80°

    On boiler rad symbol goes off and tap (water) comes on.

    Water in cylinder gets to 60° after 15 - 20 mins. (From initial temperature of 20°)

    Flow temp falls to 50°, rad symbol on boiler comes on, water symbol remains on, heating starts. On VRC700 cylinder boost active remains showing for a further 40 mins (approx) although heating is working as normal. After about 60 mins after first activating boost it reverts to the normal display and tap symbol on boiler goes off.
     
  9. Harry Bloomfield

    Harry Bloomfield

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    Thanks - as said, I wasn't sure whether or not CH was returning or not with Boost showing, I just assumed.
     
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