We're getting ready to build a new detached shop and we're going to "tube
up" the slab for radiant heat. Could you give me the links to the sites you
are looking at? I need an online supplier for the tubing and as much
education as possible. We are going to do this ourselves. Hopefully we'll
drive it with solar panels in the future.

--
Steve Barker



"Robert Gammon" wrote in message
t...
wrote:
I am looking at a website right now that is heating the slab with 83F
input water. The exit temp of the water is about 71F. Flow rate thru each
zone is about 3GPM. Total flow rate is about 9GPM. Slab temp is in the
upper 60s with outside air temp at 31F. The heat source is putting
roughly 30,000BTUH into the slab

The owner's manual for the Tagaki tankless that I am reading now says that
it will monitor the temperature of the water it outputs and adjust the
burners to LIMIT the output water temp to 120F. You can set the output
temp to be as low as 105F.

Seems to me that setting the flow rate thru the radiant loop to 3GPM, and
setting the tagaki to 105F, the Tagaki will intermittently fire to keep
its output temp near 105F, until your slab temp sensor turns off the
circulator pump. Even setting the temp to 120F, the factory setting, will
accomplish the same goal.

After all, you really want your slab temp near 70F, not 90F. Restaurants
in Korea put a shot of hot water thru the slab where you sit down. This
ONLY warms up the slab to the upper 70s, and then it cools as you sit
there.

I agree with your critics, you have focussed on the heater characteristics
without considering the safety factors built into the heater. You have
focussed on the characteristics of the radiant loop without considering
the characteristics of the loop circulator pumps.

You need to expand your view!!!




180F temps are POSSIBLE out of the tagaki, but the unit would be defective
if it permitted such a thing to occur