Independent hydronic heating and cooling designers?
Does anyone know of any North American firms that will design a hydronic heating and cooling system, regardless of equipment manufacturers? Plan A was to find someone local who could help me, and after a little over a month of calling folks, I’m now contemplating plans B, C and D.
The project:
We’re doing a major renovation and planning to electrify our heat in the process. I’m mostly sold on an air-to-water heat pump with a mix of radiant heating and cooling and individual room fan coil units where appropriate due to the ability to scale load without major impacts on performance, flexibility to support intermittent heating/cooling loads (e.g., hot tub and garage) and potential for radiant comfort (with a bonus of eliminating our noisy ducts). I’m in climate zone 5, on the front range of Colorado.
I’ve done a lot of research on this topic, reading John Siegenthaler’s textbook and many technical articles. I would love to find a firm that uses Siegenthaler’s software (Hydronics Design Studio 2.0), but I am open to any well-regarded team that would design with a range of equipment. All the folks I’ve come across who do design either work for a manufacturer (only do design for what they sell) or are local installers who aren’t a good fit.
Any recommendations or ideas would be much appreciated.
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Generally successful construction professionals get all the business they can handle through word of mouth. And it also tends to be a localized business. So you need to ask around in your community.
The heart of this project is going to be a careful, thoughtful and honest room-by-room Manual J. So you might start by asking around to get someone to do that for you, that's less specialized. That process might lead you into referrals.
My other piece of advice is that I have generally gotten better advice from experts by laying out the problem and asking for their recommendation than by telling them what I think the answer is. So you might do better to think hard about what your requirements and desires are rather than a specific implementation.
Thanks for taking the time to respond. I've been pounding the pavement and asking around. I've encountered a friend of a friend who has also had similar issues trying to replace their existing gas boiler with a heat pump.
I say "mostly sold" as I've been open to any kind of well-informed feedback I can get. I've very much taken a deferential and collaborative approach to the folks I've talked to ("here's what I've been looking at, but I'm coming to you because you are an expert; what do you think?"), but the responses are a mixed bag. Some firms seem receptive and knowledgeable, but will only do radiant floors rather than a ceiling or wall (big cost adder on our retrofit), one firm told me they don't do radiant cooling in the front range of CO anymore because of condensation problems (this raised a red flag for me, as my understanding is it's a question of controls, especially in our dry climate). Needless to say, this has been frustrating and forced me to contemplate what other paths forward might look like (hence the original post).
I'm on the same page about the manual J. I've developed a room-by-room manual J in several platforms, including a trial of LoopCad. Our design-build firm is going to work with their usual sub to do a room-by-room manual J for our permits. I've estimated the effective R-value of the existing walls based on empirical data, and my manual J calcs reflect that, along with the local building code requirements for our renovation. I'll try to work with the sub on my estimates as well. I'm hitting a sticking point with the next step beyond that.
Any additional thoughts would be much appreciated. As others on the internet have lamented, it's really frustrating how hard it is to make this happen in the US when AtW is so much more commonplace (and reasonably priced) in other parts of the world.
"one firm told me they don't do radiant cooling in the front range of CO anymore because of condensation problems (this raised a red flag for me, as my understanding is it's a question of controls, especially in our dry climate). "
I'm trying to think what "controls" you could have if your house needs dehumidification and your cooling system can't provide it.
I'm not just asking this rhetorically.
One of John Siegenthaler's first articles on radiant ceilings (I wish I could find the link) said something like "with the proper controls, the ceiling panels can also be used for cooling."
That statement has become the Fermat's Last Theorem of hydronics.
In this article from 2017 he acknowledges that such a controller doesn't exist, and lays out a proposed design: https://www.pmengineer.com/articles/93157-looking-up-to-radiant-cooling
His proposal is to have a humidity sensor and temperature sensor, and to calculate the dew point and adjust the water temperature so it is always warmer than the dew point.
I respect Siegenthaler immensely, his writings have been very influential to me, but I think he's wrong about that. The problem is that the heating or cooling that a surface provides is entirely determined by the temperature difference between that surface and room temperature. If you are modulating the temperature to avoid condensation, you can't also modulate the temperature to meet the cooling load -- you can't serve two masters. In particular, in hot, humid weather you get into a death spiral where you can't run the water cold enough to provide the cooling you need and the house gets hot and humid inside.
