I have a problem with the diverter where the DHW is heating up the CH flow pipe. I replaced the large diaphram a few months back when it turned to mush and i checked the smaller one (on top of the diverter?) which needs relacing. Is the Diverter servicable or do i have to buy another. Do i sound like i'm on the right track, i've read some of the other probs and i think i'm onto something....... Until someone pull the rug from under my feet.