Hi guys been asked to have a look at a powermax 155, HW is working fine but when advance CH is put on it trips the RCD. I had something similar in the flat opposite a few months ago. Same boiler - HW fine but when room stat turned up RCD would trip - the CH pump had been affected by a leak. I'm assuming this is the same problem. I will replace the CH pump but does anyone know what pump I should be putting in as a replacement?? I'm sure the one I used before was a heatrae sadia UPS25-50 (or is it UP525-50). Can anyone confirm what pump would be ok to use as a replacement? Many thanks. Hope you all had a good Christmas!