Siegenthaler talks about separating out the latent cooling -- humidity removal -- from the sensible cooling -- heat removal. The problem is that the way to remove humidity from air is to cool the air, and when you set out to do latent cooling you end up doing sensible cooling anyway. Would it make sense to size an air handler for the latent load, and then use hydronics for whatever load remains? Maybe. I've only ever lived in places that are humid in the summer, where it can be a struggle to get enough latent cooling with conventional HVAC. The idea of "leftover" sensible cooling just doesn't exist.
It might be that in less humid places you can make good use of radiant panels for sensible cooling. But you always need to have some capacity for latent cooling when the need arises.
Yep, by controls, I meant ensuring that the radiant panel (and, realistically, the supply piping) stays above the dew point. The only latent load in my manual J comes from the occupants of the building; otherwise, it's dry enough here that it's only sensible.
There are controllers that tackle this problem. Chillitrix makes a unit: https://www.chiltrix.com/radiant-cooling/CXRC1-Radiant-cooling-controller-v1.2.pdf. Messana also has a setup for this (link at the end of the message).
The place our design-build firm just did with all Messana panels is doing exclusively radiant cooling with a SpacePak unit. They just moved back in in the fall, so with luck, I can get a first-hand report of how it's working in the cooling season with enough time to adjust any plans on my end. It makes me nervous to have no latent capability, which is why I've been investigating a mix of fan coils and radiant panels, with latent support adjacent to big radiantly chilled loads. Since I'm out in poorly charted territory, I'm inclined to wear the suspenders with the belt.
For what its worth, I talked to another very reputable installer in the area who has radiant cooling in their office (I think it's a slab, not chilled beams). They say it's great, but they do have supplemental fan coils for when it can't keep up. In a more humid environment, I'm skeptical I'd be contemplating this, alteast without exploring dehumidifiers as well (which it sounds like is how commercial projects doing radiant cooling tackle this problem).
Messana controls pdf:
https://ucddd50ce487c2422f70d96e200c.dl.dropboxusercontent.com/cd/0/inline2/CNlNXB-OH_ToGEZnlgXCVoooGsC29ZFHD_IfJvHKhnweCUGp83-s_TMfi7eLxV8ykXvgTOejYoyf8PeJai5A0XFLNx65Anv-sgKWqOBrUxDwY_24B4PKZnaevV_q_7t9apF4sb5Rj9RYQ4VZjIxsxMk2q9hj-VnqXnZACA5D_SZ2aBaNKK97fgD--2wgZJp_cm_mMXYSUgyeg411CWdFfufiV2t-h7GEYezXxjl_FVRcDdojMGMUobXfzkE5_nBq_Sh-MyZO6jlbd14T7Sp_KIzWAd5C-XNONf49qU3pslw6j4pW3XfIr5QWD8wEbhPnCGH6zIbqdZoIl6pMwAPeAP71ATxihp9zWUCVNXnYmyg64C26NOxQwvrNvPOurUfuQHA/file
"The only latent load in my manual J comes from the occupants of the building; otherwise, it's dry enough here that it's only sensible."
You have to be very careful about how you interpret that.
With traditional AC, it more or less automatically adjusts the level of latent cooling. When you run air over a cool surface the air exiting will never have a dew point higher than its temperature. So regardless of the humidity of the incoming air, it leaves with the same humidity, or lower. The more humid the incoming air is, the more of the cooling that gets devoted to humidity removal. And this happens automatically, you don't have to do anything.
So in the Manual J all you care about is having enough capacity, and that's approximated by putting in what the humidity is likely to be in that environment on the hottest days. In most places, the hottest days aren't the most humid, but the assumption is on the most humid days you'll have more than enough cooling capacity anyway.
For example, I'm in Washington, DC, which is kind of famous as a hot, muggy, swamp. My design conditions for cooling are an outside temperature of 92F, but only 42% RH. Yes, we get days in the summer when the humidity is in the 90's, but those aren't the hottest days.
On my design day, in my house's Manual J latent cooling is only 6% of the total cooling load. But on cooler days it becomes a much bigger part. A common problem around here is super humid days in the upper 70's, where the AC doesn't run enough to dehumidify unless you set the thermostat so low that it's uncomfortable. This problem is actually worse in newer, well-insulated houses where the sensible cooling load isn't so high.
