Keeping readers abreast of new developments in plumbing materials, products, tools and practices.
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Introduction As the author mentioned upstream, utilities have run large scale tests which dramatically showed how much more energy efficient heat pump water heaters are than the standard electrical resistance type. But, until the day when we find/see the upfront costs of purchase and installation of heat pump water heaters priced within the reach of most of us, the author believes their widespread inclusion will be a tardy one. For those readers fortunate enough to be contemplating a remodel or a new home, the author would like to share with you (in Top Drawer) what he would plumb, if it were his residence. (It would not include a heat pump water heater, as made at present.) This recommendation involves a particular brand and model of standard electrical resistance fired water heater, serving a 3/8” and ¼” PEX short run home run installed Water Distribution System. However, for a replacement only situation, Pete would have to stick with (vote) the heat pump water heater. Now, structures built on a raised, (crawl-able) perimeter foundation are ‘survivable candidates’ for a PEX re-piping operation. Structures ‘on slab’ are usually trickier (and more costly) to re-pipe (in any material). Since the major available re-piping pathways for a one-story, on-slab structure are ceilings and attics space, re-piping in PEX makes the most sense for both performance and price. Top Drawer Anyone who has read Plumbing A House might recall that the author used the term ‘Top Drawer’ to describe his approval of products, practices and level of workmanship. The reader may also recall Pete telling his readers that he was of the belief that because of the nature of a plumber’s work that the plumber had a higher moral obligation to do the best work (top drawer?) than any other tradesperson. What we do affects the health of all present and future residents of the plumbed structure, until such time the product or system needs replacing. What aspect of modern life is more critically important than access to a sanitary water supply. A heated sanitary water supply. What the author discusses in Top Drawer is his recommendations for a ‘top drawer’ product and practice. Via “Top Drawer” Pete highlights the attributes of pairing a particular standard electrical resistance residential water heater, and small diameter (3/8” and 1/4”) PEX freshwater distribution piping. The combination of the Rheem Marathon standard electrical resistance water heater and manifold supplied (“home runs”) PEX (preferably UPONOR) is a ‘Pete’s Ticket’ to performance and longevity for a Fresh Water Distribution system. The first major contributor discussed is our choice of water heater. To see why we will first look at the source of the hot water used in our design (before discussing piping materials) goes back to the upstream discussion about warranties, steel, and anodes. Take a good look at what warranty’s manufacturers today are offering for their heat pump offerings. 10 years? What is a fair cost of purchase, with installation, for the average heat pump water heaters? Pete’s general contractor friend, Eddie M., billed a recent client for a heat pump water heater installation (Photo 1, below). (This included the removal of an existing natural gas fired heater.) The billing price was greater than had he been installing a standard electrical resistance water heater. To install the client’s pick of heat pump water heater it had to be moved to a new location because it did not fit in the space of the existing. There (gratefully) happened to be plenty cubic feet of open surround space, a first requirement. A new electrical supply (4,500 Watts) and a new water supply had to be run to the new heater location also.  Photo 1: Air Enabled Heat Pump Water Heater Photo Credit: Eddie Marciniak The client’s chosen Rheem heater Eddie installed has a 10 year warranty. This type of heater is referred to as a hybrid. The 4,500 Watts required is greater than other makes and models. The reason the client chose the hybrid model was because it was constructed with a good, mechanical, internal ‘insurance policy’: 2 standard electric resistance type heating elements at the ready in case the the ‘heat pump function’ of the heater failed. The extra elements would then take over (automatically) and heat until such time (automatically) heat pump function is restored. (This service failure can be due to non-maintenance, worn moving parts, or atmospheric/temperature change.) (A standard electrical resistance water heater has far fewer gremlins.) Will an owner of a heat pump water heater be a conscientious