I would appreciate some advice on the best type of shower for my new shower room which will be on the ground floor, with a bathroom above, the copper hot water storage tank on the same floor as the bathroom but in the next room along(bottom of tank is about 1.1 m above shower height), the cold water tank is in the attic(bottom of tank is about 4.36 m above shower height). The types of shower I am looking at are gravity shower, venturi shower(use mains water supply) or a power shower.
Thanks for the reply. Is there a way of calculating the pressure that 4.36m to base of CW tank will give as some shower heads specify low or high pressure? I'm also doing my bathroom(directly above the shower room) at the same time and will probably have a shower on the bath taps, that shower when used at semi standing height in the bath would be about 2.26m below the base of the cold water tank- it would be useful if I could calculate the pressure for that also as I am looking at some ceramic valve taps(Hudson Reed) that specify 0.5 bar minimum?
Martin P.S. Are ceramic valves better than screw down valves on taps?
The calculation is easy. 1 bar is approx 10m/30feet of water, so your 4+m will give nearly 1/2 bar. That may be adequate shower for many people but shower pumps usually provide a minimum of 1 bar. Ceramic valves are better but in my experience you get hopless flow, except from bath taps, on gravity fed system in a first floor bathroom. I've got the same type of monoblock tap in a downstairs toilet and in a 1st floor on-suite. Downstairs its ok but upstairs its poor.
That depends. It is possible to get ceramic valves that pass as much water as old compression taps. However, the fact is that the ceramic valves are newer and are usually designed (in Italy or Germany) for modern mains pressure supplies such as are typically installed throughout Europe. As ancient gravity fed hot water systems are a largely UK peculiarity, modern designs from countries without them tend not to be suitable.
Thanks Christian. I am actually going to change my boiler at the same time as I do my shower + bath rooms. I currently have a normal convential boiler gravity system with hot and cold water tanks. Would it be worth changing the boiler to a combi that gives mains pressure, are these less efficient than condensing boilers? Alternatively I am considering adding a twin pump to feed the bath on the 1st floor and the downstairs shower, what bar pressure would this need to be 1-3?? Would the pressure be significantly reduced in the shower(below the power of a gravity shower) if someone filled up the bath at the same time as the downstairs shower was going?
Thanks Bill. I've been looking at shower packs and separate heads/valves, they don't seem to specify if they are ceramic valve, but they do specify if suitable for high or low pressure(sometimes both), can I assume that the high pressure only ones are ceramic and the low pressure aren't?
The combiness of a boiler is independent of the condensing nature. A condensing boiler is more efficient than a non-condensing one as it exhausts the flue gas at a much lower temperature. They are much more efficient even if not run in condensing mode, so you don't need to worry about your radiator sizes.
A combi boiler is normally more efficient than a storage based hot water system, as there is no large store of hot water to cool off. The main problem with combis are that they have a limited flow rate. However, this flow is done at high pressure, making them excellent for showers. Unfortunately, bath filling performance can be poor. Some "combis" aren't really combis at all, but are integrated storage heatbank-boilers. These are better than non-storage combis for baths, although the store is soon exhausted.
The other alternative is to install a proper mains pressure hot water system, such as a heat bank or unvented cylinder. This option will provide the best solution, but will be considerably more expensive and take up much more space, if you don't have a convenient loft space or suchlike to use up.
Any mains pressure solution depends on having sufficient static pressure and maximum flow rate from your mains supply.
That would depend on the pump. A 1 bar would probably drop flow rate. However, a 3 bar pump with large bore pipework might not be badly affected at all, especially as the shower is downstairs. If it does become a problem, choking off the bath taps (with their isolator valves) a little should restore a bit of dynamic pressure for the shower.
Gravity. It's the simplest and most effective method. Any other method (electric, venturi, pumped) are usually only used to get around a lack of head problem, or where piping is a /major/ hassle.
Thanks Christian. If I didn't have a pump I assume I would have to run new pipes from the cold + hot water tanks to the gravity shower rather than branch off from the pipes that currently fill the bath? So in a way having a pump is an easier if more expensive solution? I am slightly worried about the noise of a pump though, an old all in one power shower I used to havewith the pump in the box on the wall made a hell of a racket. Thinking about reducing the noise from the pump could I site it on the ground floor(concrete) in the showerroom, that would make the pump about a couple of meters below the bath which it would pump to, would that be an OK setup?
Yeah, but pumps also need a dedicated feed from both hot and cold. Basically, they're plumbed exactly the same as for gravity, just with a big noisy pump somewhere along the line. Because they shift more water, they also require a Surrey or Essex flange on the tank rather than a normal outlet. Don't go this route if you have adequate head for a normal gravity!
Yes, fine - as long as the distance between the bottom of the cold tank and the height where the water comes out is more than the minimum stated by the pump manufacturer to trigger the flow switches. If less, or negative, get one specifically for negative head situations.
Yes, but to get a reasonable head from a gravity system, you'd need a 10 storey house. OK, a gravity system can be made to get reasonable flow rate to a bath. However, a decent shower needs pressure, not just flow rate.
I am slightly confused about how the pressure will divided if I branch off the 2 pipes from from a twin impeller pump(hot&cold), one branch of each pipe going to a bath filler + the other to a shower in a room directly below? Will the water flow equally out of the bath and the shower if I used them at the same time, or would the one that applied less resistance get more of the flow? If I was using the shower and someone turned on one or both bath taps would that reduce the flow rate in the shower to an usable point? I would be using a thermostatic shower valve so hopefully fluctuating temperature would not be a problem.
was having the same pump connected to the bath and the shower downstairs, but I wasn't sure what would happen if one or both the bath taps were turned on at the same time as the downstairs shower was being used, would that put strain on the pump? Would the water flow from the pump be equally divided between the bath taps and the shower or would one get more flow depending on the height of the outlet or resistance of the valve on the taps or shower? Sorry if this is a stupid question but I'm a plumbing noob....
They don't usually need much. I think the figure for mine was 0.3m, about a foot, but it varies per pump. Worth checking.
That's fine. Obviously flow will reduce at one point if another tap is letting water out. It won't hurt the pump at all. As for flow - depends. Water will take path of least resistance. I think it's pretty hard to estimate with any accuracy what it'll actually be like.
Pumps are often used for more than one outlet - like some flats where the whole house is pumped from a central location. Not sure what happens in that situation WRT Bylaw 30 and not being allowed to connect pumps to the rising main, though.
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