If you can, talk to the guy who used to install radiant cooling but no longer does, see if you can find out what kind of weather gave him trouble.
PositiveEnergy based in Austin, TX has installed Messana Radiant Panels in their office place and Kristof Irwin their founder has the Building Science Podcast where he interviews and discusses radiant and air-to-water heat pumps (among other topics).
But I also agree with DC that you might really only need a Manual J calculation. You should look into using Siegenthaler’s software yourself too.
Thanks for the idea. Ill do some background research and follow up with PositiveEnergy.
I'm familiar with Messana's product, our design-build firm just finished a project where they did their panels for heating and cooling a whole house (sounds like Messana did much of the design with a little support from their plumbing sub who installed the system). I'm trying to figure out a solution a lower price point than what it sounds like Messana may run (our architect said the cost of the project was about 3x what doing a highly zoned air-to-air minisplit would likely run us, and I'm leery of low-load conditions with that kind of air-ro-air setup).
If we move forward, it's becoming pretty clear I'm just going to have to design it myself. I've had enough challenges with previous big projects to be humble in the face of unknown unknowns, and life is such that my time is at a premium right now. Those are all motivations for finding someone to, ideally, do the design, or at least review my work. But, I have yet to find someone who could help me with that.
I remember reading an editorial by Siegnthaler (maybe it was in plumbing and mechanical?) where he said a homeowner bought a license for his design software because they couldn't find anyone local who seemed to understand how to fix the hydronic system a different local installer had just put in that wasn't working right. The homeowner finally accepted the fact that they were going to have to do it on their own. I naively thought to myself, I bet that won't be my experience...
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matthew25
Thanks for the idea. Ill do some background research and follow up with PositiveEnergy.
I'm familiar with Messana's product, our design-build firm just finished a project where they did their panels for heating and cooling a whole house (sounds like Messana did much of the design with a little support from their plumbing sub who installed the system). I'm trying to figure out a solution at a lower price point than what it sounds like Messana may run (our architect said the cost of the project was about 3x what doing a highly zoned air-to-air minisplit would likely run us, and I'm leery of low-load conditions with that kind of air-to-air setup). That said, maybe it's just not feasible to do what I'd like to do without spending more than I'm willing to spend.
If we move forward, it's becoming pretty clear I'm just going to have to design it myself. I've had enough challenges with previous big projects to be humble in the face of unknown unknowns, and life is such that my time is at a premium right now. Those are all motivations for finding someone to, ideally, do the design, or at least review my work. But, I have yet to find someone who could help me with that.
I remember reading an editorial by Siegnthaler (maybe it was in plumbing and mechanical?) where he said a homeowner bought a license for his design software because they couldn't find anyone local who seemed to understand how to fix the hydronic system a different local installer had just put in that wasn't working right. The homeowner finally accepted the fact that they were going to have to do it on their own. I naively thought to myself, I bet that won't be my experience...
You may want to try HeatingHelp for contacts. For my current house, I worked with a local supply-house and my heating contractor. The carpenters installed the panels, the heating contractor installed the PEX and manifolds. I did the controls and tuned the system. Siggy's book and software is very useful - I created a spreadsheet for all the loops - so we knew how much flow was required for each zone. You can take the formulas and put them into an MS-Excel spreadsheet.
You may want to contact Small Planet Supply for the Messana panels.
Uponor may have a good alternative to the Messana system. The S Matrix controls look straight-forward. You should be able to use the Xpress Trak on the ceiling (or floors) for some cooling. Again, the local supply houses may be a good source for help.
I did a heat-loss for a hot tub in CZ6 for both steady-state and for a refill (EWT of 45F). Based on factory data / product data sheets the heat-pump may struggle a bit. So make sure you play with models and non-steady state conditions.
Excellent points. To clarify my earlier point about Messana, I only meant the OP should purchase the panels from Messana, not the overpriced controls. There is nothing special about the controls that cannot be easily replicated with more modestly priced systems.
There is a Chiltrix owners Facebook group: https://www.facebook.com/groups/chiltrix.owners
You might try asking there. It seems like Chiltrix is targeting the DIY market, which seems like a curious decision to me. But you'll get first-hand experience from the members there.