one and perform the filter cleaning maintenance their heat pump water heater needs, to maintain it’s designed level of efficiency? If the maintenance is not performed, not only efficiency suffers but this can be a cause of a service shut down. The author’s recommended choice of the Rheem Marathon standard electric resistance water heater, by comparison, has minimal post-installation maintenance requirements (atmosphere and geography being benign). Pete’s recommended Rheem Marathon water heater has a tank lifetime warranty. The application of this heater choice feeding short, 3/8” and ¼” PEX ‘home run’ piping to the latest ‘low-flow’ valves and fixtures accomplishes this (silently). Sans motors/compressors, employing PEX, this Marathon needs to heat much less water (a ‘big deal’ savings, now, and a ‘huge deal’ as we move forward.) Heat pump water heaters may last 15 years with proper maintenance. The Rheem Marathon standard electrical resistance water heater has a lifetime tank warranty. The heat pump water heater using 120 Volt supply uses less electricity but has a much longer recovery time, and a relatively short life compared to the standard electrical resistance, lifetime-warranted, Rheem Marathon. (How many replacement heat pump water heaters later will be required to match the continuous service of a Rheem Marathon electrical resistance water heater?) A generational ‘chain of family’ could live, served by one Marathon paired to short ‘home run’ PEX, where another family depending on (today’s) heat pump water heaters would have to purchase several. Why: steel, anodes (the lack of), and electric motors. The Marathon has no anodes; no electric motors. It doesn’t need them! Its tank is fiberglass. The Goods If the reader has read the PEX Edition of Plumbing A House, PEX is then ‘old hat’. What Pete the Plumber did not discuss in the book (aside a few other things) was the Rheem Marathon standard electrical resistance water heater. The author now thinks (before discussing piping) it’s time to delve into why he is recommending this electrical resistance water heater. Actually, other than the standard type electrical heating elements found in mass produced electric water heaters, Pete’s choice of electric water heater has little about it that is standard. The reason he wanted to bring this water heater to your attention involves two issues: performance, economy and efficiency when serving small diameter PEX piping (preferably Uponor). Steel, Anodes and Motors Yes. The author loves the efficiency gain of heat pump water heaters (and resulting energy economy). But, steel tanks, anode rods and electric motors (for this purpose) turns Pete off. It’s like buying a car. For the first year (or two) of your ownership, all goes well. But you know in your heart you are operating a mechanical gamble. ‘Some’ component ‘down the road’ is going to retire and leave you needing someone else’s talents, accompanied by a bill. For most, installing a standard electric water heater (or even a gas one) affects their worry/concern ‘space’ in their conscience less than concerns of maintenance and repairs with heat pump water heaters. (Not to mention purchase price). The author used to kid folks that under hoods of modern cars: “It’s all belts, hoses and cables, can’t even see the engine.” Guess what it looks like under the top of a heat pump water heater? How many people do you know who might be able to troubleshoot these beauties? Extended Warranties? You’d better. It’s not just the complexity of the heat pump water heaters operation, there are things called steel and anodes which will (eventually) sink your ship. And mass marketed heat pump water heaters have both. 10 year warranties are pretty standard and five year extended warranties are also available. Still on the showroom floor, your new love will easily set you back over 2K. (Any sales tax?). However, one aspect of heat pump water heaters that does intrigue Pete is the inclusion of Wi-Fi. (While the system functioned as designed people could save money using it. The appliance can be custom regulated, remotely. (Will sunspots and hackers ruin the picnic?) Another Way? The author is next going to make a suggestion: For new construction/remodel why not use a little inefficiency to gain a much greater end efficiency. (No, it’s not a perpetual motion machine.) “It” is a choice of employing a Rheem Marathon standard electrical resistance water heater (4,500 Watts) to serve 3/8” and ¼” PEX fresh water distribution piping. This ‘combo’ suggestion is admittedly best practical for two situations: those involved with new construction or the remodeling of existing structure. (The featured Marathon water heater though, is, alone, a ‘top drawer’ choice for those just replacing a standard electrical resistance or a gas heater in existing structure.) Without the nuisance of the flue pipe and gas line for/gas water heaters, siting an electric water heater has many more possible locations. Operating a heat pump water heater using 120 Volts for a traditional “straight line” (trunk and branch) piping plan could cost as much (or more?) as the Marathon operating at 4,500 Watts serving a well-designed, short run, small diameter PEX ‘home run’ distribution plan.  