Electric shower vs. instant water heater

[SteamyTea]

3 hours ago, JSHarris said:

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

Eh Crofter, get Jeremy in as your first booking, he can do all the snagging

3 hours ago, JSHarris said:

Renault 5 Turbo

Foot down, nothing, nothing, nothing, whoops.  Why I got a 205 GTi

[Nickfromwales]

2 hours ago, Crofter said:

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.

Do you have the link for the Ebay one? 

Edit : or just the size / spec / number of immersions etc?

[Crofter]

9 minutes ago, Nickfromwales said:

Do you have the link for the Ebay one? 

Edit : or just the size / spec / number of immersions etc?

 

PM'd you...

[Nickfromwales]

?

[Crofter]

50 minutes ago, SteamyTea said:

Eh Crofter, get Jeremy in as your first booking, he can do all the snagging

 

If J wants to be my guinea pig then I'd quite happily give him a week's stay pro bono... I've certainly learned enough from his postings over the years and it would be one way to say thanks!

 

Hmmm maybe I should be offering a discount to BuildHub members...

[Stones]

Rob, just another voice to add to previous comments ( given it is a holiday let) don't whatever you do be mean or skimp on the provision of DHW.  You get this right and you will get a loyal band of annual repeat visitors, probably willing as Jeremy says, to pay a bit of a premium for something that bit better than a run of the mill offering. Obviously location and view are going to be the initial sellers, but to get people coming back, spotlessly clean and uber comfortable - warm, dry and plenty of DHW. 

 

And yes 50% discount to BH members a fantastic idea...

[dogman]

Just to add something else to the mix. We fitted TMVs to the hot water supply's in the bathrooms and wet rooms. it does help reduce hot water consumption as well as avoiding the boiled child

 

[Ferdinand]

@Crofter

 

Not sure if this helps or not, but I have a new, unused Stuart Turner RG500 Pump sitting under my desk in its box, which I believe can be used for a shower. It is about 15 years old, but has just been stored.

 

It is that last one of a batch of 10 that my father used for a project to develop a "mobile shower chair" for hospitals, and for some reason he bought 10 and I inherited 9.

 

The others sold on Ebay, but I crossed wires with one buyer. None of the others came back saying they didn't work. The thing is engineered like a battleship.

 

If it is suitable, yours for say £30 + postage. If not, I will put in the marketplace; I am sure that there is somebody on buildhub who is constructing a high volume moonshine dispenser or similar.

Ferdinand

Edited February 5, 2017 by Ferdinand

[Nickfromwales]

8 hours ago, dogman said:

Just to add something else to the mix. We fitted TMVs to the hot water supply's in the bathrooms and wet rooms. it does help reduce hot water consumption as well as avoiding the boiled child

 

Not just nice to have, but a requirement when your renting to 3rd party . 

You cant have non thermostatic devices fed from an instant water heater, electric OR combi.

You have to cap the upper temp limit somehow with an UVC too, either by setting the temp on the cyl stat to 55/60oC or by fitting a TMV ( set at 50oC ). 

A secondary TMV ( 46oC ) just for the washbasin is a nice touch, giving excellent comfort, and you'll need to go down the TMV route here imo so you can set a higher storage temp ( to get away with having a smaller cylinder ). 

Dual or triple immersions are available so you can run one for storage and set the other to come on when the occupants are bathing ( boost ) to speed up recovery when it's needed most. 

[Crofter]

Thanks for the offer but I think I'm settled on the UVC route. I didn't know Stuart Turner made pumps by the way- I'd only heard of their boat engines.

[Ferdinand]

16 minutes ago, Crofter said:

Thanks for the offer but I think I'm stettled on the UVC route. I didn't know Stuart Turner made pumps by the way- I'd only heard of their boat engines.

 

Fine.

 

Marketplace here we come.

 

One chappie had about 4 of them to be spares for his brewery :-) .

Edited February 6, 2017 by Ferdinand

[Nickfromwales]

3 hours ago, Crofter said:

Thanks for the offer but I think I'm settled on the UVC route. I didn't know Stuart Turner made pumps by the way- I'd only heard of their boat engines.

They're a big name in pumps. Very good bits of kit. . 

Hudson Reed are another. 

[Jeremy Harris]

I repaired a very old Stuart Turner hot water recirculating pump a few years ago.  Fantastically well made bit of kit, and what's more I could buy spares to fix it.  The housing and impeller were very nicely machined bronze castings, and the thing just oozed quality when taken apart.

[Nickfromwales]

9 minutes ago, JSHarris said:

I repaired a very old Stuart Turner hot water recirculating pump a few years ago.  Fantastically well made bit of kit, and what's more I could buy spares to fix it.  The housing and impeller were very nicely machined bronze castings, and the thing just oozed quality when taken apart.

Yup. You could chip a spud through one of those without missing a beat. . 

[Crofter]

I guess their pumps have a better reputation than their boat engines, which are known as 'Stuart non Turners'...

[Jeremy Harris]

10 minutes ago, Crofter said:

I guess their pumps have a better reputation than their boat engines, which are known as 'Stuart non Turners'...

 

Indeed, and for a very good reason! 

 

I used to sail a friends yacht, whilst he was working in Dubai, and I would take it over to France for him so he could have a holiday without breaking the UK "60 day" tax rule.  It had an 8hp Stuart Turner inboard, that would invariably start easily when moored up, but which I never managed to get to start when at sea.  I well remember a pretty scary night, on my own, totally becalmed about 20 miles of the French coast, with a flat battery (so no lights) and in the middle of the shipping lane.  All I could see was the loom of the Île Vierge light on the horizon, whilst the yacht drifted about in circles.  Every time a large ship came close all I could do was shine a torch on the sail, in the hope that they would see it..............

