In last month’s article, we began to rediscover non-electric thermostatic radiator valves (TRV). In this month’s article, we complete that examination.
It is a “set it and forget it” type of thermostat, and the final setting is dependent upon all of the usual variables associated with determining final degrees of comfort. Are the occupants heavily clothed or lightly clothed; are they active or are they inactive; and what is their proximity to large areas of glazing. It is a short learning curve, but one that must be taught to the consumer to avoid potential issues moving forward. Their answer will dictate the “comfort number” to which they will set these devices.
Most TRV manufacturers also make a surface mounted dial/thermostat assembly, with a micro capillary tube up to 33 feet in length (10 meters) that goes to the actual control valve. I’d recommend that the cap tube be installed in a flexible ¾-in. “conduit” of sorts, so that if it becomes necessary to replace the cap tube in the future, it can be done without having to remove drywall to facilitate replacement.
Placement of the thermostat base follows the same rules as one would use in deploying a conventional thermostat. Don’t put it where it will see the sun, near an open window, or behind an operable door. This brings me to another point that was brought to my attention today by a very learned and respected hydronics technician from New Jersey. Why do we Americans put all of our thermostats in the middle of the house, where heat loss is minor? Why don’t we place it closer to an outside wall where the major heat loss is occurring, which is typically, the same place that the occupants spend the majority of their time?
With panel radiators, they are most all located on an outside wall, and the conditioned space doesn’t over heat, nor does it under heat. The Europeans have once again proven us wrong in our thermostat placement locations.
Maybe it’s time to rethink where we are placing these thermostats. Our job is to guarantee occupant comfort and efficiency to the end user. But if the system is efficient, and the consumers are not comfortable, we are missing the mark. Simple food for thought, and thanks to our Radiant Professionals Alliance (RPA) members for bringing it to our attention.
There are numerous manufacturers of non-electric thermostatic control valves on the market. Do a search on them and try them on your next project. I think you will find the comfort is incomparable, and when coupled with a properly sized heat source and variable speed circulator will result in the ultimate comfort/efficiency combination that can’t be beat. This adds significant value to your and your company’s offering compared to your competition. It will, in fact, raise you head and shoulders above your competition.
As it pertains to being used with all of these smart, Internet-based Wi-Fi thermostats on the market, as I previously mentioned, placing the solid state thermostat in the worst case scenario zone, and when doing a deep setback, interrupting the operation of the heat source will allow the whole building the opportunity to do a deep setback to a reasonable temperature, say around 40°F or 50°F without compromising the other mechanical systems due to freeze potentials.
Our job is to guarantee occupant comfort and efficiency to the end user.
When the consumer is ready to go home, have them take the home out of setback two full days before their anticipated arrival and they will come home to a perfectly conditioned living space that has wasted a minimum of energy in recovery, but has saved a significant amount of energy during unoccupied periods.
The only caution I would give is that for this system to work as well as it possibly can, you will need to keep the solid state thermostat turned up a few degrees Fahrenheit higher than for which the TRVs are set. This keeps the system as close to a constant circulation system as is possible. If the system shuts down due to high outdoor air temperatures (WWSD) that is perfect. One last precaution would be the recommendation that the final location of the actual control valve be well documented, and access maintained in whatever manner is conducive to the building design.
In all of my years working in the field, I saw one TRV that had failed and needed replacement, and I suspect it had been damaged by the occupants moving furniture. Try it once and it will become a part and parcel of your radiant presentations. And while you are at it, join the RPA and let it become a part and parcel of your business experience. You won’t regret it!
Tune in next month as we continue to discover the world’s most efficient comfort delivery systems — that being hydronics. Until then, happy hydronicing!
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