Vaillant Ecotec Plus 430 Open Vent - Pump Overrun - Required?

Yes, Bunny, that's what they say. But user's experience seems to be different.


Hi I will tell you now that you must wire pump at boiler , I know it says not required but I fitted a glowworm energy which is the same heat ex and design, didn't wire pump to boiler which meant it overheated regularly. engineer came out and said run pump wire to boiler to sort as soon as i did, issue solved. Don't make the same mistake I made.
Good luck


I would always fit a pump over run as it reduces thermal stress and theoretically slightly increases the efficiency.
 
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I would always fit a pump over run as it reduces thermal stress and theoretically slightly increases the efficiency.
Not sure how you would do that if the boiler doesn't have connections for a pump.
 
My existing setup consists of three interconnected relays which allow either my original or extension "systems" to provide pump overrun utilising the output from the boiler and the original pump i.e. if either system causes the boiler to fire, the original pump will run on (or start up and run for a few mins if only the extension calls for heat). So, if the new boiler doesn't have a pump overrun output (shown as "From Boiler Pump Feed" on my drawing) then in it's place I could fit a timer relay (off delay of 5 mins or so?) with the relay activating when the RT signal to the boiler (or as shown on my drawing the "To Boiler Call To Heat" line) goes high - I think this would work. I have attached a copy of my existing setup wiring diagram. I have actually made a few mods to it today (not put these into practice yet) as I had a couple of issues with back feed to relay coils. Apologies for my scribbles!
pump overrun.jpg
 
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Time for an update.
I contacted Vailant and they advised that the boiler does have a pump connection and should have pump overrun (documents attached). What I don't understand is why there is no mention whatsoever of the pump connection in the manual (on-line or received with the new boiler). Anyway, the boiler was installed and what a difference it made compared to the Ravenheat - chalk and cheese. The only issue I have is that I am getting a back feed from the controller meaning when the HW is live but the CH is off the extension heating comes on (i.e. I need to modify my overrun circuit in the above post) - not particularly a problem as I have both HW and CH timed to come on at the same time anyway and if the thermostat doesn't call for heat then nothing happens but it is not right so I will sort somehow.
Thanks all for the advice.
 

Attachments

  • ecoTEC Plus 400 series PCB wiring.pdf
    1.9 MB · Views: 957
  • SEM 579A.pdf
    450.2 KB · Views: 888
Well that's very interesting about the Vaillant.

What's the Bunny response?

Is it a last minute change based on experience ?

Tony
 
I've just read the documents and nothing has changed. It is still OK to wire the boiler with 3 wires and no pump overrun according to the second pdf

All it says is that if the boiler has a perm live it must have pump overrun or it will throw up f codes. So no change to vaillants stance at all
 
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I think the documents are poorly worded and seem to contradict somewhat. What I think they are getting at is that yes you can run without pump overrun but there may be issues
 

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