Lochinvar Ramp Delay Variations and What The Heck Does The Modulation Setting Do

nosirra1Arrison

Lochinvar boilers have a nifty ramp delay adjustment that does several things. First it allows for you to temper the firing rate of your boiler when it starts a cycle. Most modulating boilers seem to fire off hard (100%) and then attempt to modulate back desperately trying to avoid overshoot. Ramp delay lets you tell the boiler to fire initially at a lower rate (say 15%) and then progressively increase toward your maximum firing rate. It will modulate to try and avoid overshoot in all steps, but mellowing out the initial firing rate does wonders to keep overshoot and cycling down to a minimum. The second benefit of ramp delay is that you can limit your maximum firing rate, effectively downsizing an oversized boiler. A ramp delay setting on the sixth (of six adjustable levels) set at 50 will limit your boiler to half its rated capacity. A 155K btu becomes around a 77.5K btu boiler. This setting only effects space heating not domestic hot water production.
Does anyone run anything other than ramp increasing steps such as ramp delay step 1@15%, 2@20%, step 3@25%, 4@30%, 5@40%, 6@50% ? Does it make sense to run that type of stepping up for low mass radiant and fan coil, but run a U shaped set of settings for high mass like cast radiators or slab radiant? 1@50%, 2@40%, 3@35%, 4@40%, 5@45%, 6@50%. High mass can handle much more initial btus than low mass. Steady increasing ramps seem counterproductive for high mass. The U shape steps seem to make more sense.
Another topic altogether is the Modulation setting adjustment. The manual does not give me much help with this one. It is adjustable from a setting of 40 up to 100. 100 is the default. It does not set the maximum firing rate. That is ramp delay setting 6 as just discussed. Through trial and error, I see it seems to adjust how hyperactively it readjusts modulation. A setting of 100 for me (low mass) seemed to make too large firing readjustments as I tried for constant circulation with outdoor reset. It appears to mellow the swings of firing rate when it is closer to 40. Does anyone know what the Modulation adjustment is best used for?

hot_rod

As I recall I set the max fire to 30,000 on my Knight, just a bit above my design.
I started a ramp like yours, but with high mass I found it too conservative, I went to 30 degree steps

I don’t think there is a suggested or ideal adjustment for any parameters. Just keep trying trial error until it does what you want

As you know, one input can put you back to factory default, if you get it to balled up.