Electric or thermostatic shower?

[Paul Giverin]

My installer has just about fitted my new combi-boiler and my HWC and cold water tank are a thing of the past. The whole house is now on mains water pressure.

This means that my tank pressure fed power shower is redundant and I need to replace it with something. I was originally looking at mains pressure thermostatic mixers but I was initially put off by the high costs. I then started looking and electric showers but googling through the archives it would seem that I would be very disappointed with the flow rate compared to what I've been used to with my power shower.

A further complication is that I would have to fit a new consumer unit as a 9.5kw shower requires a 40 amp fuse and my current consumer unit only has a 30 amp fuse.

So its back to thinking about a thermostatic unit. Will a thermostatic shower give me a similar flow rate to my power shower? Obviously the

11.4 L/minute output of the boiler will be the limiting factor.

[Christian McArdle]

Probably, unless you had a particularly powerful drencher type or panel shower with body jets.

Indeed. The electric shower will produce about 3.5 lpm.

Christian.

[Broadback]

There is one advantage to an electric shower. If your combi breaks then you can still have a nice warm shower. Both would be best, however as said the output from electric is pathetic.

[Doctor Drivel]

You can install an in-line electric instant heater in the combi outlet for that. Or if it really bothers you, have a backup combi. They are cheap enough.

[Christian McArdle]

Almost, swap "nice" with "crap" and you're there!

Christian.

[Paul Giverin]

In message , Christian McArdle writes

Thanks to everyone for their helpful replies.

I'll do the obvious and go with thermostatic mixer. I've got a few questions about them but I'll start another thread for that.

Cheers,

[Lobster]

That's an interesting thought actually - where would you get a suitable bit of kit from? Can't recall seeing anything like that. Presumably it would only provide HW to the house at a flow rate comparable to an electric shower, but even so...

Thinking along the same lines, wouldn't there be a market for an 'electric backup' combi? The extra cost of the bits would be trivial and would be saved the first time te combi broke down, by avoiding the emergency call-out fee (assuming you could survive for a day or two on electric-heating, rather than no time at all with a totally broken combi?)

David

[Doctor Drivel]

Yep. it will do, or two taps and get you wet under a shower, but not all at once. Just backup. There are plenty of these water heaters about.

[Dave Plowman (News)]

You've made a very big mistake. Why didn't you ask for advice before embarking on this route?

[Dave Plowman (News)]

[snip usual drivel from Evil]

This deranged madman should be banned from giving advice. He assumes things not even common to real world situations. In other words, a poor plumber looking for maximum profits. Avoid.

[Dave Plowman (News)]

Well, if you went to a decent system with stored hot water, an immersion will give backup for the odd failure. And until you exhausted that store would give normal performance of the shower. An instant electric shower will always be what it is - a dribble. And most domestic combi installations aren't really that much better.

[Dave Plowman (News)]

This fool should be sanctioned.

[snip the rest of the drivel]

[Doctor Drivel]

..here is a man who doesn't know, a man who has no clue ..he's no clue about the things which are known to me and you

..continually vacant in his head ..no knoweldge, reason, logic, this must be said

..drivel and babble just comes so ..relentless, incoherrent in it flow

..it's time take no notice of this hot head babbling fool ..just laugh and smile and thank the Lord, you are sane and cool

[Owain]

Or sectioned, even.

(Cue James Bond music and scary close-up of saw blade)

Owain

[John Rumm]

Is this a conventional mixer shower with separate pump, or one of the shower and pump units that looks more like an electric shower?

If the former, it may be suitable.

I am sure lots of people look at the price of a big brand thermostatic mixer, then see an electric shower and get suckered into that route because it initially looks much cheaper.

What is often not taken into account is the cost of upgrading the electrics and laying on the supply required for a shower. I just completed installing one for someone today, the cost of the parts alone was about 80 quid.

When you say "fuse" do you mean fuse (as in rewireable) or do you actually mean a MCB? Also does the CU have any spare ways?

A modern(ish) CU with MCBs and a spare way may actually be reasonably cheap to equip for an electric shower.

It ought to be as good (will depend a bit on the pressure you pump was capable of, and what your mains is good for).

BTW, you can get basic bar mixer thermostatic shower kits from Makro (made by Bristan) for under 60 quid. These are certainly acceptable on a combi.

[Paul Giverin]

Its the later. It specifically warns against using mains pressure.

No its not a MCB. Its the older ceramic fuses (like plug fuses but bigger).

Yeah, I've seen a Volex split load MCB CU in Screwfix for £53. I might even invest in that, even if I don't go down the electric shower route. I'll have to see if its just a case doing a straight swap with the old one.

Thanks John. I just need to determine the difference in performance between the cheap ones and the expensive ones and decide what I need.

[Paul Giverin]

In message , "Dave Plowman (News)" writes

You are making a rather presumptuous statement while not being in possession of all the facts.

What makes you think I didn't?

[Doctor Drivel]

He makes things up a lot.

[Doctor Drivel]

Imagine this pillock with such an implement! Just as well he uses axes for his cabers.

[John Rumm]

Right ok, not much you can do with that then.

HRC cartridge fuses by the sounds of it. You can get the fuse carriers in a variety of ratings (you need the carrier to match the load).

does assume you have a spare way in the CU however)

You would also need to ensure that your earth loop impedance is low enough to support that size of fuse, or failing that use a RCD as well.

Sorry, we are talking at slight cross purposes there. I was saying that if you already have a modernish CU with a spare way, then adding the extra circuit to it ought to be cheap enough.

Yes you could also replace the whole CU (and there may be merit in that for other reasons anyway), but then you are back into mixer shower prices...

I have two showers. One is a Mira non thermostatic mixer (left over from former gravity fed system) and one of the aforementioned Bristan ones. Direct comparison between then from a pressure and flow rate perspective is difficult since they have different shower heads, and they are also one different floors, but the Bristan certainly gives a good output. For ease of use the Bristan wins - mainly by virtue of it being thermostatic (the non thermo one takes careful adjustment, and a little experimentation to learn how to deal with the temperature quirks of a combi). The life of the mixer may be the telling factor. The Mira must be at least 15 years old (came with the house), and has had one set of replacement 'o' rings. I don't know how long the bar mixer will last or what the spares situation will be like. Having said that the O ring kit for the Mira was not that much cheaper than the cost of a new bar mixer!