I am pretty much sold on the benefits of in floor radiant heating with the exception of how to accommodate cooling.  I would hate to have to put in a separate system for the cooling (primarily the air handler and associated duct work).  Mini systems also have little appeal as do the other systems that use a separate room based fan/coil arrangement.  Some research shows that in some areas (Europe) they are using the same in floor distribution system to handle their cooling as well as their heating needs.

Understand this would not be practical in some areas of the US, but in more temperate areas (Boise Idaho) and combined with a very tight and well insulated (SIP) house, would this be practical?  I understand some of the concerns with condensation issues but this would be the cats pajamas if one had a total envelope/location conducive to this set-up.  In addition couldn't the use of ceiling fans and the ERV system help to make this doable?

I know it would take some careful engineering but I wanted to see if anyone else has any experience or thoughts along this line.  Thanks for any insights.  

Ceiling radiators would work better that floors. Plain concrete floors and ceiling fans would help some. You might be able to dehumidify and then keep it dehumidified easier by using carbon filters to clean the air (with less ERV air). Also, the ERV intake is an easy place to put some AC and remove moisture.
IMO, you still need some ducts.

you need needs for the ERV.

we are about to start our first summer with a combined heating/cooling radiant floor/ceiling system using an ERV and a chilled water condensing coil in the ERV ductwork. It does require multidisciplinary (hydronic and air) design skills and we haven't refined or tested our assumptions yet. But within a few months we should be seeing where the issues lay.

looks like floors can do at most about 10-12 BTUs/sq ft and ceilings can do 20-25 BTUs/sq ft, with all latent handled by a coil. In a tight envelope, especially in a residential situation, I imagine that should be quite achievable. and if radiant ceiling must be added to the floor system, it should work even in a cathedral area to add the convective component for a relatively modest cost.

now, controls are a kludge at this time... no one has a "home radiant cooling box" that ties all the needs together. Kludging otherwise unrelated components together is the name of the game and that is a major part of our testing this summer... to make sure there are no crazy interactions we didn't forsee. Also, to see how bad it is when you throw open a garage door in a radiant cooled warehouse

I'm not aware of anyone doing this regularly outside of very arid climates. Yet. but I think it is a feasible concept.

Boise ID is LOT drier than New England (less than an inch of rainfall in July-August combined, with low average dew points. Relative to here it has a higher sensible load, but far lower latent load for the AC- methinks radiant cooling could work very well there, and condensation issues would be very low if you were using a large surface such as a cooled floor or ceiling, which wouldn't need to be super-chilled to do the work.

But then, high thermal mass construction + nighttime ventilation schemes work very well there too, if the solar gain is carefully controlled. (I spent some time not TOO far away in Payette ID a few decades back, and used exterior window shading & nighttime ventilation exclusively.) In New England the hottest weather regularly coincides with dew points so high that nighttime ventilation raises the indoor humidity to uncomfortable or unhealthful levels (at least in southern New England)- this would be a rare condition in ID.

You'd probably be able to get away with opening the garage door of a radiant-cooled warehouse in Boise without running into condensation on the floor even under the highest sensible AC load conditions. The latent loads are WAY lower there in summer compared to here. Boise has more than twice the cooling degree-days of Worcester, MA, but it has a lower seasonal AC load due to the much lower humidity. (Temperature alone is too crude a model of air conditioning load.)

well, the real beauty of the decoupled dehumidification and radiant cooling though, in my mind, is that it can work nearly anywhere. with a big coil, at least, and cold water, you can remove a very large amount of moisture. and since you're only doing IAQ vent, you're doing it in 200 CFM airstreams or lower, typically. So even in very moist climates I think this concept can work very well. and in very dry ones too... very adaptable. Unless, of course, it doesn't work at all for some reason I haven't seen yet...

Certainly if a home is specifically designed to be cooled a different way that work well. But since that's fairly uncommon, this provides an active system that could work almost anywhere (I think) in any home that simply its sensible cooling load to 10-12 BTUs/sq ft, or 20-24 for ceiling systems, with little to no additional design restrictions on the building. and BTU removal is much higher when solar gain shines right on the cooling panel as well. Fun stuff.

You should take a trip up here later in the summer Dana. we'll have a fun system you'd like to check out by then. July is a good slower time to do a tour if you'd like.

