Try changing your thermostat. It may be faulty.
corrosion somewhere between the boiler and the tap (or in the boiler) is most likely. Give it a good clean- look on the internet for how to get the rust off it. Good luck sexy!
It regulates the temperature of the water in the radiator and tells the fan when to switch on to start cooling or to switch off if its too cool. Engines have an optimum running temperature, and the Thermostat helps keep it at that.
its a device use for measuring the salinity of boiler water. it is generally fitted in water drums .its is provided to prevent the flashing off of boiler water under high pressure condition.
Not for the faint of heart! For a Combi/Evaporation boiler: Switch off the boiler. Take a reading of the boiler water pressure gauge. Shut off the radiator's thermostat valve(if fitted)/supply valve and return valves, connect a hose to the drain and put the other end into a large container below the level of the bottom of the radiator. Open the draincock first and then the air bleed valve and let the radiator drain. Close the draincock. When refilling the radiator put the anti-corrosion treatment in first then open the thermostat valve and return valve as wide as possible. when the air is expelled, close the air bleed screw. Using the fill loop restore boiler pressure. Put all thermostat valves(if fitted) to max and fire up the boiler. After the boiler has run for 10 minutes, switch off, or so go to the highest radiator and bleed out the air. WARNING: the water/steam will be very hot and likely to spit. Use a cloth as a barrier and to mop up any spills. Recheck the boiler pressure and top up as necessary.
Because you are using the Hot water faster than the boiler can produce it. Turn the tap/faucet off a bit. Get the proper sized boiler
When 1990 Honda is running cooling fan does not come on but comes on when engine is off and I thermostat and temperature switch changed?"
For a while IF the boiler has an automatic low water cut off and other safety devices but if any fail you will have a melt down and an explosion
Change 3 pin micro switch that sits on diaphram, it gets stuck which keeps pump running all the time, which causes boiler running on and off at intervals. This will cure your problem 100% micro switch cost £16, its easy to change ,
Off the water pump
take the water outlet off the top of the engine and the thermostat should be right there
When it achieves the maximum temperature, it shuts off. Then when there is demand for the water, or it is at its low setting, the boiler fires up again until it reaches the maximum temperature set.