Are there any “smart” radiant heat systems out there?
Hi all,
Wondering if there are any smart systems on the market that use microprocessors to adjust the dynamics of a radiant heat system to optimize efficiency and heating results. I know there are smart boilers and tankless heaters but what about overall system modulation?
My thought is that if zones were designed with thermostats and also temperature monitoring floor sensors a smart system could adjust the delta T between the 2 to achieve the most ideal floor temp to maintain air temp. The delta T could also vary to provide the ideal number of times the system cycles on and off. The system would cycle on and off by floor temp not air temp. Delta T pumps could be used on each circuit to optimize boiler efficiency. I don’t think this would work on low thermal mass systems that use heat fins but might be ideal for concrete. So long as the system is over engineered It would seem that accurate heat loss (pertaining to circuit design) wouldn’t be so crucial and this could be advantageous to the DIY’er. It seems that proper sizing of boiler would be crucial though. There would also need to be a high limit switch a few degrees above thermostat to prevent over heating.
Anything similar out there?
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Replies
What you are looking for is outdoor reset. Most boilers have this built in, or you can use one of the Taco 3 way outdoor reset valves.
Outdoor reset looks at the temperature outside and adjusts the boilers output temperature accordingly. The warmer it is outside the lower the boiler temperature can be and still meet the space heating needs. Lower return temperatures mean higher efficinecy for modcons.
A well setup outdoor reset can work so well that you don't even need thermostats inside the house.
For circulators, delta P is the way to go. You just adjust it once and never have to look at it again. I've tried delta T ones, it does work but doesn't buy you all that much plus now you have two extra sensors that might fail.
Thanks Akos,
So if running multiple zones, which may each require different temps. depending on flooring material, would using 1 delta P pump with multiple taco 3 way valves be the right option or are there boilers capable of providing optimal temp to all zones?
There are some boilers with separately programmable zone temperature reset curves (I believe Lochinvar's KHB series have that capability), but it's generally better to design the radiation to work at a single temperature.
Do the math first- figure out what make sense. Don't count on endless tweakery/hacker of multiple curve parameters to deliver an optimal result.
Thanks for the info.
Each time you say a different temperature zone, you are adding around $1k in parts, so make sure there is a good reason for it. The best is to run the low temp zone at a fixed temperature and have the outdoor reset only on the main boiler loop. Even better, run everything on one temperature.
Probably best is to read through this series (there are 4 volumes):
https://www.pmengineer.com/articles/94332-modern-hydronics-done-right
Also make sure there is a good reason for all the hydronics. It is fun to tinker with but if you need mini splits for cooling, better use of time is figuring out how to also heat with one. Unless your electricity is very expensive, heating with mini splits cost a bit more than natural gas and are cheaper than propane or oil.
Thanks! I’m climate zone 6 with nights that get as low a -30f. Could a mini split be used solely for heat or should I design a modest radiant heat and use mini split as supplemental?
It depends on what your actual design temperature is. There are cold climate mini splits that can deliver 80% of their rated capacity down to -13F and will continue to deliver heat bellow that (at reduced capacity).
A house usually has enough thermal mass to ride through cold snaps, there is no need to design for -30F if it is rarely seen. A couple of electric baseboards/panel heaters make for cheap backup just in case. Wood stove is even better.