Water heater problems

[vmax]

Hi, I hope someone can help with my problem. I have also posted this on the French Entree forum.

Not exactly burst but there is a leak from the thermostat. It is an electric Adesio AD 150 MVH water heater/tank. Probably around 4 - 5 years old. It is horizontally positioned.

I woke up this morning to water over the floor and a steady leak from the small aperture in which the thermostat probe is housed.

I suspect that the whole thermostat/element housing will need replacing as my guess is that the 'scabbard' or housing in which the thermostat probe sits has probably rotted. There is a circular bolted plate on the end of the tank which houses the thermostat and element. I think it may be called a 'corps de chauffe'.

There is a lower cold pipe with the usual security group valve and an upper hot outlet pipe. No obvious way to drain the tank.

I tried to drain the tank by shutting the inlet valve and opening the security group and running a hot tap in the hope that air might enter the tank to allow water out but no luck.

Does any body know how to drain a horizontal tank without having to resort to drilling a hole?

Clearly I will need to drain the tank before I can remove the 'corps de chauffe'...

I'm not even sure if I will find a replacement part as a 'Google' search throws nothing up for this specific model.

Any help would be appreciated as I am without hot water!

Many thanks in advance,

[nomoss]

Your tank layout might be different, but I have drained mine as follows: 

First run all hot taps briefly, to make sure the lines to them are full, then close them all. (To make sure there is no air in them from your previous efforts to drain the tank)

Shut off the cold water supply, disconnect the cold water pipe at the inlet and connect a suitable drain line to it.

It should be possible to do this with a minimum of spillage if you have the correct connection and drain line ready, as the closed hot taps will not allow any appreciable amount of air to enter the tank.

Once the drain line is in place and directed to a sink or a large container, open one or more hot taps to allow air to enter the cylinder. This should result in water emptying from the tank via the drain line.

With a horizontal cylinder you should not need to completely empty it before you can remove the assembly containing the thermostat etc.

 

Edit: I have just re-checked my tank, and the cold water supply comes in via a shutoff valve on the safety valve assembly.

So it is possible to shut this valve and drain the water by opening the safety valve manually (mine has a red plastic knob for this purpose)

Once again, one or more hot water taps will have to be opened to allow air into the tank.

 

[vmax]

Thank you for such a quick reply!

I did try what you have suggested as it does seem logical that the safety valve should allow air in to replace the water being drained out.

Alas it doesn't work! It seems that maybe the security valve only works in one direction? I.e. only allowing water to escape outwards?

The shut off valve and the security valve seem to work fine as intended - I can stop water flow and when I open the security valve, a small amount of water escapes.

[vmax]

Thinking further on the security valve, I think what happens is that as the hot water leaves the upper outlet, it is replaced by cold water from the inlet. The cold water stays in the bottom allowing only hot water to leave via the outlet.

When the shut off valve is closed and the security valve is opened, air enlaces the hot water leaving via the upper outlet and because the outlet is high, the replacement air goes to the top of the tank and therefore only air can now escape via the outlet leaving all the water in the tank sitting below the upper outlet in place.

I think that makes sense?

[vmax]

But why it won't go backwards via the security valve I don't know!

[nomoss]

The water is supposed to run out of the safety valve, air entering via the hot tap you opened.

The water won't run out of the safety valve because air is not entering via the hot tap. Probably because the line to the open hot tap is partly filled with water and the hot tap, or the pipe to it, is probably lower than the valve.

Try cracking the hot connection at the heater tank. This should allow air into the tank.

 

 

[BIG MAC]

Most tanks work on the principle that hot rises over cold and will have the cold feed enter the tank at the lowest suitable level and the domestic

hot water exit at the top. Switch off mains and open your highest hot tap followed by the groupe securite (usually pull out the knob and turn) water should flow out.