Hi there, new member here with a problem with our heating system thermostat and posting in the hope that someone in the know can assist with what might be complete user error.
I can't find the answer to this problem after a search, but as I have absolutely no idea what I am doing, i'm unsure if i've used the correct search terms. Please forgive me if that is the case.
We have a Drayton Digistat RF1 (pic below) and although it has the temperature on it and the flame next to it, adjusting the temperature on the screen seems to do absolutely nothing to the actual temperature of the house. I can't remember if there have ever been any LEDs on the unit and wouldn't know where they are anyway.
I've found this link -
formatting link
have no idea what an SCR is (sorry, complete novice at this) and no idea how I can make it work. My initial thought is that it has lost connection with the boiler system but in all honesty, I just can't remember if the thing ever worked in the first place.
I know I haven't explained myself properly but I am hopeful there is someone on here who knows what I am talking about and can assist.
Presumably the heating does come on and the radiators do heat up most of the time? Is your problem that when the thermostat appears to be calling for heat the boiler does not always come on?
Do you mean the boiler is not coming on at all for heating, or it is not keeping to the required temperature? Is it a combi boiler? If not, is the hot water working? If it is a combi, is the hot water working?
Could be a poor wifi signal between the thermostat handset and the base station (SCR). There is a reset button on the box, which is usually beside the boiler. The light is green if it is calling for heat, I thinkit is red if no communication.
Could be the thermostat has failed if it will not communicate with the base station. Far too many variables to give a good diagnosis.
If you feel competent, it s a 5 minute job to bypass the thermostat if your heating is not working, you just join up 2 terminals at either the boiler, or the stat base. Once they are joined the heating will be on all the time, unless there is a clock controlling the time it comes on.
We had one that went faulty some months after installation. Don't know whether there was a problem with them but they put a new one in the post and trusted me to return the old one. The problem was with the receiver in the airing cupboard rather than with the sender. Our one never answered the call for heat from the sender and we had a couple of very cold January mornings
I have the instructions for the digistat 3 and digistat+3 If that is any good to you.(can email) I have the 3 and it drives me insane trying to programme the damn thing, too complicated for my liking. I just like on & off switches.
The receiver bit (which has the red and green LEDs on it) will probably be somewhere near the boiler, as it has to be physically wired to it. If the red LED is on then it's lost contact with the sender (the unit in the room, with the temperature display and flame symbol on an LCD). Then you have to rebind it by removing the right-hand battery drawer on the sender (which has a cunning plastic clip which breaks so you then need to tape it up shut), pressing buttons on the receiver and then replacing the battery drawer. You'll have to do this anytime the power to the receiver gets turned off. Yes, really. And when the battery drawer on the sender comes open because the stupid friggin clip that holds it shut has broken.
Rinse and repeat until you get fed up enough to shell out for a Honeywell CMT927 or suchlike :-|
I have a new Honywell CM 927 - which is why I asked if the 'call for heat' sometimes worked and sometimes didn't. The CM 927 is just too bl**dy smart at times. It doesn't always respond to a 'call for heat' if it thinks it shouldn't. From an online copy of the manual (at least one similar to the paper copy).
Symptom "The thermostat's LCD display shows a symbol but the heating does not switch on." Posible Cause "The heating is not required at this moment." Remedy "The heat demand is send to the HC60NG as a value between 0-100%. The HC60NG will adjust the boiler on time to meet this requirement. That is why the heating will be off sometimes even if the symbol is displayed. To check if RF system is communicating properly press the button to increase the set temperature a few degrees above the current temperature. The heating should come on after a few seconds."
Not quite the same wording as in my manual which says "This is normal operation. The Relay Box cycles the relay on and off for times proportional to the demand signal (0-100%) from the room thermostat. The flame symbol only indicates that the demand value is greater than
0%.(!!)"
So the relay box is told by the thermostat that the room is colder than the set value, and some heat is required. The relay box then goes "Maybee I will, maybee I won't. It just depends.".
I think this is tied in with some Category 2 System Settings. Ot is the minimum on time - set to 1 minute by default. Cr is the Cycle Rate - set to 6 cycles per hour by default.
So if the thermostat calls for heat more than 6 times an hour you may not get it.
Section 4.3 says that Cr 6 and Ot 1 is standard for gas boilers under 30kW. It gives other settings for Oil boilers, thermal actuators and zone valves. It doesn't however give values for gas boilers over 30kW. Our boiler is rated at 38kW.
So at times it can be just too bl**dy clever by half.
If the thermostat is in an area with rapid fluctuation of temperature (e.g. near an outside door - and a common location is the hall) then the temperature can drop below the demand threshold each time the door opens. You can see that if the house is warm and the hall radiator is warm then the temperature could come up again quite quickly without firing up the boiler so there does seem to be some sense in the setting. However if you get a lot of in-and-out traffic at the front door this may mean the house is without heating for the next hour.
I am currently puzzling as to what values to set for our 38kW boiler - longer minimum run time, more cycles per hour, both.
So it would be useful if the OP came back with more information on the problem.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.