Just been to a friend's house across the street to look at a Triton instant shower (fitted by yours truly about 4 years ago). It's a 7.5kW model with dual-element and the common high/low power switch on the front. Reported that the water is now "barely luke warm" even on the highest setting.

I was expecting to open it up and find either one half of the element open circuit, or a faulty high/low switch, bad connection etc.

Electrically, everything checks out though. The pressure & temperature cutouts are fine, all connections sound, both elements showing 13-ish ohms cold resistance. When powered up, I had 235V across both sets of terminals, and the ammeter shows a steady 16 to 16.5 amps being drawn by each element.

So why isn't the darn thing heating the water? The element housing feels barely warm when running, although it does get slightly warm around the top after shutting off. The flow rate is still as it was before, by the way.

There must be 7kW+ of heat being dissipated in there somewhere by the voltage/current readings. I'm not familiar with the internal construction of Triton assemblies, but the only thing I can think of is that somehow the elements inside have become detached from the fins or whatever other exchanger is used to transfer heat to the water passing through.

Ideas?

Paul,

Is it a combined heater and shower unit or a heater which then feeds the shower? If it is the latter, my guess is that the mixing valve has developed a problem. The water heater is heating water, but the cold water is overpowering any hot water coming thru the mixing valve.

If you let the shower run, does the water heater thermostat cycle on and off? If so, the heater is functioning, just that no water is leaving the heater.

Larry C

Larry,

It's one of the self-contained showers which heats the water as it passes through the unit. You just have a cold supply which goes via a control valve, then to the heating elements and straight out of the hose. Temperature adjustment is made by regulating the flow with the valve (i.e. slower rate of flow results in hotter water).

The heating elements on these do not normally cycle on and off during operation, unless reduced pressure or a restriction on the outlet causes the water to get so hot that the safety 'stat on the output opens.

Here's the actual model in question:
http://www.shower-spares.co.uk/triton/tx7000i_and_tx7500i.htm

Paul. If 7.5kW of heat is being produced in the unit and it's not coming out of the shower head, the only other route is to back up heat into the cold water supply, either as high-pressure steam bubbles or pressurised hot water. It's probably scaled-up between the element bottle and the outlet, causing restricted flow. Is this shower connected to a gravity cold water tank in the loft as the cold supply, the traditional bathroom feed in Britain?

I would not turn it on again till it has been dismantled and checked for blockages in the internal waterways.

Alan

Paul

If you are still stuck ask these guys Uk Whitegoods another good forum. They have a general public forum but I am shure that if you ask you may get access to the trade forums as well.

Kenny

Paul, I'm as stumped as you are. Just replace the Triton unit with a new one and see if that works.

Those Triton water heaters only deliver cool water if they are located too far from the outlet.

Was it delivering hot water previously ?

It's amazing how much better a normal shower fed by stored hotwater is.

I really find instantaneous electric showers very poor. I've yet to use one that provides a constant stream of hot water, doesn't go cold / attempt to scald you.

Many of them would be better described as an electric trickle than an electric shower. The flow rates can be utterly pathetic.

Paul, take a look at the ScrewFix site. They are selling a powershower pump + thermostatic control rail, all hoses and the head for less than £200, sp. offer. It needs a hot water feed but as Dave says, far superior than an element heated one. I had one of these in the UK and really miss it! That's if your friend would like to upgrade, of course- depends on the cost of spares or a new Triton unit.

Alan

As Alan says, if the power is going in, its also coming out. I don't really see how it can be dissipated back into the supply. Don't forget that the cold water supply is several degrees lower in winter and this is reflected directly in the output temperature. From my recollections you can't actually have much water flowing from these devices if you want it hot, and 7.5kW is a fairly modest rating for one.

Thanks for all the replies and suggestions.

To answer some of the assorted queries:
The unit is fed directly from the incoming mains supply. Although instant showers aren't my favorite units either for the reasons already stated, he opted for one mostly so that it could be used quickly during summer when the wood burner won't be providing a full cylinder of hot water all the time.

The flow rate seems to be quite adequate, and in fact pretty much the same as when fitted. Wouldn't restricted flow result in the water coming out hotter, anyway?

Yes, it's worked fine for 4 years or so since it was fitted. The heating element is right in the unit, so it comes straight out of the can into the shower hose.

When he said the water's now barely lukewarm, I think even that was an optimistic assessment. I think "Just about got the chill off it," would probably better describe it -- Warmer than the cold supply, but not by much.

