5 Showers

[scook17]

I have bought a house we intend to renovate and rent out as a holiday home. Currently there are two electric showers. I wanted to add a futher three showers. I am concerned about the amount of power required to run five electric showers. Typically 40A per shower, is 200A in total if they are all turned on at the same time. All the consumer units I can find are rated to 100A, so this looks like a non starter.

I can therefore, use either a pumped system from the hot water cylinder for the three new showers, or perhaps a main pressure hot water cylinder. Two showers will be on the first floor and one on the ground floor, so I'm not sure if this causes any problems. Would anyone care to suggest which would provide the better solution? Has anyone had an experience with main pressure hot water cylinders? I'm considering the Potten Powermax HE.

If anyone can think of another solution, I'd love to hear it. Thanks.

Electric Showers - Too much current?
Pumped - Too noisy?
Mains pressure cylinder - Rather expensive?

Kind Regards,
Shane Cook.

 

[breezer]

you asked a similar question in the electrics forum, but if you try here again early this evening our "resident" heating people will give their opinion. i would say the water option will be better

 

[scook17]

It seems the Heatrae Megaflo cylinder seems to be a good bet. However, it's expensive. I'm not sure how much water, three, main pressure showers use. I think I probably need the 210L, 250L or 300L models, neither of which are particularly cheap. What sort of flow rate do you get from the mains? Is one third mains pressure per shower, ok for a reasonable shower?

Has anyone had any experience with these, or would recommend something different? If this is the best solution, then I'll go with it. What do people think? Thanks.

Kind Regards,
Shane Cook.

 

[corgiman]

forthat many showers then a nice big megaflow is the kiddy

BUT (always a but sorry) you MUST seek professional advice to make sure that your supply is up to it and where you want to position it is possible

Installation of this type of cylinder is NOT a DIY job, some things need trained people to do.

 

[oilman]

You are going to need in excess of 50kW to run all the showers at the same time no domestic boiler will do this, so you will need heat storage. There is the pumped system, but rather ou than me to look after that lot. There is the unvented cylinder (I think the Megaflow is one example), and there is the thermal store. (Gledhill or Albion for example) The unvented cylinder is a high pressure water container, DEMANDS certified installer and annual service. The thermal store is a low pressure store with a heat exchanger which passes mains water to the shower.

Mains pressure is not the only requirement, flow rate is just as important.

 

[breezer]

just out of interest then, how do you suppose big hotels heat their water? obviously money is no object in their case

 

[scook17]

Megaflow do a 300 litre cylinder. I'm guessing a mains pressure shower uses around 10 litres per minute. A typical shower is ten minutes, so that's 100 litres of water. 300 litre cylinder should supply enough for three showers using the volume of water inside the cylinder. However, new cold water is being let in all the time to replace the hot being sucked out, and the boiler is going full blast to heat the incoming water. I only have a standard domestic (oil powered) boiler, so typically 25Kw or so. I sort of hope it will all work.

The thermal store idea is a nice one, but I've yet to see any feedback on how good or bad they are. There seem to be plenty of good testimonials available for Megaflow. I'm also a bit concerned about how they can heat a reasonable flow of water in such a short time period. Sounds a little like the typical combi 'cant supply enough water for the shower' problem to me.

Kind Regards,
Shane Cook.

 

[oilman]

It's nothing like the combi problem, the combi COULD perhaps produce 28kW, but this means instant heating flow has to be restricted. With the thermal store esp Gledhill the tap output = mains input and the rate of heat extraction is adjusted to give a temperature of 55 deg C. HEAT is stored, but this will need to be sufficient volume, just as any other type of system.


If you have 3 showers at 10 l/min a typical inlet to the house will have difficulty with the flow rate, so you will probably have to store water, and that means a header tank and conventional cylinder and pumps. An unvented cylinder would be no advantage as the water out of the tap is only forced out of the cylinder by the mains water coming in.

Follow corgiman's advice and get professional help, after all yours is a commercial requirement, this is only a DIY forum.

Breezer, for hotels I suspect things are just bigger. The other day I saw an unvented cylinder 1-1/4 inch pipes 3ft diameter, stood 7ft high and made from 1/4 inch plate. Cost about £2000

 

[scook17]

Oilman,

I do intend to employ a plumber to install whatever I decide is the best solution. However, I'm an engineer by profession, so I like to understand the options available. If I speak to a plumber and he suggests 'x', and clearly 'x' is no good, I'd like to know before I get it installed. As for being a commercial requirement, we'll perhaps it's borderline. I bought a house that we intended to live in, then my circumstances changed and I now have to rent it out as a holiday home, so I'm trying to make the best of a bad situation.

Does anyone know what the typical flow rate is from the mains water supply, and how I might find this out?

I don't really want to go for a stored water solution, with a pump because it's noisy and I'm told that all pumps will leak, eventually. So the extra cost of something like Megaflow seems a better choice than replacing a ceiling a few years down the road.

Kind Regards,
Shane Cook.

 

[breezer]

checking your flow rate is easy. get a litre or pint measure and put it under the tap, turn the tap full on and time it to see how long it takes to fill your chosen container. I am sure you can figure out the rest

 

[oilman]

Unfortunately there's no typical mains flow, supply pipes may be similar, but the routes they take and the loading are different even for the same pipes at different times of day.

 

[corgiman]

Unfortunately there's no typical mains flow, supply pipes may be similar, but the routes they take and the loading are different even for the same pipes at different times of day.

true but you must treat every where as an individual or you would not be able to install a unvented cylinder in WOKING because the water pressure in inverness is a bit pants .

get your engineer to use a pressure guage and flow cup on the system before he/she starts waffling on about what system to put in, as it has been known that plumbers will recommend a system that rather than being the most appropriate is the most profitable and easiest to install for them shocking I know