Unusual Viessmann 111w problem

[jakubjakub]

Hi,
I have a problem with Viessmann 111w
I have a Vicare sensor and app.
It goes like this :
If I have a boiler in DHW only everything works as it should, but then I switch it to DHW and heating. Temperature in a room is 21 degrees. I set the boiler to come on when the temperature is 17 degrees.
Every time I run a hot water, boiler comes on, fills a hot water tank, and as soon as it switches off, it dumps a lot of hot water into the radiators. Every time.
I put my baby to bed at 7pm (and my heating is on from 7) and I still have a shower, do washing up, wash my hands etc. Every time it dumps hot water to the radiors. By 10-11pm when I go to bed , temperature in the bedroom is 25-26degrees!

I had Viessmann engineer coming 4 times, he can't figure out what's wrong. Now they start telling me it's normal, that it has to dump that water to radiators. Surely that's not normal. My bedroom gets hotter every time even I don't want it to. And it doesn't dump any hot water when only in DHW mode.
Anyone might know what's going on? I'm not wrong it's not normal, am I?

Anyone's got the same boiler and could check for me what does your boiler do?
I would really appreciate any help.
Thanks
Jakub

 

[John.g]

You have a HW cylinder, not a Combi boiler??, if so can you see if you have one motorized valve with 3 pipes or a number of motorized valves with 2 pipes.

 

[jakubjakub]

I believe it's one valve with three pipes. They changed it today. Behaves the same. Opens for a few minutes and circulates the water. They changed motherboard/programmer and still the same. Bypass too.

 

[Gasmk1]

The heat has to go somewhere

 

[jakubjakub]

The heat has to go somewhere

Why doesn't it need to go somewhere when boiler is in DHW only mode ?
I'm sorry, I don't get it (little confused)

 

[John.g]

Have you got a hot water cylinder or not, that looks like a Combi boiler to me.

 

[jakubjakub]

Have you got a hot water cylinder or not, that looks like a Combi boiler to me.

It's got a 46lt hot water cylinder integrated , inside a boiler

 

[John.g]

OK, its a stored Combi Boiler.

If there's no demand for CH and the HW store is being heated the rads certainly should not be heating, is this happening?. If the CH is on, and its programmed off or a roomstat if installed, switches off the boiler then the circ pump should run (overrun) for a few minutes but rads should then cool down until next the next call for CH.
If the CH is off and you are not running a hot tap or whatever then the boiler may fire up occasionally to keep the stored HW up to temperature but the rads should not heat up, you will have to pester them (or keep pestering) until its sorted out,

 

[John.g]

I remember reading somewhere about someone who had the same problem with a Viessmann 200-W apparently cured I think by replacing the bypass cartridge although someone else stated that if "continuous heating" is selected that the CH will heat as well except that there are zone valves to prevent this happening, thats the way I interpreted it anyway.

 

[jakubjakub]

OK, its a stored Combi Boiler.

If there's no demand for CH and the HW store is being heated the rads certainly should not be heating, is this happening?

Nope. (CH off)

. If the CH is on, and its programmed off or a roomstat if installed, switches off the boiler then the circ pump should run (overrun) for a few minutes but rads should then cool down until next the next call for CH.

Yes. CH is on but thermostat is set to, say, 3degrees so keep CH from firing. I use hot water. HW store is being heated, rads still cold. As soon as the boiler stops heating the HW store it dumps hot water into rads and circulates for some time.
And it happens every time I use hot water. I wash my hands, another rush of hot water into rads. My wife washes her hands - another, I do washing up - another, etc. When we had guests rads were properly hot as there's always someone using water. Surely it isn't normal , is it?
I only use radiators in two bedrooms as I have a wood stove downstairs. And I only want it for the night in case temperature drops outside (and thus inside). Surely that's what thermostat is for (especially wireless one you can take to the bedroom)? Someone told me I should have all rads open but what's the point in that ? I don't want to heat whole house all night, why would I?
Sorry if it looks like I'm ranting, I'm not I'm just really confused by all this. (And especially not having a go at you, just frustrated , sorry)
Especially why does it apparently have to dump the water when heating is on (even if thermostat keeps it off) but it doesn't have to do it when heating off, when it does exactly the same thing, which is heating hot water ?