electric shower

[lechop]

hi,
i've moved into a new house with a gainsborough 400x electric shower fitted. the output is pretty poor and so i'm intending to replace it with something that kicks out more water. when the shower is set is to cold the water pressure out of the shower head is sufficiently high for a decent shower so i am assuming the poor flow when the setting is made hotter is due to insufficent hot water being created.

i've got two questions i'd appreciate some advice on. from my understanding the 400x is an 8.5kw shower, would converting it to a 10.5kw shower greatly improve the hot water output and result in a more powerful shower? and if so can the existing wiring be used on a new higher wattage shower? the old one was only installed a few years ago i think, and has its own dedicated rda circuit on the circuit board.

thanks for any help.

 

[Agile]

I do have to say that is seems a pretty stupid question to me.

Obviously if it is 8.5 kW now then increasing it to 10.5 kW is going to increase the hot water output by about a quarter or 23.5% to be more accurate.

A slight increase but hardly breath taking and hardly worth spending several hundred pounds is it?

As to whether the existing supply cable ( and distribution ) will suit a 10.5 kW shower can only be determined by a knowledge of the existing cable type, size, mounting and distribution.

If you want a significantly more powerful shower then you will need stored water or a gas boiler.

Tony Glazier

 

[lechop]

thanks for taking the time to reply tony.

(1) i was hoping for a subjective comment on the difference between an 8.5kw and 10.5kw shower on the same mains pipe. i would imagine a quarter increase in hot water flow, matched by an increase in cold water flow to maintain the same temperature, would make a significant difference to the "feel" of the shower. has anyone carried out a similar replacement?

(2) I'm not sure where your figure of several hundred pounds comes from. I was planning to replace the gainsborough like for like with a higher wattage model costing about £120. assuming the wiring is ok, is there something else i'm going to need?

(3) with regard to the wiring, perhaps i should have been clearer. what i was hoping someone could tell me is would the minimum specification wiring required for a 8.5kw shower (the worst case scenario i could be facing) be suitable for a 10.5kw shower? ie are there different regulations for the different sizes or is there no way of knowing without looking what has been used?

once again thanks for any constructive advice anyone can give.

 

[kevplumb]

3) with regard to the wiring, perhaps i should have been clearer. what i was hoping someone could tell me is would the minimum specification wiring required for a 8.5kw shower (the worst case scenario i could be facing) be suitable for a 10.5kw shower? ie are there different regulations for the different sizes or is there no way of knowing without looking what has been used?

in a word no there are toooo many variables


MOD moved to electrics

 

[andy]

thanks for taking the time to reply tony.

(1) i was hoping for a subjective comment on the difference between an 8.5kw and 10.5kw shower on the same mains pipe. i would imagine a quarter increase in hot water flow, matched by an increase in cold water flow to maintain the same temperature, would make a significant difference to the "feel" of the shower. has anyone carried out a similar replacement?

(2) I'm not sure where your figure of several hundred pounds comes from. I was planning to replace the gainsborough like for like with a higher wattage model costing about £120. assuming the wiring is ok, is there something else i'm going to need?

(3) with regard to the wiring, perhaps i should have been clearer. what i was hoping someone could tell me is would the minimum specification wiring required for a 8.5kw shower (the worst case scenario i could be facing) be suitable for a 10.5kw shower? ie are there different regulations for the different sizes or is there no way of knowing without looking what has been used?

once again thanks for any constructive advice anyone can give.

the 10.5KW shower will give more heat to the water to the flow can be greater/hotter. however, the cable used may not (and most likely wont) be adequate for the 10KW shower. what size is it? how long it it? does it go thru any insulation etc?. also the MCB will need changing. do you have an RCD protecting the shower?

 

[Agile]

I am not sure why you were calling me "Dave". Is that intentional as some kind of insult? Whilst writing I see that you have now edited my name to Tony so presume it was a mistake or something.

I am also sorry that you dont think that I am helping you. I have already said that a 23% increase in hot water is "not breathtaking" in my opinion. Surely you are the better judge of whats significant. Certainly to me its not worth the extra £300 or so.

Since you have not quantified the power supply specifications I cannot comment further without full details. It is quite possible that you will need to have the consumer unit upgraded and possibly the incoming supply uprated as well, several hundred pounds perhaps.