We installed a radiant cooling and heating system in the ceiling of a new home, it has a simple designed DOAS for positive pressure on the interior of the space, with a ducted dehumidifier. controls and ceiling mats were manufactured by BEKA, the BEKA controller has a dew point limit built into it. The system was designed by Radiant Cooling Inc. in Chicago. previous entry was correct controls are an issue but we worked it out with switches and relays. WFI has Hydro controller now that should simplify the switchover issues. This system has been running for three years now and is operated by an EW040 unit and an 80 gallon buffer tank. we used Aqua therm pipe for all the pipe from manifolds to matts. The average shilled water temp is 58* and heating setpoint for water is 105 degrees.
This system is currently without any backup and takes care of two dwellings that are two stories apiece with living space of around 1,500 sq ft each. It was built with an energy star builder. complete with blower door certification.

Sweet, I wasn't aware this had ever been done in a residential application. Any other feedback on how it's working, how the occupants like it, how it stacks up to other cooling, any issues?

I thought about a dehumidifier but most of them reheat the air so I thought it might be counterproductive. Which unit did you use? and what are you using for an ERV?

those are impressive targets for water temp setpoints too. 58 is pretty warm for cooling, and 105 is very low for ceiling heat. this is BEKA mats in plaster?

NRT Rob;
The owners only response on the cooling end was when it got into the 90 for summer it was little warmer than than setpoint. I imagine he choose not to drop the water temperature. humidity levels have been between 35 and 45 RH. They like this method since they requested not fossil fuels and little forced air in the home. It is for a chimically sensitive owner.
the dehumidification is with a Therma Stor unit in each dwelling. Also funny you mentioned and ERV and not a HRV. You are correct it would have to be an ERV. We installed a Venmar unit with the enthalphic wheel and rated at 190CFM. We installed an electric preheat coil on the intake to the ERV's to keep the discharge temp at a tolerable level when it gets mixed in with the filtration system and eventually out the grill in the hallway.
We did install the BEKA mats in plaster. The challenge was providing a notch in the ceiling for the headers on the mats. The plaster was about 3/8" to 1/2" thick. The wall board was Calcium Carbonate not drywall.

Well I did just design this kind of a system for my own shop using Mumma's research as a template so I picked up a few things about the requirements I'm surprised to see a preheat coil on the venmar, usually they don't use one unlike most other ERVs but I suppose if you have a high rate supply port it could be kind of chilly.

I'm set up with an ECM motor ERV (UltimateAir). so my entire air side energy usage is 40-250 watts, modulating, plus electric preheat below 17 deg F outdoor, and over 90% exchange efficiency I'm told. Sensors will be wired up soon to verify those claims!

I would love to see any documentation you had on your system design if you were willing to share. I understand if not, but if you're game it's [email protected]

thanks for posting in any case... glad to see we're not the only crazy people out there!

> We installed a radiant cooling and heating system in the ceiling of a new home

I agree that ceiling radiators make sense for radiant cooling.

Like Rob, not so sure about typical dehumidifiers - why reheat if you need cooling anyway? Better to use a small amount of AC + a desiccant wheel to remove moisture. Perhaps this is what it is doing?

> the average chilled water temp is 58*

Interesting, around here one can get that directly from a well - no heat pump needed.

Keeping houses completely sealed and using some other type of air purification (carbon filters, etc) could eliminate almost all dehumidification requirements. Not to mention potentially cleaner air.

Posted By NRT.Rob on 01 May 2010 12:56 PM
well, the real beauty of the decoupled dehumidification and radiant cooling though, in my mind, is that it can work nearly anywhere. with a big coil, at least, and cold water, you can remove a very large amount of moisture. and since you're only doing IAQ vent, you're doing it in 200 CFM airstreams or lower, typically. So even in very moist climates I think this concept can work very well. and in very dry ones too... very adaptable. Unless, of course, it doesn't work at all for some reason I haven't seen yet...

Certainly if a home is specifically designed to be cooled a different way that work well. But since that's fairly uncommon, this provides an active system that could work almost anywhere (I think) in any home that simply its sensible cooling load to 10-12 BTUs/sq ft, or 20-24 for ceiling systems, with little to no additional design restrictions on the building. and BTU removal is much higher when solar gain shines right on the cooling panel as well. Fun stuff.

You should take a trip up here later in the summer Dana. we'll have a fun system you'd like to check out by then. July is a good slower time to do a tour if you'd like.

Thanks for the invite- the hints have piqued my interest, but I expect to be in WA/OR for a good part of July, but maybe later in the month...

