Geothermal radiant cooling

mars_6

I am in the design phase of a radiant heating and radiant cooling system for a 9500 sq, ft ranch in Colorado the home owner wants radiant cooling as well as radiant heating. I have alerted the home owner to the fact that the manual J load calc indicates he will need supplemental cooling for the system at design conditions. He gets that which is a good thing, I will be installing a Hydronic AHU system to do the supplemental cooling as well as dehumidification when we have the monsoon seasons here in July and August. Any input on control logic for this system would be greatly appreciated. This will be a 2 tank system with one tank cold and one being hot. Thanks for any input. Sincerely Mars

Bob Bona_4

For now, since ductwork is needed for supplemental cooling, does it make sense to bother with the radiant cooling and all the added complexities? What kind of chiller AHU were they going with?

Mark Eatherton

Matt, Check out Rehau. They carry a line of controls (ENV re-packaged) that is so flexible, if you can imagine it, they can write the script, and make it work. This is what I have in my house in the mountains. They also provide radiant cooling package designs. Talk to Mike Dietrich and he will head you in the right direction. Mike sits on my Executive Committee for the RPA. To be fair, most other large tubing extruders ALL have radiant cooling software now, and it is no longer a "concept", but rather a very efficient proven method for delivering excellent radiant comfort. I'd also suggest 4 Seasons join the RPA! www.radiantprofessionalsalliance,org

We should do lunch some day soon and discuss.

mars_6

Mark thanks for the tip, that is just what I was looking for. I sat in a class for the Viessmann CM2 the last 2 days and had the chance to catch up with carol Fey, she looks great and seem's to be a perfect fit for the Viessmann line. Would you be around next week for lunch? I would enjoy that. Thanks Matt

mars_6

Bob thanks for the reply, the system will be 2 Bosch water to water units with a hot tank and a cold tank . At this point in the design phase I am thinking of a 2 stage cooling system as the radiant cooling will not be able to keep up with the house at design conditions consequently the AHU system will do double duty. Designed to manuall J cooling loads as well as humidification removal when the dew point in the structure is present. My thought processes is that if dew point humidity levels are present the radiant floor zone valve is shut down and the AHU goes into dehumidification mode. The ahus will fire on 1st stage of cooling as they will be 2 stage units. If further cooling is required the units will fire at full capacity to continue dehumidification as well as provide for the cooling to the zone in question. Again thanks for any input, Matt

Bob Bona_4

I'm hearing you. I did the same 2 tank W/W Waterfurnace setup last year. The AHU's had to be slightly oversized to make the capacity on the chiller side. I did have trouble then bringing down the CFM for better dehum due to the ECM rpm range on those WaterFurnace units though.
They desired an external dehum system to help out. This was about a 6000 sq ft Warmboard job. No radiant cooling, just heat, with an LP Triangle wall hung boiler for an 80 gall pre superheated DHW and hydro heat back up. 3 AHU.

This was a very exasperating job to do and size things due to strict parameters for the Energy Star 3 program.

mars_6

Ouch the energy star thing is a complete pain in the but. I get that, funny how energy star sizes to non comfort parameters. We deal with this on a daily basis. You can build to energy star but you better tell the home owner that this is not built to there comfort expations. But to the energy conservation expations. These are to different points of reference. It is a much more European approach to heating and cooling in so much as put a sweater on if your cold and open some windows if your hot. Funny that.