There are two types of electric shower. One heats the water and has one inlet. The other has a hot and cold inlet and thus doesn't heat the water it just pumps/mixes the feeds. Can any one tell me what the latter is called (IE no heating element two inlets) I don't want to order the wrong type and have to return it etc. I could buy the same make and model but I am loathe to, if it will just die like the one I have did (and it will, because it's badly designed). TIA.