Change apartment hot water system

cbruen1

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So I have an apartment in Dublin city centre that was built some time in the 90s. The sitting room has an electric storage heater and the bedrooms have standard electric heaters.

The water system consists of a hot water cylinder and a cold water tank with a ballcock. The water is heated overnight and the shower is a Mira Essentials with a pump that's fed with hot water from the cylinder. So it's not an instant electric shower - once all the hot water is used the heater / immersion has to be turned on again.

So I want to change the shower to an instant electric - a Triton T90 or similar so I won't have to heat the water overnight.

Some questions:

- can I swap the Mira directly for a Triton T90 - will the pipework be the same?
- I have a dishwasher so I don't need hot water in the kitchen (or bathroom tap). Can I get rid of the hot water cylinder?
- anything else I should be aware of?
 

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can I swap the Mira directly for a Triton T90 - will the pipework be the same?
The Mira will have a hot and cold feed to it, which yes you should be able to connect into the T90. Where the pipes enter the back of the shower unit etc. is likely to be different though, which can get quite messy on a tiled wall like that. I'd open the Mira and see where pipes/cables enter it, then see how the replacement shower you're looking at is laid out. You may find that replacing with another Mira (with heater and pump) is a much easier job as it could have a similar layout.
More important than the piping here is the electrical feed though. That Mira is probably only using something like 150W, whereas a shower that also heats the water will use anything up to 9000W. It's possible the apartment was wired with the appropriate cable to carry this kind of load, connected to an appropriately rated fuse, but it would need to be checked before you buy anything.


I have a dishwasher so I don't need hot water in the kitchen (or bathroom tap). Can I get rid of the hot water cylinder?
Yes, but before you do, I'd consider what impact this will have on the value of the property. While you may have no need for hot water coming out of the taps in the kitchen/bathroom, a future buyer most likely will and finding these sorts of 'unusual' modifications will often turn people away, as they wonder what other skeletons are hiding around the property.


anything else I should be aware of?
FWIW I wouldn't dream of putting a heated&pumped shower into my house, the showering experience is really really poor compared to pre-heated water pumped at decent pressure. Electric showers like these can be quite expensive to run, often more expensive than heating water in-advance with gas.


Maybe if you can give some more info, like how the water is currently heated and what you're trying we could give alternative suggestions.
 
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Electric showers like these can be quite expensive to run, often more expensive than heating water in-advance with gas.

An apartment with storage heaters likely doesn't have access to a gas supply, it'll be electrical heat on demand or in advance with storage. There will also likely be a split meter with the ability to use night rate to heat water. So long as the tank is very well insulated this should make overnight heating less expensive.

Definitely agree with the point on retaining the hot water tank. People expect access to hot running water for the basics like washing hands, shaving, etc..

I'd be surprised if the existing shower has the required cable diameter to power an electric shower. Large scale developments rarely over-specify on details such as this, but you might be lucky.
 
An electric shower requires it's own fuse rated at 40 amps.If you don't have this,then it's could be a big job replacing the cable and upgrading the fuse board.
If you have night rate electricity and a modern well insulated tank of big enough size,then what's the problem?
As for getting rid of the tank,are you going to get in the shower to wash your hands?
 
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The heating and hot water is all electric, no gas. I have a day and night meter. The reason I want an instant electric is for convenience and also I think it'll be cheaper overall. Currently I heat a full tank of water every night but the next day I might shower in the gym and not use the water at all. Also sometimes I go away for a weekend or a few days and forget to turn off the water heater, so in these scenarios the water is being heated but not used. Another thing is if I have a few people staying and taking showers the hot water can run out.

So based on the above feedback I'm thinking it's easier / better to leave the hot water cylinder as is but I'd still like to replace the shower with an instant electric if possible. Sounds like a job for an electrician more than a plumber?
 
... also I think it'll be cheaper overall. Currently I heat a full tank of water every night but the next day I might shower in the gym and not use the water at all. Also sometimes I go away for a weekend or a few days and forget to turn off the water heater, so in these scenarios the water is being heated but not used.

