Radiant Floor Heating/Cooling 1

[AdrianQ]

I was curious to see if anyone has encountered the problem of developing a underfloor heating/cooling system for a building or home and dealing with vapor condensation of out door air within the cooling space.

 

[willard3]

Raidant floor heaing is not a problem because there is no condensation.

Radiant floor cooling will require treating any outside air that enters the space so it is BELOW dew-point. Dew-point in my climate is around 55F. I have seen it and had to fix it.

 

[KiwiMace]

or, control your underfloor cooling surface temp to be above the dewpoint - surely any lower would be too cool for a floor?

 

[ChrisConley]

With radiant cooling in addition to treating outdoor air I also recomment a supply water temperature reset. By actually measuring humidity (to get dew point) you can reset the water temperature and ensure no condensation occurs (matched with condensation sensors possibly as well).

If the water temperature climbs too high to do active cooling this means that the humidity in the space is too high. Fortunetly you should now have additional capacity in your chiller for use in dehumidifying the space.

 

[AdrianQ]

I'm sorry if my questions seem vague. What I am trying to get at is: Can condensation of air be controlled using a radiant floor cooling system (if you have to go below dew point to cool an occupied space to a comfortable temp [72-75]F) with the introduction of some sort of condensing unit, and have it be just as cost effective as a regular AHU?

Specific applications might be school use or residential where water stains on the walls and roof would be a huge NO NO.

 

[ChrisConley]

Humidity of the space cannot be controlled with a cooled floor, you will require a DOAS with dehumdification.

If you go below dewpoint, moisture will condense on the floor.

 

[IRstuff]

A more germane question might be how you're going to minimize stratification of the cold air on the floor. While it's nice to have cool feet, getting cool air to my head would seem to be a higher priority.

TTFN

 

[GMcD]

And why just the floor? A combined radiant heating/cooling system is best applied from a ceiling- no furniture or floor finish masking to deal with, a fully exposed radiant surface. I trust you've done some internet searches- there is a ton of material out there on radiant cooling system design.

One key fundamental issue you have to keep in mind is that radiant heat transfer is very different from convection (air) heat transfer and you cannot equate the two. "Air conditioning" is just that- "air" conditioning, while radiant heat transfer works by direct heat transfer from your body to the radiant surfaces around you. Radiant heating and cooling is a sensible temperature control function and any latent control has to be done by the air system (DOAS).

I've designed many radiant cooling, as well as radiant heating/cooling systems, and it is a well known and widely used system in many parts of the world.

 

[AbbyNormal]

You want radiant cooling then you need to do it from the ceiling, big reason for radiant heat in the floor is also the comfort of a warm floor. No one wants a cold floor.

I think it is viable when you can get it to work with fluid temperatures above the ambient dewpoint else it is a disaster waiting to happen.Bet most places that use it do not have much more than say a 60F ambient dewpoint to deal with.

Specialized outside air equipment etc goes down and its raining inside.