Ceiling Radiant cooling/Heating
Ceiling Radiant cooling/Heating
(OP)
I'm planning to use waste heat and some redundant cooling from a refrigeration system (Water Glycol-40%) for an office building. I'll go with radiant ceiling to get dual function, but I'm not sure about the temperatures of cooling and heating liquid.
- Should heating temperature for ceiling panels be higher compared to floor heating.
- Does heating liquid temp depend on room height
- What temp should I use for cooling.
- Does WG mix vs water have a big impact on heating/cooling performance?
Thanks,
- Should heating temperature for ceiling panels be higher compared to floor heating.
- Does heating liquid temp depend on room height
- What temp should I use for cooling.
- Does WG mix vs water have a big impact on heating/cooling performance?
Thanks,





RE: Ceiling Radiant cooling/Heating
Yes, ceiling radiant panels will generally be hotter than underfloor systems. Cooling in a radiant panel can only be sensible. You will have no way to remove condensate, so water temp will need to be higher than a chilled water coil. This type of system does not bring in any ventilation air, so you have that whole issue to address. Adding glycol to the fluid reduces heat transfer, reduced heat capacity, and increases viscosity. This is particularly a problem with cooling. Not so much with heating but it can't be ignored.
RE: Ceiling Radiant cooling/Heating
Let me give you some numbers, the primary heat/cold source is refrigeration engine room that we're designing:
- I can get a high grade heat as water of 120 F from superheated refrigerant HEX. (around 600 MBH)
- Condensing temp on my refrigeration system is 95 F, which shall be WG mix. I have plenty of this low grade heat.
- For cooling, I can have an HEX and get whatever temperature required for cooling ranging from 20 F to 50 F.
Another question, what should be liquid velocity in pipes for heating and cooling systems? And what's temperature difference on supply and return lines on each manifold?
RE: Ceiling Radiant cooling/Heating
I don't know where you are located, but 120 deg water would not be hot enough in my neck of the woods.
RE: Ceiling Radiant cooling/Heating
So, you mean the numbers are very close to conventional heating/cooling systems.
What if I increase the velocity and minimize temp difference, I'm hoping to maintain relatively constant surface temperatures on panels and work with lower temperatures.
Many panel manufacturers claim that 95 F is a good temperature for heating especially for ceiling radiant systems.
RE: Ceiling Radiant cooling/Heating
RE: Ceiling Radiant cooling/Heating
Heating from radiant panels is dead easy and what you need to do is size the perimeter radiant panels to get your maximum effective area for cooling (the worst case) and then back-calculate what your entering heating water temperature should be for that panel area, based on the manufacturers data.
That's a very quick summary of what to think about for a starting point - you need to do a heck of a lot more design research to understand how to design and operate a radiant cooling system.
RE: Ceiling Radiant cooling/Heating