I purchased a greenfire 130 which I believe is now a green horizon 130, it is a Seton design gasification boiler. My boiler came with two exhaust ports, one up high on the back of the unit and the regular low exhaust for operation. The upper one is to only be opened when loading wood and with an exhaust blower motor will hopefully reduce smoke when loading or checking on fire. I looked at grainger online and there are many different models and I am hoping someone on here has experience with one model or another. I have opted not to install my boiler until I can get storage, even though my electric boiler (back up) is making my electric bill very high. I will ask for help on the optimum piping later, as far as tying storage into my supply/return piping for the house and DHW I have 1800 all new vaulted living space upstairs with in floor staple up radiant heat, then downstairs where my boiler is is 1800 sf slab shop/garage, with infloor heat which was going to be my dump zone if I have an overheat situation, figured that much concrete could eat up a lot of BTU's and the boiler and piping will heat the shop anyways?????