Talk:Hydronics

Baseboard heating

No mention of the term "baseboard". Maybe this term is only used in North America, and whoever wrote the article is from elsewhere? 24.161.96.239 05:40, 16 July 2006 (UTC)

This is Wiki, so you know what to do: be bold and edit the article to include it!--Atlant 12:41, 17 July 2006 (UTC)

The article is about a particular way of delivering heat from a central location to individual rooms, not about how the heat, once there, is dispersed into the room. If you wrote about baseboard radiators here, where would you write about electric baseboard heat? By the way, the British English equivalent of a baseboard radiator is a skirting radiator (baseboards are skirting boards).--GrahamDavies 21:47, 25 October 2007 (UTC)

External links contain advertizing claims

"The Leader in Hydronic Systems and Components", "100% Efficient Radiant Heat Products". It looks and it is advertizing of commercial companies and their products. 194.24.171.196 (talk) 13:03, 28 August 2008 (UTC)

Steam

How common is it to include steam systems when describing "hydronic" systems? I would qualify the lead sentence by adding "liquid" and expand it a bit:

Hydronics is the name for the use of liquid water (or aqueous solutions) as the heat-transfer medium in heating and cooling systems.

The chapter on pipe sizing in the ASHRAE Handbook of Fundamentals has separate sections for "Hydronic System Piping" (as a subsection of "Water Piping") and "Steam Piping" (as its own major section). It seems that ASHRAE does not include steam as a "hydronic" system in this context. -Ac44ck (talk) 23:56, 11 December 2008 (UTC)

re: steam is/not hydronic, it is in the most literal sense and for the purpose of categorizing heating and cooling systems, but to heating and cooling equipment manufacturers, installers, and service companies the details are different enough to be a specialty. That's why ASHRAE, an industry group, separates the topics. In the unlikely event that Wikipedia develops a sufficiently lengthy description of the differences between a two-pipe supply/return steam heating system and a two pipe supply/return water heating system that it might be helpful to segregate the material into another article and adopting the heating industry's distinction. As long as the material remains vague and generic, the similarities outweigh the differences. For example, oil and gas fired cast iron steam boilers can be used as hot water boilers, although using a cast iron hot water boiler as a steam boiler usually leads to a cracked boiler section because it isn't reinforced internally to withstand the stress of the temperature difference between the water filled part and the steam filled part. At the level of detail a Wikipedia article can explain to the general public, all cast iron boilers are identical. Likewise explaining the differences between a steam radiator and a hot water radiator would focus on technical details not useful to the general public. They both have tubes, surface area, and an air bleeder, and can have a valve to keep it from getting hot. If effort is expended to develop this article, it would be more useful to extend the article to cover the more complex two loop hydronic system used by commercial properties where one loop circulates heated water and one loop circulates chilled water to air handlers and other building systems to provide heat, air conditioning, dehumidification, hot tap water, etc. It would be simpler to ignore 2 pipe seasonal changeover systems and 3 pipe common return systems. PolychromePlatypus (talk) 21:43, 14 November 2020 (UTC)

How well does this system work driveways. Or is there a different type of system out there that is better.71.105.128.66 (talk) 03:25, 27 January 2009 (UTC)

re driveway and walkway snow melting/deicing systems. Aside from areas like lower Manhattan and some campuses where steam distributed in underground utility tunnels warms the walkways anyway, melting systems are made using either direct electrical resistance heating or a water loop scheme similar to radiant slab building heat. Direct electrical resistance heating cables tend to be expensive to operate, electricity isn't a bargain in $/BTU. The cables don't last indefinitely so it has to allow for replacing the cables by putting them in tubes. Putting them in metal tubes to mitigate the shock hazard sets up corrosion problems, but plastic tubes don't age well when heated by a narrow cable and can be damaged by a hot spot when a cable burns out. It was the preferred choice in the late 1960's when electric resistance heating in general was briefly popular. Nuclear power was going to make electricity so cheap it wasn't worth metering it. Things didn't turn out that way. The water loop requires using a non-toxic antifreeze like propylene glycol or limonene (citrus based) to avoid burst tubes. Separating the low temperature antifreeze loop from the heat source with a heat exchanger, similar to an indirect domestic hot water, confers two benefits. First, it avoids the putting the reduced heat capacity of an antifreeze mixture in the boiler which would decrease the boiler's heat exchanger capacity and efficiency. Second, the water returning to the boiler from the indirect heater isn't intrinsically ice cold like the water returning from under the frozen driveway. Without a water to water heat exchanger there would still be a second pumped loop but it would have a mixing valves so that 32°F water didn't return to the boiler. Excessively cold return water can cause condensation in the boiler which absorbs flue gasses becoming acidic and eroding the boiler. Excessively cold return water also creates a large thermal gradient across the boiler with the thermal expansion difference creating large stress forces, which can result in cracking. A gas or oil fired boiler is being assumed because a heat pump isn't efficient in precisely the kind of outdoor conditions when a driveway heating system would be operated. If a large geothermal heat sink is available at a particular site that assumption might be incorrect and the heat source for the antifreeze loop might be a heat pump. PolychromePlatypus (talk) 21:43, 14 November 2020 (UTC)

