New Commercial Water Heaters Ask Chuck Appleby, president of Old Lyme, CT-based Appleby Plumbing Co. if he recalls an emergency job. One he quickly remembers began with an urgent, Christmas day plea from a restauranteur who needed half a million BTUs of water heating at the height of their businest season (see sidebar story). Appleby Read more
2014 January-February
New Commercial Water Heaters
Ask Chuck Appleby, president of Old Lyme, CT-based Appleby Plumbing Co. if he recalls an emergency job. One he quickly remembers began with an urgent, Christmas day plea from a restauranteur who needed half a million BTUs of water heating at the height of their businest season (see sidebar story).
Appleby was there on site within 30 minutes. While studying their need for hot water he discovered that the old, leaking beast was sized for peak load, making it at least 20 percent too large 90 percent of the time. The big, atmospheric system could be replaced by a 400 MBH condensing unit that would be smaller in size, a whole lot less expensive to operate and – if need be – could be coupled with a smaller indirect water heater to meet peak loads.
The new water heater, which offered a much greater recovery rate, was also a lot less burdensome to install than the old one, not requiring the large, ducted air vent. The new system, a condensing water heater, would require only a 3-inch PVC air intake and a 3-inch PVC flue gas discharge. “A piece of cake,” said Appleby while marveling the extraordinary efforts taken (and expense) to install the intricate air passageway for the unit that would soon be replaced.
“The new unit’s sealed combustion is a huge benefit for restaurant jobs, eliminating all concern about one of the trickiest challenges with commercial facilities where food is prepared,” added Appleby. “Large ventilation hoods are notoriusly adept at stealing combustion air from atmospherically-fired systems. Those days – thanks to new, sealed combustion technology – may soon be gone.”
Appleby’s experience with the system he replaced is illustrative of the way water heating technology has changed in just the past couple of years. Not long ago, contractors, engineers and building owners were routinely challenged by an inability to easily place and locate commercial water heaters. The limitations of atmospherically-vented systems, facility design, aesthetics and close proximity to other buildings all factored-in.
Today it’s not uncommon for facility managers, late in the game, to express an aversion to visible venting, based purely on aesthetic reasons. This is especially true in historic districts.
Fortunately, many of the obstacles to easy placement of water heaters – at least those tied to building design and construction – are overcome with the emergence of new water heater systems, making it much easier to achieve manufacturer-specified combustion air or venting runs.
The arsenal of commercial water heater products and associated technology has grown considerably, availing a wide range of fuel, venting and combustion air options. There are also many new application-friendly components and techniques to enable trouble-free specification and installation, though – with the new, green systems – a few new needs emerge.
Higher efficiency, condensing systems are great for end-users in terms of energy consumed, chiefly because they harvest heat from waste condensate. The energy advantage requires modest design and installation changes to meet the need for condensate treatment and drainage. This may translate to an inability to use existing venting if the original water heater was atmospherically vented, and the availability of electricity. Some systems require hard-wiring; other commercial systems need only a simple wall plug-in.
Condensate drainage is a likely necessity. Often, fluids to be drained are too acidic for metal drain lines. Routing the condensate through a simple, lime-bed acid neutralizer may solve the problem easily. Better yet: CPVC or PVC drain lines can handle the acidity. Condensate typically has a pH of 4.0, about that of Coka-Cola – just enough to attack any metal it connects with. Over time, the cumulative effect of exposure to acidic runoff threatens the integrity of the drain lines.
Venting. If new, high-efficiency water heaters are planned as a retrofit, existing, single-wall B-vent must be replaced in favor of PVC, CPVC or ABS plastic. The majority of venting lines are three or four inches in diameter, precisely matched to the design requirements of new blower motor assemblies that discharge from the top of water heaters.
Plastic vent materials are inexpensive and easy to work with, and yet present no compromise in safety or performance. Some new water heater systems have the ability to vent through the roof and pull air in for combustion through the wall; this is a big advantage. The need to improve flexibility of installation and placement has driven the development of power, power direct vent; through-roof and side-wall venting options.
Finally, if the application offers abundant atmospheric combustion air, some water heater models require only one pipe: for venting.
Multi-story and high-rise installations challenge traditional venting. High efficiency water heaters often can accommodate to long venting runs. Often, there’s no need to run vertical venting all the way to the roof, requiring a roof penetration. Many systems are now just as well served with side-wall venting.
