I still have a few questions about how best to heat DHW. Superstor probably the best option but in my case I would still like the electric to take over in the summer months or in cases where I let the storage cool too much. Even one cold shower and I would probably never hear the end of it. Superstors are expensive (>$1000) and not something you buy when you already have a new electric tank type. Many are using the flat plates now with a flow switch to make an on demand heater kind of like the new gas fired tankless ones that have recently became popular. While I see this working fine for the most part, I still see a few times on a gasser/storage setup where the storage gets too cold due to a missed firing or a larger than expected demand (ie. dishwasher, extra laundry, jacuzzi bathtub). I saw this Ebay Sidearm that looked interesting. It has 7 small tubes with an 1 1/2" outer tube that is only 13" long compared to typically 48". The claim is that the extra tubes gives the extra heat transfer making the long tube unnecessary. Also they claim that the short HX allows for better thermosiphon action compared to a full length sidearm. I'm assuming they mean you can mount it closer to the bottom of the tank which should improve the flow. One thing that concerns me is the possibility of a leak which would be disastrous. I would think even the plate HXs have to potential of this happening. I'm guessing on a Superstor the piping is continuous without any joints touching the DHW making it very safe. On an old style sidearm the only danger of a leak would mean a mess on the floor not contamination of drinking water. Unfortunately the way they made this one it looks like a failure on the solder could be disaster. If the properties of their design really does improve heat transfer and thermosiphoning, I wonder how an improved version of theirs would work moving the connection of the 7 smaller tubes into one DHW fitting outside the 1 1/2" pipe holding the boiler water. Bottom line the 7 small tubes would be completely continuous where they touched boiler water. Worse case of a solder failure would be boiler water leaking on the floor, not contamination of the drinking water. Maybe I'm too cautious but I don't like taking chances when I don't have to. I would rather stick with electric DHW than have a 0.1% chance of failure. Any thoughts?