This is the WP pellet boiler that Marc Caluwe is manufacturing here in the States. The model you are looking at is the 135 with the XL pellet hopper which holds about 350# of pellets. It's a nice basic unit sold without a lot of bells and whistles.
We have it set up to simply run on the boiler temp setpoint (fully adjustable) and circulate heat to the 6,000 sq ft pole barn/machinery shop it is heating. The system inside is set up very nicely for this being 5 zones of radiant slab controlled Wirsbo room temp sensors and a Tekmar 356 injection mixing control. If I had my choice I would have liked to install it with an enable/disable control based on indoor temp but there is no option to run a control wire in the existing undergound conduit/piping. (Always run extra conduits in your underground people)
The boiler itself sits on a slab that used to have an OWB on it and the owner elected to build a little boiler shed to house it and have room for a pallet of pellets. The control on the boiler allows you to set your firing rate in 5 increments of roughly 20% so you can run this particular model at 20,40,60,80 or 100% of 135,000btu. It has a built in boiler protection aquastat that kills circulation if the water temp drops too low. I really like this feature because it makes piping and installation much less difficult than having to install a mixing device like a Termovar or equivalent.We have it set to start the boiler circ at about 145 and turn it off if the water temp hits 135*. This gives plenty of leeway to avoid condensation issues from excessively low water temps. (The Testo showed a dew point of 115-118* in the flue gas)
We have no storage connected to the boiler and I doubt very much if any will be needed in this particular case for a couple reasons. The first being that the boiler is capable of 5 different firing rates so its output can be matched to the outside conditions. The second being the nature of the system and load it is connected to. (variable demand due to proportional control of the load). This will allow the owner to basically set the boiler at level 2 (40%) until probably mid to late December and then step it up to 60% and maybe 80% during the January-February time frame.
The water temp setpoint is on at about 163 and off at 177 the way we have it set right now which gives us plenty of "headroom" before reaching emergency dump temperature setting of 210*. I purposely ran the boiler to about 170 at max firing rate and then killed the power to see what would happen. The water temp crept up to about 195 before stabilizing and then heading back down. This is a notable difference when compared to a cordwood fired boiler which can continue to make heat long after things are shut off due to a circ failure or power outage. There is only about a pound of fuel maximum in the firepot at one time so there is little residual heat rise. Makes it a lot less problematic from a dump zone standpoint.