UKH

Recently moved house and found out that the downstairs shower room (there is a family bathroom upstairs) only has a 15L electric water heater to supply it. This only gives hot water for about 3mins max, which is not great. It is a type that looks more suitable for a sink.

I think there are 4 options (other than quick showers):

1)Plumb in shower to mains water systems (combo boiler) - concern here is whether the boiler could cope, plus would prefer an alternative system in case of boiler problems etc.

2) Get an electric shower installed, might not be too difficult but extra pipework/electrics and replacing tiles etc Plus would need hot water for the sink somehow.

3) Look to replace the water heater (that is in the eaves above the shower room) with some kind of 'on demand' water heater, using the existing plumbing and electrics where possible. In my mind this might be the easiest but I am struggling to find a suitable unit, or find any info on if such things exist.

4)Replace the 15L unit with a much bigger one, I'm guessing at least 50L

Any thought or ideas welcome - obviously will be seeking out 'professional' advice as well.

In reply to djwilse:

Go with the combi, without a doubt.  All electric showers are inferior.

In reply to djwilse:

I'd probably go for using the existing water heater for the sink (or replace it with a more modern smaller one)  and put in an electric shower.  The cold water for the electric shower won't be far away and won't need a lot of change.  

However this would depend on  having the capacity on your electricity supply if you want a decent shower.  

In reply to Neil Williams:

Personally I'd go for redundancy, if the boiler breaks you still have hot water.

Adding it to the combination depends on the power.  

In reply to djwilse:

How much use will the downstairs shower actually get if it's not the main bathroom?  

In reply to marsbar:

Depends how often you have a shower.  I have one daily (don't do baths), so the quality of the shower is more important than the "if the boiler breaks" scenario, in which case I'd go to the gym for a shower until sorted (other needs for hot water you can just boil a kettle).

Any combi will be able to cope with a regular shower.  I have a large rain shower head and a fairly small combi and it's fine.

In reply to marsbar:

I guess 3 or so times a week, more if we have guests staying. The family shower is not the most powerful, so if the new one was powerful I would tend to use this more.

In reply to djwilse:

1) The best shower experience.  Modern combis should be just fine.

2) Gives you a backup to the boiler.  But will be a disappointing shower experience.  

• What’s the cable diameter for the current electric water heater?  If it’s less than 10 mm^2 it would need replacing for a 10 kW electric shower.  Potentially messy...  
• A waste water > incoming cold water heat exchanger will boost the flow rate for any given temperature which makes them a bit less crap; your options are more limited without a vertical drop.  Eg http://shower-save.com/products/joulia.html

3) Sounds a lot like an electric shower with the heater element in a different place...  Electric showers tend to run at the max power level you can access domestically in a house with other loads, and without a higher rated incoming fuse and wiring.

4) If you’ve got the space, it’s a simple solution that gives you redundant hot water.   

In reply to djwilse:

Present system sounds a bit of a bodge. You are probably best getting rid of it and going for either:

1. Electric shower. Needs a cold water supply (the one for the present set-up could well work) and a dedicated electricity circuit (correct rated cable, isolation switch etc.). Would be independent of the boiler, which is one thing you wanted, but electric showers generally won't give as good a showering experience as a mains/mixer. As you said, you would still need to sort out hw for basin (assuming there is no basin in that room now?).

2. Mains/mixer shower. Needs hw and cw supply but if you're putting hw in for a basin then you are halfway there. Dependent on boiler performance: if your boiler sends hw to everywhere in house that you want it at a good rate and temperature (does it fill a bath?) then it should be fine for a shower - if the boiler is downstairs near the shower room then even better. Almost-always a better and more enjoyable shower than an electric.

If the downstairs is going to be the primary shower then go for a mains/mixer and maybe put an electric shower upstairs in the family room as a backup/secondary; obviously, swap them round if upstairs is the most-used shower. Hard to give details without seeing the rooms but it's just running pipes to get water to the showers, really.

Various options with mains/mixer units: exposed valves, fully covered etc. Whichever type you decide on, I'd recommend just getting something basic and robust. Mira are pretty good (cue everyone posting to say how their Mira shower is the worst ever), something along the lines of https://www.mirashowers.co.uk/showers/mixer-showers/mira-excel-ev/ for a mixer. If you go electric, get a powerful one https://www.mirashowers.co.uk/showers/electric-showers/mira-sport-max-with-... I'd avoid 'high-tech' things like digital displays, remote controls, built-in radios and similar gimmicks, spend the money on the shower.

In reply to djwilse:

As long as you can easily get H and C pipes to it I'd go for a combi supplied shower with an external (for easy maintenance) thermostatic valve).  I put one in our bathroom a few years back and its been great. No problems with having any electrical supply either. Admittedly no redundancy but TBH in some areas a common problem is with electrical supply when neither electric heater nor combi work anyway. 

In reply to oldie:

The irony of me fitting an electric shower for redundancy is that the only significant outages we’ve had have been power cuts, and our combi boiler kept working just fine with a little 800 W inverter and a couple of 12V batteries...

In reply to djwilse:

Whoever invented electric showers ought to be flogged with a toilet brush; I have never experienced a good shower with one of these, either the flow is pathetic or the temperature fluctuates wildly as the cold water pressure varies when people turn on taps.

In reply to wintertree:

Thanks. Useful to know. However probably few of us have that option ready to use.

In reply to djwilse: If you really want the redundancy go for (4). I looked at (3) when I was in an all electric flat.....you will need new cabling as you'd be looking at a 12kW heater, and it will still be a bit crap.

In reply to Rigid Raider:

A high powered electric shower can be just as good as an average shower.  It does need heavier wiring and capacity for a bigger breaker though.  

In reply to Mike Stretford:

I actually fitted option 3 when I put in an en-suite as we had concerns about the length of the hot water pipe run from combi to shower ('L' shape 3 bed bungalow with combi and shower as far apart as could be).

Absolute waste of money. By the time you've throttled it back so the shower feed is warm, (then climbed back up into the loft and throttled it back again in winter because the cold feed has got colder), you'll have a miserable dribble to shower under. (They also don't run with a thermostatic mixer fitted to the shower for some reason). 

How I wish I fitted an electric shower, with a small electric heater for the sink, in the first place.

Currently now running off a 15 litre tank in the loft. TBH if you crank the thermostat in the tank uo to max there's enough hot water for a shower, but not if you like standing under it for 10 minutes.