Some of my experiences cleaning sediment out of a hot water tank, in this case, powered by electricity: The first time was about three years ago. I started to drain the tank in preparation for replacing the burned-out lower heat element. I had attached a garden hose as most instructions tell you to do. At first the water (quite black with sediment) drained out as expected, but in a minute or two, it slowed to a trickle; I was sure the tank could not yet be empty. I soon discovered the outlet valve was plugged, and eventually removed it to get the water running again, directing it to the basement drain across a plastic sheet fashioned into a sort of trench with sides made of some short 2x4s and bricks under the plastic. The sediment came out in chunks up to 3/4" across. They were easily crumbled, but nevertheless had been solid enough to impede water flow through the valve. I reattached the valve, but felt that wasn't good enough. Following some advice from somewhere on the web, I purchased a brass nipple and ball valve from a local plumbing store and installed them to replace the original plastic valve. The inner diameter was now larger and without bends, so less likely to clog. That helped quite a lot. Meanwhile I had removed the old element. So I had an extra access hole available. I rigged up a piece of 1" plastic pipe to the end of my shop-vac hose and was able to insert that into the element hole and pull out a substantial amount of sediment. I also was able to insert a garden hose into the same element hole and flush out more sediment through the new valve outlet. I'm sure I never got it completely clean, but at least the escaping water was now clean and running freely. I installed the new heat element, and all has been fine since then, except of course, I would like to be able to do a proper regular cleaning without removing that heat element. Since that time, I have tried to remember to flush out the tank every six months or so. It hasn't been completely satisfactory, but I think if it's done regularly, at least the build-up won't be too great. Just today, I had some trouble even with that better brass valve. It became clogged as the other one had before. This time I found a good remedy in a length of 3-wire 10-gauge soft-coated electrical cable. It seemed to have just the right amount of flexibility and stiffness. Poking that through the valve and into the tank removed the obstacle. I'm thinking that for my next cleaning, I will try to attach a piece of narrow tubing to the end of a garden hose and push it into the outlet valve to do some back-flushing. At least I'm lucky in a way to have an old unfinished basement with a concrete floor and a big drain hole. Spills are not much of a problem. I'm very happy too with my makeshift "trench" which works very well to take the outflowing water to the drain. It cannot clog like a hose, and I'm even able to make a dam to catch the sediment by means of a simple fold in the plastic sheet.

Regarding SFR, Service Flow Rate, in water softeners there is more than the control valve to consider. The peak SFR of the control valve is one consideration but another consideration is the SFR of the resin. The SFR of the resin varies based on the volume and type of resin and is more often the factor limiting the SFR of the softener. According to a Purolite rep, a resin manufacturer, the SFR of 1.5 cu ft of C100 (a common resin) is 7.5gpm. A 1.5 cu ft softener is commonly referred to as a 48k softener but the amount of resin is a more accurate description than the "K". You want to size your softener so that the SFR of the resin is higher than the peak SFR of the house plumbing and fixtures. If you don't then when the water flow of the house or fixtures exceeds the SFR of the resin hardness will leak through. If you want to use the big blue filters then perhaps two housings in parallel will provide adequate flow. It's a good idea to install pressure gauges before and after filter housings to monitor the pressure drop so you know when to change the elements. A water test from your tap is always recommended, but based on your post... with 20g harness, .3ppm iron, and 4 people I'd be looking at a larger softener in the 2 cu ft to 2.5 cu ft range.

Nothing to see here.

So definitely a thermostatic valve and not just a pressure balanced valve? Geoffrey, I believe most locales require pressure balanced valves, not thermostatic. I appreciate your opinions on the heat recovery system. It might be true that you might not see much payback if you have natural gas, with lower operating costs and quicker hot water recovery. However, I don't have access to NG, so I have to go all electric, which is more expensive and has a much slower recovery time. I was skeptical at first as well. But I have talked to people that have them and they work. And I have read the independent research papers that show they work. And I have calculated the affects on a water heater if you change the incoming water temperature from 50F to 75F. If my calculations are correct, my payback will be instantaneous, because the money I spend on the DWHR system will be saved by being able to purchase a smaller capacity water heater.