Hey - only one typo. I'll see if a clone can delete the preceding mess.
I'm not sure how much it will contribute to the "fold process" but the differences between us are interesting.
Some differences between US and UK practices will be apparent to US users by looking at the "typical(?)" UK domestic hot water systems shown at Plumbworld
UK people will have to tell us whether it's really typical.
The illustration for the "Unvented system: (sealed system)" about 2/3 of the way down the page is probably closest to what is common in the US, at least in my area.
The exchange coil shown at the bottom will seldom be used in "domestic water" heating in the US. In places where I've been in the US, any house heating by "water radiators" was always by means of a completely independent system. "Radiators" are still found in a few older homes, but most of them get converted to "forced air" as the old systems break down. Systems to tap the central heating boiler for "domestic water" often get replaced to install a more efficient "tapwater" heater closer to the point(s) of use.
Central fired hot water is used fairly often in multi-dwelling buildings, but the occupants seldom know anything about the systems used in such places. Even where a central boiler is used for space heating, many individual units have their own "domestic water" heater (so they can pay the bill for their own usage?).
The electric "immersion heater" would nearly always be at the very bottom of the tank. A secondary "recovery" element is found rarely – but only in "high priced/deluxe" units not too commonly used.
The "pressure vessel" shown quite prominently in the illustration is seldom used as such in US systems that I've seen. A small "deadhead" piece of pipe, to trap a very small air space as an "anti-hammer" device is sometimes used in the same location, and sometimes (rarely) on the hot water outlet line as well. Occasionally you'll see commercial "anti-surge traps" used there, which are just a "prettier" chunk of empty pipe.
The illustration shows an "expansion relief" valve on the cold water inlet line, and also a "pressure regulator" and a "nonreturn valve," none of which are commonly required by US general or municipal codes in this usage. In a few areas, they may be used, but are generally considered part of the "water inlet system" rather than part of the "hot water system," and would not necessarily be located near the water heating system(s). (Some other water systems, e.g. lawn irrigation, may require even "fancier" devices in some places in the US.)
The general tone of the article implies that UK domestic water is commonly heated by electric heaters. While this is done to some extent in the US, natural gas is much more commonly used, wherever available. This generally means a burner at the bottom of the tank, a "flue pipe" through the middle, and exiting at the top. Codes in most US areas prohibit "anything flammable" within 6 inches (or more) of the exit flue pipe, which pretty well wipes out any space directly above the tank that might be used for storage. Many municipal codes require a specific "clearance" around the entire tank, usually something on the order of 6 inches or so.
(Natural gas, or even propane, has traditionally been much cheaper to use in most parts of the US than electricity, for "bulk heating" applications. Since the gas companies have learned to price it at "what the market will bear," rather than at "cost of production plus fair markup," the situation is changing, and electric heating continues to become more common.)
The common US building codes, particularly for gas water heaters, pretty much rule out the use of the "waste heat" for warming a clothing/linen storage area, since any device that uses "combustion" may be required to be "enclosed" so as to separate it from "living areas" of the home. Although there's much variation in local codes, heaters beyond a certain size are frequently required to be provided with "outside air" for combustion. Since the products required are seldom locally produced, the manufacturers conform to "the most restrictive" codes in order to able to market nationally.
The article states that in the UK the tank itself is commonly made from thin walled copper. Copper in this application is pretty much prohibited by "pressure vessel" codes in the US in general, and in most areas by building codes. (There are always exceptions.) The common material used for the tanks here is steel, heavily galvanized in the cheaper tanks but most commonly "glass lined," which means the interior is glazed with a porcelain coating. "Bare" tanks are seldom seen. The "commercial" product is almost always wrapped with a substantial layer of insulation, usually fiberglass, and the whole thing is inside a thin enamelled steel "case."
My recently installed 40 gallon (that's 9,240 cubic inches) tank is 18 inches in diameter and 56 inches tall (15,000 cubic inches) in its insulated case. I was forced to do significant modifications to "bring to code" with the replacement installation, which required a larger base/drain pan, new overflow line to drain outside the foundation, new flue pipe, and minor changes in water connections. It's installed now in a "closet" that's 27 inches x 27 inches (inside), floor to ceiling. Local codes say that I cannot store anything flammable in that space, or anything within 6 inches of the tank or within 10 inches of the flue pipe.
On the plus(?) side, the insulation is good enough so that there is less than a 2 degree F rise in closet temperature even when the burner is on. There really isn't much waste heat to use to warm your skivvies.
An "interesting" article at Citizen Survey (pdf) implies quite a bit of difference between UK and US practices. It reports that 91.7 percent of respondents use circulating hot water heat, and only 1.2 percent use warm air. These ratios would be essentially reversed in the US, except in a few local areas.
It also says that 88.9 percent of respondents use "mains gas" heating, and only 0.5 percent reported using electric heat. It's likely that the survey dealt mainly with space heating as opposed to "domestic water" heating, so this result is not surprising; although it differs from what's implied by some other sites.
It also strongly suggests that most people who use gas heat don't know what kind of system they have. This would probably be the same as the result to be expected in the US.
Question 18 on the survey reports that 76.3 percent of respondents get their "domestic hot water" (at the tap) from their central heating boiler. Few individual homes in the US have a water based central heating system, so virtually all individual homes, and many apartment units, will have a separate domestic hot water heating unit.
The main difficulty with this Citizens Survey is that I can't identify where it was conducted, or who was queried – except that they were mostly home owners (91.5%) and old farts (or fartesses – they don't say) (48.8% over 60). I'd suspect it was in a larger, mostly metropolitan area?