Drayton Wiser operating questions

[Mister Banks]

As far as I can see, the app mirrors the thermostat display.

As ian says, there's a bit of learning involved for Comfort mode and Eco mode. Comfort mode will essentially move the next scheduled set point earlier so that the room is at the desired temperature when you asked for it - so it has to estimate how long that will take based on history and outside temperature. However this is off by default. Eco mode does the same for a reduction in temperature. The room stat and app will indicate when they are in these modes.

Aside from comfort/eco modes, the behaviour is very simple: demand for heat = LED on + relay on + boiler on.

I am not using the smart modes yet but once the system settles I will give eco mode a try. I get that the basic principle is simple but the reality when the boiler and the Wiser work together is a little more complex.

 

[harrythefurrysquid]

never mind then
peace out

Hope you get your system setup correctly.

 

[ian1182]

I have looked to see what has happened on my system this morning.

As background, it's set to be 21.0C from 07:15 to 09:00 and then 20.0C until 5pm. At 09:00 it was 20.9C, dropping to 20.3C at 10am and eventually 19.8C at 10:50 when the boiler fired up for 5 minutes. The temp then slowly increased and after 40 minutes hit 20.0C. Although the boiler only ran for 5 minutes the pump runs for an additional 5 minutes or so as part of the "pump overrun" feature.

My experience with Wiser is the boiler runs more frequently but for short periods. With an old style thermostat there is far more hysteresis between when the thermostat cuts out and then back in, often 2-3 C. The boiler would run for 30-60 minutes, the room would then exceed the nominal temp as the radiators continued to put out their heat, room cools and the cycle resumes.

However I'm certainly not seeing much difference between the desired and actual temperatures with the Wiser system.

 

[mcprinter]

Mine has been in a month or so. Have been tweaking start times to get rooms up to temp.
With the colder weather rooms are not getting up to temp in time.

Are any of you using Eco or Comfort Mode?
Is this likely to help?

 

[ian1182]

As for Comfort and Eco settings. You need to have a reasonable understanding of their characteristics.

Comfort works well as a preheat to get the system up to temp. With an old style dumb programmer/thermostat you would set the heating to come on early. For example if you got up at 7am, then the heating would be set to come on at 6am to ensure the temp was suitable. With Comfort mode you basically say "I'd like it to be 21C at 7am" and Wiser makes an estimate when to bring the heating on to achieve that. So in winter it could be 5am and spring 06:30 (or whatever). I find this works well.

Eco is the opposite to comfort in that it turns the heating off early. Initially I found this to be a problem. I set the system to be 21C up to 10pm and then 17C overnight. But the system was saying "you want it to be 17C at 10pm, so I better turn the heating off at 8pm" which was not what I really desired. With Eco you need to play the system a bit, so now I set it to be 19C at 11pm and 17C at 1am. This actually results in the heating cutting out at about 10pm. You may need to adjust a bit to see how it works for you.

 

[ian1182]

The advantage of Comfort is that there is no need to change the on/off times as the seasons change. The Wiser system adjusts itself based on how the house is performing and I assume some external data such as outside temp via the internet connection.

I have both Comfort & Eco enabled but see caveat in my earlier reply.

 

[mcprinter]

If enabling Comfort, I guess my set points would need changing to the actual time I want the temp?

This what I am getting in my Mrs Office. Quite a big upstairs room. 5M x 3M approx.
She starts at 9am and finishes at 5pm

 

[ian1182]

correct. Looking at those charts you have 20C set at 8am but its not getting there until 10:30 (ish). If comfort was enabled the heating would probably fire up at around 5am asis. It seems it takes 3 hours to go from 15.5C to 20C. Hence you could change it to 20C at 9am (with Comfort) and the heating would start around 6am. It must be rather chilly in the room when Mrs starts work. Note comfort is a system wide option and other settings might need changing. I assume you have other rooms working to separate schedules, they would also need to be corrected to once/if comfort was enabled.

Is the insulation poor in that room, it does seem to drop rather rapidly. My lounge only decreased 2.3C between 23:00 and 5:30am (23rd to 24th Nov) until the heating kicked in.

 

[mcprinter]

Thanks Ian.

1930s Semi
Big windows in the office front and back. The whole house is like that. Very airy.
Front is a bay with hanging tiles. There was zero insulation with no felt/membrane. Insulated with PIR last year. New rad.
I did the loft with 300mm this Year. New window at the rear and decent curtains.
Better than it was. Struggled to keep it warm before.
I don't know if I am being a bit mean dropping it to 15? Once she finishes for the day the room does not get used.

In Manchester. Recent overnight has been 3-6 C

Humidity is a bit high 65-70% which I believe doesn't help with heating and heat loss. Have a PIV system on the way.

 

[Mister Banks]

Here is a reply I had from Drayton tech support re when the thermostats react to temperature changes……

“It is normally about 2C for the system to get full demand. What you are experiencing is the correct behaviour;
Whenever the setpoint temperature is above the room temperature the flame will be present/coloured. This does not mean that the boiler is on or that the system is calling for heat.
It is likely that although the flame is present the Heating LED will be off.

The heating LED is the only true tell to whether or not Wiser is calling for heat.
The relay will not energise until the PercentageDemand & PercentageDemandForItrv in a room reach 20%.

The system is designed to work in this way so that the hub is not calling for heat for only small differences, e.g. everytime the temperature drops 0.5C.”

I have asked for further clarification regarding the 20% as that seems a bit high if my understanding is correct, which it probably isn’t!

 

[ian1182]

Thanks Ian.

1930s Semi
Big windows in the office front and back. The whole house is like that. Very airy.
Front is a bay with hanging tiles. There was zero insulation with no felt/membrane. Insulated with PIR last year. New rad.
I did the loft with 300mm this Year. New window at the rear and decent curtains.
Better than it was. Struggled to keep it warm before.
I don't know if I am being a bit mean dropping it to 15? Once she finishes for the day the room does not get used.

In Manchester. Recent overnight has been 3-6 C

Humidity is a bit high 65-70% which I believe doesn't help with heating and heat loss. Have a PIV system on the way.

It was more an observation that the room is decreasing at a faster rate than I would expect. If the room is unused, there is little point keeping it heated evenings/overnight.

Comfort mode would allow the system to target your desired temp for 9am. At the moment you are providing 1 hour of preheat which does look a bit optimistic and will only worsen going into the winter proper. That said, it's a balance between room temp, cost and perhaps happier Mrs. The advantage of comfort mode is that it takes some of the guess work out of how long it takes to get up to temperature.

 

[JonathanM]

It is normally about 2C for the system to get full demand. What you are experiencing is the correct behaviour;

That sounds strange. My basic thermostat turns the heating on when it falls 0.25C below the set point.

 

[Mister Banks]

That sounds strange. My basic thermostat turns the heating on when it falls 0.25C below the set point.

I think 2c sounds a lot but 0.25c seems a bit aggressive. I’m sure I read somewhere that the human body can not detect temperature changes of less than 1c

 

[JonathanM]

I think 2c sounds a lot but 0.25c seems a bit aggressive.

Mine is old fashioned hysteresis. I turned off TPI. So, it comes on 0.25C below, but with the overshoot, it finally ends up about 1C over set point. It actually works really well.

But TPI, or equivalent, which yours is using, isn't supposed to work like that. It should do short burns, as soon as the temperature starts to drop below the set point.

 

[JonathanM]

The room temp is 18.5c, the stat on temp is 19c but the stat doesn't turn the boiler on until the room temp drops to about 17c.

So, what happens then? If the boiler comes on at 17C, when does it turn off, and how much overshoot above 19C do you end up with?