Got pictures? (backchannel email or on a web forum)

You're welcome (as is anyone else interested in the area) anytime Dana, July is just a good time to hang out for a longer period of time. should have all our monitoring equipment up and functional and be into real cooling demands by June. you should wait for that for optimal fun

we have pics... will be doing a website overhaul in the next few months and getting all the stuff up there. haven't weeded through yet!

why reheat question if you are cooling?
the reheat was for winter temps when the mixed air discharge from the ERV is cool it needs to be warmed up and the efficiency of the ERV is improved with this as well.

well water temperature question....
True well water would accomodate the temperature but the water condition is a big issue as well as now you have a closed pressurized system that you want to introduce the well water into. It is also about natural resources, how water is being used to cool the home and then discharged out to where ever it is being put. Also how much energy is the well pump using  compared to the cycles of the compressor?

Air quality.......
a Pure Air fiter system is used on this project, this has no relationship to RH in the home, even though the home is at a positve pressure to prevent infiltration, open doors and people and cooking all add RH to a space and so the installed dehum is designed to cover this. Even though the ERV is capable of trading off some RH back out to the exhaust stream, the type of system requires an RH below 50%, as mentioned this was an Energy Star Home, complete with certification by a blower door test.

Dana, if by chance you're driving to OR/WA I'd love to have you make a swing by my place and see my ICF house. I'm in Parma, ~20 miles south of Payette, where you said you lived once. I've got a Daikin system and use the crawl space for supply plenum and the attic for return. I think I've got a greater solar gain than I expected but not sure why. I'm still trying to get a handle on my house energy usage. It seems to be higher than I expected, but on the other hand it appears to be well within the Manual J numbers. If you're interested in seeing my setup send me a PM.

3cityblue, Send me a private message with your contact info. I live in Parma, ~ 50 miles from you, and went through the process of planning to do radiant heating & cooling in my ICF house. I'd love to share with you what I learned. In spite of what some naysayers try to tell you, it can be done and is feasible here in SW Idaho.

It is not so much a question of "can" but "should". When all is in and paid for, pride seems to overcome science.

"I'm still trying to get a handle on my house energy usage. It seems to be higher than I expected, but on the other hand it appears to be well within the Manual J numbers."

I see this statement - or something akin to it - on nearly every solar, wind and radiant cooling blog.

dmaceld, I would love to see any info on what you've done. rob emailatsymbol nrtradiant.com.

Posted By NRT.Rob on 18 May 2010 12:53 PM
dmaceld, I would love to see any info on what you've done. rob emailatsymbol nrtradiant.com.

If you search back about 2 1/2 to 3 years ago you'll find the exchanges you and I had about my plans for radiant heating. I discussed what I learned from Beka USA's design manual as well as Uponor's. We discussed various plates, and using tube and plate vs. Beka mats. We discussed heating only vs heating/cooling radiant.

I ultimately abandoned the radiant heat approach, primarily on economic grounds. I learned about, and decided to use, the Daikin air/air heat pump. Daikin did not have the air-to-water system available then, and the cost of wells for a DX system drove the geosource heat pump cost too high for a reasonable payback. I don't have a large enough lot for a trench system. My max heat load calculated out at about 35,000 Btuh, not accounting for life activity heat supply.

I use the crawl space as the supply plenum. I anticipated having a 'decidedly warm' floor, and thus 'quasi floor radiant heat', because the warm air (maybe as high as 120F) would be circulating under it. As it turned out this past winter, the first winter of use, I have a 'not cold' floor. The crawl space temp seldom went above 85F and top of floor temp, when I measured it, was only about 2 - 3°F above room air temp. The heat output of the Daikin is very closely proportioned to current room temp vs. control setting. Subsequently, once it kicks on in heat mode in early to late evening, it runs continuously until late the next morning when solar and life activity heat start helping the warming process. It can put out up to 130F air, but I don't think it ever did even when outdoor temp was at 0F.

I am quoting a 24,000 square foot building for radiant heating & cooling in the floor with some sidewall.  It's a historical building so I am limited on wall space.  I have never done radiant cooling.  I have talked with Radiant Cooling in Chicago yesterday about the project.  They want to use heat pumps from Germany but I want to use something locally.  Do you know of US made heat pumps in the 5 ton range?

How does the dehumidifier handle the humidity load?  I thought about installing a few mini-splits for dehumidification.  I am asking for any advice since I am in a warm and humid Michigan climate in the summer.

I would be very concerned if you are doing mostly floor for cooling unless you know the load is low. what are you expecting for a cooling load per square foot here?