Electric shower vs. instant water heater

[joe90]

With a new build I am fortunate that I can select a tank for the cupboard to get max insulation all round, over insulating an immersion I know to be a problem so probably won't have one just an inline heater if the tank runs out. Sorry crofter for diverting your thread, more on my build to come.........

[SteamyTea]

9 minutes ago, JSHarris said:

Any thoughts on using a venturi hot water supply booster rather than a pump

I did not even think about it ten years ago.

I am not sure what they cost or how easy they are to fit.  I did not want to do any major work to the party wall (casing in pipes) or pulling up flooring.

When I did it, I think the total cost was less than £200 including the DPS, the DP RCD, pipe and fittings (sill have a load of the pipe left), new mixer tap with the shower attachment and pump.

 

If I was building a new place, I may well do things differently, not sure.  I like the simplicity of my system, and the reliability has been excellent.  Without having ever seen, let alone tried a venturi system, I cannot really comment on them.

 

 

 

[Jeremy Harris]

I've been doing a bit of web searching since Peter S mentioned venturi showers, as I'd never heard of them either.  This (commercial) link has some basic info, but generally they look an ideal solution for Crofter's situation, and probably something that guests would be less likely to be able to break/complain about etc: https://www.plumbingforless.co.uk/showers/venturi-showers

 

There's also a thread on another forum about them that seems fairly well balanced: http://www.diynot.com/diy/threads/venturi-showers.33623/

Edited February 5, 2017 by JSHarris

[SteamyTea]

I just had a look too.  Seems you can get then from about £300, so no real price difference.

Be nice to see one in action.

[Jeremy Harris]

1 minute ago, SteamyTea said:

I just had a look too.  Seems you can get then from about £300, so no real price difference.

Be nice to see one in action.

 

Perhaps Peter S can give us a bit more feedback on how his performs.  I agree it would be nice to see one in action, but after 20 minutes or so of web surfing I've struggled to find anything really negative about them, and generally people seem more willing to complain about something than praise it.  That leads me to believe that they work OK, the old "absence of evidence to the contrary" argument, but not definitive proof!

[SteamyTea]

There is no reason why they should not work (never answer a question with a negative, but hey ho).

As long as there is a good stable water supply they should perform as expected (not difficult physics).

 

Would make the plumbing in a new build or major refurbishment easier too.

 

Just for a laugh, and not having done a Silly Sunday Experiment for a while, I just filled up my 2 litre water jug from my kitchen tap, too 5 seconds, so 24 litres/minutes flow, took 6 seconds on the basin tap.  So 20 lt/min flow there.

 

So even allowing for some losses (friction, pressure and generally efficiency), I would think that a shower with a flow of 15 lt/min would be quite possible at my house.

That is almost 50% greater than what I have (and I have no real complaints with the shower).

 

Knowing that leads nicely into sizing a cylinder.

I have 200lt of water at 50°C, which is probably closer to a mean of 40°C, but as Crofter will be running his at a minimum of 65°C, his mean would be closer to 50°C overall I would think (there are ways to reduce the temperature gradient to get a greater capacity from the same size cylinder).

As a shower does not really need to be hotter than 40°C, 90% cold water would need to be added (almost 50/50 mix as it depends on mains temperature).  This would give an equivalent of a  420 lt store of water for showering.

At 15 lt/minute, that would give 28 minutes of showering (all these figures are a bit rough).

 

Might not sound much, but that is before any extra energy is inputted, and working from a 200 lt cylinder (and about what my old lodger did before I educated her, with a stick).

This might cause problems when on E7/10 only, but an extra 10 kWh of energy at day rate would be about £2/day.  As I suspect the place will not be rented out at 50 quid a week, not really a real problem.  Just let the secondary immersion heater deal with it via the thermostat (say set 10°C lower than the main E7 one).

