vaillant boiler help required

[l0dave]

this is my first post so i`m really hoping someone can help me out.
my system is as follows
vaillant turbomax plus 828e (3 years old)running 8 rads
danfoss rx1/tp5e-rf radio controlled receiver/thermostat
when the heating reaches set temprature the boiler still carries on working eg.room temp set at 20o actual temp 25o, at shutdown at bedtime temp set at 5o boiler continues to run until i turn the control knob down even then in the early hours i can hear the boiler running (display s.07) at no time is the hot water affected , but i have had to re pressurise the system twice to 1.5bar in 3 years (water evident dripping from the prv overflow) this problem started before the cold weather set in so i don`t think it`s the frost protection device ,any help preferable with detailed instructions would be much appreciated. i`m competent enough to tackle most jobs but leave anything involving gas to the experts. i contacted vaillantthey said it wasthe diverter valve but i`m not so sure as both the heating and hot water are working.

 

[Agile]

It does not sound like teh diverter valve yet.

The immediate question is what the thermostat shows when it should be off? Isnt there a flame symbol when the thermostat is calling for heat?

The first thing to check is to see if the thermostat is really calling for heat at the boiler. It sounds as if it is!

When were the batteries last changed in the thermostat?

Tony

 

[l0dave]

hello tony, thanks for your reply,
i know what you`re saying the batteries have been changed and everything has been re-set and re- programmed, as far as the display is concerned when the programmed time is reached (shutdown) the temprature display indicates the set temprature (5o) and there is no flame (demand for heating) icon on the lcd but the boiler still runs until i turn it down manually the boiler continues to run but obviously at a reduced output

 

[Agile]

If I was called to diagnose the fault then I would have to start by seeing if the stat receiver was giving the correct signal to the boiler, i.e. off when the sending unit said off!

However, I dont know if you have sufficient skills and a multimeter to do that.

If that were also off then the PCB becomes the prime suspect but thats expensive!

As its so easy to do then the temperature sensor resistance should be checked when cold but thats unlikely to be the fault as it would fool the boiler into thinking there is a fault.

I assume the boiler is inside the house and NOT in a loft or garage where the ambient temperature is cold! Also that there is no external frost stat connected anywhere?

Tony Glazier

 

[l0dave]

Hi Tony thanks for your reply and patience!!
I am in posession of a multimeter but have limited skills using it (continuity /feeds) if you explained the setting and what the reading should be i`m sure i could give you more information , i also wondered if this was the cause working it out logically if the thermostat sends the info is the receiver collecting the info and in turn telling the boiler what to do etc. The boiler is located in a bedroom with radiator fitted with a trv.

regards Andy

 

[l0dave]

Still have a problem anybody offer any solutions ? please