Mine's set at 60ºC (140ºF) and there's a mix-down to 55ºC (131ºF) after the tank, which is a thermostatic valve, similar to what you'd have in your shower, that ads a second step to prevent scald risks. The solar regs require that + thermostatic showers etc.
Water heating's indirect, so there's a large, insulated tank with a heat exchange coil from the gas boiler. When the thermostat 'calls' for heat, the gas boiler switches to rapid heat mode - a diverter valve operates and a pump starts for the hot water circuit, the boiler then cranks up the temperature to around 85ºC (185ºF) and that water is circulated through the heat exchange coils in the tank until the set point is reached. It then goes back to heating radiators again, at about 60ºC.
The gas boiler modulates and condenses, so basically you've a continuous Δt calculation - temperature output is measured and temperature returned is measured and as the heat absorption of the circuit goes up/down the heat input goes up/down to match. the gas flame is modulated down to match. So it will heat the water or radiators pretty efficiently. So, if the hot water cylinder is cold and is absorbing lots of heat, it will really crank up the gas flames.
At some stage, I will probably add a heat pump, but I need to do a fairly big retrofit of the house to achieve that as I'd need to replace a lot of late 70s plumbing and I don't fancy doing that until I want to do a major redecoration job. Also, want to see what the grant / tax incentives are. If I get the right deal, I might do it.
Also we're starting to see more high-temperature hydronic output heat pumps appearing. Those are suitable to basically replace the gas boiler directly. Low temp systems require a deep retrofit of the house as all the radiators are designed to run at about 60-70ºC, not the low temps that some of those heat pump systems output.
The various probes go into 'pockets' on the tank, so the solar heating and gas heating controls can monitor the temp at two points.
There's also a second coil from the solar panels and a priority system to ensure that the gas heating is only used if there's insufficient sun.
There's also an electric heater in the tank as a back up, but that's basically never used. It's really just a back up i case the gas boiler went down.
The tank stores 500 litres (132 US gallons)
@Laundress: Miele is usually ok with up to 85ºC, you are only up at 82ºC. If the pipes are soft, it's likely the hot water was >85ºC at some stage. Also if water / steam shot out of the drawer, it sounds like your water system may have a pressure relief issue! Is there steam shooting out of the taps?
Probably worth getting a plumber to check those thermostats!!!
It should be OK, but in general if you get close to boiling water, some of the internals may not like it, particularly the diverter valves in the water path selectors etc etc, but I'd be surprised if they were particularly offended by anything short of 95ºC - the machine itself (beyond the drawer) is quite happy to deal with near boiling water.
My grandmother used to have a 1920s hot water system that used direct-heat from a fireplace in the kitchen, as well as an later electric heater in the tank. Water was hot often hot enough to make tea. That thing destroyed a modern dishwasher, yet her old Electrolux washing machine never had any issues with it.
Hot and Cold fill washing machines were pretty standard here until the early 90s. In fact, most houses still have hot and cold connection points for them. I think, because they were less common on the continent, they just stopped producing special versions, particularly as water consumption levels dropped and it probably didn't make much difference anyway. The machines still had the same 230V supply and fairly beefy internal heaters, whether or not they'd hot fill or not.[this post was last edited: 12/9/2020-19:29]
Water heating's indirect, so there's a large, insulated tank with a heat exchange coil from the gas boiler. When the thermostat 'calls' for heat, the gas boiler switches to rapid heat mode - a diverter valve operates and a pump starts for the hot water circuit, the boiler then cranks up the temperature to around 85ºC (185ºF) and that water is circulated through the heat exchange coils in the tank until the set point is reached. It then goes back to heating radiators again, at about 60ºC.
The gas boiler modulates and condenses, so basically you've a continuous Δt calculation - temperature output is measured and temperature returned is measured and as the heat absorption of the circuit goes up/down the heat input goes up/down to match. the gas flame is modulated down to match. So it will heat the water or radiators pretty efficiently. So, if the hot water cylinder is cold and is absorbing lots of heat, it will really crank up the gas flames.
At some stage, I will probably add a heat pump, but I need to do a fairly big retrofit of the house to achieve that as I'd need to replace a lot of late 70s plumbing and I don't fancy doing that until I want to do a major redecoration job. Also, want to see what the grant / tax incentives are. If I get the right deal, I might do it.
Also we're starting to see more high-temperature hydronic output heat pumps appearing. Those are suitable to basically replace the gas boiler directly. Low temp systems require a deep retrofit of the house as all the radiators are designed to run at about 60-70ºC, not the low temps that some of those heat pump systems output.
The various probes go into 'pockets' on the tank, so the solar heating and gas heating controls can monitor the temp at two points.
There's also a second coil from the solar panels and a priority system to ensure that the gas heating is only used if there's insufficient sun.
There's also an electric heater in the tank as a back up, but that's basically never used. It's really just a back up i case the gas boiler went down.
The tank stores 500 litres (132 US gallons)
@Laundress: Miele is usually ok with up to 85ºC, you are only up at 82ºC. If the pipes are soft, it's likely the hot water was >85ºC at some stage. Also if water / steam shot out of the drawer, it sounds like your water system may have a pressure relief issue! Is there steam shooting out of the taps?
Probably worth getting a plumber to check those thermostats!!!
It should be OK, but in general if you get close to boiling water, some of the internals may not like it, particularly the diverter valves in the water path selectors etc etc, but I'd be surprised if they were particularly offended by anything short of 95ºC - the machine itself (beyond the drawer) is quite happy to deal with near boiling water.
My grandmother used to have a 1920s hot water system that used direct-heat from a fireplace in the kitchen, as well as an later electric heater in the tank. Water was hot often hot enough to make tea. That thing destroyed a modern dishwasher, yet her old Electrolux washing machine never had any issues with it.
Hot and Cold fill washing machines were pretty standard here until the early 90s. In fact, most houses still have hot and cold connection points for them. I think, because they were less common on the continent, they just stopped producing special versions, particularly as water consumption levels dropped and it probably didn't make much difference anyway. The machines still had the same 230V supply and fairly beefy internal heaters, whether or not they'd hot fill or not.[this post was last edited: 12/9/2020-19:29]
