various radiant supply water temps

PORKCHOP

after doing a load calc for a new system in a new construction home that will have infloor radiant heat we have a wide swing of supply water temps.  is there rule of thumb to use for when to install a mixing valve? we will have a geo system connected to the floor heat system with a buffer tank in between the two.  the swt;s to the floor range from 85 to 120.

has anyone ran across this question before?

thanks

Mark Eatherton

As with any hydronic question, the only correct answer is....

It DEPENDS!



If you are using non electric TRV's, then in your case, you probably don't need a lot of extra controls other than an outdoor reset controller.



Tells us specifically how you intend to control flow (bang bang versus non electric TRV's) and exactly what temperatures you feel you will need.



That 120 degree F ceiling is very limiting as to what you can place over the floors in the way of finish materials. Think LOW R value and high efficiency emitters, like Warmboard.



ME

PORKCHOP

radiant floor temps

we are using infloor board with 3/8 tubing,  floor covering varies from hardwood to ceramic,  we are using tekmar wall stats with in floor sensors,  we are using a geothermal heat pump to heat the water for the floor system.  there will be a buffer tank between the floor and geo unit,  the max. temp from geo unit is 120,  we will be using manifolds that will have flow adjustment and flow indicators,  we will be using a mixing device to reduce the water temp as needed,  the thermostats will energize a zone valve with an end switch that will energize the primary circulator and an additional cirulator that will be associated with that zone,  we will have a bypass differential valve at the circulator for use when only a small amount of zones will be calling,  there is only one zone that requires the 120 degree temp which is a small sunroom with limited floor space,  all other zones require between 85 and 107,  do i need to be concerned about the wide variation of supply water temps?  if i send hotter water to the areas that do not require the hotter water am i right to think we get to set point quicker?  attached is a breakdown of how the home is divided among zones,  thanks

NRT_Rob

put a radiator in the sunroom

get its water temp down to 110.



better for geo, better for the rest of the system.



get reset on there too... no fixed temp bang bang geo.