Vitodens Modulation Question

Gary Albaum

I have a Viessmann Vitodens 6-24C supplying a single loop staple up radiant / panel radiator with thermostatic valve system. Heating curve is 0.6 +10 max 125F. Design heat loss is ~55,000 at 0F. Everything works fine during the winter. In the fall and spring with a low heat load, the boiler starts short cycling which Viessmann and everyone here say is the expected behavior. My problem is that the staple up radiant is attached to a less than structural 60 year old tongue and groove sub-floor which tends to creak when the hot pulses pass on by every 5 minutes.

I assume there is not way to control this with programming, but would a buffer tank (Amtrol StorageMate, etc) on the outbound pipe from the boiler blend the pulse enough to fix this problem.

Uni R_3

Maybe use the setback...

What about just reducing the "occupied" time on the timer an hour at a time until it stops pulsing? You could have it add heat in the morning, the evening or a mix of the two.

Once it starts pulsing again take another hour away, maybe less when the occupied time band(s) get pretty narrow.

In the fall add heat as you see it start to notice higher rad temps. Put a simple wired indoor outdoor t-stat on one of your panel rads - somewhere you can keep an eye on it. When the temps start creeping up add more occupied time.

Constantin

Programming Error?

Gary,
Like you, I am but a homeowner that drinks from the fountain here. However, I did take a couple of classes at Viessmann in Warwick, including programming the Vitotronic.

Your scenario sounds like a curve slope that is incorrect a the low end. There would be fewer to no hot pulses if the circulating water was cooler during the shoulder months and the circulator ran longer to satisfy the heat loss.

I would consult the charts and go for a steeper curve with a smaller offset and see if that improves the sound effects first since that will not cost you any money. Cheers!

heatboy

Why..........

....a thermostatic mixing valve and not Viessmann's three way motorized valve? The thermostatic valve is causing your noise.

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Simply Rad_2

Heating curve