Edited February 5, 2017 by SteamyTea

[Jeremy Harris]

ST, I'm even more convinced this is probably the best solution for Crofter's needs after that.  Best of all, I think, is that it's all pretty simple stuff to put together, with a performance that's likely to keep his guests happy and which has a very low maintenance overhead.  I would imagine the reliability is pretty good, too.  The only thing I remember watching out for, from our time spent living in Scotland, was that immersion heater elements would tend to corrode a bit, due to the slightly acidic water.  I know I had to replace ours, when it was around 4 years old, as it tripped the RCD, and heard tales from around the village that it wasn't uncommon for them to have around a 5 year life up there.

[Nickfromwales]

Ok. A LOT of options and info here from many different perspectives . 

With the quality of your build Rob, it's clearly possible to heat electrically. ( edited to add : so basically ruling out the need for an LPG boiler / combi ). 

Just how much electricity do you have available? Instants of any decent size eat through electric and drawing 50-60A is typical. Soon starts adding up . 

I can't recall what your doing for cooking. I assume you'd prefer to go all electric, but hopefully you've decided on an LPG hob at least? I'd recommend that option in a heartbeat as not only does it free up some juice, it also gives you means of cooking / boiling a kettle in a power cut. 

 

I think this is all getting over complicated, just to avoid a quick annual G3 inspection, which is a step in the wrong direction imo. This install screams UVC to me, and it's a no-brainer. Balanced high pressure hot and colds throughout, mixer taps and thermostatic shower mixer and shut the door. Simples. 

Have the UVC anywhere you like as you e got warm roof space, iirc, but I'd put it in the habitable area to create a warm airing cupboard if possible. I've fitted a 210 Ltr ones in a standard 600mm kitchen larder unit, ( in a hairdressers ), so they can be integrated with a bit of forethought. Similarly they can go into a fitted wardrobe space / similar too . Better to have the bit of heat loss used advantageously if poss so in the airing cupboard would be the No.1 choice here afaic. 

You can have an UVC made bespoke with 2 or theee x 3kw immersions. This would give you options of a smaller cylinder but faster recovery / re-heat times. You'd have to store at around 70oC for that option and blend the output at ~50-55oC to maximise delivery vs size. 

A basic, robust thermostatic shower valve will come in change of £100 and you've got a high pressure / high flow shower that will knock the occupants socks off. 

With your good cold mains pressure, there will still be enough headroom for someone to run hot or cold water from the kitchen sink / washing machine filling. 

 

Regarding the shower as an aside, let's not forget about tank fed electric showers ( like the Triton T80Si 'pumped' ) which has an integral impeller pump and gives the same electric shower performance ( better actually ) and convenience as a regular cold mains fed electric. 

[SteamyTea]

Nick

Is there any reason, other than personal preference and cost, to just vent a UVC.  That way you get the built in heat exchanger (only a coil of pipe after all) and you can then just plumb in as normal.

I know you very much like UVC as it saves a bit of plumbing up to a tank, but that seems to be all it saves.

 

I almost agree with you on the G3 inspection on rented places, which is why I disagree with you on a gas hob, just something else that needs inspecting and can go wrong (I can see a visitor not bothering to twist a valve to the on position and the husband pulling the installation apart to 'fix it').  A two 'ring' induction hob is probably all that is needed for a holiday cottage.  Flick the switch on the wall and it is ready to go.

Might be worth getting one of those pyrolytic ovens though.  A clean oven says a lot (says you can't cook generally, or your staff need more training, says someone that has a dirty oven at home and a spotless one at work).

 

This is an alternative for the shower, very cheap to fit, about as efficient as you can get, probably could be modified to work as an inline heater, and the user will not be able to say much when it fails.

 

[SteamyTea]

1 hour ago, JSHarris said:

The only thing I remember watching out for, from our time spent living in Scotland, was that immersion heater elements would tend to corrode a bit, due to the slightly acidic water.

Not sure about the acidity of the water down here, but my element is probably the original, so 30 years old this year.

This is the inside of my ten year old and ten quid Tesco kettle (and it has a lot of use in my house).