Clarifications on Hydronics

Steam is a completely separate method of distributing/transferring heat throughout a system, it should not be mentioned under the "Hydronics" section EXCEPT as a potential source of heat through the use of a steam-to-water heat exchanger that transfers the heat from steam to the Hydronic "Closed Loop" water system. This approach is used when the facility or building has other steam loads and wishes to confine their boiler type(s) to steam only. If no other steam load exists then hot water boilers are usually installed.

Steam is a more efficient form of providing heat to a building due to it's higher heat transfer coefficient. From a design/build standpoint a Hydronic system is less expensive to purchase & install, so many owners will take the lower up-front cost of a hydronic heating system & pay more operating/fuel costs throughout the life of the system.

Hydronic baseboard heaters are classified as radiators, the core or tube bundle is fabricated of finned tubing that air either passes over via natural convection or is blown over by a thermostatically-controlled fan.

There are no 1-pipe or 2-pipe systems associated with Hydronic systems. There are primary & secondary loops & zones. The primary loop runs from the boiler room (this end of the loop is called the "supply" piping), throughout the building and returns to the boiler room (this end of the loop is called the "return" piping). It's job is to circulate hot water throughout the building, and includes circulating pumps for this purpose. The secondary loop refers to the design of the boiler piping integration into the primary loop for keeping the primary loop at it's temperature setpoint. The zones pull water from the primary loop supply & pass it through the actual "Load" (air handler coil, re-heat coil, baseboard heaters, etcetera). The cooler water which has given up a portion of it's heat to these "loads" then feeds into the return piping of the primary loop. From there it returns to the boiler room to be reheated & recirculated. Sdunaway (talk) 23:00, 8 October 2009 (UTC)

I respectfully disagree with two sets of preceeding assertions; The assertion that all hydronic systems have primary and secondary loops and zones, and the assertion that steam and hydronic are separate topics including the assertion that the only intersection is when a heat exchanger is used to for a closed hydronic loop.

The assertion that hydronic systems have primary and secondary loops is a pat answer and vaguely naive. A system may be quite simple with a single zone and water loop for the entire building. It may be a single zone with "venturi" diverters and manual zone valves. There are a variety of schemes to avoid a returning water with a large temperature difference to a cast iron boiler, ranging from simply recirculating a null loop around the boiler at a high flow rate to make the boiler isothermal, they may have a 4 pipe mix valve to always circulate to the radiators and vary the temperature to respond to the thermostat, and they may have a thermostatic valve to mix the return water, which may have the effect of blocking flow from the secondary zones from returning to the boiler on a cold start. The thermostatic return mixing typically contemplated as primary and secondary loops may be feeding a slab (radiant floor) heating zone, which would be a "tertiary" zone? The general concepts are that independent heat loads loads are independent water circuits, boiler return water temperature control may occur as a circuit partially isolating the boiler, and heat loads requiring a lower circulating temperature, like radiant floor heating or snow melting, may occur as a circuit partially isolating the heat load.

The assertion that steam and hydronic were separate system types is one I would have agreed with until a friend purchased a home in Gardner, MA in the 1980's where the boiler supplied 1 pipe steam to the upper part of the house and hydronic baseboard heat for the finished part of the basement. Obviously enough, it's done to avoid to needing to either pump condensate for return, or to install a heat exchanger for a closed hydronic loop, which would require a host of supporting equipment, a second auto-fill, an expansion tank, a de-aerator, a float valve, and so on. This economical solution was confirmed by others to be reasonably common in that area. The obvious limitations of the scheme are that the hydronic loop may be circulating very hot water - or not, when the hydronic circulator starts the cold return water pulse tends to pause the delivery of steam, and the hydronic load has to be a small enough fraction of system capacity to allow for good steam delivery. The boiler controls were in effect duplicated in parallel to the burner so that on a hydronic zone call for heat the burner was interrupted by high limit water temperature and for a steam call for heat at a high pressure limit. I always tended to look at that heating plant as "wrong" in some fundamental way, but it was functional and economical. They sold the house in the late 1990's and I have no idea if that kind of system is still common there, but a 2016 article suggests this hack is still around.PolychromePlatypus (talk) 22:51, 18 December 2020 (UTC)

References