Heads up...
As of September this year manufacturers will not be allowed to import or manufacture for sale in Spain conventional gas wáter heaters or conventional boilers into Spain. All boilers will need to be:
- balanced flu wáter heaters
- condensing boilers

Existing stocks can continue to be sold until exhausted.

So what?
1. They are more expensive
2. They need electric power to function

In the case of the boilers this is normal so shouldn't cause problems (excpt in installations running on solar - see the bit about an earth below).

In the case of wáter heaters there are many installed in houses where there is no 220V power available (running on 12V system) or generator only. Some are installed in places where there is no power available.

A secondary problem is that some boilers and heaters require an earth to correctly function. Most solar systems are installed without an earth or in a way that an earth wasn't deemed necessary.

So, just in case you are planning your big reform/rebuild/new build, take into account that you will need to have a power source for your wáter heater, if not today then in the future when your existing heater breaks down.

Does this apply to an externally mounted contraption ?

As far as I'm aware it is all domestic units without exception.

How did we all survive the ascots of the 1950's?

After the Corfu incident I will be glad to be rid of mine. I'm installing a few extra solars and going to electric heaters. I know there are more 'efficient' ways of doing it but the fragility and cost of a glass tube system or the cost of a heat pump don't add up against €500 of extra solar PV. Add the fact that the extra juice is available for other things once the water is hot and I'm hoping for a winner. - I'll let you know.

Many didn't  :(

The change however isn't for safety more for energy saving and is from the eu - ErP (Energy Related Products) directive.

It comes into forcé on 26th September

Having worked in the domestic gas industry for almost 40 years I can safely say that every incident of carbon monoxide poisoning I came across was due to
1/ poor installation
2/ lack of maintenance   
3/ poor or inadequate ventilation

The Corfu incident was a combination of all three, Conventionally flued appliances are always a higher risk but please remember ANY FOSSIL FUEL BURNING APPLIANCE HAS THE POTENTIAL TO PRODUCE CARBON MONOXIDE