I have an antiquated system, boiler with a hot water cylinder poss 30 years old. Since having new gas & elec meters the hot water is far too hot. There is no thermostat on the cylinder, the only thing I've found is a Honeywell 40003916-001 which according to Google is just a motorised valve but no thermostat in it. It isn't on the pipe to the cylinder but comes from another pipe which may (or may not) either add cold water to it or let some of the hot water bypass the cylinder (22mm pipe). It's a major job to follow this pipe back or to see where the wiring to the valve comes from. Is it possible this motorised valve is the only control or is there going to be something else I haven't found? The Anything there is will be further away from the cylinder.
Hot water far too hot
- Thread starter royw
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Should be a thermostatic on the hot water cylinder.
It's strapped to the hot water tank. It's dangerous if water gets too hot. People often just have the hot water on for an hour twice a day if thermostat is faulty. Crazy way to control temperature.
If you cant work it out get someone in to look and advise. Don't leave it
It's strapped to the hot water tank. It's dangerous if water gets too hot. People often just have the hot water on for an hour twice a day if thermostat is faulty. Crazy way to control temperature.
If you cant work it out get someone in to look and advise. Don't leave it
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I also have no tank thermostat which connects to the central heating, the only way to set DHW cooler is to also have the CH water cooler, that was how it was done years ago.
The C Plan had two upgrades, original
then a thermostat for summer use 
and finally a motorised valve, 
but mine is still the original. As we moved to Y Plan and S Plan we saw the DHW having its own controls, but years ago, the central heating was used with the open fire, rather than instead of it, and my parent would just use it in the morning while lighting their open fire.
The idea is when the heating turns off, it can get rid of the heat in the boiler by heating the DHW, you can get
mixing valves to reduce the DHW temperature at the taps, but 60°C is far too hot to wash your hands under the hot tap, and 60°C is required to stop legionaries, so the storage tank needs to be over 60°C, all the tank thermostat does is reduce losses from the DHW tank.
The C Plan had two upgrades, original
then a thermostat for summer use and finally a motorised valve, but mine is still the original. As we moved to Y Plan and S Plan we saw the DHW having its own controls, but years ago, the central heating was used with the open fire, rather than instead of it, and my parent would just use it in the morning while lighting their open fire.The idea is when the heating turns off, it can get rid of the heat in the boiler by heating the DHW, you can get
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