Single impeller pumps.....electrics and flow switches I imagine. That's me helping her down the pan (no pun intended). Like a typical women she's doing everything a**e about face. The heating and hot water system is ancient and in my opinion should have been one of the first jobs to be done whether with a combi installation or something else. However she's just spent a vast sum of money having fancy flooring laid throughout the house and now she's on about getting the bathrooms done. I know that in the end she'll do what she wants, but she's family and on her own with 2 kids and I get it in the neck if I don't chip in.