General Danfoss LC13 question

[m-joy 3]

Hello,

I am using danfoss lc13 thermostat with my hc2.

There is also a main thermostat by viessmann controlling all thermostats in the house. The main thermostat has a day and night temperature set. Also the lc13 has day and night temps set individually via fibaro. Now i wonder if the temp control of the viessmann thermostat can cause troubles here, and how to set it for best results...

Greets

[SHorsham 0]

The rad thermostat will set a temperature level based on what you have set in Fibaro. If your heating is off or set to a low temp the thermostat will just continue with what you have set and stay open as it won't reach the temp it's set at.

[petergebruers 1,268]

Agree with SHorsham. And I can talk from experience. If you have a room thermostat and thermostatic heads in the room with the room thermostat, then the situation is less than optimal. In this case, the thermostats will "fight" each other. This can lead to oscillations in temperature. If you have and outside probe and thermostatic heads on all radiators then you should disable the room thermostat and depend on outside temperature only. You set the parameters of the boiler so that the water is hot enough to get sufficient heating and ramp-up during cold days. For me that means water temp = 10 degrees plus 1.5* (21 degrees - outside temp)

[m-joy 3]

Agree with SHorsham. And I can talk from experience. If you have a room thermostat and thermostatic heads in the room with the room thermostat, then the situation is less than optimal. In this case, the thermostats will "fight" each other. This can lead to oscillations in temperature. If you have and outside probe and thermostatic heads on all radiators then you should disable the room thermostat and depend on outside temperature only. You set the parameters of the boiler so that the water is hot enough to get sufficient heating and ramp-up during cold days. For me that means around 10 degrees plus 1.6* (21 - outside temp).

Huhu,

Yes i think there is an outside temp probe

for the main thermostat to boil the water to a desired temperature.

There is no probe in thr rooms. But now with the lc13 there is one inside the lc13. Does that mean i do not really need the lc13?

I am not sure if i got this alright...

[m-joy 3]

So my main thermostat viessmann is set to 21 degree day, and 19 degree night. That means tge maximum temp in any room during day is 21degree?

So this must mean i can set the fibaro temp during day to every temp up to 21 degree max. But when i go to 22 degree for example, the thermostat can never reach? This would at least make sense when i want different temps in different rooms to the maximum allowed temperature...

[cford67 0]

I am using the danfoss TRV's and don't have a problem with it doing its own thing when the heating is off, so If we are away the TRV's will open and close as set by Fibaro and only used the battery up. It depends what room your boiler thermostat is in and the radiator (or other heating method) needs to be heating when your boiler is on so that the boiler knows your house is at temperature and turns the boiler off.
I use the danfoss TRV's in rooms we don't use much, so the dining room comes on later and goes off earlier, bedrooms are kept cooler until later in the evening.
Other rooms and the hall where the boiler thermostat is has a standard TRV so the boiler is switched off when the set temperature is reached.

[petergebruers 1,268]

So my main thermostat viessmann is set to 21 degree day, and 19 degree night. That means tge maximum temp in any room during day is 21degree?

So this must mean i can set the fibaro temp during day to every temp up to 21 degree max. But when i go to 22 degree for example, the thermostat can never reach? This would at least make sense when i want different temps in different rooms to the maximum allowed temperature...

If you put the room thermostat to 22 and the LC13 to 21 then your room thermostat, if it is a true temperature sensing and controlling one, will send the boiler to maximum water temperature (probably 75 degrees on your Viessman). Because it can never reach its set point. In practice the system has (high) inertia so the response would differ from this simplified view. But... I own a Viessman since 2001 and even then it had about 150 controller parameters. You'll need the technical manual to understand what they all mean. And in my case, there is an option that says that the room thermostat actually *does not do any temperature sensing* - so the 21 degrees it displays is something *totally different* from what you expect! You see the formula I posted earlier? Water temp = 10 degrees plus 1.5* (21 degrees - outside temp). Actually the "21" in that formula is the "21" on my room "thermostat". So what it does, is lower or higher the water temperature based on the outside temperature, nothing to do with inside temperature. Your thermostat may very well be set like that, I'm not a heating specialist. I'd say: to be checked...

[Bamsefar 13]

I will borrow this thread:

 

I have 4 LC13, and from what I can understand, even though I have set the temp from HC2 (22 degrees celsius), it will every night lower the temp with 2-3 degrees? Like some sort of night schedule? Anoyone have anything like this?

 

Yes I live in a building with multiple flats, so we do have a central heating system which could have night schedule built in also - I have no idea (yet). But what I am after now is: Does a LC13 have any sort of pre program routine that it follows for night? and any other schedule? Or can I trust the target temp setting I will do in my HC2 GUI. NO I do NOT use the heating panel in my HC2 (and I do not plan to do that either), I owuld like to use my own algorith - however to be able to do so I need to know that I can trust the temp setting on my LC13s - If I change the LC13 will try to follow, and not mix it up with some sort of internal schedule that overides everything....

 

I have read that it could have 9 set points per day in an internal schedule - however I have no way of controlling that from HC2 - so why would it be active?

[SHorsham 0]

Dont the thermostats do an exercise on the valve? Not sure if it does it everynight.

[Bamsefar 13]

Yes they do, however they will never do it during such long period that I have noticed.

 

Also, I have been able to verify that my LC13s do not have night schedule inside them (or at least not active), since we had a failure in the heating system that clearly showed that the LC13s does what they are supposed to do!