I currently dont have any timer function, its just connected to a honeywell dial thermostat. The boiler is plugged into a normal switched plug socket on the wall. From what i have so far read, i gather this is not technically OK, but is safe enough (the plug is right next to the boiler, and the socket will not ever be used for anything else, i live on a houseboat and the boiler is down in the engine room). I have not lived here long but i know that it has been like this many years, and the boiler is always serviced yearly, so presumably the engineer doesn't have a problem (although i will ask him next timer he comes of course). So my question is, could i put some kind of electrical timer into the plug socket so that i can turn the boiler on/off at set intervals. As long as its rated at the very least 5A (from the data sheet) would it be an issue electrically? On the other hand, would cutting the power on / off, especially cutting it off whilst the boiler is running cause the boiler any harm?
In the main no, most boilers need to cool down before being switched off, they are OK with an odd power cut, but not regular switching off. Normal is to use a programmable thermostat today, so boiler not switched off completely it will maintain a back ground heat to stop freezing, the old idea was a programmer which was in real terms a time switch, and two thermostats one for room temperature and other to stop freezing.
The rules for houses do not extend to boats, so boilers do not have to comply with energy saving rules, often there are heat exchangers so both engine cooling water and the boiler heat the boat and domestic hot water, and often there is a large hot water tank.
So the boiler heats water tank as and when required, and water tank heats boat, so boiler, engine, and solid fuel stove all heat the domestic water, and pumps are doubled up for safety, and 12 or 24 volt direct from battery so lost of mains supply will not over heat water.
I have only worked on a narrow boat, and there are some special rules, most houses, caravans etc can have a vent to allow heavy flue gasses to escape, but clearly with a boat that vent would cause boat to sink. So the gas fridges used in caravans, can't be used with a boat.
Some times you need extractor fans with flaps and micro switches to auto switch off boiler should fan fail. Seem to remember the The Recreational Craft Directive, Directive 94/25/EC on recreational craft, as amended by Directive 2003/44/EC, is a European Union directive which sets out minimum technical, safety and environmental standards for the trade of boats, personal watercraft, marine engines and components in Europe controls what you can and can't do.
Since I don't work on boats any more, not sure what the RCD says as far as house boats go, or even if it covers house boats.
Thanks for your very detailed answer - i will give the idea a miss then. I actually have a programmer but i just have not had it installed yet and was looking for a short term fix, but ill not risk it.
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