Boiler Issue....help needed

[crouch12345]

Our boiler has developed a mind of it's own over the past week that I suspect is an issue with the programming unit but my limited diagnostic skills (turn off/on and reseting) have not resolved the problem.

The boiler is a vitodens 100W running off LPG with a drayton tempus 7 programming unit. It appears that the boiler is not getting the correct mode input from the programmer.

Starting with what does appear to be working; the heating comes on when the heating mode is turned on (and the heating indicator symbol displays on the boiler). However, when the hot water mode is on the indicator symbol on the boiler does not show but the central heating indicator symbol does come on and the boiler still runs (but doesn't heat up the radiators so I assume it is filling the HW tank). Finally, most confusing was this morning when neither the hot water or heating modes were on but the boiler was still running (again with the heating indicator symbol showing but the radiators stone cold)!

There has been another issue with the water tank taking a long time to fill up due to a partially blocked ball valve but i assume that is unrelated (I may be wrong!).

Any help/advice/experience anyone can give would be massively appreciated.

Thanks

 

[Phill Peck]

Your boiler will show the rad "heating" symbol when heating the tank. Unless it has Viessmann controls on a 4 pipe system it doesn't know wether it's doing heating or hw.

The boiler firing without demand? No symbol, was it actually firing or running the pump. Could be frost protection depending on loaction.
If it is showing a symbol and firing when timer is off if have a look at motorised valves.

 

[crouch12345]

Your boiler will show the rad "heating" symbol when heating the tank. Unless it has Viessmann controls on a 4 pipe system it doesn't know wether it's doing heating or hw.

The boiler firing without demand? No symbol, was it actually firing or running the pump. Could be frost protection depending on loaction.
If it is showing a symbol and firing when timer is off if have a look at motorised valves.

The boiler has previously shown a 'tap' symbol when the hw mode was on so it does differentiate between heating and hw.

It was definitely firing and showing the heating symbol without either mode on.

 

[Phill Peck]

How many pipes come out the bottom?