Baxi assure 524 boiler and sundial rf2 pack 1 room thermistat

[jacqueline23]

could you try answering this for me please.
i have new boiler and room thermostat , ive seen on someposts that it is usual that .when you set room thermostat say to 20° it is correct for boiler to ignite even at 20° as a smaller drop than 0.5 degrees is registered and boiler is maintaining rooms at 20°..even though room stat is not showing 19.5° which is when I expected boiler to kick in. could you just clarify this is still correct kicking in at 20°.
then this is the query..what happens..is this...so room thermostat set to 20°, boiler ignites whilst room tempeeature is showing 20°, flame symbol showing on both room thermistat and programmer.
so, ignites , runs for literally 30 seconds ,flame symbol goes off on both programmer and thermostat, i hear a click, then something continues running for 3 mins exactly and goes off.this repeats again exactly same every 3 to 4 mins later ..ignites runs for 30 secs, clicks off , something running 3 mins then off (fan or pump?)is this normal to run for just 30 secs and repeat over and over.
if I turn up the room thermostat manually from say 18 to 22 boiler ignites and runs as long as needs to reach 22° then clicks off but then does same thing as described ..ignites runs 30 seconds , 3 minutes fan or pump runs goes off..and repeats 3 to 4 mins later is this normal
please help advise
had several engineers out plus a basic warranty engineer from Baxi who said doesn't get involved with the room thermostat so did nothing ..other engineers hardly know how to set up the particular thermostat so am stuck..

 

[CBW]

The 3 mins sounds like pump overrun. A thermostat will usually bring the boiler on at a slightly higher temperature than the room/ambient temperature, so say room thermostat set to 20 but ambient is 21, then all good and satisfied. If the ambient temperature is say 19 and room thermostat is set to 20 then it’ll come on for a short period. If it’s only coming on for 30 seconds, I doubt it’s the room thermostat.

 

[jacqueline23]

and it's a brand new boiler and thermostat fitted 30 aug , I'm a council tenant and everyone seems foxed as to whether it's normal to do this or not..its maintaining the temperature that the room thermostats is set to very well but is it normal to come on for just 30 seconds and go off and then the pump run 3 mins then repeat the whole thing again 3 to 4 mins later..

 

[CBW]

If it’s maintaining the temperature, then yes, could be true. What thermostat is it?

 

[jacqueline23]

it's a honeywell sundial rf2 pack 1 and boiler is baxi assure combi 524 ..

 

[Johntheo5]

You probably have a DT92E thermostat with what is known as TPI control, you can't switch this off but can change the number of cycles per hour from probably its now 6 cycles per hour to 3 cycles per hour which means the boiler will stay off for longer and run for longer, say maybe 2 mins every 20 minutes, there should be plenty of people on here to tell you how to change this, if you wish.

 

[jacqueline23]

hi yes it is a DT92E R/T WITH The ST9120C programmer..
sounds helpful if someone can tell me how to do that.....

 

[CBW]

hi yes it is a DT92E R/T WITH The ST9120C programmer..
sounds helpful if someone can tell me how to do that.....

Honeywell DT92E Wireless Room Thermostat Installation Manual - thermostat.guide

Contents hide 1 Honeywell DT92E Wireless Room Thermostat 2 Installation 3 Installing the BDR91 Relay Box 4 Installing the DT92 Room Thermostat 5 Basic System Operation 6 Installer Mode 7 Binding 8 Reference Honeywell DT92E Wireless Room Thermostat Installation The DT92 wireless room thermostat...

thermostat.guide

If you scroll down to just past installer section, it explains parameters and values/how to change

 

[jacqueline23]

I'm looking at the page abd currently I'm looking thinking..crikey can't get my head round hiw to change it..its not very clear gir me how to do it..could anyone explain it to me step by step ..nit very good at these things..
but thankyou fir helping...when the council git the boiler they only show you how to up and down the thermostat temp and thats it. !

 

[Johntheo5]

I'm afraid I couldn't talk you through it even though I probably could if sitting in front of the controller, probably best to get someone in to do it, surprising that any of of these engineers couldn't.

It shows a minimum on time of 1 minute (default) and the default cycle time is 6/hr, so in your case, the boiler should fire for 1 minute minimum, then do a 3 min pump overrun and then refire after a further 6 minutes, strange that its only running for 30 secs.

 

[jacqueline23]

it is definitely running 30 secs off then 3 mins pump over run..I'm checking it again listening and documenting times on off etc..a sparky was here Friday with the gas repairs supervisor the sparky got involved with the thermostat and tried something that he thought wud help but it just altered the temp reading by 2 degrees so it had be changed back , but he was very bright and worked out how to change things on it..the supervisor had no clue, I can ask the sparky on Tues to come back and change cycle ..thank you for your very helpful info...