Viessmann Vitodens 200-W shuts off when outside temp goes up?

AKTor

Hi, first time poster here, apologies if this isn't the right category for this question.

 

We live in the top floor of a two-story house (+ basement) that's been converted into apartments (1 per floor).  The owner/landlord recently installed a Viessman Vitodens 200-W boiler, and we've notice a problem with the system that we can't seem to resolve using the basic controls (room temperature setting, reduced room temp setting, etc.).



Basically, the system works fine when the temperature outside is fairly consistently cold (it's winter here in Toronto, so we're talking a stretch of, say, minus-10'c to minus-15'c days).  However, whenever the temperature outside shifts from relatively cold to relatively warmer (say, from a minus-15'c day to a minus-2'c day), the rads go completely cold. 



I'm not a heating expert, but from what I've read from the Viessmann website, is this due to the heating curve not being set properly for the (almost 100 year old) house (i.e., the system is underestimating the rate of heat loss)?



Any ideas on troubleshooting the system would be much appreciated.

CMadatMe

Basic Controls

What do you mean by basic controls. Are we talking the control at the boiler or there is a Vitotrol (Thermostat) in the apartment that you are playing with. What is the Room Setpoint the boiler is seeing at the boiler control? What curve is the boiler running at? Do the rads have thermostatic valves on them? Has someone played with the shift and slope?  It's most likely a coding issue.

zacmobile

it does sound like the curve

In the owners (not installers) manual there are step by step instructions that explain how to adjust your heating curve and a good explanation on how outdoor reset works. It sounds like you may have to adjust the shift up a couple of degrees though. It took me a few months to get it dialed in on mine (but then i'm finicky about these things should only  take you a few weeks to get it set accurately though. make small adjustments and wait at least a day or two to make any more, it may sound like a bit of a pain but the end results are worth it in terms of comfort and energy savings.