If you have access to your meters, you should be able to work out how much it costs to heat a tank of water from cold, and how much it costs to top up that heat where a the water heated the night before hasn't been used. When the storage heating isn't being used and there are no other loads on overnight, empty the tank of all hot water and take a meter reading prior to going to bed. In the morning, take another reading after the nightly heating cycle. The difference is the units required to heat the water from cold, plus whatever other usage you had overnight. Don't use any hot water that day, and again take before and after meter readings to see how many units the top-up required to compensate for heat losses during the day.

A 10kW electric shower will use 10 units for every hour running, or 1 unit every 6 minutes. More powerful showers will obviously use more. Figure out how that compares to the length of time you'll get a warm shower from a heated tank.

Sounds like a job for an electrician more than a plumber?

A job for both really. A plumber can't legally do the electrics required, and an electrician likely won't want to touch plumbing.
 
Definitely go for the instant shower, while leaving the HW cylinder in situ.
They are so, so handy, especially during the summer when you don't have/need the immersion on, a 5min shower will
cost you about 20c. Remember they are nearly 100% efficient and modern units are a lot better and quieter than those
of old.

As previously pointed out the plumbing is already there, albeit you will only be using the cold feed.
Any electrician, 'worth his salt' should have no problem doing the small amount of plumbing required.
The only caveat would be the routing of the supply cable, may be awkward but usually never insurmountable.
Even if there is no space on your MCB board (consumer unit) the fitting of an RCBO in its own small enclosure is
a handy alternative.
 
I can look it up but to be honest it's not a question of which is cheaper, it's more for the convenience. Even if it's more expensive I don't mind paying it. And I wash my hands with cold water ;)

A 5 min daily shower is all the hot water I would use, and not every day, so it's seems silly to be heating a full tank of water every night for this.

I added a pic of the bathroom - the water tanks are behind the wall along the bath. Someone suggested installing a new instant shower on this wall or the one at the other end of the bath and leaving the Mira as is. Any thoughts on this?
 

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A 5 min daily shower is all the hot water I would use, and not every day, so it's seems silly to be heating a full tank of water every night for this.
Surely you don't leave the immersion on all night for this ? I'm guessing you have a tank with two elements, one nearer the top and the other nearer the bottom. The nightime will use the bottom one so will heat the full tank. The daytime will just heat the top part of the tank for your shower. Change the time on your timer to make sure that daytime comes on at 6 am and set the timer for 30 minutes before you get up and away you go.
 
Yes you're right the tank has 2 elements and I set a timer to heat the water overnight - see the pic of the heating switch in the first post
 
Thought so. The problem you have is that the timer automatically changes to the bottom element at night so change the clock dial so that it only goes night time between say 9pm and 5am. Then just switch on the immersion 30 minutes before you get up and time it for 30 - 40 minutes in the bottom dial. Don't leave the switch on at any other time (although it will only kick in between the hours you have set the night time to be).
 
Someone suggested installing a new instant shower on this wall or the one at the other end of the bath and leaving the Mira as is. Any thoughts on this?
Certainly possible, but it's a bit of a hack isn't it. If you're getting an electrician out to commission the new shower and do some plumbing, may as well get them to just replace the Mira assuming it's possible.

As you definitely want an instant electric shower, your next step is to speak to an electrician, they'll come have a look and see what is required. Chances are the walls are hollow and feeding a cable through may not be too big a deal, but you cannot make any other decisions until you get this answered I think.
 
Your shower experience will not be the same, we have two powered showers and two instant electric showers, the powered showers give a better shower, greater flow and hotter.

The instant shower gives a poorer flow and heat, it is also a multiple to use, another poster suggested a 5 min shower costs 20 cent, I doubt that very much.

Add to that your cost to replace, shower, plumber and electrician, the trades do not mess with water/electricity, you will need both, and I do not see the benefits, also washing hands in cold water does not kill the bugs that live in your cold water system, legionnaires being the obvious one.
 
another poster suggested a 5 min shower costs 20 cent, I doubt that very much.