 

[Jeremy Harris]

2 minutes ago, SteamyTea said:

Not sure about the acidity of the water down here, but my element is probably the original, so 30 years old this year.

This is the inside of my ten year old and ten quid Tesco kettle (and it has a lot of use in my house).

 

 

In the 16 years I lived down near you, I can't ever recall having an immersion heater fail, so I suspect the water isn't as acidic as that in some areas of Scotland.  Our kettle used to always look like that when we lived down there, too!

 

One thing we did notice in Scotland was that the water always had a brown tinge.  We rarely used the bath, but when we did a full bath looked like it was filled with weak tea.

[Nickfromwales]

1 hour ago, SteamyTea said:

Nick

Is there any reason, other than personal preference and cost, to just vent a UVC.  That way you get the built in heat exchanger (only a coil of pipe after all) and you can then just plumb in as normal.

I know you very much like UVC as it saves a bit of plumbing up to a tank, but that seems to be all it saves.

 

I almost agree with you on the G3 inspection on rented places, which is why I disagree with you on a gas hob, just something else that needs inspecting and can go wrong (I can see a visitor not bothering to twist a valve to the on position and the husband pulling the installation apart to 'fix it').  A two 'ring' induction hob is probably all that is needed for a holiday cottage.  Flick the switch on the wall and it is ready to go.

 

You wouldn't spend all that money on an uvc and then strap it into the Delorian and take it back to the 60's by venting it and adding an open tank . If the decision is to go vented, then you buy a copper cylinder for a few hundred and a placky CWS and off you go. 

Reasons why not to?

Cost. 

 

Complexity.

 

Increased heat losses.

 

Risk from having tanks in the attic, leaks etc.  

 

Incompatibility from mixed pressures to devices such as mixer taps and mixer showers. ( imbalanced hot and cold ). 

 

Needing to buy, fit, and maintain a pump for decent pressure. ( Certainly useful if your cold mains is crap ), but as @Crofter has stated his is good, so why would you steer away from good pressure, fit an open gravity system and THEN go and buy a pump to get good pressure ? 

 

Oh, and my favourite........My personal dislike of bathing in water that comes from an open tank, born, I guess, from me taking out so many with feathers, fur, and skeletons of its victims still at the bottom . Yuk. 

 

I did think about you getting a bit of uplift from fitting a huge CWS in the heated loft space and using that to 'assist' with water sitting at a bit above ambient, but the reality is it would just about nip at the problem. Plus, you'd have to store enough to get you through the mornings ablutions, and fit a solenoid on the fill valve to stop cold water entering during the morning, thus killing off any stored warmth by pouring cold water over it. 

Its an UVC for me here. Simple, reliable, and if sized correctly and fitted with multiple immersion or one big 6 or 9 kW one, you'll have no major issues with running out of hot water. 

You'll then still have ample headroom in the electric supply to have a decent induction hob. Remember that an instant and a decent hob will want upward of 80amps if running simultaneously. Might have to turn the telly off to have a shower,

 

 If power cuts are a problem, and it's a rental, dual fuel is a real consideration that shouldn't be discounted so quickly. Fitted a dual fuel LPG range in the last rental that was out in the sticks. 

[SteamyTea]

Do UVC need a separate expansion vessels?  If they still do (I have no idea), then the heat loss and leak problem is about the same as a vented cylinder I would have thought.

[Nickfromwales]

The expansion vessel goes with / alongside the uvc. Some are integrated into the physical cylinder size eg there is a false top to them with the EV inside. You can even get bubble top cylinders which trap a pocket of air in the top for expansion to negate the EV. 

A sealed system is far less likely to give you grief IMO, but your stats are undeniably attractive . Maybe best to consider the use for this situation, as its a renter, and I'm allowing for one shower after the other, up to 4 showers in succession, at any one time. If they're ramblers, then the same of an evening. That's a chunk of DHW and they won't want to be disappointed. 

