Vaillant EcoTec 831 - Help with setup

[Ian Clarke]

Hi ended up with vrc700f as they didn’t stock the newer 720f and offered it me at 55.00 with returning the 350f.

Couple of questions as installer wasn’t sure how to set it up as he hadn’t come across one before,

Set heating curve to adaptive.

Set room temp mod to thermostat ( it’s in the lounge)

Auto heat off to eco. However this didn’t use set back temp overnight room dropped to 14.5 even though setback at 16.

Noticing it’s struggling to get the room up to 21c.

Although am noticing it is learning heat curve, currently it’s on 1.45

Can someone explain temp mod vs thermostat as confused by the manual

 

[rbranco]

You still have to set the heat curve initially, it's way way too low by default for UK homes, mine is 2.3 as its an old 1910 house. Push it up to 1.7 minimum then let it adapt from there, or go higher.

 

[ScottishGasMan]

Auto off needs to be set to set back if you want setback to work, not eco

 

[Ian Clarke]

Thanks guys, should it be set as thermostat too

 

[ScottishGasMan]

Yea keep it at thermostat

 

[Ian Clarke]

Thanks ScottishGasMan, much appreciated. Set heat curve 1.7 now, setback and thermostat. Hopefully with those settings will start to see improvement in comfort levels and usage.

Thanks rbranco too

 

[Ian Clarke]

Read that vaillant recommend 2.3 in the uk for the heating curve

 

[Ian Clarke]

Actually ignore that as I set to 2.0 and adaptive curve I just checked as altered it to 1.8, leaving alone now for it to set over next few days and see what happens, max temp set to 70 and d0 increased to 12 to give some leighway in my figures making 10 max. Room has heated to 21 now when it wasn’t before.

 

[ScottishGasMan]

2.3 to 2.5 for standard old UK systems which should have been designed for 75/80 degree flow at -1⁰c outside. Folk rarely design systems just fit a double rad the same width as room window, so often your already oversized radiator wise with improved insulation since then so often don't need that high a heat curve

 

[rbranco]

2.3 to 2.5 for standard old UK systems which should have been designed for 75/80 degree flow at -1⁰c outside. Folk rarely design systems just fit a double rad the same width as room window, so often your already oversized radiator wise with improved insulation since then so often don't need that high a heat curve

My house is mostly old 25y+year old Type10 radiators, ile be replacing some of them for Type 21 etc and then my curve should go down

 

[Ian Clarke]

Mine are all 25 year old too, so now you both got me thinking should be 2.3 but I set it at 2.0 and it’s automatically come down to 1.8

 

[rbranco]

Mine are all 25 year old too, so now you both got me thinking should be 2.3 but I set it at 2.0 and it’s automatically come down to 1.8

I've got 1910 solid brick house, huge windows etc. So insulation of house will vary this quite a bit.

 

[Ian Clarke]

Well I hope these weather compensation units learn quick, as this so far way more expensive than a load modulation. 55kwh of gas and only 12pm

 

[rbranco]

Well I hope these weather compensation units learn quick, as this so far way more expensive than a load modulation. 55kwh of gas and only 12pm

It should not use more gas as if you were using more then the house would be hotter than the temp you have set, you can not compare day to day when the weather is varying quite a bit at the moment.

Remember than VRC is reactive to outside temp drops primarily so it should maintain the internal temperature more accurately across the whole house vs a single room stat (if all areas have similar heat loss, if not then it can throw it out a bit), it will modulate as low as possible to maintain most eco condensing, this is where the savings comes from instead of firing at max and having return temps so high it can not maintain efficient condensing.

I used an average of 70kwh a day from dec->jan keeping my house at 20c from 8am->11pm plus two times heating 120L water cylinder, that was without WC, ile see over the next month how it changes.

 

[Harry Bloomfield]

I used an average of 70kwh a day from dec->jan keeping my house at 20c from 8am->11pm plus two times heating 120L water cylinder, that was without WC, ile see over the next month how it changes.

75Kwh per day, but averaged over the last very cold 7 days, Sunday to Sunday, 21C from around 8am to 11pm, 16C 11pm to 8am but with no firing recorded. HW maintained most of the day.

Averaged over entire December and January through to yesterday 68Kwh.