Viessman Vitodens 100 with Santon cylinder - no hot water

[drewburdon]

Hello, I have a newly installed Vitodens 100 (35kw) connected to a Sandon 210 indirect cylinder. I noticed yesterday that we had no hot water and when I switched to manual HW - even though the boiler light for hot water demand came on - the boiler didn't fire.

i'm pretty competent around the airing cupboard so before I call out the guys who fitted it I'd be grateful for some advice to fix the problem myself.

I've switched the boiler on and off several times and whilst it fires upon reboot, the burner goes out within 5 minutes or so.

• There's no fault indicated on the boiler.
• The cylinder has power and water.

Thanks all

 

[Agile]

Motorised valve?

Tony

 

[drewburdon]

thanks

That was my hunch but both are new Honeywells. I've tested them out by reducing the water temp on the cylinder and the HW valve changes position.

Other than that I'm pretty short on ideas of how to test an electrical fault. Are you suggesting that the valve is set to closed position? Would this stop the boiler from firing?

 

[JohnD]

newly installed

Who installed it, and what did he do when you reported the fault?

Did it ever work properly?

Does the pump start? If you feel all the pipes, which of them get hot?

You say it stops firing after a few minutes. What temperature does the boiler indicate in those few minutes? It is possible for air to collect in the coils of the heat exchanger, but turning the pump to max might blow them out.

What happens when you turn the CH on?

 

[drewburdon]

newly installed

Who installed it, and what did he do when you reported the fault? - Engineers subcontracted by my builder, I haven't called them out yet.

Did it ever work properly? - Yes, perfectly for the last month

Does the pump start? If you feel all the pipes, which of them get hot? - Yes, all of them that are supposed to but the CH hotter than the HW

You say it stops firing after a few minutes. What temperature does the boiler indicate in those few minutes? It is possible for air to collect in the coils of the heat exchanger, but turning the pump to max might blow them out. - Around 50º

What happens when you turn the CH on? - Just the HW demand light stays on but no boiler firing

 

[Phill Peck]

What programmer hve you got?

You say when u turn on ch no light comes on? Do you mean on the programmer

 

[drewburdon]

I have the Viessman wireless controller for the boiler.

The HW demand light comes on on the programmer and the boiler.
The wireless connection is working OK.