Illus. 1: Rheem Marathon WH Cutaway Illus. 1, above, is a cut-a-way view of the Marathon heater. No metal outside skin to rust; no steel tank to rust/corrode; no need for sacrificial anodes. Plus, a union top connection for the Temperature and Pressure Relief Valve and a Titanium lower heating element... Good reasons why the ‘out the door’ price (though considerably less than a heat pump water heater) is sufficiently ‘dear’ that most homeowners faced with an unplanned water heater replacement might settle for a lot less. (For fear of not living long enough to ‘spend that kind of money’. In some instances there may well be some truth to that. However, the author believes there are many others who will find the ‘peace of mind’ of being served by Marathon and Uponor worth the investment. Frown The author’s Mid-Western ‘dairy’ folk had a saying: “Even good chickens can lay bad eggs.” Well, there is a component aspect of Pete’s choice of water heater that the author wishes to caution you about. In Photo 2 we see an assembly of valve and fitting Pete would say: “Definitely not Top Drawer” (for this purpose). What’s ‘going on’ here? What is not going on is an efficient means of draining the tank of both water and sediment. Anyone who purchased a Rheem Marathon and found a facsimile of Photo 2, Pete would highly recommend an immediate removal and replacement with a ¾” ‘full-port’ ball valve such as Photo 3 which allows for the removal of sediment build-up (not just the water in the tank).
 Photo 3 Valve Specifications The valve in Photo 3a, below is what is called a ‘globe’ valve (shown next to a ball valve for comparison). This designation of valve has been with us for a very long time. It has a couple of qualities still appreciated mostly by industrial/agricultural interests. The globe valve though is not the best choice for thoroughly draining a water heater with sediment.  Photo 3a: Ball Valve has a “straight through” passage best for draining sediment. Photo Credit: Stormquist & Company The reason today that few favor it for this application is because of the level of friction the water (and sediment ) is subjected to as it passes through the valve. The friction slows down the waters velocity and flow, Illus. 2. Engineers have a term for this: Frictional Loss. Photo 4 is a graph comparing the frictional loss of various valves, fittings and pipe materials. We see that a globe valve for ½” pipe has a frictional loss co-efficient of 340 and the frictional loss of a ½” (full port) ball valve is 3, many times less. The 50 gallons in a Marathon would drain dramatically slower through a globe valve than through a full port ball valve.
But, it is not the water drain rate that Pete is most concerned about; it’s the ability of being able to remove sediment from the tank. Compared to a full port ball valve, much less sediment will pass through a globe valve. In Larry Weingarten’s book: the Water Heater Workbook, the reader learns how important sediment removal is for tanks of all materials. Full Port ball valves are crucial to an efficient routine of maintaining clean holding tanks of all types. Caveat Globe valves are considered superior to gate valves for remaining leak/drip-free. Could that be why someone found it applicable for duty on a water heater? Stop-Cock The author hopes readers who managed to ‘hang on’ until this point found out new things about water heaters which might be of help ‘someday’. On that subject, me is now ‘stop’erd’.. If we are all lucky the rains will continue soft and on schedule and the sun will shine benignly upon us and our lands. Reality, we know, is not likely to ‘play out’, such. Somebody will be needing a new water heater…soon! Until ‘something’ in plumbing gets Pete off-the couch, again, readers may want to get off their couches and familiarize themselves with how and from where their hot water is produced. PtP
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Author
Peter Hemp is a San Francisco East Bay residential plumber and plumbing author and former R & D steam vehicle plumber. His hobbies are ocean kayaking and touring the Left Coast by bicycle. Archives
March 2025
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