Vaillant Ecotec plus 937 with Opentherm and Evohome

[DukeGB]

Hi All,

I'm looking to wire up our Ecotec 937 plus with Opentherm and Evohome. So far I can source the VR33 module and have located the X31 interface on the PCB where this should be plugged in. Unfortunately it appears to have another connection already plugged into this serving the shift load storage tank. There are the free ebus connections - does anyone know how I can get this to work? I'd really like to get OT running, if not I'll use the more conventional BDR91 approach.

Thanks for any help in advance.

 

[mrStat]

VR33 is not designed for use in the UK, neither is it approved.




Note: You should now be getting a suitably qualified/registered person to check the boiler over on completion as the front panel forms a secondary combustion seal on this appliance.

 

[DukeGB]

Thanks for the response, I'm aware that VR33 is not approved for use in the UK. Regarding the combustion seal, thanks for the heads up - you must find yourself repeating yourself rather often with these boilers....

 

[ianmcd]

The VR33 although not approved will work though, but if your boiler is still under warranty they will not honour the warranty, if it is out of warranty no reason to worry

 

[DukeGB]

Thanks Ian, it is well out of warranty - 9 years old. My issue is where or how to plug in the VR33 now X31 appears to be taken. Any solutions welcome.

 

[mrStat]

You would be 100% right - Copy and paste is my friend at the best of times.

As ianmcd said, but as yours is 8yrs old now; I am guessing you are not too worried about warranty. The VR33 can work with your 937 but there is a slight bug which I have noticed with the 9 series... Because the hot water is controlled with OpenTherm, it can clash with max rates permitted for the heating. I have noticed that the heating on max never seems to actually allow the burner to fire at max because I have a theory that the hot water tank in the bank is limiting the boiler.

Personally I dis-advise the 33 on the 9 series, however I know some installers are happy to fit them; they seem to be especially good with purely underfloor systems.

 

[ScottishGasMan]

You would be 100% right - Copy and paste is my friend at the best of times.

As ianmcd said, but as yours is 8yrs old now; I am guessing you are not too worried about warranty. The VR33 can work with your 937 but there is a slight bug which I have noticed with the 9 series... Because the hot water is controlled with OpenTherm, it can clash with max rates permitted for the heating. I have noticed that the heating on max never seems to actually allow the burner to fire at max because I have a theory that the hot water tank in the bank is limiting the boiler.

Personally I dis-advise the 33 on the 9 series, however I know some installers are happy to fit them; they seem to be especially good with purely underfloor systems.

The heating would never have the burner at max on a Vaillant combi anyway as max output for heating on those will be about 28kw off the top of my heat where the HW output will be 37/38kw.

Where would you plug the VR33 in on that boiler if X31 is being used for the tank electronics?

I wouldnt advise it myself. And as said shouldnt be in there if your not competent to ensure full safe working of the appliance afterwards

 

[0161coop]

I have the same issue as the OP. Is there a solution?

 

[DukeGB]

Hi, Yes - you can use the VR33 as a pass through - there is a second terminal on the board that will allow you to plug in the X31 connection.