Ariston water heater maintenance question

It looks like you’ll have to uninstall it to do any serious work on it. At the plumbing is all at the top there’s no reason why you should spill much once you’re depressurised it.

Tim

Bah. “At” = as and “you’re” = you’ve.

Thanks for the advice Tim. Having turned off the cold water supply to the unit, there is nothing coming out of the hot taps, as expected. There is an expansion vessel which may cause water to spurt out when I undo the connections if that is a standard effect of the disconnection process. I'm soon to find out.

I'm quite confident about making the main pipework connections with this water heater replacement. What I'm not yet sure about is whether the expansion tank will need recharging and if so, at what stage in the sequence of events I would need to do this. Any advice available on this?

The expansion tank has two compartments, a water comparment and an air compartment separated by a diaphragm. (The diaphragm can fail, but the only difference this makes to your servicing operation is that the tank needs replacing.) In principle the air compartment is closed, normally with a Schrader valve. The water compartment will lose all pressure when the hot tap is open and the water turned off. So it will not cause you any problems, unless you have to disconnect the tank because the tank itself is faulty. You should check the pressure in the air commpartment with a normal tyre pressure guage. If it is below the specifiec pressure (normally about 10 to 15 PSI or the equivalent in Bar). If it is low try to pump it up. It should normally be set with the water pressure low/absent so servicing the heater is a good time to do this. If it won't hold pressure the diaphragm is probably leaking and the tank needs replacing. It will be full of water so this where leaking water will have to be handled, seeing it seems to be on its side!

Oh and if you have to replace the expansion tank it can be a generic one but it must be suitable for potable water, not one of those sold for CH systems which isn't.

Very helpful information Roger. Thanks for that.

That's cleared up most things nicely, thanks.

As the lifespan of these heaters isn't terribly impressive and as the dimensions of each replacement heater varies slightly in shape and size, is it possible and reasonable to convert the last foot of each of the two connecting pipes to flexible hoses to allow for any future variations?