If the supply cable for the 8.5 kW shower was installed at the minimum size for that loading it will need to be uprated. Also the RCD will probably need to be uprated. There are so many variables and you obviously do not have the ability to define what you have so the only solution is for you to call a competent electrician to see what you have and advise what is required.

All in all I still think that a gas heated water supply is the best option and this will give you about 10 litres per min instead of the 4 that you will get now! Storage would give you 15 li/min.

Tony Glazier

 

[andy]

Also the RCD will probably need to be uprated.

i think you mean MCB

 

[lechop]

no insult intended, just my poor memory for names. thanks for the replies, will have to think again about the best solution to my problem.

 

[Agile]

""I think you mean MCB""

Sorry Andrew, I was being economic with the words because I was only thinking about replying to the original enquirer.

My actual thoughts were:-

Probably has no RCD at present, will need one and they cost a bit.

MCB will probably already be adequate but if not are cheap and old one can be recovered so little net cost.

Is that better?

We know that cable sizes have so many variables but you will see that the "user" has no idea that it will probably be necessary to upgrade the cable size. I usually tell people on the phone that it may cost up to £400 to instal a new supply for a 10 kW electric shower, that makes them think again about their nice new £130 new shower from the shed!

Tony Glazier

 

[andy]

""I think you mean MCB""

Sorry Andrew, I was being economic with the words because I was only thinking about replying to the original enquirer.

My actual thoughts were:-

Probably has no RCD at present, will need one and they cost a bit.

MCB will probably already be adequate but if not are cheap and old one can be recovered so little net cost.

Is that better?

We know that cable sizes have so many variables but you will see that the "user" has no idea that it will probably be necessary to upgrade the cable size. I usually tell people on the phone that it may cost up to £400 to instal a new supply for a 10 kW electric shower, that makes them think again about their nice new £130 new shower from the shed!

Tony Glazier

the current MCB will need changing, providing it was correct for the 8.5KW shower. wether there is an RCD or not is a totally different case, but if fitted, will probably be adequate

 

[HDRW]

hi,
i've moved into a new house with a gainsborough 400x electric shower fitted. the output is pretty poor and so i'm intending to replace it with something that kicks out more water. when the shower is set is to cold the water pressure out of the shower head is sufficiently high for a decent shower so i am assuming the poor flow when the setting is made hotter is due to insufficent hot water being created.

Are you sure it's not just furred-up, so operating below its capabilities?

Not easy to tell, of course, but if you're in a hard water area it's a definite possibility. Around here (Hertfordshire) the water's hard enough to stand a mouse on!

Cheers,

Howard

 

[BenStiller]

Gainsbourough showers are rubbish, especially the 8.5, i always tell people, "buy anything but a gainy"

 

[breezer]

Gainsbourough showers are rubbish, especially the 8.5, i always tell people, "buy anything but a gainy"

and they then go and buy a gainsborough, because it isn't a

gainy"

 

[mapj1]

To be able to asses the suitability or otherwise of the wiring for a greater load, you need to know -
What cable is fitted now (normally quoted as so many square mm cross-section of live conductor. Note this is sometimes stamped on the jacket but not always If not a comparison with a reference sample, or micrometers are needed.)
If not sure budget to replace by a run of 10mmsq if it runs though an open floor void/in an uninsulated wall. Or 16mmsq if it runs through insulation. An RCD may be worth adding to the estimate if there isn't one.
Then for 10KW plus the fuse or breaker wil need to be 45A type. Some CU s cannot handle a 45A breaker, and so a new CU is needed, or a supplimentatry one alongside the original. If either of these cases apply work is required on the tails to the company meter, which is not really a DIY job..

As pointed out, consider descaling, and if you still want noticably more oomph, then look at gas fired water heating.

 

[ChrisR]

On the other hand (!) 10.5 kW does feel noticeably better than 8.5, especially in the winter when the incoming mains is that much cooler.

Once plumbed a 10.5 kW in a house where there was already a shower from a combi boiler (28kW). Lady phoned to say something was wrong as the performance was terrible. She insisted I went back to feel it. Instead I got her to measure the flow into a bucket at showering temp. SHe said 4 litres per minute, which is correct. But she couldn't believe it and told me to go and look at it. Instead I gave her the number for the technical enqs line at the manufacturer. She then said that if I didn't go and look at it she'd report me to Corgi.

What can a chap do?