What is this ?!

[NewCanalBoy]

And what about the red valve on the left ? Seems to let water go past by the sound of it.

[BEngo]

That is the PRV test knob. It causes the Pressure Relief Valve to open, which is why you can hear water coming out.  Needs to be twiddled about once a month to confirm that the PRV is not stuck shut (usually by limescale). If the PRV sticks shut your calorifier can overpressure and may burst.

 After twiddling it is good practiceto check it is not now stuck open (again, usually by some limescale))  - look to see that water is not coming out of the white pipe running away from it.

 

N

PS The big red can thing is the cover for the immersion heater electrical terminals and thermostat.

N

Edited August 22, 2019 by BEngo
Add PS

[NewCanalBoy]

Thanks for that. It's saved me a big scare tomorrow morning before setting off - now to get out the mop and bucket...........

 

And the electric terminals and the thermostat - do they only come into play when connected to shore power ?

[Chewbacka]

11 minutes ago, NewCanalBoy said:

Thanks for that. It's saved me a big scare tomorrow morning before setting off - now to get out the mop and bucket...........

 

And the electric terminals and the thermostat - do they only come into play when connected to shore power ?

On some boats yes, on others no.  So on mine I can turn on the immersion and use the inverter which heats up the water faster than engine alone, but I must only do this when the engine is running, and must switch off when done, otherwise the batteries will be destroyed.

 

Added - If you buy a Ford Escort they are all wired the same, so any escort owner can answer your question, but boats are all one off and wired depending on the whim of the builder and what ever the customer asked for.

Edited August 22, 2019 by Chewbacka

[NewCanalBoy]

Yes thanks. I have no inverter so can only heat by engine or shore power.