Two things to keep in mind: it's a private group, you have to request membership. And it's moderated, and the moderators are pretty strict about not allowing discussion of brands other than Chiltrix.
Thanks for all the input folks.
I actually just stumbled across the chilitrix facebook group browsing another thread here.
I suspect, if I can pull this off, it will look a lot like BirchwoodBill's approach. I'm anticipating starting with some off-the-shelf controls, but I almost certainly will be augmenting them with some additional pieces I create myself (which is well in my wheelhouse from past projects). The climate in CO could accommodate a 'reverse outdoor reset' , raising the supply temp to take advantage of 50 and 60 degree winter days to charge thermal storage in a modestly large buffer tank at a good COP. But all of that needs more numbers crunched to see if I can make it pencil.
I'd appreciate any other ideas folks may have.
I'd be very surprised if a storage tank penciled out.
You may want to look at Building Equinox CERV2. It supports Andrew Ask’s iso-thermal dehumidification model by using a dehumidifier and water coil along with the CERV2 heat pump. It would need a CodeSys PLC (Wago) to control the pump on the water coil. That gives you an independent control loop, to manage the dew point. Attached is an illustration of the CERV2 doing ISO-Thermal dehumidification.
Wago also supports Enocean..so you can monitor the humidity throughout the house using temperature humidity sensors. You want the control system to shut down cooling loops if you start to approach the condensation limit.
A house built to modern standards is going to need ventilation, and I agree that the way to do it is with a whole-house system like the CERV2, and then you can implement dehumidification as well. Two caveats though:
1. I don't know of any methodology for sizing a dehumidifier, similar to Manual J. So I don't know how you would "design" it in any sense of the word.
2. Looking at that diagram, it looks to me like the dehumidification is provided by the Aprilaire E080. I have a CERV2 in my house, and unless there's a setting I'm not aware of it's limited to heating, cooling and ventilating, there's no straight dehumidification. The Aprilaire is noted as adding 2088 BTU/hr, which the CERV2 could help remove, as could the house AC.
And that kind of gets to the problem with radiant cooling. Dehumidifiers are very efficient space heaters. If you're running a dehumidifier inside the house just so you can have radiant cooling you're artificially increasing the cooling load. A conventional AC would use less energy.
With AWHP you are doing:
latent heat removed by dehumidifier turned into -> sensible + heat load penalty -> air-to-water heat pump removes sensible heat only
With regular air-to-air HP you are doing:
latent + sensible -> heat pump removes both latent and sensible
So the only time AWHP makes sense is if one of the following are true:
1) The COP of the AWHP + dehumidifier dwarfs the COP of the regular HP
2) You plan on combining both radiant panels and fan coils together to tackle the latent heat removal
3) The sensible heat ratio on your HP is too high to handle the humidity in your climate/home (and you don't want to oversize it to be capable of removing enough)
4) You already have or need a dehumidifier anyways because the HP alone is not sized or capable of removing enough latent heat by itself and it wouldn't take much to size the dehumidifier to handle all latent loads in the home
Regarding #1, the best ducted heat pump units according to AHRI directory are 21.1 SEER (5.4 COP) and the best mini split head heat pumps are 24 SEER (6.1 COP). If we use the Chiltrix AWHP as an example of an efficient unit, IF the unit has to produce water cold enough to dehumidify, its COP is around 6 so it's not any better than the better mini splits available. But, if it is allowed to produce warmer temperature water (because the dedicated dehumidifier is already doing the latent heat removal), it can jump up to 9.0 COP (leaving water temperature at 55 degF instead of standard 44 degF) as an example. So I think there is some edge cases where the dehumidifier + AHWP can beat the air-to-air heat pump configuration, but there are a lot of numbers to crunch to be sure. I am not sure how to quantify the COP of a dehumidifier but this earlier Q&A might be helpful:
https://www.greenbuildingadvisor.com/question/are-dehumidifiers-really-heaters-in-disguises
You may want to contact Avenir software - who developed LoopCAD - they may put you in touch with an independent Hydronic designer. They have a 30-day evaluation version - to see if you want to layout the panels yourself. I imported the house design from Chief Architect and then started to layout the circuits. Pretty intuitive.