[Jeremy Harris]

Just to add to the mix, we regularly have holidays in just the sort of place that Crofter is building.  Our last one was this windmill in Devon last October: http://devonwindmills.co.uk/ (I'll own up that the owner, Vince, is a flying friend of mine - but I'm not trying to advertise for him, honest).  We've stayed in places like a converted pigeon loft in the Lake District, sailing boats on the Broads, a log cabin by a lake, heated by a water source heat pump, even a rented "cottage" at the South end of Sanibel Island, Florida, right on the beach by the old light house.

 

Everywhere we've ever stayed, I think, has needed something fixing, and I've usually had a go at fixing it, rather than call the owner!  I would guess a fair few guests would do the same, so things really do need to be locked down, as near maintenance free as you can make them.  My wife's greatest cause for complaint anywhere we've stayed has been the shower, without question.  I'm not that fussy as long as it works, but she does like a decent shower.  My greatest cause for complaint is noise.  The water source heat pump in the log cabin made such a noise that we'd not stay there again.  The same with the idyllic "cottage" on Sanibel, the A/C was very noisy and had to be on because Florida is sub-tropical and we couldn't sleep without it on.

 

I've fixed jammed radiator valves and refilled the water in an oil fired combi that had a slow leak and lost enough pressure that it stopped working - no morning shower! 

 

So, I'm either a fairly typical self catering guest, or an example of the guest from hell that fiddles with everything, but it might give you some idea as to why I think that the simplest possible and most foolproof system you can come up with, would be best.

[Crofter]

Well that's given me a lot to think about- thanks all!

Just a quick note just now (heading out in a minute to catch the last of the daylight..)

- power cuts: we've been here about four years and had two power cuts in that time that I can remember. One was 37hrs which was quite exceptional, the other about 4hrs. So we may be in the sticks but it's hardly something I would worry about. Plus they occur during low season anyway. If it were to happen whilst guests were staying, I do have a genny in the shed and there is a woodburner in the cottage. It would be easy enough to provide a camping stove for emergency cooking.

- not going for an LPG hob, it's got to be either ceramic or induction, primarily for cleaning purposes.

- the cottage will sleep two, and that's it. I've had advice from letting agents and was dissuaded from aiming for the family or group markets. It's simply too small, at 43m2, to realistically squeeze anybody else in. At most I might consider having a travel cot available but that would be the limit.

 

A note on water quality- down in the south of Skye there is actually an area of hard water, due to the limestone. Our own water is good, no trace of colour, and no problems with scale or sediment.

[Jeremy Harris]

There's a good market for smaller places for just a couple, people just like us! 

 

We always seek out the smaller self-catering places in rural areas, and they are in short supply.  Given that there are quite a few people in our general demographic; retired, no kids at home, like peace and quiet and have a reasonable disposable income, I think you could do worse than focus at that end of the market.  For example, we would happily pay somewhat over the odds for somewhere that is cosy, sleeps two and is comfortable and in a quiet location.  From my perspective, if it's a bit quirky that adds to the charm - not quite so for my wife!

 

Oh, and we quite enjoy holidays out of season.  We've spent Christmas away (not self-catering, but the hotel on Burgh Island......), spent a week last October in the Windmill and spent New Year in the log cabin by the lake, when the temperature outside was about -8 deg C and the lake was frozen.  So perhaps look at keeping it available through the winter, too.

Edited February 5, 2017 by JSHarris

[ProDave]

The brown tinge in Scottish water is almost certainly peat. Our water comes from Loch Glass, about 6 miles away. when we first moved here when it was windy, our water would turn slightly brown. It was described to me as the water outake from the loch was quite low, and in windy weather, the waves stirred up the silt.  About 5 years ago they built an upgraded treatment works and no more brown water. No chlorine or other stuff either.

 

It is very common for isolated houses wiith private water supplies still to have often VERY brown water.

 

 

As Crofter says, there's a limestone band all across the top of Scotland. A small isolated group of 5 houses 10 miles from us share a common borehole into that limestone aquifer.  I have replaced one of their immersion heaters every 5 years. and when I do so, I spoon a good bucket full of limestone out of the bottom of the HW tank.

