New Bathroom in a first-floor Flat

[threeReefs]

Hi...

I'm helping my son sort out a newly-acquired first floor flat. We've got around to the bathroom so I thought I'd post a potential 'pipework diagram' and see if people think it's sensible.

Note I'm not planning to do this myself - I live in Guildford and the flat's in Bristol - but I like to understand things. I did re-plumb our house a few years back with invaluable advice from a retired plumber next door, but he's moved away now.

It's a simple layout - one bathroom, one kitchen to think about, no heating involvement (that's all electric) so we're looking at trying to do a really nice pumped shower, basins in bathroom and kitchen, and a WC. It'll be a shared mains riser. How does this look ? A couple of specific questions :

1. Run the WC off the cold tank, or mains ? Is that allowed, with a NR valve ?
2. There isn't a lot of head in a flat (if you see what I mean). Worth using 22mm to feed the sinks ? will there be enough pressure even then ? (flat has quite high ceilings)
3. Is there a risk a pumped shower might empty the small header tank ?

I'm opting for a pumped shower rather than anything complex like a thermal store or unvented mains-pressure hot-water, because I like simplicity. Any comments on that line of thinking are welcome !

Thanks
Richard

 

[flameport]

1 - Can be either, but in this case use the mains supply as it will take hours to fill otherwise.
2 - Perhaps. Won't help with pressure at all, but will have less resistance to flow. However larger pipes means a lot more hot water wasted.
3 - Yes, the tiny header will empty in less than a minute and your shower will be useless. With no water, the pump will be quickly destroyed.

There is no benefit of a 22mm feed to the cold water storage.

If possible, fit an unvented cylinder. They are not complex devices and you won't need a pump for the shower.
If not and you want a pumped shower, a hot water cylinder with a separate and much larger cold storage is required. Taps must be suitable for low pressure and anything which connects with flexible hoses is likely to be a huge fail.
Other options include an electric shower, and if there is no bath you could dispose of the large cylinder completely and just fit a much smaller hot water heater for the basin and kitchen sink.

 

[Bosswhite]

Its a small layout for a flat,
I would be tempted to go for a basic Electric Shower straight off the mains,
Just make sure that anyone filling a kettle that the shower is in use.
You could also incorporate the Toilet/ hand basin/bath cold water in with the mains supply leaving the Tank to supply the Immersion/hot water

 

[leakydave]

You can't pump from a Fortic Cylinder. It will more than likely not refill quickly enough and run the pump dry.

Electric shower methinks

 

[Steelmasons]

Jeez...

 

[Madrab]

As @leakydave says, you don't want to pump that type of HW cylinder and if that's the cylinder currently installed then everything else will be fed from the cold mains or another cold cistern somewhere (communal attic).
If it's simple you want, without changing the current HW design, that it's an mains electric shower as the guys have mentioned. That will also need a new circuit installed with the correct sized cabling and circuit capacity/protection.

Really comes down to what is he happy with or wanting shower wise? Could do with finding out the current static and dynamic mains pressure/flow too. That will define what else could be implemented.

 

[threeReefs]

Thanks guys, that's really helpful. I guess I'm spoilt at home with 75gall cold and 50gall hot, pumping is not a problem, but then space is easier too.

The current shower is electric, and it always seems hard to get a really good flow out of those. So sounds like mains-fed hot water with an unvented cylinder is worth exploring. Presumably in that case the mains is feeding both pressure into the hot tank, and the cold side of the shower, so total shower output flow is controlled by the overall delivery rate of that 15mm main ?

I will try and find out the static mains pressure there and the flow rate.

 

[Madrab]

Yes, the dynamic rate is more prevalent in a flat though, you want to know worst case and see if an unvented is an available option.

 

[threeReefs]

As a small update on this, we've done a simple measure of flow rate from the bath cold tap - which seems to be off the mains - and found 0.41 litres / second. I don't have a way to measure static pressure but that doesn't sound bad at all. The kitchen tap gives 0.11 l/s. The bath piping is probably 22mm all the way.

Sounds like an unvented cylinder would give a good shower flow, and then everything cold runs off the mains and you don't need a cold tank ?

I guess the downside is if it's a shared riser then the pressure and flow will depend on what other people are doing - but that's an issue with an electric shower too, presumably. Next step is to find a good local pro, I suspect. Thanks for all the feedback.

 

[AGAS]

Dam good luck