instant water heaters

[sparkattack]

hi, been asked to fit some of these instant water heaters because he doesnt like idea of heating all imersion tank up for the little he uses. Also he hasnt got a gas boiler just storage heaters. He wants one of the kitchen sink, bathroom sink and also the bath. Ive had a look in my catalogues but cant see any suitable for a bath, even an electric shower at 8.5kw i think would struggle to fill a bath. Any ideas or thoughts? i havent got no experience with these yet, cheers

 

[Manator]

The price of any large heater may just disuade the client from getting any instant water heaters. You are right about the filling a bath, the ones that will would be the 3ph units. I doubt any home would have more than the occasional sink heater, and shower, but not one that would fill a bath, far too expensive.

 

[Andy™]

smaller tank?

 

[sparkattack]

are the ones for sinks a simple plug in the socket job or fused spur? or on its own radial circuit normally?

 

[Manator]

are the ones for sinks a simple plug in the socket job or fused spur? or on its own radial circuit normally?

Would depend on the size, I will find a couple of links for you, I have fitted larger water heaters but all the high volume ones I have fitted have had a storage tank to hold enough to fill a commercial sink.

http://www.tradeplumbing.co.uk/Electric-Water-Heaters_c_910.html

 

[Andy™]

best on their own radial.

 

[sprocketflup]

Ive fitted them in the past for temp site supplies ( welfare these days is better than the finished product sometimes lol)

Ran them off fused spurs because couldnt give them thier own dedicated circuit which would have been preferable methinx.

Never seen one big enough to fill a bath tho

 

[Andy™]

given time it would. think about it - 3KW immersion heater is enough to heat a water tank. so a 3kw instant heater should be able to fill a bath. just it would take almost as long as it would for the tank to heat up

 

[kme]

There are two variants on a theme available:

One stored a quantity of water (normally 5-15 litres), and heats it up with an element (between 2 and 3 KW) ; turning the tap allows mains pressure to enter the cylinder, pushing the pre-heated (stored) water out.

The other is instantaneous; works similar to a shower - downside is they`re usually 9-10 KW (for single phase usage) ; and the flow rate isn`t going to be very good, especially for filling a bath!

 

[PC Electrics]

The cost of heating water by electricity is determined by just two primary factors:

1. the cost of the electricity: you mention the client has E7. He should heat as much of his water usage on the overnight rate as possible. The overnight rate is roughly 1/3 the daytime rate. So the tank should be as large as is necessary to provide a days supply of hot water each night. For a single person a c120 litre tank full should be about right if he's bathing each day. If the usage is very low then use the higher element on a twin element tank to only heat the top half. In this instance though it would be necessary to use something like a Horstmann E7 controller to allow daytime boost to the same element. Also heat the water to the highest safe temperature possible to maximise the stored energy at lowest cost (65C).

2. Standing losses. this is where much of the cost lies. Most people fail to appreciate just how much energy they are pouring out of their airing cupboard every second of every day, week in week out, year after year. The British Standard for the standing loss of a standard foam lagged tank is 2.4kWhr per 24hr. This equates to a standing loss of 100W. You wouldn't deliberately leave a 100 watt light on constantly would you? That's about

 

[aptsys]

^^ Good post. I agree that stored hot water is the only way to go if electrically heating bath water.

We have a 9.5kW instantaneous heater for the sink in the garage and downstairs WC (on other side of the wall) where it wasn't possible to get DHW from the boiler without going all the way round the house. It has turned into a godsend in that the water in the tap is hot about 1 second after turning on the tap whereas it would have taken 30 seconds to get warm had we used the DHW.

I haven't noticed any increase in our electricity usage and it gets used all the time, though you'd never ever want to get 100 litres out the thing.

 

[sprocketflup]

Informative post PC ( wheres the thanks button?) what about Combi boilers? Would they fall somewhere in between?

 

[Sidewinder]

sprocketflup,

the thanks is now the little black star in the bottom left, yolu can give positive & negative thanks.