Nice Lister CHP system (with natural gas capability)

[veggie]

very nice job !
http://www.youtube.com/watch?v=MmuCrjTn_Pc

[LowGear]

Interesting set up.  Funny, he complains about the water temperature at the house but doesn't seem to have much of anything insulated?  I appreciate 80 meters is a long run.  I'd be interested in how the line to the house was configured.

Casey

[Ronmar]

Yep, 250' of line direct buried line along with all the other uninsulated surface area in his shed is plenty to keep the beast cool.  I didn't get a chance to watch the whole video, but I didn't see his alternate cooling...  His system looks well thought out, but what does he do with the heat when he dosn't need it in the house?  I guess by his description, that problem has never come up:) 

[BruceM]

The concrete/block muffler is  interesting, and I was very  impressed with his setup. The sound of the belted generator/starter winding up was awesome. 

Pity that run to the house was so long.  I don't think 80 meters (262 ft)  is viable; I spent about $1800 on blue board and spray foam to insulate a 50 foot run!  OK, I did get carried away a little (R24- 4" of foam minimum around the 1" in floor pex and domestic hot water).

I've seen a lot of homes with in floor heat systems that were very expensive to run, often requiring an oversized boiler because the plumber decided that the earth was a good insulator- even though most of the precipitation here is in the winter, and the ground is largely clay. (Wet clay is the ultimate in soil thermal conduction- something you hope for with ground source heat pump systems.)

Even a 75 foot run in wet clay is a disaster.  A disabled housing project in the area was done that way, and the operating costs for the central boiler are outrageous, and when we have zero temps the system can't keep the units up to 60F.  When it gets sub zero overnight, the pipes freeze, probably where they come up through a slab somewhere and all four separate houses have no heat at all. 

[Tom Reed]

The run to my house from the generator shed is only about 1'. Did that on purpose to get the most hot water. It works too. The generator can barely be heard in the house when running.

[artificer]

I can't understand why anyone would run a heating line outdoors, without any insulation.  A run in wet clay is just nuts.  It reminds me of what seems to be schizophrenia at work:  Get the Cadillac version of everything, until you run out of money, then get something to make due.  Both ends of the quality scale on the same project.

BruceM:  When I get the power room built at our off-grid farm, I'm planning on the same idea you had.  Extruded polystyrene insulation making a box that the PEX tubing runs in.  When I pour my floor slab, I'll excavate an extra foot deep.  The hole will get a poly liner, then 2" min of foam, then dry sand.  The reinforcing wire and pex radiant heating coils go on top of that, and the slab gets poured.  Should be lots of thermal mass.

Its expensive, but the guy in the video should have used insulated outdoor piping like the stuff below.  After spending all that money on the power shed...  its a waste to skimp on the water lines.  Fortunately its a mistake that can be fixed, maybe.

Michael

[Geno]

Did he specifically say "no insulation" I did hear him say he only got luke warm water 80 meters away. I'd be willing to bet with no insulation at that distance the water would be the same as ground temp. He could easily be in a damp cool climate as well. I've been known to scrimp too much at times when the $$$ signs grow.

The gent did a beautiful job on the installation and certainly knows how to DIY.
That's not his only DIY project either. Check this out.
http://www.youtube.com/watch?v=UHKY6ONOOts&context=C4886f58ADvjVQa1PpcFOL23-WLeKS1r7MAhHAzYzpTcyi393r1bU=

Thanks, Geno

[BruceM]

Hi Micheal,
Yep, I'm an insulation fanatic.  It's the only energy cost saving measure that lasts forever and requires zero ongoing maintenance cost.  For my new off grid house I decided to go whole hog on insulation.

I used what you plan; 2" of foam ("blue board") under the slab, on sand and plastic sheeting, and also 4 inches of foam  between slab and stem wall, plus another 3/4" of foam outside the stem wall. (One 2" layer to the footing, one just one block high, with a 6" top block.) The  thermal model I was using showed that the slab edge to stem wall losses were very important for a super insulated house.  I bridged that massive 4" of foam around the slab by doing double wall construction, with 12" of fiberglass total in the sidewalls. The inner wall is 2x4 sitting on the slab, the outer sits on the somewhat insulated stem wall.  Double wall is much easier and cheaper to build than most people think, it adds maybe 20% to the total framing cost.  Pipe and wire/conduit runs are easy because  the gap between walls requires no drilling.

The attic was blown with glass to 28" minimum depth, about R75 and we used the "energy heal" trusses to avoid cold spots at the roof/wall joint.

I went to a 5 1/2" slab, for relatively cheap extra thermal mass (no extra labor cost, really). I did 5/8" drywall for extra mass too (again relatively cheap mass, no extra labor cost), and there is a huge amount of wall tile  and all tile floors.

One thing I tried on this house that I liked was putting 3/8" rebar at 14" centers, and then zip tying the 1/2" pex to that (rebar on plastic chairs on the foam). We had no lifting of loops or troubles with pex when pouring. It was much easier and faster than using the foam screw/clips to hold the pex.  The 1" pex feeder runs to the manifolds we could run under the rebar.  We formed  bends in the 1" pex by heating the bend section carefully with a weed burner. We could make nice 12" radius bends that would stay bent.

In sub zero weather, with Astrofoil stuffed in the windows at night, the house loses 3 degrees overnight with the heating system switched off.  It does take about 3 hours of running the 10 watt circ pump to heat that 3 degrees back up, using a small propane hot water heater as the boiler.  So for solar heating, I wouldn't have to have a tank to store the heat, I could just use the floor and house mass to get through the night.  Cooling really isn't needed, the house only changes 3 degrees on a 110F day from low to high (because of gain from windows-  less if some are covered in the afternoons with Astrofoil), and our nights are cool enough almost every night to chill out the house via windows. Only when there are several cloudy, warm nights in a row do I wish for a bit of cooling the next day.  

[BruceM]

Thanks for the second video link, Geno.  This guy is has done some amazing work! 

[Tom Reed]

We built our home similar to yours Bruce. We have a full daylight basement with ICF walls insulated to R40 and hydronic loops in both the basement slab and the 1.5" light weight concrete slab on the main floor. Did 5/8 rock too. We don't have as much insulation as you, but since our weather is mild we don't really need it. In addition we did a steel roof which reflects heat and with the solar panels on the roof shading it, summer time interior temps rarely venture above 75f.

[BruceM]

Nice work, Tom.  Even in a milder climate, insulating to about double the norm will pay off in terms of comfort and energy cost as the years go by.

[Tom Reed]

Thanks, all that insulation just means I have to cut less wood. We currently burn 2 cords of oak/madrone per year. The lister adds a bit if heat through the chp system too.