Solar Thermal for In Floor Radiant Heating

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Hello,

I have a project that uses solar thermal tubes to heat up water, which is
used for radiant floor heating. During the peak hours, solar thermal is
boosted by a boiler. Can anyone please expalin how I can model that? If it
can be modelled, how do I control the loop in a way that the boilers kick in
only when solar thermal cannot keep up? Thanks everyone.

Hassan Qauzi

Maudud Quazi's picture
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System type FPH meets your needs.

SYSTEM Type = FPH



SYSTEM Type = FPH

Floor Panel Heating System

The Floor Panel Heating System provides heating for one or more zones by
circulation of heated fluid through a network of pipes embedded in the floor
or ceiling. A single pump, rather than the primary-secondary pumping
arrangement shown in the schematic, is installed for single-zone systems.
Space temperature in each zone is controlled by varying the temperature of
the fluid circulating in that zone. Hourly head addition rate is determined
for this system exactly as for other types of systems. Pumping energy
associated with this system is accounted for by the PUMP attached to the
CIRCULATION-LOOP. The ratio of panel heat losses to panel heating output
must be estimated by you and entered; see the keyword PANEL-HEAT-LOSS in the
ZONE command). The program assumes that this ratio of heat loss to
heatoutput remains constant over the full range of panel output.

Figure 59 Floor panel heating system

Other names and/or applications for FPH

None. Note that the simulation does not account for the radiant comfort
aspects of panel heating; therefore, a lower heating setpoint is
appropriate.
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Subtopic help for this Topic:

Input template for a standard FPH unit

Covered in detail by separate Topics are the
following:

cmg750's picture
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The only issue with FPH is that outdoor air and exhaust fans may not
be simulated.

Chris Jones

Chris Jones's picture
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Correct me if I'm wrong here, but I read the question as less about radiant
floor heating, and more about solar thermal water heating with a backup
boiler.

If my memory serves from this very listserv, eQuest does not model thermal
storage (hot water, or otherwise) very well; it considers only the 1st law
of thermodynamics, that is- BTU's in-- BTU's out. It does not monitor
temperature of the thermal storage. So, if you put 1 MBTU into a water tank
(no matter the size or starting temperature), you'll get 1 MBTU of useful
heating out. This also means that it cannot model the need for a backup
when temperatures in the thermal storage are not sufficient for the load.
At least, that's the information that I gathered when I tried to answer your
exact question Maudud.

For a more careful analysis, I've heard others mention the use of SunREL,
EnergyPlus, and TRANSYS. For the time being, I have been creating some
rather unwieldy spreadsheets to answer these sorts of questions for myself.

--Luke Morton

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