[Crofter]

So the answer to my original questions turns out to be 'neither'.

 

As a further thread drift... I know the idea of the second immersion on a UVC is for use on E7, but would it make any sense whatsoever to swap it out for a DC unit and hook it up to a solar panel? Just to provide a low level of heating to counter standing losses and reduce bills. The £/w of solar is just so low these days, and the house is mostly going to be used in the summer

 

(in answer to a previous question, yes I will keep it open all year round but I expect to be at 50% occupancy or less in the off season ).

[SteamyTea]

43 minutes ago, Crofter said:

use on E7

Out of context to your last comment, but worth remembering just how cheap E7 is really.

Even if it goes up 25%, it will still only be 10p/kWh for a cheap to install and maintain system.

So if you need 10 kWh for all the DHW (including standing losses), it would still only be £1/day.

 

Sometimes the law of diminishing returns comes into play.

[Nickfromwales]

Only problem with the dc route is you'd have to have one or both immersions on a changeover relay so you could 'mains boost' when hot water is being used en-mass.  

The relay ( contactor ) can be used to switch from dc solar to ac mains accordingly, remembering that solar will be of little or no use for the morning bathing, literally just offsetting the losses would be a good option though. 

Also remembr that you'll need a legionella purge cycle too so it'll need a time clock on the boost element to do a 1-2 hour heat cycle weekly. 

 

Edit : one or both immersions instead of both immersions 

[Nickfromwales]

15 minutes ago, Nickfromwales said:

Only problem with the dc route is you'd have to have one or both immersions on a changeover relay so you could 'mains boost' when hot water is being used en-mass.  

The relay ( contactor ) can be used to switch from dc solar to ac mains accordingly, remembering that solar will be of little or no use for the morning bathing, literally just offsetting the losses would be a good option though. 

Also remembr that you'll need a legionella purge cycle too so it'll need a time clock on the boost element to do a 1-2 hour heat cycle weekly. 

 

Edit : one or both immersions instead of both immersions 

Ah, just re-read this and you mean an ALL DC solar arrangement including a DC element.  

It may be worth looking at a higher kw AC ( primary ) immersion if going that route. Sounds like more complication TBH, so maybe just go AC solar and use the excess to power the fridge freezer or take @SteamyTea's advice and just pay for the electric on demand. 

[SteamyTea]

I think any DC route is going to be troublesome.  An extreme example would be the creation of hydrogen and oxygen in the cylinder.  I know Scotland wants to join the space race, by Cornwall is much better suited to it. (https://www.newscientist.com/article/dn25897-spaceport-uk-locations-for-launch-sites-unveiled/)

 

One has to be careful when designing a system not to get carried away.

We have gone from about a £1000 DIY system (my idea)

To a £2000 plus system (Nick's idea)

To a £4000 plus system (Terry's idea)

 

(all figures are bad estimates to make me look good )

[Crofter]

It was just a bit of a throwaway thought really- keep one big AC immersion for doing the bulk of the work, and spend a couple of hundred quid on a DC solar system for the second immersion. I was assuming it would mean giving up on E7 so probably not worth it at all. Just curiosity really, prompted by the low cost of solar and the mainly summer usage of the house. Also I've been assuming that E7 comes with some drawbacks like higher peak rates, install cost of second meter, fewer tarrifs to choose from, etc. Could be completely wrong about that!

[SteamyTea]

My new rate is now 20p/kWh I think.  EDF has pushed the price up 8% on average, but for my usage (sub 4,000 kWh/year), they are as competitive as anyone.

 

Just as an example, if I go away for a few days and the cylinder cools to about 30°C, it only takes half and hour with the top immersion (3kW) to heat up a baths worth.

So if you set the thermostats right, and someone does take a very long shower, there will almost be enough put back in for the next one.

[Triassic]

I had a look at a small 20litre under the sink water heater on display in a well known DIY store.

 

The installation on display did not include an expansion vessel or pressure relief valves. In fact, they had 8 of the units for sale, but no expansion vessels or Releif valves, I assume these additional items are only required in particular special circumstances?.  

[Jeremy Harris]

1 minute ago, Triassic said:

I had a look at a small 20litre under the sink water heater on display in a well known DIY store.

 

The installation on display did not include an expansion vessel or pressure relief valves. In fact, they had 8 of the units for sale, but no expansion vessels or Releif valves, I assume these additional items are only required in particular special circumstances?.  

 

Curious.............

 

We have a boiling water tap with a heated reservoir under the plinth, and that has to have a PRV and tundish, in fact it's supplied with one.  The PRV is of the type that can operate regularly, every time the tank heats up and the water expands, as it needs to in order to keep water in the trap under the tundish (all part of the same moulding).  Similarly, when we had these under-unit hot water heater at a place I worked, they had a separate tap and outlet, and the outlet was the expansion opening, as it was connected to the tank, the tap just turned on cold water to displace hot water and drive it out the outlet.  The over-sink units are the same, I believe.  I also remember an over-sink very hot water dispenser (for making tea and coffee etc) that had an overflow pipe led into the sink, that I always assumed was connected to a PRV.

 

Be interesting to find out how the 20 litre unit mentioned deals with expansion and pressure relief.