Jump to content
C4 Forums | Control4

C4 Thermostat Overshoot Undershoot Functionality?


paulbirk

Recommended Posts

Please could anyone describe the functionality of the thermostat overshoot "buffer".

If I set the heat point to 23, with a "buffer" of 1, is that exactly the same as just setting the heat point to 22?

In other words, will it just stop heating at 1 degree below the heat point, because the heat left over in the radiators will continue to heat the room for a short while even when they're switched off?

What will happen if the temperature drops from 23 to 22?

Or does it work both sides of the 23? In other words, heats to 24, then allows to cool until 21 before heating again, to reduce the amount of on/off switches?

Thanks for any info,

Link to comment
Share on other sites


  • 1 month later...

The link on www.C4diy.com isn't working for me. Could someone repost the link (I also tried searching on the DIY site as well with no luck). I, too, am wondering about the over/under shoot as I see the same issue with my system.

Thanks.

Link to comment
Share on other sites

Hey neeshu,

I'm no pro, but the basic idea is this:

Heating cutoff point is how many degrees ABOVE the set temperature it will go before it cuts the heat.

For example a set point of 20C with a cutoff at 2 will heat until 22C and then stop calling for heat.

Heat Stage 1

Delta (degrees)

is how many degrees BELOW the set temperature it will get to before it cuts the heat

For example a set point of 20C with a delta of 0.6 will heat until 19.4C and then stop heating. This is kind of assuming that your heating will keep warming the room for a short while after the thermostat keeps calling for heat (e.g. underfloor heating)

Now, I may have got those 2 settings the wrong way round, but that's how I remember it.

Heat stage2 delta I think only matters if you have some kind of extra heating that comes on for some reason.

Cool cutoff and delta I can only assume are the same as what I described, but for air conditioning.

Don't assume anything I said is right, but I hope my guess helps.

Link to comment
Share on other sites

OK, that makes sense. I'm not sure how well my setup is working. And right now I just need to figure out how it can turn on/off by itself.

Similar subject (thermostats), but different topic....

Under the thermostat, there is a view/edit schedule that can be changed. I have revised this so that at 6PM the heat comes on and is set at 65F. Then the setpoint changes to 59F at 10PM. Yet nothing happened at 10PM. Does the thermostat react automatically without any additional programming at the times and setpoints shown under the view/edit schedule? In other words, is this similar to a "regular" programmable thermostat?

If so, mine isn't working correctly. It's 10:13PM and the heat is still on and set to 65F. I have no other thermostat programming.

Also, does the thermostat need to be in auto for the view/edit schedule to work? I tried it both ways (in the off and in the heat/auto mode), but neither worked.

Any thoughts?

Link to comment
Share on other sites

Here are my best guesses from experience...

Does the thermostat react automatically without any additional programming at the times and setpoints shown under the view/edit schedule? In other words, is this similar to a "regular" programmable thermostat?

Yes, but you need to understand a few more things...

If the thermostat is in off mode, it will ignore all scheduling and stay off.

You want to leave it in heat, or auto mode. And at times when you would like it to not be heating, set the schedule to a very low temp, or set it to a very low temp and set the hold mode to "on" (or it may be called "hold").

Also, if the hold mode is "on" or it might be called "hold, then the thermostat WILL change with the next scheduled change. If the hold mode is permanent, then the thermostat WILL NOT CHANGE until there is user intervention. If the hold mode is 2 hours, after 2 hours it will go to whatever the schedule says at that time.

hope that helps!

Link to comment
Share on other sites

Yes, this was helpful, Paul. Thanks.

Now another question.... this is in regards to how the thermostat will operate using a wakeup scene/agent.

I have a wakeup programmed to turn on the furnace/heat 30 minutes before I get up - my question is, what MODE does it put the thermostat into? Will it be set to 2 hours or permanent?

What I'm doing is this: I have a heated floor in my MBath and I'm setting the wake-up for 2 hours before I really want to get up. It will then turn on the heated floor. 90 minutes into the scene, it will turn on the furnace/heat to the house to 65 degrees (30 minutes prior to actually getting up). I still want to use the normal next scheduled change to turn off the furnace/heat at a certain time.

But in the case where I am on vacation for a day, I don't want it to turn off at the next scheduled change, but keep the furnace/heat on. So if the furnace/heat is placed in permanent mode it will work as programmed. If it shuts off after 2 hours, I will need to do something different, but not sure what.

Again, help is appreciated.

Link to comment
Share on other sites

Sorry I don't know much about the scene agent.

Some confusion in your wording though. MODE cannot be 2 hours or permanent, it can be heat, auto, cool, off.

It sounds to me like you need the mode to be heat. Then your scene needs to set the hold mode to one of the following:

ON (=until next), then the furnace will stay on until a scheduled change (e.g. 1 hour after you wake up) that turns the temp back down.

On days when you want it to stay on, you could press the hold button to change it to permanent. (but you'd have to turn it off later)

2 HOURS, then the furnace will come on for 2 hours, and then switch back to whatever temp the schedule says.

On days when you want it to stay on, you could press the hold button to change it to "hold on", then it will change back at the next scheduled change, which could be in the evening.. Or press the hold button to change it back to permanent (but you'd have to turn it off later).

PERMANENT, then the furnace will come on, and you will have to have another programmed event or scene that turns it back to "hold off" at a time specified. On days when you want it to stay on, you could program something else that delays the 2nd programmed event or scene. Or press the hold button to change it back to permanent (but you'd have to turn it off later).

I'm not really sure if any of that's helpful, good luck!

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...