Vaillant VRC 430 setup

[flycop2000]

Hi, new on this forum although I have been viewing it for a while.

I have installed the VRC 430 into my Eco plus 831 boiler and installed the remote VR81 in my living room. Wiring up the controls was the easy bit. I am trying to setup the system to give the most efficient heating/ fuel saving and have a few questions:
1. Do I set the room temp control to 'modulating' or 'thermostat' for best results?
2. Is it a case of trial and error to find the correct heating curve ? currently set at 1.7.
3. Does anyone know if the software in the VRC430 has been updated (current 2.15) as the screen on the VRC 430 gives me the option of night time set-back temp? I see from the manual that if frost protection is set?, you don't get the set-back temp option. I don't think frost option is set as I have start and end dates the same. Am I doing something wrong?
4. Do I need to set a target flow temp or is this all done automatically?

regards.

 

[flycop2000]

Hello Anybody out there able to help with this one ?

 

[D_Hailsham]

Is it a case of trial and error to find the correct heating curve ? currently set at 1.7.

Yes. If the room is below the required temperature, select a higher curve

4. Do I need to set a target flow temp or is this all done automatically?

You can do this but, obviously it must be high enough to meet the requirement as set by the heating curve. For example, if you have the curve set to 1.5, this means that at 0C the flow temp will be 56C. If you set the target temp to 60, the boiler will not be capable of providing enough heat if the temperature drops below -3C.

So you have to consider the coldest outside temperature you expect. Of course, if the radiators have been selected based on a temperature of -1C, you can't expect them to produce the extra heat required if the temperature drops to -8C just by raising the boiler temperature. It doesn't work like that.

 

[flycop2000]

Thanks for the info. Do you know if its better to set the VRC430 to modulating or thermostat for the most efficient heating ?

 

[MHOL]

I have done a long post under "Vaillant weather comp - lower curve = less gas used" which explains my special interest in setting the VRC430. I will try not to repeat too much of that. I think that it IS a case of trial and error. It ought to be straightforward unless the integration in the system is problematical as in my case.

If you are on 1.7, you are already in interesting country and I would be agog to hear how well you are doing. I'm on 1.5 and may edge a little lower yet when I install my latest planned improvement (I'm going to take control of the pump as I have found that a regime of pumping for 1.5 minutes then not for 3 minutes is 20% more effective in getting the heat to the radiator and saves 2/3 of the pumping electricity - retired people need electronics projects to keep the brain active).

My VRC430 is set to Thermostatic. Whenever I have tried to use Modulating the room temperature gets too high. If you read the
manual it would seem that the controller has the option to call for heat even when the room temp exceeds target, it would then modulate the flow temp down accordingly. In my system that doesn't work because
flow temps below 45 simply don't work. I'm guessing that the Modulating option is intended for systems in which the heating requirements always exceed the boiler minimum.

Left to themselves my VRC430 and Ecotec 415 don't get on that well. The controller is trying to use water as cool as possible (based on my heating curve setting) while the boiler struggles to run effectively at those temps. In my system (high bypass flow proportion) it is necessary to avoid any premature restart attempts which fail. I have managed to modify and tune so that this works in a range 45-75C as long as the VRC430 doesn't try anything too clever. Clearly the boiler is a dimwit and the controller isn't much smarter. Modulating is way too smart.
If I ever need to heat up a cold house rapidly then I give the VRC430 a temporary lobotomy by setting the heating curve to 0.5 and minimum to some high figure (up to 74) Of course I have to know what the effect will be. Rather like setting the gas fire control in the old days.

My main anxiety is how would I be able to explain this to a purchaser if I was to sell up.

 

[flycop2000]

Hi,

I have been using the 1.7 curve all winter and things seem to be going fine. I have no idea if I have saved gas as it was very cold winter and I would have used more fuel anyway. I can't find last years bill? I also found that using 'modulating' setting, the house got way too hot. I have just turned down the curve to 1.5 after reading your post as the weather is getting milder, as I write this post the outside temp (not using the VRC430) is 10 degrees C.
I must make an effort to check my Gas bill to compare previous years.

 

[MHOL]

Hi,

I have just turned down the curve to 1.5 after reading your post as the weather is getting milder, as I write this post the outside temp (not using the VRC430) is 10 degrees C.
I must make an effort to check my Gas bill to compare previous years.

If weather compensation works at all, then milder weather leads to lower flow temperatures anyway. What sort of flow temperatures does your system get down to?

My fuel bills have been very low. Which is the good news in what has been a pretty sad affair.

 

[flycop2000]

The outside temp just now is 12.6 celcius and the boiler flow is 46 celcius.

The heating is active at the moment, it boosts the living room to 21 from 6pm each night.