Plumbing advice please.. I have an ensuite mixer shower which was plumbed hot and cold the wrong way around before I moved in. I don't usually use it for this reason however I have a house full of guests this weekend and would like to. The thermostat on it seems to be working fine currently but I'm told the plumbing mix up means the temp valve could fail and I'm worried about scalding.. is this true? All the workings are concealed behind tiles so I can't check or change anything quickly. The boiler is electric. Thanks for any replies!