New codes are forcing all of us to be attentive to a broad range of emerging requirements. National, state and local codes are changing in the wake of the green movement’s more stringent environmental policies and initiatives. Among the applicable national codes is the need for water heater system over 199,999 MBH to be ASME-certified.
Historic settings are commonly guarded by restrictions that regulate the presence and appearance of modern building systems and attachments (i.e., wire, regulators, transformers and venting). In fact, the presence of old and unsightly or loud venting systems has actually encouraged the replacement of aging atmospheric water heaters.
Case in point: New system shaves cost of operation
Recently, Appleby received an emergency replacement call from the 232-year-old Griswold Inn, founded in 1776 near the banks of the Connecticut River and nestled among many other old and beautifully preserved buildings.
The Inn needed a substantial overhaul brought on by the sudden death of an eight year-old, half million BTU commercial water heater, the only source of domestic hot water for the Gris’ award-winning kitchen.
“Of course, the old Inn wasn’t built to accommodate modern mechanical systems,” said Appleby. “He specified a new, 400 MBH, LP-fired, high-efficiency eF water heater by Bradford White to replace the quickly deteriorating system installed by another firm.
The water heater they replaced had required a 12-inch stainless steel draft hood and chimney. “Too bad they had to spend that kind of money on a water heater with such a short life span,” said Appleby. “The new system we installed requires only a simple, four-inch PVC stack, and at 98% efficiency, would cost them a whole lot less to operate. The key advantage was the new, condensing unit’s super-high recovery rate. Because we could heat so much more water, we were able to size it at 100,000 fewer BTUs, a move that also had a huge impact in their fuel consumption.”
Another attribute is that there are no stack losses because the new system is equipped with sealed combustion and uses both PVC exhaust and combustion air lines. The water heater also offered several venting options, electronic controls, four protective magnesium anode rods, a sediment reduction system and factory-installed dielectric fittings.
Considering the sad waste of resources on the stainless steel stack, which Appleby left in place, he devised a plan that gave it new purpose. “We used it as an intake air ventilation duct to cool the restaurant’s large refrigeration equipment,” he said. “They had a growing problem there because the equipment had been running hot, and this was consuming electricity [highest, by far, of all energy sources in the state] at an alarming rate. Typically, the air around the refrigeration systems was 120 to 130 degrees, year-round. Using the 12-inch duct to bring fresh air in, we were able to get those temperatures down substantially.”
“The biggest benefit of all was in the energy savings,” concluded Appleby. “Today, no one can responsibly afford to waste energy.”
By Jim Hinshaw This article was prompted by my wife and me watching a great movie: Saving Mr. Banks, starring Tom Hanks, Collin Ferrell, and Emma Thompson. Lots of others in the cast, but these are the main players. It is the story about how Walt Disney got the film rights to Mary Poppins from Read more
By Jim Hinshaw
This article was prompted by my wife and me watching a great movie: Saving Mr. Banks, starring Tom Hanks, Collin Ferrell, and Emma Thompson. Lots of others in the cast, but these are the main players. It is the story about how Walt Disney got the film rights to Mary Poppins from the author of the book, who lived in England. He pursued her for 20 years! Yep, 20. Not an exaggeration. She was certain he just wanted to improve his already profit-filled empire, just print some more dollar bills to add to the mouse kingdom. But Emma stays in England, not even coming over to discuss it.
What changes her mind is her agent; he lets her know she is out of money. So, to maintain her home and provide some funds to live on, she agrees to go to LA to discuss the script for the movie. She has been told she has absolute control, and plays it like she has absolute control. She was adamant that there be no animation, no cartoon characters in her movie. In fact, she wanted no red colors to be used. She is a woman who is set in her ways, not to be confused by the laws of physics or what makes sense.
The movie is not a Disney movie, it is a grown-up movie. Your 10-year-old would be bored to death. It is told using a flashback system, going back to Australia when Emma was a small girl and Collin Ferrell, as her alcoholic father, is a bank manager. We see his gradual descent into alcoholism, and the effect it has on the family. Some of those effects are played out when Disney tries to put the movie together. Of course, we see this via the flashback; Disney and his team do not. They just see a woman who is hard to deal with, uncompromising, unwill- ing to give in on any little item.
