[Greenbuilding] [BULK] Re: [BULK] controlling floor heat

[Lawrence Lile]

>Someone else mentioned outdoor reset controls, which I don't know how 
you'd implement on the Takagi as it's doing double duty, but otherwise 
the outdoor reset idea can be good.

I'm thinking I might disconnect the Tagaki from the DHW altogether, and
move to solar with electric backup.  I have the panels, they've been
sitting in my garage for a while, it is just a matter of elbow grease
now.  


> And yes, your floor temp should be 
much lower, more like 100-110 probably, in a slab. It should reduce the 
amount of heat you're losing into the ground. 

Once I ditch the double-duty system, the simplest thing I could do is
run cooler water into the system, crank the temperature up and down
manually and seasonally, and maybe override it with a cheap indoor stat
to keep from overheating when the solar is working.  I think one of the
main problems besides not insulation, is I'm ouring too-hot water into
the slab, and the first few feet of pipe overheat the ground.  

I'm not sure I can implement a true outdoor temp reset on the Tagaki
unless I put in some kind of controlled mixing valve as was suggested.  

Thanks for helping me think this through.  


>But yes, you might still 
want to ditch the radiant, put some insulation on TOP of the slab 
(carpet? cork floor?) and use something else. Mini-splits are certainly 
an option. 

Hmm - a mini-split in the bedroom, which is the coolest room with the
least sun, might just be the ticket.  


>You mention air-source air-to-water heat pumps: do you 
actually know anyone that makes those? They are fairly few and far 
between, often called "chillers", rarely used for residential 
applications. I wouldn't be confident that they'd save you that much in 
fuel cost, unless you can get something with really high SEER.

Yes, they do exist, but they are rather expensive and tend to be
commercial units.  They also tend to be from rather obscure
manufacturers, and I'm not sure that they are the right thing to do.  


-LL