radiant cooled bed- brrrrrrr Bob Gagnon plumbing and htg.

Bob Gagnon plumbing and heating

after spending most of the summer on the bed i can tell you the comfort is unbelieveable. yesterday it was 100 degrees in boston when i woke up my mattress was 67 degrees and the room temp. was 70 degrees. i cooled of the air with a fan coil unit and piped the bed just like a simple radiant floor system. all using only well water. no sign of condensation, not even on the exposed pex. but the humidity level in the house seems to go up when i'm running the cooling. does anyone have any idea why that is? it feels very comfortable- like a fall day. bob

Unknown

Rh

It has something to do with temperature; you're right. Humidity is measured as Relative humidity. How much water is contained in the air relative to how much it can hold at that temperature. Cooler air CAN hold less than warm air can. Therefore the RELATIVE humidity at a cooler temp is higher.......I think that's how it works. It sure feels that way...Noel

don_9

enthalpy

your system is no more then a direct evaporative cooler.its does not actually reduce the energy content(enthalpy) of the air.your air is sensibly cooled the dry bulb temp drop,
but the latent load is actually increased (moisture is added to the air when fan is turn on.you have to get your water temp lower then your wet bulb temp and with out a vapor compression system its not going to happen.bob its a good idea for the senible load,look at it on the bright side
you dont have to worry about drain lines or a drain pan.don

Bob Gagnon plumbing and heating

drip pans

the fan coil units condensate a lot, and i had to put pans and drain lines for each unit. thanks for helping me understand this little better, bob

Earthfire

humidity

RH goes up for a lower temp air mass with same moisture content . As temp goes up for given air mass with no change in moisture content RH goes down. Since you are already getting condensate at the air coils. you are getting some dehumidification. try slower fan speed for more dehumidifaction or larger coil area. The more contact time the air has with the colder coil the more condensate (Dehumidifaction) you will get.

Mark J Strawcutter

don't think he's got evap cooling

I think he's just running cold water thru a fan coil
so there is no evaporation going on

Probably no condensation under the matress since the high
humidity air can't get to it very well - heat transfer is
all between the mattress and pipe/water.

If the water goes thru the fan coil first (where he indicates condensation does occur) then it may be above dew point by the time it hits the bed which would also explain why no condensation there.