I live in the west-side of WA state, where it rarely gets very cold. I am replacing aging gas forced-air furnace and gas tank-HWH. We have a small 1200sqft house that has been retrofit with insulation (walls, floors and attic). We are pretty good about not keeping the thermostat ~66 when we are home/awake, and are good at conserving water in showers. We are looking into getting a high-efficiency gas boiler and hydronic radiator (not in-floor radiant) heating AND hot water system:

Scenario #1: a Triangle Tube Solo 110 with SuperStor 60 tank with two heat exchangers AND a solar DHW pre-heat Veissman flat plate collector closed-loop.

Scenario #2: If I decide not to do solar, a Triangle Tube Prestige Excellence boiler (has a smaller internal tank, so no external is needed). Our house is small and space is precious, so that is attractive.

I am getting a quote from an experienced, licensed contractor. I would like to know what questions I should ask him. Also any thoughts you have about these scenarios (solar compatible vs. not) are appreciated. Thanks.