I thought the same thing on initial reaction, but a 9kW electric shower run for 5 minutes on 17c/kWh electricity would cost you €0.12. Agree with everything else you've said though!
 
My well insulated cylinder (125L) has 2 elements, 3kWh each. Only one of them can be on at any one time. There's a booster option on my console which will turn on the top element if the bottom one is off. If both are on, the bottom one takes precedence. For this reason the clock is set up a few hours fast. This way you can be sure you're using the top element and not the bottom one when you turn on the booster (manually). This is important so that you have enough hot water.

If the water in the tank is not totally cold, 20 min on the booster (top element) is more than enough for a 5 min shower, 30 min for 2. That usually happens in the morning so 20 min = 1 unit (at night rate) = not a lot.

I heat a full tank maybe twice a month to prevent bacteria from growing inside (I hope it's enough). So the water is never totally cold.

I do all this manually though. E.g. I turn on the booster first thing in the morning, then go about getting everything and everybody ready. I also check I've turned it off when I leave the apartment and before going to bed. It took a while but it became routine. A few reminders and notes on the doors helped.
 
Your shower experience will not be the same, we have two powered showers and two instant electric showers, the powered showers give a better shower, greater flow and hotter.

Your correct, the power shower does give a better shower, but at a cost. Some will use over twice the volume of water over the same time as an instant shower, resulting in over twice the cost as in the OP's case electricity is the only means of heating said water. Not to mention the 'green' aspect of the instant shower using less water.

The instant shower gives a poorer flow and heat, it is also a multiple to use, another poster suggested a 5 min shower costs 20 cent, I doubt that very much.

Again you're correct, I was giving the worst case scenario ie. a 10KW shower with a 'highish' (KWHr) unit price. Generally, as was pointed out above, it will indeed be cheaper than 20 cent per 5 min. shower, so you were right to 'doubt' it.

As regards temp., the usual advised temperature to shower at is 41c (max), a temp easily achieved by a 9/10KW instant shower while still delivering a decent flow. During the warmer months, this can even be achieved, at times, on half power resulting in even more savings. Also, remember, unlike a HW cylinder immersion, the instant shower only heats the amount of water used, no more,no less.


Add to that your cost to replace, shower, plumber and electrician, the trades do not mess with water/electricity, you will need both

My experience of over 35 years involved within the trade says otherwise, however I have certainly noticed a move within the younger/newly qualified electricians a reluctance to do so. Hence, I used the term 'any electrician worth his salt', inferring a more mature/experienced tradesman.

I do not see the benefits, also washing hands in cold water does not kill the bugs that live in your cold water system, legionnaires being the obvious one.

Legionella bacteria do not live/multiply in cold water systems and many modern soaps employ an anti bacterial agent.
In fact they thrive where temperatures are between 20-45°C and nutrients are available. The most obvious place in the home being a HW cylinder while cooling down.

I don't think it can be argued, at least not successfully, that the instant shower is not so much 'handier', than an immersion fed shower, ie. no messing with timers, planning water usage, waiting times etc. Heading out unexpectedly ? Think I'll grab a quick shower, strip off, press a button and voila!

Anyway, at the end of the day, as they say....... 'You pay your money and you make your choice'.


Just my 'tuppence' worth.
 
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I changed an apartment to electric shower and when living there my lecky usage was approx 130 units (summer). In the one I'm in now I have the same immersion system as you and my summer readings are about 260. All things equal I think the usage difference is about 130 per 2 month bill or 780 a year. So you might save up to 80 a year depending although add on how long you are in the shower with lecky.
BUT
Putting in a lecky now where there wasn't one before will be the guts of 800 euro.
I could shower for 20 minutes with the immersion.
Better pressure with immersion.
I can have a shave/wash hands/dishes well after having a shower as the tank is well sealed.
Resale value is greater with a well insulated tank.

I really think you need to just follow the instructions on using it from spinner above and you will be way better off and not really much worse off cost wise.
 
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