Remember I told you, Disney had spent 20 years chasing her, and now she is on his court, and still it seems like it is going to unravel. In fact, near the movie’s end, Emma finds out they are going to have dancing penguins. She is amazed that they would go to the trouble to train penguins to dance. One of the producers finally admits, they are going to use animation! She leaves town, will not sign off on the movie rights, all is lost. Or so it would seem.
Walt gets on an airplane and flies 11 hours the very next day to meet at her home, no appointment, just a big surprise. He confronts her with the idea that the problems she has with the movie are actually problems with her relationship with her pop, which have spilled over into her adult life, some 50 years later.
So he sits there, does an outstanding job analyzing her responses, and asks again for the right to produce the movie, complete with dancing penguins. It is amazing.
Here is my application. I realize 20 years is not a realistic time to follow up in our industry. But how about three years? I talk to too many sales reps who don’t follow up the next year. I have seen studies that tell me 70 precent of sales are sold after the customer has been asked five times. Five! The second con- cept is that you are never done selling. Walt realized when Emma hit his town; it was not a done deal. He never gave up! He went to extreme lengths to put the package together, flying half way across the globe. Lastly, ask more questions. Walt did his homework, found out she had changed her name, and why and where the pain was coming from. Only after doing all that, he could did he get the signature.
So my question to you is: What are you going to do different- ly this year? I just had a conversation with Eric Kjelshus, talk- ing about his goals for this year. He is looking to grow sales 25 percent; not a small number. He asked me what would be the obstacles he may find on that path to profits. I told him that I see three opportunities as I travel across the nation: (1) Not enough leads; (2) close ratio is too low; (3) gross margin is too low, not enough profits in the job.
Those are my three opportunities that are almost always present. To hear how to solve them, send $20 cash …
OK, just tune in next month, we will work on this and a bunch more. Don’t send any money! Thanks for listening, we’ll talk later.
By Rich Grimes Please explain a “cold water sandwich” and what causes this to happen? A cold water sandwich can occur on tankless water heaters when the system keeps drawing hot water, but the heater cycles off and then back on again, after a time delay. This does not occur with every tankless model, but Read more
By Rich Grimes
Please explain a “cold water sandwich” and what causes this to happen?
A cold water sandwich can occur on tankless water heaters when the system keeps drawing hot water, but the heater cycles off and then back on again, after a time delay. This does not occur with every tankless model, but it is relative to water pressure change, typically triggered by a single-handle faucet or shower valve.
Some manufacturers sense only flow rate and do not use any time delay. These heaters are sensing a minimum flow rate (typically .5 gpm to activate) and will shut the burner down if the flow rate falls below .4 gpm. Once a flow rate of .5 gpm is reestablished, the heater will immediately restart. Heaters that sense only flow rate do not produce cold water sand- wiches.
The heaters that tend to experience cold water sandwiches sense flow, but they also sense pressure. When a single-han- dle faucet is adjusted from full hot and then back to center (mixed hot and cold), the heater senses the pressure drop and can cut the burner out. Before the heater will restart, there is a delay of 15 to 25 seconds before the burner fires. The result is someone taking a shower with steady hot water flowing. If they make enough of an adjustment on the shower valve, the burn- er cuts off and restarts in approximately 15 seconds. So what happens is steady hot water is followed by a 15-second slug of cold water and then followed by hot water again. It will get your attention if you experience it!
In summary, flow-only sensitive heaters do not have any delays in re-ignition and do not create cold water sandwich effects. Heaters that are flow and pressure sensitive can create a cold water sandwich in certain conditions, but not always. A two-handle faucet does not mix within a single cartridge like a pressure-balancing valve and therefore has zero effect on a heater that is flow and pressure sensitive.
What are the requirements for ASME construction in the State of Florida?
The ASME boiler code calls for ASME construction of water heaters, boilers, storage tanks, and expansion tanks if one or more of the following conditions apply:
1) Any unit that is rated at 400,000 Btu or more (gas fired)
2) Any unit that is rated at 120 gallons or more
3) Any unit that is rated over 58 kW Input (electric fired)
Most states use 200,000 Btu as their threshold for ASME, but Florida is higher at 400,000 Btu. You get an understanding why there are many units rated at 199,999 or 399,999 Btu or 119 gallons or 54 kW maximum.
