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Various domestic supply pipe sizes - Help needed!

Postby Chippy86 » Sat Jan 04, 2020 9:13 pm

Evening All,

First time using this forum, be gentle!

I’m a joiner currently renovating a three floor townhouse (my own). I’ve got a few questions about plumbing and would be eternally grateful for trade advice (I’m getting mixed responses from mates in the trade) - been let down by plumbers and need to get cracking.

Just had a 42Kw boiler fitted professionally. The supply lines for the bathrooms (3), aren’t in place yet.

My plan so far..

22mm cold supply running straight from mains directly up three floors, T off in 15mm for ground toilet/sink, 1st floor thermo shower/bath/toilet/sinks, 3rd floor electric shower/toilet/sink/bath.

DHW supply run in 15 mm straight from the boiler, T off where required for each supply.

My concerns..

Will the 15mm supply DHW have enough pressure/flow for a bath/thermo shower on the 1st floor and a bath on the 3rd

I noticed the diameters of things like bath and sink taps are larger than 15mm, should I be running those supplies larger or is it ok to use 15mm and convert at thread?

Few other factors..

Using the Hep20 system, two elbows in the main supply line, Victorian property so you are taking about very high ceilings floor to floor.

Ground floor bathroom is just a toilet and sink.

1st floor is thermo shower, bath, double sink, toilet.

3rd floor is electric shower, sink, toilet, bath.

I’m putting in an electric shower on 3rd simply because I’m worried about the pressure/flow by the time heated water from the boiler would make it to a thermo. But, if you reckon a thermo would be fine.. please correct me.

Thanks in advance!
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