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

[Lawrence Lile]

I wonder why the Grundfos pump specifically mentions that is is not
supposed to be used with tankless water heaters?  Should work the same
way with either kind of heater, no?
 
 
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 Keith
Winston
Sent: Tuesday, February 13, 2007 4:13 PM
To: Greenbuilder list
Subject: [BULK] Re: [Greenbuilding] [BULK] Re: Radiant heat boiler--heat
exchanger for tiny buildings/families?
Importance: Low

Hmm, well, I'm not sure what you mean by automatic. The Grundfos comes 
with a timer that you can set for any number of half-hour periods during

the day: typically it would be something like breakfast lunch and 
dinner, and maybe bedtime. The advantage to the timer is the water is 
warm when you walk up to the sink, the disadvantage is that you keep 
pumping warm water up to the sink even when no one is using it (the 
water then subsequently cooling in the lines, and starting the process 
all over, and thereby demanding more water heating energy.

A button or a proximity sensor only does the water when you want it, but

requires wiring that's a little more specific, and/or requires a unit 
under every sink you care about.

Big buildings typically have a full-time recirculation loop. I'm 
inclined to believe that would be wasteful for a house, too much heat 
energy dumped into the envelope (not to mention the additional plumbing 
cost, with no possibility of retrofit). Both the systems above tend to 
use the cold water line as a backfeed for the hot water as it heats up 
(they reverse the flow in the cold line as they charge the hot line). 
Gurndfos also makes a whole-house recirculation pump that must be 
plumbed in during construction (since it requires a full-loop hot water 
layout). You can see it, and the unit I was talking about (Model 
UP15-10SU7P / TLC 
<http://www.houseneeds.com/Shop/plumbing/recirculators/grundfos/grundfos
up1510su7ptlcbuypage.asp> 
) and the Chilipepper for that matter here:

http://www.houseneeds.com/Shop/plumbing/recirculators/waterrecirculatori
ndex.asp

The Grundfos is all over the place. RE Michel has it (sometimes on the 
shelf). It might be cheaper elsewhere. Good luck!

Oh: as someone mentioned, Taco makes an option too. I think they 
actually bought another company, d-mand or something like that. It's 
much like the Chilipepper, though it looks like a pump (the Chilipepper 
always concerned me because whatever hardware it's using is hidden in 
that box -- it looks like an aquarium pump or something. Is it really up

to pumping for the many accumulated hundreds of hours that one hopes it 
will sustain?). Some of the Taco systems are visible here:

http://www.blueridgecompany.com/radiant/hydronic/428

Note Blueridge, they've got some nice stuff.

Keith