The 2019 Hot Water Forum
The Hot Water Forum (HWF) has been around for about ten years, meeting yearly. I missed one, once and still regret it. It’s a mix of manufacturers, code folks, researchers, utilities, local, state and federal governments, engineers and the odd hot water nerd, like me. People come from all over the US and some other countries to attend. It’s the place to learn what new stuff is coming, from energy codes, to new product roll-outs, to finding civil ways of duking it out between competing utilities… there is nothing else at all like the HWF. The event is put on by The American Council for an Energy Efficient Economy, (ACEEE) https://aceee.org/conferences/2019/hwf . It’s a small conference, where everyone there is treated as a peer. I’ll guess that close to half of the participants are involved in giving presentations… so clearly there is a lot of know how in the room.
I moderated a panel on solar water heating this year. They even let me present a very brief history of solar thermal! For too long, there has been a tug between solar photovoltaic, (electric) and water heating, (thermal). One of my presenters had a collector that was electric on top and thermal on the back side. The idea has been floating around for years with nobody being that successful at it. But this one seems to work and has a good track record. One interesting thing is that if you keep photovoltaics (PV) cool, they work better. By collecting thermal energy as well as electric, the competition between energy outputs is gone and you get more electricity! Not bad.
Another fun thing was we got to tour the biggest water heater manufacturing plant in the world. It’s just outside of Nashville, Tennessee. They put us in an electric trolley and drove us around, so we could see just how heaters are made. They create a new heater roughly every 20 seconds. It’s rather impressive!
Back at the conference there was talk of a new kind of heat pump water heater, one that runs on 120 volts and can simply be plugged in. With California and other places looking to reduce their use of fossil fuels, this could be a game changer. Gas has long been considered to be a clean fuel, but nobody took into account how much gas the distribution systems leak, something on the order of four percent. Natural gas, or methane is a potent greenhouse gas and that much leakage makes it worse than burning coal, pollution-wise. There may still be good uses of methane, like capturing it from landfills and cattle ranches, and using it where it’s produced will largely eliminate the leakage concern. In California, about 90% of our water heaters are gas, yet the state is telling us we need to get off gas soon. This new heat pump could help make it possible.
One nice thing ACEEE does is to put up on the web all the slides from the presentations. They are organized by the year given and available for free. In the link above, you’ll see a link to “past hot water forums”. Please do go have a look. There is a LOT of good stuff there.
One last but rather important thing we’re learning is about pathogens in the water supply. The take away is that there are lots and lots of bugs in our water, not just legionella. Mostly they are not harmful, but there are still many that are. There are even bugs that are resistant to chlorine and chloramine! There are bugs that resist heat! Bugs live in the bio-films that form inside of pipes, particularly pipes that are oversized for the use, which is most plumbing. Codes have not caught up with the use of water saving fixtures, so flow rates in pipes are slower. This prevents the scrubbing that happens with higher flow rates and encourages bio-film growth. Turns out one of the most effective ways of dealing with bad bugs is to introduce good bugs. Who wants to do that? It would be a very hard sell.
It’s pretty easy to get into the technical weeds at the Hot Water Forum, and there is no better or more supportive group for doing so. It’s a perfect place for hot water nerds! If you are one, consider going. The HWF will be in Atlanta, Georgia next year.
Hot Water Heaven
The real world isn't an easy place to be idealistic about hot water systems and what could be. Many compromises are made in cost, quality, expectation and education. Money and ego play a part as well. We'd like to daydream out loud for a bit and share some 'what could be's" and 'only if's" as they relate to hot water.
The ideal water heating system would be supremely energy efficient. It would last as long as the building it was installed in. It would be a pleasure to live with. It would be absolutely safe and of course, the cost wouldn't be too much.
You're not going to get such an elegant system installed by a plumber who isn't thoroughly trained in hot water work, or one who may be more interested in bringing home the most dollars per job, rather than insuring your satisfaction. The challenge here is how to properly educate the workforce, not just in things technical, but also in business basics and management. Correctly trained plumbers wouldn't lose so much work to relatively unskilled (and possibly unsafe) handymen.
Fortunately, when it comes to efficiency and longevity, we have lots of examples from the past to help show us the way. In 1906, there were condensing water heaters which claimed 92% efficiency (most modern gas fired heaters are more like 60% efficient). Since these were point of use heaters, there were no distribution losses or waiting for hot water. These were 'bath heaters' and the downside is they weren't all that safe. There were also "U" tube heaters. In these gas fired, tank heaters, the flue went up, near the top, then turned 180 degrees and headed down again. It would exit near the bottom. This doubled the heat exchange area of the flue, but even better, stopped much of the standby loss gas heaters suffer from. Our daydream has modern hot water engineers looking at old designs like these in order to incorporate the good ideas from the past into today's heaters. We’ve collected a bunch of interesting old heaters which the General Society of Mechanics and Tradesmen in New York will be putting on permanent display. Hopefully it will serve as a resource to future hot water engineers and anyone who’s interested in hot water.
