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

[craig1234]

I am looking to replace my existing boiler (Ravenheat) with a Vaillant Ecotec Plus 430 Open Vent unit and from looking at the manual that I downloaded from Vaillant's web site, I don't believe I need to wire the pump to the boiler for pump overrun. I query this as I think that other models in the Ecotec family (system or combi) may require pump overrun. In the manual I have, there is reference to accessory relays which I believe may be setup for pump control but can anyone offer any advice as to whether pump overrun is a definite requirement for my proposed model of boiler and if so do I use an accessory relay?
I guess my second query is somewhat related to the point above and it concerns the need to have a bypass valve. On my existing setup there is no bypass but as I have a mid position valve for HW, I have been told that a separate bypass is not required as there will always be a path for the pump (if it indeed needs to overrun) to be able to dissipate the heat either though the HW cylinder or through the bathroom rad which is without a TRV. So, assuming I have to worry about overrun etc, do I need to fit a separate bypass valve?

 

[Agile]

Pump over run is required and the pump is run from the appropriate terminals on the boiler to the pump!

Tony

 

[kittedup]

A bypass is handy to keep the minimum flow going through the boiler.

 

[hertsboilers]

I haven't got a chance to read new ecoTEC 4xx manual, but I was led to believe new version doesn't need pump over run.

 

[D_Hailsham]

I am looking to replace my existing boiler (Ravenheat) with a Vaillant Ecotec Plus 430 Open Vent unit

Why do you need such a large boiler? Do you have a very big house with no insulation?

The size of the existing boiler and the total wattage of the rads is not always a reliable indication of what you actually require.

 

[TCCHeating]

I haven't got a chance to read new ecoTEC 4xx manual, but I was led to believe new version doesn't need pump over run.

You would be correct.

The new 4 series boilers up to 30kw have a new aluminium heat exchanger. (38kw still has stainless steel hex). Apparently vaillants official stance is that the new ali hex's don't need a pump overrun or a permanent live. But it is recommended that they have both perm live and pump overrun if possible.

 

[craig1234]

All,
Thanks all for your replies - much appreciated - I thought I was correct on the pump overrun - would be helpful if there was a definitive statement on this in the installation manual

D_Hailsham - apologies, I started a thread a couple of years back(Pipe runs for 2 storey extension) and you queried at the time as to the size of boiler required and whether I had done a heat calculation - at that time I hadn't done one! However, I knew that my existing boiler was undersize to support the original and new rads in my extension and now I am going to change it out. I have now done three heat calcs (using different web sites to get an "average" score) and I calculate that I need around 26KW worst case scenario (the house with extension is now quite large with some big glazed areas) hence my thoughts about using a 30KW boiler. Unless anyone advises strongly against it, I will stick with Vaillant as after ploughing through various forums etc. this manufacturer seemed to come out marginally on top as being the most reliable although I do appreciate that they are not cheap.

 

[Hason]

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, didnt wire pump to boiler which meant it overheated regually. engi eer came out and said run pump wire to boiler to sort as soon as i did, issue solved. Dont make the same mistake i made.
Good luck

 

[hertsboilers]

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, didnt wire pump to boiler which meant it overheated regually. engi eer came out and said run pump wire to boiler to sort as soon as i did, issue solved. Dont make the same mistake i made.
Good luck

Dose Glow Worm Energy say pump over run isn't required?

 

[Hason]

It says you dont need pump supplie,/no perm live

 

[craig1234]

Ok thanks Hason. I don't have access to the manual at the moment but there doesn't seem to be anywhere on the boiler for a direct pump connection. There is reference in the setup for configuration of the accessory relays for pump control but I couldn't see any wiring diagrams for accessory relays so I wonder if these may only be available on other models - will probably have to call Vaillant next week to find out

 

[AGAS]

All,
Thanks all for your replies - much appreciated - I thought I was correct on the pump overrun - would be helpful if there was a definitive statement on this in the installation manual

D_Hailsham - apologies, I started a thread a couple of years back(Pipe runs for 2 storey extension) and you queried at the time as to the size of boiler required and whether I had done a heat calculation - at that time I hadn't done one! However, I knew that my existing boiler was undersize to support the original and new rads in my extension and now I am going to change it out. I have now done three heat calcs (using different web sites to get an "average" score) and I calculate that I need around 26KW worst case scenario (the house with extension is now quite large with some big glazed areas) hence my thoughts about using a 30KW boiler. Unless anyone advises strongly against it, I will stick with Vaillant as after ploughing through various forums etc. this manufacturer seemed to come out marginally on top as being the most reliable although I do appreciate that they are not cheap.

just expect a good bill when a repair required with prices of parts and also make sure pump is wired to boiler so they can't get out of warranty e.g over heating for whatever reason to be on safe side .

 

[muggles]

The new Vaillant 4-series is little more than a Glowworm Energy in a smarter dinner jacket. May as well have the Energy if you're going down that road. Personally, I'd have an Intergas (which has a heat exchanger proven to last, rather than something new and largely untested, and definitely doesn't need a pump overrun)

 

[hertsboilers]

It says you dont need pump supplie,/no perm live

Are you sure?

I just had a quick look on Glow worm Energy heat only boiler manual but nowhere I found it mentions you don't need pump over run!

 

[Bunnyman]

Np pump over run req Tony , don't comment unless your sure as it's misleading. Wire your permanent live to the switched live if no pump wire is present and remove the 24v link