[Greenbuilding] Radiant heat boiler--heat exchanger for tiny buildings/families?

Sat Feb 10 10:31:24 CST 2007

Dr. Vasile,

I asked our greenbuilder/designer about your heat exchanger, and he said it
was overkill for applications/buildings our size in our climate and so on
(our building is a three-story strawbale tower with a 420SF footprint for
two people on the Sonoma, California, coast). What do you think?

Thanks!

Mary Bull, Co-director
Greenwood Earth Alliance, Save the Redwoods - Boycott the Gap Campaign
252 Frederick, San Francisco, CA 94117 http://www.gapsucks.org
Chalice Farm and Sustainable Living Center, 748 Montgomery Rd, Sebastopol CA
95472
415-731-7924 - 415-509-1188 chalicenew at earthlink.net

----- Original Message ----- 
From: "Dr. C.F. Vasile" <gfx-ch at msn.com>
To: "Lawrence Lile" <LLile at projsolco.com>; "David Seth Melchert"
<dmelchert at earthlink.net>; "Greenbuilder list"
<greenbuilding at listserv.repp.org>
Sent: Friday, February 09, 2007 3:12 PM
Subject: Re: [Greenbuilding] [BULK] Radiant heat boiler

> Why are you guys on the "GREEN" Building List; three (3) tankless water
> heaters are "excessive" because 80-90% of their outputs (shower power &
> energy) are wasted down-the-drain; when 50%-60% of it could be recycled
> (www.gfxtechnology.com)!
>
> ----- Original Message ----- 
> From: "Lawrence Lile" <LLile at projsolco.com>
> To: "David Seth Melchert" <dmelchert at earthlink.net>; "Greenbuilder list"
> <greenbuilding at listserv.repp.org>
> Sent: Tuesday, February 06, 2007 7:33 PM
> Subject: Re: [Greenbuilding] [BULK] Radiant heat boiler
>
>
> > Well, a shower head is about 3 GPM, you can figure your peak flow from
> > there.  For the most part, people don't use the shower and the sink at
> > the same time in one bathroom, and the shower generally can't be used at
> > the same time as the tub.  You can also figure peak flows from the
> > number of occupants - are there enough people in the house to take 3
> > showers at a time?  People may also use the washer and dishwasher at the
> > same time as a bath.  In my current house, they won't do this more than
> > once, since we have a wimpy tankless that can't keep up with more than
> > one load at a go.  Brrr.
> >
> > In my new house, a Tagaki jr, model is keeping up with two showers at
> > once.
> >
> >
> > If these bathrooms are not grouped, or if the kitchen is not nearby,
> > you'll want two sources of hot water.  A typical tankless heater has
> > several seconds of delay (My tagaki waits 6 seconds before firing) plus
> > the long run, can mean minutes of wait to get hot water.  The buffer
> > tank sounds like a good idea actually - I was considering putting
> > something like that in a kitchen that has the long run problem.  Add
> > extra insulation to whatever the manufacturer thought was enough,
> > because the buffer tank defeats some of the savings associated with the
> > tankless.
> >
> > I can't imagine 3 tankless heaters, seems pretty excessive.  Do the math
> > and see what you come up with.
> >
> >
> >
> > Lawrence Lile, P.E., LEED AP
> >
> > -----Original Message-----
> > From: greenbuilding-bounces at listserv.repp.org
> > [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of David Seth
> > Melchert
> > Sent: Tuesday, February 06, 2007 6:04 PM
> > To: Greenbuilder list
> > Subject: [BULK] [Greenbuilding] Radiant heat boiler
> > Importance: Low
> >
> > We have started a large residential remodel in Orinda, CA. The 2,800 sf
> > house will be heated with radiant floor heat. We were planning to use a
> > Baxi Luna 330 instant heater for combined radiant and domestic hot
> > water. I really love the Baxi Luna for its compact design and simplicity
> >
> > of installation, not to mention its general high efficiency.
> >
> > However we are concerned about its capacity to serve the demands of a 3
> > bath house. The homeowner consulted with a supplier who suggested that 5
> >
> > gpm, delta 70 degrees is the minimum required, more than the 144,000
> > BTU's the Baxi Luna provides. Baxi has a new Modula supplemental tank
> > that holds 21 gallons and serves as a kind of buffer for temporary high
> > demands. My homeowner is concerned this will not cut it. They are edging
> >
> > towards having separate heat sources, such as a Noritz or an efficient
> > large tank for DHW.
> >
> > Here are my questions: how many gpm should we figure for hot water needs
> >
> > at any one time, and how often might a family of four run into
> > insufficient hot water using the Baxi? Would you agree that providing
> > separate heat sources for radiant and DHW would be the best path?
> >
> > Thanks
> >
> > Seth Melchert
> > Oakland CA
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