Digistat 3

nxdmsandkaskdjaqd

Are there any other members here that have a Digistat 3 fitted on their central heating.

I recently purchased one, but the way it controls the temperature seems very poor (uses PWM pulse width modulation). For instance if set to 21C and the room temperature is 20.5C it will pulse the heating on for JUST 1 minute - 4 times an hour. But this is just not sufficient to raise the room temperature, the radiators only get luke warm.

I am interested in other user experiences.

John_the_Boy

Hi - I had one of these fitted and I found it very poor:-

The click on and off was loud and it used to wake my wife up who is a light sleeper.

The temperature range was very inaccurate - it would often switch off 2 degrees below the temp and then come on again 5 minutes later.

When the boiler wasn't on we would ofen hear the thermostat click on and off even when the temp in the house was below what it was set for - it appeared to do this for up to 3 or degrees below the thermostat temp before it finally stopped.

British Gas said it was faulty but I found a few negative comments on the digistat on the web that backed up my experience so I got them to replace it with the old fashioned type of thermostat.

nickj_2

i have a digistat2 and all aspects of it seem totally useless
to set it you need a degree in quantum physics , it has 6 different time = temp settings
i don't know about anyone else but i only need 2 , on in the morning and then in the evening
i have altered it so it does only 2 but it doesn't let the rads warm up the room , i have the temp set for 21deg but it takes ages to get there and sometimes it doesn't get there at all

i'm sure all people want is an on and off x twice a day or constant with the option of adjusting the temp to suit needs

alanobrien

You may find this of interest. Credit to Meerkat on the Screwfix site for this useful info.


"I had the original Digistat 3 and it was brill. When it failed after many years I purchased one of these. It has been connected 2 days and I am having problems maintaining an even temperature. Having had the old one which was great I decided not to give up with this one. So I have contacted support at Drayton (Really Good Support) and I now have an understanding of what the stat is trying to do. You have to put it in set it and leave it for 5 days. It will go over the set temp and it will cut off early. It is learning about the conditions in the house (Heat loss ect). I was told that all stats in the future will be made this way for energy saving. I will let it run and report back in a few weeks
This was sent to me from Drayton Support it might help you.
Digistat+2 and Digistat+3 Control Function Explained
• Digistat+2 and +3 uses a Pulse Width Modulated (PWM) system.
• A 15 minute cycle time is used.
• The output is on for a proportion of the 15minute cycle determined by a function of the difference
between the set point and the measured temperature.
• While the measured temperature is more than 2 degrees below the set point, then the output is
continuously on.
• While the measured temperature is more than 2 degrees above the set point, then the output is
continuously off.
• Between these limits, at the start of the 15 minute cycle, the Digistat makes a calculation of the required on
time of the output.
• It makes a new calculation at the start of every successive 15 minute cycle.
• The calculation aims to reduce the difference between the measured temperature and the set point.
• It tries to compensate for the heat loss it expects over the next cycle with the heat input it expects from the
on time of the heat source (normally the boiler).
• The longer the Digistat is at one set point, the more accurate will be the calculation and the closer will be
the control to the set point.
So, to answer some comments that have been made:
– The boiler is switched too frequently.
• No it is not, a 15 minute cycle is compatible with the control accuracy we are trying to achieve.
– The displayed temperature is not at the set point.
• True, most controls have an similar accuracy, but we display to 1/10th degree resolution so any
difference is more noticeable.
– The display temperature is above set point, but the boiler is on.
• This is not inconsistent with the algorithm. It is trying to predict the losses for the next 15 minutes,
and supply sufficient heat to compensate.
– The display temperature is below the set point, but the boiler is off.
• This is not inconsistent, the control will try to inject sufficient heat to compensate for the losses and
lift the controlled temperature to the set point and no more. If it calculates that it requires 2/3rds of
the boiler output to achieve that, it will switch the output on for 10 of the 15 minute cycle. The
boiler will be off for 5 minutes.
Remember the thermostat is about setting a comfort level, not a specific number. Position of the
thermostat and system conditions play an important role."

lagi

Glad there are others. I have digi 3.

I fully agree with the quantum physics involved in basic setting. (nail on the head theory).

Used to have a british gas boiler which was easy to set up, instant heat button.

Had new boiler fitted and asked for non wireless thermostat and this one was fitted.

Like everyone else, just want it to come on in the morning for a while, then come on again in the evening.

Every time i need to adjust the thing i have to dig out the manual, and when i want to turn it off, i have to change the menu setting to on!!!

I even have the manual on the pc, as i have misplaced the original as it kept coming out of the drawer. (although i don't think its far from the stat.)

Nice to know somebody else thought it was loud as this often clicks loudly and as i am in a bungalow its right near me. Didn't know any different because other was in a house.

If it could be replaced its something i would think about. Something that was still quite modern to look at, maybe with a nice backlit panel.

nxdmsandkaskdjaqd

alanobrien wrote: »

It is learning about the conditions in the house (Heat loss ect). I was told that all stats in the future will be made this way for energy saving. I will let it run and report back in a few weeks."

I don't believe that the unit learns your system, it may calculate the temeperature on/off period every 15 mins, but that's about it(*). I have spoken to Drayton, whilst they were helpful, at the end of the day they told me to GO BACK TO A NORMAL ROOM STAT!!!!

And yes that relay is rather loud.

(*) I asked how you do a system reset, in the end I found out that User Option 7 only resets the defined temperature settings. There is no reset for going back to factory set conditions (even to reset it's learning).

amcluesent

I didn't know such devices existed! But am interested in a smarter thermostat which has 5/2 day awareness.

However, I already have a noddy Drayton LP241 Programmer in the airing cupboard with a room-stat in the lounge. The Digistat seems smarter than the Programmer, so how would they integrate with each having programmes they are trying to follow? I could see the Programmer C/H being set 'always on' with the Digistat switching heat as needed, but this would leave the C/H pump on 24/7 surely...

moneysaver

amcluesent wrote: »

I didn't know such devices existed! But am interested in a smarter thermostat which has 5/2 day awareness.

However, I already have a noddy Drayton LP241 Programmer in the airing cupboard with a room-stat in the lounge. The Digistat seems smarter than the Programmer, so how would they integrate with each having programmes they are trying to follow? I could see the Programmer C/H being set 'always on' with the Digistat switching heat as needed, but this would leave the C/H pump on 24/7 surely...

Hi,
The LP241 would be replaced with the reciever unit of the Digistat. Then you would use the digistat to do all your programming. That is what was done with mine when it was installed a few months ago



Moneysaver

gas4you

Personally I find Drayton controls nothing but hassle.

Honeywell are the easiest to use and the best at present.

nxdmsandkaskdjaqd

gas4you wrote: »

Personally I find Drayton controls nothing but hassle.

Honeywell are the easiest to use and the best at present.

Could you please expand on your reasons/experience. i would like to know more.

C_Mababejive

Surely the digistat +3 is an intelligent controller and people are simply misunderstanding its mode of operation.

Its role is to control temperature,learn its environment over time and anticipate comfort levels thus saving energy.

This may well mean that the radiators are just slightly warm instead of bouncing hot...thats the idea. You only supply the energy required without supplying it un-necessarily and without overshoot.