radiant cooling

Brad White_9

the cooling medium (water, glycol, what have you) and the final surface temperatures all remain above the ambient dewpoint (with a margin, let's not get cocky here!), condensation cannot occur.

Add to this, other parallel means such as AC dehumidification (Unico type HV systems are great for this) enhance the experience even if not sized to do total cooling, they do wring out the air well.

JBW_2

radaint cooling

Hello,

Does anyone know of any books on radiant cooling. Better yet, has anyone done a radiant cooling installation? If so, how do you control condensation on your radiant lines.
I have a client that is interested in having an installation done.

Please advise.

Thanks,

Josh W

Josh_10

This will get you started: http://www.healthyheating.com/Page 55/Page_55_i_cooling_eq.htm

Feel free to email me. We have two Radiant Cooling systems out there. Controlling is the hard part. We have come up with some ways to integrate it with Tekmar controls.

Bob Gagnon plumbing and heating

Radiant Cooling

I insulated all the copper piping and manifolds, they really sweat, but the exposed pex dosen't sweat much at all, and my staple up pex, with insulation underneath, doesn't condensate at all. Bob Gagnon



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L'town radiant

Condensation Problems

It has always been my understanding that in-floor radiant cooling is really only applicable in the southwest US due to the very low humidity conditions. Is it not likely that is most places the actual radiant panel (floor, wall) would condensate...not just the pipe?

L'town radiant

Sounds like we need a dewpoint-sensing, outdoor reset!

Bob Gagnon plumbing and heating

Dehumidification

and cooling the air is most important with radiant cooling. You could use a supplemental standard air conditioning for that or you could install a fan coil unit and it will do the same thing. I run the same well water through my fan coil unit that cools my floors off. I have had no problems with condensation on the floors for 6 years now but I would like a dewpoint sensor to shut off my floor cooling pump when the dew point is higher than the floor dew point. Anyone know where I could get a dew point sensor?
Thanks Bob Gagnon

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Brad White_9

Dews and Don'ts

The way we effect dewpoints at least in commercial/institutional work is via the DDC system, something your average house will not have. Within the algorithm is a pivot table based on analog inputs of temperature and RH (two things which are readily "readable" with a variety of common sensors.

Taking that information, the table then calculates the corresponding dewpoint. Seems complicated for a house system.

Personally, if I were to scale this down, I would use a good RH sensor on the assumption that the space temperature can be held fairly constantly within a band of say four degrees. Then you have a known band of corresponding fluid temperatures. Not perfect but far less money to implement.

Trouble with any of this kind of reset is, you are already dealing with narrow temperature differences. To keep the Water Slide at bay, you narrow them further.


On top of this, I agree, an under-sized AC system to keep up with dehumidification needs (and responding to maintain RH as noted above) would do wonders and also form a solid base of cooling capacity to compensate for diminished radiant effect. I have been in spaces with radiant ceilings and they are rather refreshing, yet subtle. Cool heads.

L'town radiant

Hmmmmm....

I certainly understand the advantages in radiant heating over scorched air, but from what I can tell (in a residential application) it would be necessary to supplement any radiant cooling system with a whole house dehumidifier, split AC, or fan coil...plus all the associated duct work. With this in mind where is there any benefit to have a radiant cooling system if other methods of cooling would still be required....what am I missing here...and, keep in mind I speaking residentially.

GMcD

It Depends

Radiant cooling is another component to Total Human Comfort. I agree that the more de-humidification you need to control indoor humidity, the more "air side" cooling there is by default, so the less "need" for radiant cooling on a strictly load-matching approach. It will depend on the local climate, and how tight the house is, and what type of ventilation system is used. In places like the mid-west US up to the Pacific NW and many parts of Canada, radiant cooling can perform most or all of the sensible cooling in the room, provided the cooling loads are kept below the local summer indoor dewpoint threshold of the location. Places like the SE US areas, with very high summer humidity require a lot of de-humidification anyway for the ventilation air comfort, so the radiant cooling would only play a smaller part in those climate zones relative to the overall house cooling system.

Humans aren't numbers, and given that human comfort is made up from 40%-50% radiant heat exchange, 30%-35% convection (air movement) and 10%-15% perspiration (humidity), any radiant heating and cooling component is a good thing, and will enhance the indoor comfort.

Bob Gagnon plumbing and heating

dehumidification and cooling the air

at my house is acheived with the fan coil unit piped into the same piping as my radiant floor panels, and uses the same cool water from my point driven well. No separate system, it is piped in like a kick space heater on a baseboard heating system. Like when you need extra heating. I have the fan coil in a closet with no duct work simply drawing air out of one side of my house and blowing it into the other side. Bob Gagnon

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L'town radiant

Ok, this all sounds very reasonable to me....great responses, appreciate it! In the case of using your well water system to run the floor and fan coils...what if you're on city water, is your only choice a chiller if you want to stick to just water vs freon in the house?

Brad White_9

City Water

Most water conservation statutes prohibit "once-through" water cooling systems using city water. Principally these are of the condenser water variety but if used directly in the "evaporator" (net cooling surface) I see no exception.

There used to be an allowance for systems of up to five tons (five tons and over were banned) but that was only to allow phase-out of remaining systems.

So, your only options beyond well water (and who knows if those are restricted in your particular area!) are to use closed systems such as a chiller, air or water cooled with a cooling tower, or a heat pump using whatever primary heat source (geo or hydro).

Weezbo

We have \"Latterals\"

this means one pipe comming "In" and one going "Out" and though i have explained the advantage to the water company they see it as it as costing them(pumping) and potential problems...