In-Ceiling Hydronic Radiant System
Hello,
This is my first post to the Q&A and I’m only comfortable posting because this is the most respectful and vibrant online forum I have ever come across. I hope “help wanted” posts are not frowned-upon…
I’m gearing-up to have a residential dwelling built in what is referred to as Upstate New York — not far from Woodstock NY in my case. I would like to explore the possibility of using in-ceiling hydronic radiant heat as my primary heating system for the house, even though it seems to be a fringe approach to heating homes at-best. I have searched the forum and found nothing, but perhaps it’s because I’m new at searching as well.
I’ve contacted a number of MEP engineers around the USA about designing such a system for me. Only one bothered to reply to my request (which, in my experience, seems to be the norm these days no matter what services are being requested) and it was outside his scope of expertise.
Can anyone recommend (or self-recommend) someone who has successfully and reliably implemented such systems?
Thank you, Scott
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Replies
I don't think there are more than a handful of guys in the whole country doing ceiling hydronics professionally.
I did it in my own home, but I'm kind of a mad scientist.
How did you set up your ceiling panels? It seems like if you have hydronics, you can pretty easily stick it behind drywall with aluminum heat transfer plates. Do you like it?
I do like it. It's very subtle heat. In the bathrooms I did more traditional underfloor, which is good there, but I don't like the feeling of warm feet all the time.
I just did aluminum plates under drywall. In a couple of rooms I didn't have enough ceiling area to meet the heat loss of the room and I did a wall too. That's nice too, but you have to be so careful with putting stuff onto the wall!
I'm glad to hear you like it. I'm definitely going to persist until I get there. Thank you for your response.
Reach out to Eric Aune (@mechanicalhub) on instagram. I talked to him briefly about hydronic radiant in the ceiling. He actually suggested it for me, and I would imagine he has some experience with it.
Thank you... much appreciated I'm messaged him on Instagram. I'll let you know how it goes.
You may to look at the Messana radiant panel system
I came across that company a while back. I assumed it would be an expensive system to purchase (but would likely save on install cost), but I should contact them instead of making assumptions. Thank you for bringing it back to my attention.
I did contact them when I was curious about ERVs with built in heat pumps. They offer 3 options for that. Expensive is right.
Not directly answering your question, but John Siegenthaler (one of the top hydronics experts) wrote a great article a while back in JLC on radiant walls and ceilings:
Installing a Radiant Wall
You can use walls and ceilings to provide warmth with this innovative variation on radiant floor heating
https://www.jlconline.com/how-to/hvac/installing-a-radiant-wall_o
I believe his firm is out of upstate New York--but I have no idea how much they're doing design vs. educational work:
https://www.hydronicpros.com/about-us.php
Thank you. I reached out to his firm a couple of weeks ago but didn't see a response. And thank you for the link to his wall radiant article. I had come across a very similar article by him -- but ceiling focused -- that has been useful both for me and for bringing local installers up-to-speed. Everyone here is skeptical about the approach. They all believe my head will be sweating all winter long. Here is his radiant ceiling article:
https://www.pmmag.com/ext/resources/PM/2014/June/016-020-0614-Siggy.pdf
Thank you once again.
Also, if you have time to watch some videos, see the recent BS and Beer show (11/07/22), Hydronic Heating and Cooling. John Siegenthaler's presentation is very informative. For more, see the two-part Air to Water Heat Pump Summit (May 2019). Siegenthaler specifically covers hydronic ceilings and walls in Part 2 / 38:12 to 45:43, but the ceiling/wall panels crop up frequently whenever he is discussing low water-temp emitters (often). The whole 2-part video is a very good mix of theory and practice. I highly recommend it.
For what it is worth, I am working through Siggy’s Modern Hydronics and designing a combination of Warmboard and Messana radiant panel system. I have Warmboard in the current house, but I would only use it bathrooms or a porch where you can “feel” the difference. radiant panels in the ceiling look very straight forward to install, very similar to Warmboard. Here in Zone 6 (Minnesota), I should be able to heat the house with 95F water, so the COP of the heat pump most of the time will be in the 2.0 to 3.0 range. The backup boiler should only fire when the grid gets disrupted or when the temps drop below -5F.
So do your heat loss calculations and see if the radiant panels emit enough BTU per hour to compensate for the loss for each room. This is an iterative process, but I would start with an average temperature of 100F for the water temperature.
The Messana ATU is a HRV/iso-thermal dehumidifier/makeup air unit, this coupled with a modern control system should eliminate a lot of ancillary costs.
Caveat, i grew up with hot water heating and my background is in control systems, so I am biased toward the Messana approach
In one of Siggy's articles he states that the BTU output per square foot of a radiant ceiling is 0.71 times the temperature difference between the room and the water. He provides no citation, but I took it as gospel. I designed my system based on a supply water temperature of 100F, a return water temp of 90F and an average water temp of 95F, which gives an output of 16.33 BTU/sf. The Manual J load of my house worked out to under 6 BTU/sf. But finding ceiling space for radiant tubing is tricky, the total installed square footage of panels was less than a quarter of the house and the capacity of it is about 60% of the capacity needed for the house.
To make up the other 40%, I did two things:
1. In the bathrooms I heated the floors. I set the floors as their own zone, and I used a two-stage thermostat. If the room temperature is within one degree of the set point only the floors are on, if the temperature falls further then the ceiling panels come on too. I really, really like this setup, in mild weather often the bathroom floors are the only heat on the second floor or even the whole house.
2. I use hydronic fan coil units to supplement. The third floor doesn't have enough ceiling area to meet the heating need, so I decided to skip the ceiling radiant and just use a fan coil for the whole floor. The finished basement also just has fan coils, the ceilings there are full of mechanicals.
The fan coils also provide cooling in the summer, so I also have one on each floor where there is ceiling heat. My plan was to combine the fan coils with a little bit of ceiling radiant cooling, but I haven't been able to get the control mechanism down, and we got through last summer fine on just the fan units.
Mini splits could be used instead of the fan coil units if you're not a hydronic purist.
Also, on the third floor the cooling load is substantially higher than the heating load, so the fan coil needed to meet the cooling load would easily meet the heating load.
Overall I'm in a slightly heating-dominant climate (DC).
@BirchwoodBill, regarding the Messana panels, are you taking their published heat outputs at their word in your design or are you assuming a different value? I would love to know more details on what panel type you are considering, and if you did any cost comparison between their different options (standard vs graphite, etc.).
Here is the link to their specs I am referring to: https://radiantcooling.com/messana-radiant-cooling-products/ray-magic-radiant-panel/tech-specs/
I started laying out the Messana NK panels and the ATU in CAD and working through the BOM. The panels require 22 inches so you need to fur down with 2x2 and add another top plate to get the ceiling height correct. The panels are new for residential design and I was warned about markups around “new” products. Took the feedback from contractor friends and went back to Warmboard, a CERV2 and Jaga Design fan coils. The cooling load was too low to justify the work here in Zone 6A. We run AC about 3 weeks out of the year. But our dehumidifier runs from June through September.
Before going down any route, be sure to do a room by room load analysis.
In my case, this will be another Warmboard project, the last one is shown here. https://www.applewoodremodelers.com/birchwood-renovation.
We do something similar to DC, the bedrooms are at 67 and bathrooms at 72f. This keeps the bathroom floor and shower floor warm all winter.
For the Messana NK panel system, the temperature was supply temperature of 95, and an average temperature of 90 F. Cooling water was 60F based on their charts. I really like the Messana control system options, the CERV2 is good enough for my PGH design.