Have you heard of Monel? It’s a copper / nickel mix that is currently used on high end boat fittings. From the 1930s to the 1950s you could get water heaters made of Monel. These and copper tanks were often the last tank a homeowner would ever need to buy. Such long lived tanks are essentially not available now. Roughly 85% of the nine million or so water heaters made yearly are sold as replacements. The manufacturers seem convinced that low cost is the most important thing to buyers, so proven long lived tanks are just a memory. Our dream has manufacturers competing to produce the highest quality heater, just as their predecessors did, instead of competing to make the cheapest heater. There are exceptions, but they make up a tiny fraction of the market.
The cost of the hot water system needs to be put in perspective. Manufacturers and plumbers both compete on price, but how cost effective is something that needs more service and frequent replacement? End users would need to be educated in the hows and whys of life cycle costing, where all costs over time are taken into account. This is the only way to know what really is a good deal. This may be an area where government and other institutions could set a good example and help to retrain the home owning public. More demand for long lived equipment would help to make such equipment readily available at reasonable prices.
Just as there are rating systems for energy performance in new construction, we'd like to see the same thing done for hot water systems. Ratings could be based on total energy use per person, waiting times for hot water, etcetera. This could motivate plumbers to do better than just meet code. Gary Klein is working on that with his “hot water rectangle”, which is a way of looking at wet room placement in a building and being able to see in general just how efficient it may be. See: http://www.garykleinassociates.com/
Sediment is a problem in many modern heaters, particularly those with aluminum anode rods. One fix could be the "external flue" heater. This had a narrow flue wrapping completely around the tank instead of the central flue common in modern heaters. Aside from increased surface area for better heat transfer, this heater allowed the lower tank head to be domed down. Sediment would collect at the low point in the center and be easily removed by opening a drain valve attached there. With modern insulation, external flue heaters would have much lower standby losses, making them very attractive. Us moderns have to live with pounding and thumping in gas heaters because sediment is so hard to remove from today's tanks. Aluminum anodes contribute by adding a great volume of corrosion byproduct. Magnesium anodes (although slightly more expensive) used to be the norm and don't make such a mess.
In our daydream, metal distribution piping, stealing BTUs from the hot water and holding way too much water would be a relic of the inefficient past. Manifold systems using well insulated 3/8" PEX tubing (or even 1/4” tubing for short runs) would be the norm for medium sized and smaller homes. This method provides quick hot water delivery, has much less water waste, and is installed more like wiring than rigid pipe, making new construction simpler and retrofit much easier. Efficiency can be had with devices that use electronics, pumps and various other active things, but long term reliability is one of our goals. For example: You can cut standby heat loss from an electric water heater with a time clock or with heavy insulation. We would opt for the "nothing to go wrong" insulation first. Of course a timer could be added to keep the heater off during peak periods, but it IS one more thing to get out of whack.
In an effort to keep heat from being lost, we've paid a lot of attention to combustion efficiency and insulation, but then we let all that heat go down the drain. Going the extra distance to recapture those BTUs with drain line heat exchangers (which are now made for both vertical and horizontal applications) begins to make better sense as the actual costs, both monetary and otherwise become known. In our dream, long lived, efficient systems would have minimal environmental impact.
We've been watching the progress of a non-electric flue damper for some years. It is a simple and inexpensive device that fits under the draft hood and cuts standby losses at least thirty percent. That could amount to a huge savings, but somehow, the long and winding process of getting approvals, perhaps combined with egos and territorialism all conspire to keep the device off the market. It would be nice to see more regulators and industry representatives looking at the common good rather than their own turf. As energy and clean water grow ever more expensive, such turf wars must become less relevant. Now, if you put one of these dampers on an external flue heater, you'll have one simple and high performance water heater!
Please don't think we have pessimistic daydreams. All the necessary technology already exists. Together we have the talent and muscle necessary to make dreams of efficient, safe and easy to live with systems a reality. We are only lacking consensus of all the players.
Looking back over my working life of 50+ years, it seems clear that self sufficiency has always been the best way for me to be useful. Now, mix in a strong interest in water in its many forms and the wide world of animals and you'll know what's important to me.