Plumbing specifically shower question

foofi22

Hi

I'm considering adding a downstairs bathroom with a shower however I'm a little confused with the shower options.

I have a hot water tank (upstairs) so fairly sure I have a gravity-fed system - at least for the hot water. I have pretty good pressure mains water feed.

I was considering an electric shower, but I have seen "digital mixer" showers which apparently work with gravity-fed systems - is this true?  Or do they only work with gravity-fed hot and cold?

I've been searching online and I can't find anything definitive!

THanks

ThisIsWeird

AfaIk, 'digital' control just means a more refined and simpler way of controlling the temp - you dial up the exact oC you want, and jobbie jobbed.
It doesn't, in itself, mean it'll cope with unbalanced supplies.
Almost always (perhaps always), the H and C need to be at similar pressures, and near similar flows. So, if your hot cylinder is 'vented' or 'gravity', then your cold supply to the shower mixer should be ditto. That might mean having to take a dedicated cold supply from the CWS tank in your loft to your new shower.
It is often possible to boost the 'gravity' hot to match the higher pressure cold 'mains', but really better to try and have them matching naturally. Avoid pumps if you can.
Q's; is your hot system 'gravity'? Photo of your hot cylinder, please.
Is the cold in this bathroom 'mains'? Does it stop flowing when you close your mains stopcock?

If you post a link to the digital shower you were considering, then we can look it up to see what it supply requirements are.

FreeBear

ThisIsWeird said:

AfaIk, 'digital' control just means a more refined and simpler way of controlling the temp - you dial up the exact oC you want, and jobbie jobbed.

"Digital" adds complexity, cost, and unnecessary widgets like an app (at least to some of the units I looked at). Beyond a marginally more accurate thermostatic control, the "digital" control doesn't offer any real advantage over old fashion showers.

With a vented DHW tank (gravity system), anything without a pump is going to be a disappointment. A pumped shower will (generally) need gravity fed hot and cold water. It is possible to fit a booster pump to the DHW such as the SP2B - Fitted next to the tank, it would boost hot water pressure to the taps as well.

Albermarle

I have a hot water tank (upstairs) so fairly sure I have a gravity-fed system

I have a hot water tank upstairs, and it is NOT a gravity fed system. It is under mains pressure.

As requested above, a photo would confirm or deny ( An unvented/under pressure one will have more pipework/safety valves etc )

ThisIsWeird

FreeBear said:

ThisIsWeird said:

AfaIk, 'digital' control just means a more refined and simpler way of controlling the temp - you dial up the exact oC you want, and jobbie jobbed.

With a vented DHW tank (gravity system), anything without a pump is going to be a disappointment. A pumped shower will (generally) need gravity fed hot and cold water. It is possible to fit a booster pump to the DHW such as the SP2B - Fitted next to the tank, it would boost hot water pressure to the taps as well.

A CWS in the loft should provide a superb shower on the ground floor with a suitable low pressure mixer. And without yucky pumps :-)

Foofi needs to confirm whether both supplies in the downstairs bathroom are gravity.

Martyn_H

I have a gravity-fed system similar to the OP. The pressure to both taps is poor. I would consider having an electric shower installed.

A water pump is an option but would mean having dedicated pipe runs from the tank all the way down to the next floor, plus you'd need somewhere to install it where pump noise wouldn't be an issue.

ThisIsWeird

Foofi first needs to determine whether the H&C in that bathroom is balanced - Ie from the same source.
If 'yes' and this source is from a CWS, then the next step would be to determine whether this gravity from 2 storeys above is good enough to provide a decent shower passively, Ie without being boosted. This should be easy enough to do, eg by fitting a push-on shower hose on to the taps, and testing it at shower head height. If that gives good results, then a low pressure thermo mixer like the Mira should work.
Alternatively, you could fit a shower pump - noisy hateful things - or a wall-mounted booster shower which has a small pump inside it. They work well, but yes also make a noise.
If the H&C is not balanced, then options are to boost only the weaker H to match the C - wee pumps exist that should do this - or to fit an electric instant shower - even more hateful than pumps.
Or, completely revise their system to make it all pressurised, but that's £ks.

FreeBear

ThisIsWeird said: If the H&C is not balanced, then options are to boost only the weaker H to match the C - wee pumps exist that should do this - or to fit an electric instant shower - even more hateful than pumps.

Already linked to a small (low voltage) pump. They are not particularly noisy.

Now't wrong with an electric shower - Some come with fancy digital controls (and perhaps an app), others have thermostatic controls (well worth having). Should your gas boiler fail, an electric shower will still work to keep you clean.