New functionality requested to address too many hub (r) start/stop commands in a given hour.

[SAtewart]

Hi I'm new to this forum so apologies if this should be part of another thread.

I have installed a six stat system in my parents house and a 14 stat system in my own. Both run combi's and have been running well for about two months. However I have noticed that the hub cycles the boiler several times an hour when the rooms are at setpoint and not actually calling for heat (as shown in the app). This may be some kind of latency between hub and app or the hub is responding to  values that the app rounds up or down.

My gripe is that during the night (in particular) when all the valves are off as per their schedule but at setpoint, the controller calls several times per hour for heat but for such a short time that the boiler barely has time to accumulate and then distribute heat to the rads. I believe the result is gas waste and boiler wear.

I understand there is a CPH parameter (heater cycles per hour) that limits the number of on/off cycles in any hour. This is not a user definable parameter. For natural gas I understand this is set to six. I am experiencing a lot of boiler cycling for very little gain. Surely this can be improved and can I raise two routes?

Option 1. Give users control over the CPH value.

Option 2. Introduce a user configurable parameter that sets the minimum run time that the boiler maintains - my boiler would need maybe 5 to 15 minutes depending on the season.

Option 3. Set a dead band that forces (in a heating application) a drop of one or two degrees from the achieved set point before an on signal is sent. (Maybe the least elegant of options here)

I will happily trade a little set point overshoot for a much reduced boiler cycling.

From another thread see below

"FuelType": "Oil",
"CycleRate": "CPH_3",

"FuelType": "Gas",
"CycleRate": "CPH_6",

"FuelType": "Electric",
"CycleRate": "CPH_12",

"FuelType": "HeatPump",
"CycleRate": "CPH_3",

[chrisphysics · Accepted solution]

Yes, set the Heat Source Type to "Oil" and you'll half your cycles to 3.

It's still missing a minimum on time but it's much better.

[SAtewart]

A neat get around. I wonder if the engineers respond to this sort of idea/observation/enquiry.

Many Thanks, Stewart

[SAtewart]

I think I've found a bug in the new app.

Settings/Devices/then tap on Hub R.

Heat Source Type Isn't clickablke

[chrisphysics]

Yes there's definitely some bug, I had that problem, Restart the app, sometimes a couple of times if required. (I just checked now and had to do that but it worked after killing the app and reopening it)

Once you've selected the heat source it will show underneath for a few seconds, then disappears. (that I guess is another bug, and it always shows gas if you reopen the option). But  it does change the cycle count.

[SAtewart]

Alas the field remains un-editable for me even after a couple of cold reboots (admittedly on a budget phone). Oddly enough I have just remote accessed the other system I have and its hub was quite happy to let me change to oil. I guess a re-boot of the hub or god forbid, wiping the account and starting from scratch. 

[PhilHornby]

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@SAtewart wrote:

or the hub is responding to  values that the app rounds up or down.

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I think it's probably that - the system works in 0.1C increments - but not the App or the Roomstat displays.

(Using the API I successfully set one of my schedules to use 21.3°C - this means I no longer have to intervene to boost it from 21.0° to 21.5°, when I feel chilly)

I think I've found a bug in the new app.

Someone else mentioned that, so I added it to my review on the Google Play store. The reply I got, was that I should mention it on the forum 🤔 

Someone needs to log it with Scheider as a bug. (You'd think their paid support staff would be capable of that, but apparently not!)