Tim Skufca wrote:we have a ground-source heat-pump which heats our hydronic floors from a well in our in-town Missoula well. In-floor heat is very comfortable. In the summer heat we circulate well temperature water through the floors to keep the space comfortable, which is very important if the Missoula air quality gets bad from forest fires. Closing the windows and running 55 degree water through the floors is an effective way to hold off those awful smokey periods.
ALSO: what is not talked about with Rocket Mass Heaters/Stoves is the necessity to be there at all times. There is no way to take off for a few days, or else everything freezes. I have the mind-set of embracing technology and install solar panels that power the electrically sourced hot water.
Again, in a 9a climate, you don't have the same freezing issues as in a 4 or 5 climate. Indoor plumbing for a 4b climate is a whole nother topic; but in my experience, a masonry heater beats any other wood heat for days you can leave the house untended before freeze-crunch. In those settings, you learn to invest in good neighbors, vacation-style drain systems, and/or heat tape.
In this case,
Climate sounds like it needs more cooling than heating. Shaded collonades, courtyard with fountain, or grape arbors are good. Run air through these spaces, draw it up into the main house by solar chimneys or wind scoops aiding natural convection.
If you have the option to run well temp water thru floor, why not? But it is more complicated than traditional methods. Air flow aids evaporation, which is a huge asset for cooling, unlike heating.
For underfloor: if you like digging, and you haven't hit bedrock yet, you can run the RMH pipes under part of the floor. Insulate wall perimeter, keep heater pipes at least 12 inches (30 cm) away from any combustible insulation.
Give yourself a margin of safety from the maximum lengths of pipe runs in our book, because you are in a warmish climate, and old and work-worn enough that you may want to run the heater when it is actually still warmer outside than in. I would take about 25% to 30,% off those maximum lengths, or add a bypass for chimney priming.
Use a vertical chimney, to about a meter above roof height, and insulated where it is exposed outdoors.
Since there is boiler experience in the house, I don't think running a pump and pipe system is beyond your capacity. You need to decide whether the heat exhange pipes will be kept potable, or non potable.
If potable, you can run well water thru them to a sink or other uses for cooling. But the heat exchanger run must not have dead ends, and must be careful with all heated water sources to avoid warm stagnation.
If non potable, you can run any old water thru, recirculate, or collect excess for gardens, until algae gunks up the works.
I like Tim's systems with an open pot or tank for the heater, which is non potable and easily cleaned out, and a coil in the tank thru which you run pressurized clean water. This offers pressurized warm water with built in protection from boilover; reduces the stagnation problems substantially; and gives the option of running a shower or washing-up station off the same system, if wanted.
You could do the same for a solar collector tank, run separate heating coils to a tank and a potable coil for heat transfer. Many systems run water thru solar first to warm it, then use fueled heat to reach final target temps.
Again, pressurized usually goes with potable, because both require clean, alga and scuzz-free pipes. Which means precautions against warm stagnation in the lines. More options means longer pipes and longer stay times. If any loop is being shut off for weeks or months depending on weather, or for repairs and tinkering, it needs to be flushed and possibly decontaminated when re-activated.
However, I don't know if you'll produce enough extra heat off a tank on top of the rocket to heat the rest of the floor anything like the area just over the RMH ducts. Might want the hydronic heated areas to be shallower, with copper conductors under tile, and better insulation.
If you can live with hot, warm, tepid, and cool zones, like an old fashioned wood cookstove, then this sounds DIY doable for an old steam engineer. Cooling this way may produce floor temps that are not entirely comfortable while the air is still too warm, so a zone for chilling might be better than the whole floor anyway.
It will turn the entire space into a project, and one which may invite tweaking and improvements over time. If you tend to let projects take their own time, you may want a spare barn for overflow while tinkering, since this is the primary utility room.
I would also not be inclined to pour solid concrete over everything, at least not without careful attention to cleanout access points. Discrete tiles or pavers may serve better, since you can bet that anything with functioning parts will eventually need inspection, cleaning, repair, or replacement. Just removing a bit of sidewalk that was mistakenly laid over a septic tank is a major hassle, which I would hate to deal with indoors.
This will probably be a sort of personal system, due to unusual features. I would not expect the next owner to want to operate and maintain it. So invest what effort and value in it you feel is worthwhile to please yourselves.
If you want zone control, where you can direct and dial the heating and cooling, or do that programmable timing stuff, I'd look for commercial products and an experienced local installer.
Please let me know if you'd like to hire us for a customized plan set or tech support. Burra gets special rates. 😘