IBC ramp speed selection ?

Dave Carpentier

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Ramp speed for all touchscreen controllers

How fast the boiler tries to raise the water temperature flowing through the heat emitters.
With a fin tube baseboard radiator, you may want the water temperature to rise quickly to provide heat as quickly as possible. This type of heat emitter has very little mass, so it can heat up quickly. When the call for heat is removed, it cools down quickly. Generally this requires a higher (faster) ramp speed.
A radiant floor, on the other hand, has significant mass, and therefore takes a long time to heat up. When the call for heat is removed, the floor is still warm and continues to add heat to the space for a significant period of time. If the indoor temperature overshoots the desired indoor temperature, we recommend reducing the Ramp Speed value. Generally this requires a lower (slower) ramp speed.
You can manually set the Ramp Speed by choosing a value from 1 to 10. A setting of 1 will raise the water temperature very slowly and 10 will raise the water temperature very quickly.

Below is a table that shows ramp speed vs time.

Ramp Speed	°F per Minute	°F per Hour	°C per Minute	°C per Hour
1	0.06	3.6	0.033	2
2	0.12	7.2	0.067	4
3	0.24	14.4	0.133	8
4	0.45	27	0.25	15
5	0.9	54	0.5	30
6	1.8	108	1	60
7	3.6	216	2	120
8	7.2	432	4	240
9	14.4	864	8	480
10	27	1620	15	900

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( VX-110 into a 2-pipe 12g buffer which then feeds an in-floor with 7 zones. )

In this mode, it appears to use whatever burner % it needs to hit the temp rise rate.

They recommend setting 1 for in-floor, but do I consider the effect of the buffer tank ?

Its not clear if the temp rise is across the boiler or between boiler input and buffer tank sensor. My boiler loop will be flowing faster than the in-floor loops by anywhere between 2 and 6 gpm.

hot_rod

You want to use ODR with high mass systems. That helps with the flywheel effect, a lot.

With the buffer, and ODR, the ramp is not that critical.

It might take some trial and error.

I started my shop radiant today for the first time today. The ramp did slow down the start up somewhat. The 8 steps were spread out over 30 minutes.

Once it hit the top step it stayed at high fire for hours.

So it depends a little bit on how you run the system.

In a home I think you want to tweak various settings with a goal of near continuous operation. Comfort, efficiency and longer component life when you lessen or eliminate on/off cycles.