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Adding a Second Shower and Need Advice on Pump Size

Posted: Wed May 08, 2019 9:00 am
by RL424
Hi looking for some advice. Currently have a small twin pump approx. 1 bar serving a shower in the en-suite. I am considering adding another shower into the main bathroom. I understand I will need a larger pump (guessing around 3.0 bar to be safe). System is a F&E tank in loft with HW tank below in airing cuboard. My questions are as follows:

The existing pump is fed by 2 no, 15mm pipes which are T'eed off a 22mm pipe approx. 400mm away from pump inlet. Will these be ok feeding a larger pump?

Also the pump outlet pipes are 2 no. 15mm pipes which I am hoping to split to feed the 2 showers. Can I simply split these outlets and run the new 15mm pipes to the new shower or do I need to increase the outlet size to 22mm then split to 2 no. 15mm?

And finally, at present I understand the system is positive head as the outlet of the pump goes straight through the wall to the shower behind and is approx. 1m below the outlet of the storage tank. I am hoping to split the outlet from the pump before it goes through the wall, and run the new pipework straight back up into the loft, across the loft (at approx 200mm below the height of the storage tank outlet), and then dropping back down into the new shower location. Would this now be creating a negative head for the new shower and so should I be using a negative head pump? Or should I avoid going through the loft and go down under the floorboards (undesirable as flooring is fairly new).