I am confused by inspectors who call for conformance with the Florida boiler dode when my heater is rated at 300,000 Btu with 65 gallons of storage. Doesn’t my heater fall below the ASME requirements of the State of Florida?
Your heater does fall below the ASME requirements, but the inspector is referring to the boiler room itself, not the water heater. The heater does not have to be ASME constructed. However, the Florida boiler code calls for a two-hour fire-rated mechanical room with sealed, fire-stopped penetrations on units of 250,000 Btu or more. It can be tricky to figure out sometimes, but it is always best to ask for code interpretation from your inspector prior to final installation.
I have a high-efficiency heater that vents with plastic piping due to its low exhaust temperature. My installation requires the vent piping to run through a return air plenum. Can I use plastic piping such as PVC or CPVC?
No, not in this application. Many high-efficiency, gas-fired units can be vented with a sealed plastic vent system. Most manufacturers specify either PVC, CPVC or ABS as an ap- proved vent material.
Any plastic piping that runs through return air plenums must be water-filled or specifically rated for use in return air plenums. In these instances, it is recommended to use a metallic vent material such as AL29-4C stainless steel in plenum areas. It is approved as a sealed Category IV vent system and can transi- tion to and from plastic piping. Another alternative is to use a metallic sleeve, but that can be cost prohibitive and require larg- er penetrations, firestopping, etc.
Many heater controls, like flow switches and pressure switches, have multiple electrical contacts. Please explain the COMMON, NO and NC contacts on these controls.
An internal switch will turn the control on and off based on flow, pressure, temperature, etc. A switch has a normal position of either open or closed. When activated, the switch will per- form its specific duty to open or close a circuit.
• The COMMON contact is where incoming power enters the device and is connected to this contact.
• The NC contact is the normally closed contact. It has power already from the COMMON, but will lose power once the switch is made.
• The NO contact is the normally open contact. It is an open cir- cuit that receives power once the switch is made.
We will use a flow switch as an example. The flow switch is a normally open device that closes (switches) upon flow. When flow reaches a set, minimum flow rate, the power is switched from the NC contact to the NO contact. So, if wired to the NC contact, the power is lost upon switch activation. If wired to the NO contact, power is gained upon switch activation.
A pressure switch may be a normally closed switch or a nor- mally open switch depending on its service. An air-intake switch is likely to be an NC device allowing power across its cir- cuit, but if the intake gets closed off, the switch will open and not allow power to pass through. A fan prover switch is likely an NO device that completes its circuit once the fan has reached a certain speed or CFM, proving proper combustion fan opera- tion.
There is a document you can download that will give a great- er description of diaphragm switches and how they operate at: http://www.statewaterheaters.com/lit/handbooks/320988-000.pdf.
Why are there multiple high limits and other additional controls on many heaters and boilers?
Depending on its Btu rating, certain controls are required for safety. As a unit exceeds the ASME requirement, more controls are required to meet the ASME standard. For instance, in Flor- ida HLW-stamped boilers are required to have a low water cut- off device (LWCO) and manual reset high limit (MRHL). H- stamped boilers may require additional high and low gas pres- sure switches. Each state’s boiler inspectors have different re- quirements to meet their code. Some will require a float-type LWCO where others will accept a probe-type. A flow switch is an acceptable form of a LWCO on a circulating boiler/water heater in Florida.
There are also special insurance requirements like FM (fac- tory mutual) and IRI (individual risk insurers) that have addi- tional controls they will require. Most insurers accept manufac- turer’s standard controls on units under 400,000 Btu with addi- tional controls added on larger models. Depending on a unit’s approval by CSA, UL, ETL, etc., they will dictate the standard controls. Controls requirements increase with higher Btu in- puts, as set forth by the approving agency.
It is very common to see a couple of high limit controls. One is typically auto-reset and another is manual reset. These con- trols are wired in series with the operating thermostat. The high limit controls are designed to prevent over-temperature by shutting off the boiler. The auto reset control will reset itself once the temperature has been lowered to a safe condition. The manual reset is set a little higher than the auto reset and has the same function. However, if the manual reset is tripped on temperature, it requires someone to physically reset it.