In My Dreams ...
John Siegenthaler, PE
Every once in a while it's good to think back on the hydronic heating systems you designed or installed 10 to15 years ago. It's likely your current piping designs and hardware choices have changed considerably from back then, and for the better. Although most of your earlier installations are probably still operating, it's likely you're now providing systems with higher efficiency, a wider mix of materials, and overall more bang for the buck.
Like many of you, I often think about what new products or services might come along to further improve what we do as hydronic heating pros. This month I'll mention a few that I think could sell as quickly as they roll off the assembly line. See what you think ...
Instead of placing thousands of fasteners, imagine that you could simply peel a paper strip off the back of the heat transfer plate, align the groove with the tube, press the plate up against the subfloor and let go. No hoses, no fasteners, no blasts of oily air in your face.
A pre-applied adhesive layer on the upper side of the plate would permanently bond the plate to the floor and provide increased contact area for better heat transfer. Its bonding strength would only get stronger with heat and time.
Given the vast array of adhesives now available, there must be a potential product that could facilitate such an item.
Rather than use an oversized circulator, why not create a small DC-powered circulator specifically for smaller injection mixing applications? To keep the cost down, the majority of this device could be made of a polymer material rather than cast metal. It could be installed in the return injection riser where water temperatures are well within the range that polymers can handle. DC motor technology would provide high torque at low speeds and precise speed control.
The pump could have an integral controller with simple settings, allowing for outdoor reset or setpoint control. Taking a cue from zone valves, the device could have a removable “powerhead,” allowing the motor and electronics to be easily replaced or upgraded without breaking into the wetted components.
Having such a product available for say $150 would probably convert many who now throw a 3/4-inch three-way thermostatic valve at every mixing requirement regardless of flow requirements. Considering how the latter approach can easily lead to flow bottlenecks and costly callbacks, the small injection mixing device would be a real bargain. This price range would also allow multiple mixing devices to be installed in systems that need different water temperatures without breaking the bank in the process.
This paradigm was fine when houses had higher heat loads and the DHW requirements of two modest bathrooms. However, the growing demand for luxury bathrooms and their associated DHW requirements opens up a great new opportunity for perceptive hydronic heating pros. Here's the concept in a nutshell ...
In many homes, especially those with several luxury bathrooms, a multiple boiler system and indirect DHW tank should be proposed first and foremost as a means of providing high capacity domestic water heating.
Once the boiler system is “in the picture” to handle the copious DHW demands, the owner can be further counseled about all sorts of hydronic ancillaries. These include radiant panel heating in appropriate areas, towel warmers, hydro/air subsystems, pool heating and maybe even some snowmelting. None of these are likely when the decision is made to use furnaces for space heating along with multiple direct-fired tanks for DHW. What a shame.
The “DHW first” concept provides a fresh and functional approach to situations that didn't exist a couple of decades ago. It's especially relevant in markets such as the Southeast where hydronic space heating (as a single purpose system) often meets considerable resistance.
Given the DHW demand of some high-flow fixtures, the installed boiler capacity might have to be several hundred thousand Btu/hour. This requires what I call “full afterburner” mode for the multiple boiler system. The staging control targets a relatively high supply water temperature, lights up all the boilers, and focuses all heat output solely on the DHW tank.
This operating mode can also be invoked for snowmelting or when a pool needs to be warmed as quickly as possible. All three of these loads might even exist on a single project, but rarely will they occur simultaneously. If they do, the control system handles them on an assigned priority basis.
When the high demand loads are satisfied, the staging control ramps things down to required space heating levels and helps maintain good seasonal efficiency of the boiler system. Multiple modulating boiler systems with their wide turndown ratio are currently the ultimate power plant to support this concept.
Unfortunately, many currently available indirect tanks can't “sink” the high rates of heat transfer needed to put all the heat the boiler system can deliver into the potable water. These tanks are often bottlenecked by the heat transfer potential of internal heat exchangers (as discussed in last month's column, “Avoiding Bottlenecks”).
I think there's a great opportunity for more manufacturers to develop and sell indirect water heaters with significantly larger heat exchangers to serve this growing market niche. Some might even consider offering a multiple boiler system with a pre-engineered tank, circulator, staging control and piping layout as the building block for a high capacity DHW system.
Wireless thermostats hold the potential to eliminate much of this low voltage spaghetti. They've been available in North America, at times, from at least two companies. Still, for various reasons, this concept has not gained a solid foothold in our market, perhaps because early efforts involved imported European technology that wasn't quite ready for prime time in the North American residential heating market.
Given that we can now setup wireless home computer networks for around $100, and that Blue-Tooth™ technology allows all sorts of electronic devices to wirelessly communicate, it seems the raw technology needed for reliable wireless thermostats already exists. Ditto for wireless sensors. A good example of the latter being a wireless outdoor temperature sensor that sends digitally encoded temperature data to a reset control in the mechanical room.
Without the encumbrance of thermostat cable, wireless thermostats and sensors could be semipermanently bonded to a wall and easily moved if necessary. A fully wireless thermostat/sensor system would shave hours off most installations and produce a neater looking result. Our industry needs this technology now.
Btu/hour = 500 x gpm x ∆T
Your digital thermometer could read the temperature drop, but without the flow rate you can't complete the calculation.
Although inline flow meters have been around for decades, they're often aimed at the process industry and priced beyond what the average hydronic heating installer can justify, especially if required in multiple locations. Flow meters with clear glass or polymer cylinders also tend to cloud up with thin opaque films after a few months of operation, rendering them all but useless.
Wouldn't it be nice to have a device that simply clamps to the outside of the pipe and then displays the current flow rate? Such devices do exist; they're called Doppler flow meters and presently cost thousands of dollars. Come to think of it, computers also cost thousands of dollars not that long ago. Maybe someone can work a similar technological quantum leap in flow meter technology.
Given what's happened to our own energy costs, and with little hope of a significant or sustained drop, it's time the North American hydronics industry got serious about deploying variable speed circulators on a broad scale. I do think 2005 will see some major strides in this direction.
Hydronic heating pros need to learn all they can about variable speed pumping because it soon will (not may) become a new standard in our industry.
Wouldn't it be great if someone offered a user friendly, fully outfitted kit of equipment, chemicals and instructions on how to perform a water quality assessment on site, and provide corrective actions when necessary?
Aqueous solutions of methyl alcohol have been used as lower-cost antifreeze fluids in geothermal heat pump systems, but the thought of handling gallons of flammable alcohol in a boiler room really doesn't settle well with me. It sure would be nice to have a reasonably priced alternative antifreeze with the thermal properties of methanol, minus its flammability.
I'm probably reaching into the twilight zone on this one considering that companies like Dow Chemical surely know about alternatives to glycol-based antifreeze and apparently don't have a silver bullet product waiting in the wings as a replacement. Still, there's hope for the future.
After reading this, you might be thinking, “Hey, I know someone who already offers that product or something similar to it.” If so, drop me an e-mail so I can check it out. Few people, including me, can keep track of every new product that comes into our industry. However, when I do come across innovative new products or concepts that have reached the “for public release” phase, I'll do my best to keep PM readers informed. As in many areas of technology, the best is still ahead for hydronic heating.