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Vaillant Arotherm Settings for New Installation

bontwoody · 2024-04-19T12:50:39Z

Im just helping my brother in law with his new 7kW Arotherm installation. I looked at a few youtube videos and found my way around the controller but Im unsure about a couple of things and the COP of the unit for heating is currently poor at about 3 (DHW is OK at 2.5). Firstly the current room temperature on the controller seems to bear no resemblance to the actual room temperature. (see pic). Is this an issue or just annoying? Next the unit is set up for pure weather compensation, but i can see the option for using room temperature modulation as well, has anyone any experience of this? The current curve is 0.85, am I right in assuming that the upper and lower limits of the WC can be set separately to the curve? Any other tips welcome :-)

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bontwoody

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Topic starter 25/04/2024 12:55 pm

@drew-pa

It is set on pure weather compensation at internal temperature of 22C. The unit runs 24hrs with a setback overnight. Theoretically that should be good for COP even if the electricity usage could be higher than running it for a shorter period.

I cant really drop the desired temperature or curve as the BIL's wife likes it warm. It was running at 20C initially but that didnt seem to help the COP greatly.

Your COP figure looks lovely. What sort of flow temperature are you using to get that high?

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Drew Pa

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25/04/2024 5:37 pm

Dropping the curve won’t drop the temp, it just adjusts the time it takes to get there. (Well in my simple mind lol).

Our present heat curve setting is 0.3. That’s been set by Vaillant using the adaptive heat curve setting. Next time the system fires up I’ll check what the flow temp is for you.

drew

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bontwoody

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Topic starter 25/04/2024 5:50 pm

@drew-pa

Thanks Drew

that isn’t how I understand it. To me the curve sets the “gradient” on the weather compensation chart. The desired room temperature moves that gradient up or down the flow temperature axis.

I’ve put gradient in inverted comments as I know that it isn’t a straight line.

I might be wrong but coming from a system where I enter the min and max flow temps for different outside air temperatures, it makes sense in my mind.

In that case, if too low a curve is selected, a room might never reach the desired temperature.

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Drew Pa

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25/04/2024 6:06 pm

You are correct. I just tend to over simplify things. We’ve never had it not reach temperature; it seems to just take longer the lower the curve number is. With the Vaillant system there is no option to adjust the temps individually so the curve is the only option we have to play with. It may be worth trying to lower yours to 0.6 and seeing how it goes.

simplistically, with ours the higher the number the higher the electrical bill.

Drew

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bontwoody

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