Quote:
Originally Posted by chaley
This is really 
Where I am (Nottinghamshire England) there are four hot water types that I know of: - Gas "combi boilers" that produce hot water at need. No tank. Whole-house non-gas tankless heaters are extremely rare.
- "Power showers", an electric heater for water in a shower, are very common. Some houses don't have any central hot water, instead using these wherever hot water is required, such as the kitchen sink.
- Water mains pressure, where the tank has a secondary pressure control air tank. The secondary tank prevents the water tank from exploding from over pressure. It is a mystery to me why English tanks require this extra tank so they don't explode while French and US tanks don't (I've lived in all three countries).
- Gravity feed, where the tank is in the attic, open to the air.
It is worth noting that some houses here have cold water cisterns in the attic, filled by the water main and emptied by gravity. Reason: the water main can't supply enough water at pressure to be usable. These cisterns must be emptied and cleaned occasionally to avoid mold and critters taking up residence. There are frequent stories about finding floating rodents in the cisterns.
The hot water tanks are heated by one or both: - Indirect heating, where the water in a tank is heated by a boiler (oil or gas), a heat pump, some solar system, or perhaps an alternate fuel burner such as wood or peat.
- Electric immersion heater(s). In my experience an immersion heater is 3kW (13 amps at 240v). In my flat, one tank has two of them and another tank has one of them.
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Very comprehensive. The indirect uses a coiled pipe in the hot tank carrying the boiler water so the boiler water is never fresh and thus doesn't corrode the boiler or radiators.
The actual boilers can be atmospheric, with a separate header tank (Most common in UK & Ireland), but newer systems are pressurised and need no header tank, even in England.
Most places have higher mains cold water pressure than the cold header tank. The drinking water is direct from the mains and some guest houses used to have a third green tap off the mains for drinking.
It serves three purposes:
- Evens demand (imagine all the taps running at once and toilet(s) flushed.
- Reserve supply during short outages and when mains pressure is low.
- Isolates the mains from your water.
The "immersion" heaters can be 4KW as they use their own feed from the fuse box. There are 3 kinds in the UK (inc mainland GB).
- Single element
- Two elements (Sink and Bath). Shorter one for sink.
- The third is sold by Screwfix in GB and is less common in GB and Ireland than N.I., and isn't an immersion at all. It's the external Willis heater (Economiser), easily retrofitted if the immersion fails.
Very ancient stoves used a direct copper boiler in the stove with the regular water going through it. I fitted one, once, to a restored cooker/stove. The house had been plumbed for an oil boiler so already had an indirect coil in the hot tank and radiators. Naturally, while it heated water well enough, you'd want it roaring with coal rather than glowing with peat/turf/briquettes to turn on the pump for the radiators. The actual boiler on indirect systems can be cast iron or steel as it never gets fresh water.
The non-pressurised heating systems do slowly take in air through the header and over the years you can get a build up of black iron oxide sludge (due to less oxygen you don't get the orangey iron oxide called rust) and it may need flushed. They sell very expensive inhibitors.
One lower pipe under our solid kichen floor totally blocked and wouldn't flush, so to get the lounge and hall radiators going a second parallel pipe on the floor at the wall was added. Cupboards and stove in front so can't be seen.
Solar water heating needs a pump unless less you can fit the indirectly heated hot tank higher. You see those on a platform higher than the panels on flat roofs in some countries.
Also, fun trap for visitors from countries where hot and cold are always at the same sides of the sink, is that the placement seems to be random here. There may of course be a spec.
The major UK / Ireland services differences:
No DAB radio in Ireland. Turned off some years ago. The now ended AM on LW
lasted longer.
Single water authority that they suddenly decided might be a bad idea to privatise.
Each electricity meter box has it's own huge earth spike in the ground connected to neutral, in UK that's only at the substations. From 1947 the UK had ring mains to feed the rectangular pins sockets, so a fuse in each plug (previously there was 2A, 5A in two and 3 pin, 15A three pin and appliances plugged into the bayonet lamp sockets with a Y adaptor). Ireland had that as well as German Schuko plugs and adopted the UK plugs (as did Hong Kong, Malta and Kenya. South Africa stayed on the old system), But Ireland never adopted the "ring mains", but the US/European and previous UK system of spurs.
Also Digital HDTV in Ireland uses DVB-T, but UK is DVB-T2. The UK SD is on DVB-T, but isn't H.264. Irish SD uses H.264. So newer UK TV sets work here, but older UK TVs and setboxes with only DVB-T don't work here because those don't have H.264 encoding.
Also road distances and speed limit in Ireland are Km but in UK are miles.
Also it's not the Republic of Ireland, just Ireland (only Éire in Irish), though part of the Island of Ireland is in the UK, but still keeping many EU systems.