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In my part of the country, hydronics in residential and light commercial applications has a tendency to take a back seat to forced air. It’s a sad fact, mostly due to the hot and humid summers making cooling a necessity. This means that hydronics can be a world of mystery for many technicians. Trust me; I can verify this first hand as I’m still learning every day!
If you couple this along with the fact that hydronic systems tend to be thought of as overly complicated, it’s no wonder people steer away. The truth is, hydronic systems don’t need to be complicated at all.
What worries me is what I’ve found visiting different HVACR educational facilities in my travels. Some take a deep dive into hydronics, while others only offer a crash course for their students. I completely understand that these facilities and educators need to cater to their market and the needs of the contractors in that area taking on graduates, but it is at the risk of making their students less valuable.
I’ve also had the displeasure of hearing instructors tell me they don’t have time for hydronics; it’s all they can do to get their students a good understanding of forced-air systems.
So, if you’re new to hydronics, don’t be shy. The fact is, the transferring of heat through the use of different mediums isn’t usually what trips up most people. The combustion process and refrigeration circuits are the basis of most space heating and cooling systems; we’re just transferring BTUs to water or glycol instead of directly to air.
Where most run into trouble is how to control it. We’ve all gazed upon the awe-inspiring mechanical rooms full of shiny pipe, circulators, zone valves, mixing valves, diamond plate and the coolest new boilers, but what makes it all come together are the controls.
All those controls need to work together in harmony — the boiler control, staging control, injection mixing control, outdoor reset, zone control, and even the thermostats. If they’re not wired or set up properly to get the most out of the system, all that hard work is just for vanity’s sake. It may look awfully pretty, but it’s not going to get the job done. The worst part is the customer probably won’t even know the difference!
When I mentioned overly complicated before, this is what I was referring to. Hydronics, just like any other form of heating, can be as simple or as complex as you (or your customer) wish. Just be careful what you (or, again, your customer) wish for. I can’t tell you how many programmable thermostats I took off the wall and replaced with something closely related to the infamous round thermostats. The system may have all the potential in the world, but it’s useless if your customer doesn’t know how to use it.
(subhead) No need for wires
One of the most unique and simple systems I was read in on was a hydronic system in a multifamily building. It had pneumatic controls in various stages of disrepair and a building owner who was less than interested in bringing them back to life. Running control wiring in this building would be its own special nightmare, so they turned to simplicity.
Through the use of mechanical controls in each tenant space, they deferred the need for wires. Back in the boiler room, the contractor piped a high-efficiency boiler to a buffer tank. The boiler maintained a buffer tank temperature; on the other side of the buffer tank, a variable-speed circulator was used.
That circulator ramped up and down based on how the mechanical controls were modulating in each living space. At this point, everything runs until a certain outdoor temperature is reached. Then the warm weather shutdown function built into the boiler control shuts everything down.
Would you think about that for a second? A hydronic system that functions and you didn’t even have to pull a single thermostat wire! The boiler is jumped across the thermostat terminals and fires based on a sensor in the buffer tank in relation to the outdoor reset curve.
The contractor took advantage of existing series baseboard loops in each residence, added a valve and mechanical control. Every tenant also had control of the temperature in their space as well as being somewhat limited through the use of outdoor reset. This last note will make the person who pays the utility bill very happy; it will prevent tenants from actually achieving sauna status just because the heat is included.
If they wanted, they could spice things up a bit and put a master thermostat somewhere, perhaps in the building manager’s apartment, to control the on and off of the system outside of outdoor reset. That thermostat would usually be set one or two degrees higher than the desired temperature in the residences to make sure everyone would be comfortable, especially as the load requirements may vary throughout the building.
Are there better or more efficient ways to get the job done? There definitely is! Don’t get me wrong, there’s definitely a time and a place to go bonkers with controls. Some of the features and benefits associated with zoning, modulating boiler control and staging are certainly worth their weight! However, I would caution you to understand your customer’s needs and realize that hydronic systems don’t need to be overly complicated. Sometimes the keep-it-simple method is all you need.
In the end, just remember that having a broader understanding of our industry will make you more valuable. I believe it’s something to be proud of, but it also means that you’ll always have work.
So, get out of your comfort zone and tackle different fuels, equipment types, controls and heat transfer mediums. Don’t be afraid to ask for help or lean on those around you for advice and resources. Your employer, wholesalers, manufacturer reps and even the manufacturers have a lot to gain by helping you to broaden your horizons and making you a better tech!
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