 

[Jeremy Harris]

26 minutes ago, ProDave said:

The brown tinge in Scottish water is almost certainly peat. Our water comes from Loch Glass, about 6 miles away. when we first moved here when it was windy, our water would turn slightly brown. It was described to me as the water outake from the loch was quite low, and in windy weather, the waves stirred up the silt.  About 5 years ago they built an upgraded treatment works and no more brown water. No chlorine or other stuff either.

 

It is very common for isolated houses wiith private water supplies still to have often VERY brown water.

 

 

As Crofter says, there's a limestone band all across the top of Scotland. A small isolated group of 5 houses 10 miles from us share a common borehole into that limestone aquifer.  I have replaced one of their immersion heaters every 5 years. and when I do so, I spoon a good bucket full of limestone out of the bottom of the HW tank.

 

 

 

Yes, the Portpatrick supply was from a part loch, part reservoir, up in the Rhins above the village, and it was pretty peaty water.

 

Funny you mention that band of limestone.  I spent a week on holiday inside it, with a handful of caving friends.  It was a hell of a long drive up to Sutherland from Cornwall, in a Renault 5 Turbo.................

[ProDave]

1 hour ago, JSHarris said:

 

Funny you mention that band of limestone.  I spent a week on holiday inside it, with a handful of caving friends.  It was a hell of a long drive up to Sutherland from Cornwall, in a Renault 5 Turbo.................

Interesting. This part of Scotland is not exactly well known for it's caving, but where there is limestone....

 

Just curious to know the entry points to the caves (not that I am intending to go exploring)
 

[Jeremy Harris]

27 minutes ago, ProDave said:

Interesting. This part of Scotland is not exactly well known for it's caving, but where there is limestone....

 

Just curious to know the entry points to the caves (not that I am intending to go exploring)
 

 

There's a couple of show caves up there, open to the public, like Smoo and something bone cavern (can't recall the name at the moment).  None of the cave systems are big, but they are interesting because the outer parts of some were inhabited at some time.

 

I've got a book somewhere on the caves of Assynt, I'll try and dig it out, as I was last up there over 30 years ago and my memory isn't that good!

Edited February 5, 2017 by JSHarris

[Crofter]

The band of limestone is very localised. On Skye it is a small area in the south, around Torrin and Elgol. There are caves in the area which have yielded some significant archaeological finds, and where the limestone meets the sea it produces a fascinating landscape.  The only cave I've personally explored is Spar Cave, which runs 80m back. You're supposed to visit at low tide but I was there at the wrong time. Was fun to shimmy round on the limestone cliff face above the sea- the handholds are great, and the thought of falling into four degree water really focuses the mind.

 

Anyway, to get back on topic- I had a word with my local plumber and he has also suggested a UVC. So I might take a punt on the one on eBay. It does seem to be the most straightforward solution. Whilst I would like to DIY everything, I have to be realistic and admit that the summer season is approaching fast, so it makes sense to hand off discrete bits of work where possible.

[ProDave]

I'm surprised the limestone is as far north as Assynt, the limestone borehole I was referring to is still in Ross-Shire, not even quite in Sutherland.  Been to Smoo cave.

 

Of course Fingals cave on Staffa is worth a look (and the boat trip to get to it) did that last year while on Mull.

 

Back to the topic. Just about everything has to be tested and certified for rental, but I have never actually heard of anyone asking for a certificate for UVC's in rental properties.  Keep quiet or I am sure someone will introduce one.
 

[Crofter]

Fingals is of course geologically different, being part of the band of columnar basalt that runs from the Giant's Causeway.

 

I'll need to do some homework about what regulations will apply. I know a few people who rent out caravans, boats, etc via AirBnB and am crossing my fingers that I can do likewise- legally it is just a caravan, not a house. But that's another topic.

[Onoff]

 

Summer Showers Sorted:

 

 

 

 

Edited February 5, 2017 by Onoff