So, I just cleaned a bunch of mineral buildup out of 30 year old electric resistance unit for about the 4th time. I shut off the breaker, opened the pressure/temp relief valve, drained the tank. I then pulled the lower element and spent about an hour with a wet/dry shop vac connected to a piece of 1/2 PVC that was heated and bent to a custom curve. Usually I know its time to do this maintenance because the lower element has burnt out -- not this time. I recall during the last maintenance session that I'd installed a different style of heater element that is longer, doubled back on itself, and has a lower energy density output per length -- supposedly making it less likely to fry when the growing pile of minerals engulfs it. It must have worked as the element looked good and is working fine. I checked its power draw with a clamp-on amp meter when I re-powered the heater. I'd also previously replaced the drain valve with a full-flow ball valve that allows larger particulate matter to exit the heater. Mineral build-up is a very common problem in electrical resistance water heaters, especially in our area. I've found our water heaters actually function as softeners in that they remove dissolved minerals from the water. Unfortunately this leads to frequent maintenance or replacement. I opt for maintenance because it makes better use of my time and money and because I don't like sending stuff to the landfill. On a tangent here: As I inspected the mineral-crusted heating element I recalled that its widely held that scale reduces the efficiency of electric water heaters. My question is how? Electrical resistance heating is about 100% efficient and any inefficiencies that do occur would do so as heat (which is the end goal) so how does the coating of minerals on the element decrease efficiency? Getting a little deeper into the weeds I can see how the efficiency of my GeoSpring heat pump water heater might decrease with mineral buildup on the inside of the tank since the HP condenser coils wrap around the outside of the tank. The mineral build up would act as insulation and force more of the heat out through the outer tank insulation.
I don’t think it’s a good idea to open the pressure relief valve to drain a tank, they tend to leak when you do that. Open faucets upstairs. I have the same problem with my elements building up so I replace the bottom one once a year and clean the tank at the same time. It’s cheap and easy.
Do you mean that they leak later because they don't seal once closed? If so, I'd rather know that and replace it. Opening the valve allows the tank to drain much more quickly.
also after cleaning it out seal it back up and pour in some CLR, it will foam up and dissolve the small stuff. You can dilute it to gain some volume but I start full strength then add some water. you need to have something up top open for expansion I have left it for as long as a few hours while checking on it. It will take a good amount of water to rinse it out so depending on what you have to drain it into that could be a problem.
I've experienced first hand one not resealing so it can definitely happen. Edit: Funny, a home inspection site recommends owners open these valves monthly to test but don't advise inspectors to open them. TPR Valves and Discharge Piping - InterNACHI
Funny to find this post. I was talking just yesterday with a co-worker about this problem. He has high iron content in his well water, whereas I have a lot of calcium (and/or lime) in our water. I was mentioning to him that I had the same problem as Semipro and had to replace the lower element about 3-4 years ago and had to clean out the tank. I have neglected it since, and was telling him that I really need to put that on my todo list this year. I didn't put CLR in the tank, but did put Vinegar in and let it sit for an hour or so, it broke up a lot of the larger stuff and let me clean it out pretty well. Our toilet however requires some CLR at least once per month. We also have to run vinegar through the coffee pot pretty regularly, we go through them WAY too quick. Chaz
...what exactly are you doing to 'clean them out'??? I just turn the power off and open the valve on the bottom and let cold water run through the system for a while...I do like the idea of vinegar or CLR though...and how frequently do you do this?...our water here is very hard. Thanks.
Well, for the most part, that's about it. When our element blew, I drained the water and removed the element (lower of course) and found that it was completely coated in gunk. I am certain that is why it blew, too much insulating material keeping the heat in, and therefore more elec trying to overcome the resistance. During the draining of the tank it went slowly and I wasn't sure why at first, after I saw the element it made sense. Lot's of white calcium came out at the end, but not nearly what was in the system. I started to just shove a coat hanger in to bust stuff up, end rounded for extra measure. That didn't cut it. I poured about 1/2 gal of white vinegar into the lower element opening, put the old element back in and waited for about an hour. Then turned water back on, with lower drain open. I doubt I got it all out, but by the time I was done, it flowed well, and seemed clear. Put new element in, connected wiring, closed things up and haven't really thought much about it since. The last sentence is part of the problem. Not thinking about it. Preventative measures are just that, preventative, not reactive. Thx for the reminder of my to-do list. Chazz
I have to replace the lower element yearly. Thankfully, the elements are sold at the local hardware store, so I don’t have to make a 2 hr round trip to get to a big-box store. I also have a piece of 1/2” copper pipe on a fitting that goes on the shop vac. I usually get about 3 gallons of sludge out after the tank has drained. I then put a couple cups of vinegar in, add some water, then let it sit for a while. Drain and rinse, install the new element, and refill.
