Outside sensor slope vs room temperature setpoint

[Christoph]

I recently installed weather compensation on my Ideal Vogue Max and I'm very confused by the settings menu item called "outside sensor slope", which lets me select a number between 0 and 40. The manual states that this adjusts boiler performance relative to the building insulation, but doesn't tell me what unit that is measured in. Also, the picture in the menu and manual looks very much like a weather compensation graph (outside vs flow temperature), which I can also adjust by changing the room temperature (nominal, not actual).

When I change the room temperature, the boiler immediately reacts as I would expect it to, but when I change the outside sensor slope, nothing happens at all. Does anybody know what that is supposed to do?

 

[John.g]

Correct Website, sorry for confusion.

Best of luck Ian controlling with WC only, at least you have TRVs as supervisory, is your boiler enabled all the time from the programmer?, if so the circ pump will run continuously and the boiler will cycle on/off if its minimum output is more than the heat demand which it often will. Viessmann have very fancy WC where you can change the WC level as well as the slope but still very difficult to control room temperatures especially during milder periods.

I will post a link shortly, it may be of help.

can someone help me understand viessmann weather compensation?

hey all i'm having a viessmann 050-w and three rads installed into my very small one bedroom flat by a viessmann installer next month. i understand the fundamentals of weather compensation; and that the outside temperature from the sensor will correspond to a flow temperature, depending on the...

www.diynot.com

 

[ian.]

Correct Website, sorry for confusion.

Best of luck Ian controlling with WC only, at least you have TRVs as supervisory, is your boiler enabled all the time from the programmer?, if so the circ pump will run continuously and the boiler will cycle on/off if its minimum output is more than the heat demand which it often will. Viessmann have very fancy WC where you can change the WC level as well as the slope but still very difficult to control room temperatures especially during milder periods.

I will post a link shortly, it may be of help.

can someone help me understand viessmann weather compensation?

hey all i'm having a viessmann 050-w and three rads installed into my very small one bedroom flat by a viessmann installer next month. i understand the fundamentals of weather compensation; and that the outside temperature from the sensor will correspond to a flow temperature, depending on the...

www.diynot.com

I must admit this is a new control philosophy for me, especially as I have heavily invested in Hive TRVs, but as this is my first condensing boiler and I thought I'd try and get the best efficiency from it and I've read that using the boiler flow temperature control in conjunction with weather comp will deliver this.

The Hive controller has scheduled CH times, allowing for earlier ON times, with a room temp (hall stat) of 24c and a set back temp of 16C.

Room temperature controlled and limited by the boiler temp control does sound odd as its based on the heat output of the radiator in that particular room being a match for losses but not too large as to overheat the room, time will tell if I've sized these correctly.

I value warmth over economy, so if this is a spectacular fail, my fallback position is to revert the control back to Hive TRV's being set to 'Heat on Demand' and increase the flow temperature, watch this space 🙂