The control valve does slow down the flow rate when turned to the hotter end, as it should.

I do wonder why they even bother to fit the high/low power switches on some of these, since the low setting is hardly ever going to be used by anyone.

If the temperature were down a little, I could chalk it up to an unusually cold supply, or something of that nature. But the fact that the water is so cold coupled with the elements still drawing 32+ amps of current just has me stumped.

I can feel the heat around the top of the can after switching off, and there's some heat coming back up onto the terminals from the elements, but that's about it.

Paul, on the basis that the "silliest question is one that is not asked" - did you measure the current on both the live and neutral sides of the circuit? I am perplexed as to where 7.5kW of energy is going.

No, I only measured the live side of each half of the element. I think I see where you're headed, but the shower is fed via an RCD, and the supply is TT with a EFLI of over 20 ohms, so I think that knocks out that possibility.

So am I!

I am playing in the left field here but what if the current is passing through the water rather than the element. The water system may not be at earth potential in this case - plastic pipes etc - so no tripping of the RCD. I could then only assume that 7.5kW is being used for electrolysis!

Paul,
Why is it that people in the UK prefer to use an Instant Water heater rather than the normal Stored Hot Water Cylinder?.
The savings in power must justify using a stored water cylinder?.
I've installed a few of the Instant Hot water units here (in a Gym shower room) and thought maybe it was because they couldn't get the required fall to get good enough water pressure.
The units I installed here were 7kW each, spread over 3 phases, but the question still lies.

Trumpy,

A lot of UK (and Irish) homes have fairly primative victorian plumbing. The old standard immersion heater tank is grossly inefficient and often totally uninsulated. Also, there are plenty of houses around that didn't have any central heating at all. Thus had no central hotwater storage! (plumbing might date from the 1800s or early 1900s!) There was an attitude that until the 1960s or so central heating was considered a totally unnecessary luxury. It's partially down to the fact that the climate in the British isles, other than perhaps the north of Scotland, is quite survivable in winter with pretty woefully inadequate space heating. Also, much of the housing stock dates from a time when there was a fireplace in every room and retrofitting it is very very disruptive.

The net result is that a lot of those systems are either incapable of supplying hotwater at all or, more commonly, don't provide enough hot water to adequately keep up with showers. i.e. they'll provide enough hot water for 1 or 2 short showers and then run cold and then take over an hour to get the tank back up to temprature again. Basically they'll provide enough hot water for 1 bath!

Many homes would have been heated with open fires (fireplaces), plug-in 3KW portable electric heaters etc.

Also, pre 1960s, most homes didn't have showers. People took baths! The concept of showering really only took off in the 1970s in a truely big way. So, a lot of plumbing systems were rather incapable of supplying showers properly.

Installing an electric shower was a simple "add on" i.e. you can take a water supply from the attic tank (almost all homes had one) and power was easily routable from the attic. So, voila.. instant hot showers..

From the late 50s/early 1960s onwards, most homes built(in Ireland anyway) had central heating as standard. In Ireland, typically hydronic and heated by pressure jet gasoil/kerosine burning boilers (Fuel oil burning's generally illegal here and has been for a very long time, other than in industrial situations where emissions can be controlled / monitiored e.g. power stations). Natural gas only came to Ireland in the 80s! (There was "town gas" made from gassifying coal/oil [the oldest type of gas used for heat/light since the 1800s] and LPG via storage tank on your premsis)

So, in general from that period on you start to see systems that were more capable of providing enough hot water for showers. However, many of them continued to use the traditional copper cylinder tank for hotwater without any sort of insulation at all and the 3KW immersion element to heat it electrically if no oil/gas heating was available.

The other problem is that the hot water tanks are usually heated by a fairly primiative water-to-water heat exchanger i.e.a coil of pipes in the bottom of the cylinder. That sources its heat from the hydronic system i.e. the water flowing through the radiators.

They do have an immersion element too for electric heating, but it's usually extremely slow.

Many such systems aren't really capable of operating in summer when the radiators are not required, or if they do they're grossly inefficient.

So, lots of people would have electric showers installed as a back up or for summer use.

Things have drastically improved though, most of those hotwater tanks installed thesedays use much more efficient heat exhangers they're refered to as "rapid recovery" and generally have much large capacity and better insulation.

In general though, the UK and Ireland (perhaps to a slightly lesser extend due to the average of houses being that bit lower) have traditionally had rather crappy heating systems

There's no doubt that the electric shower / point of use hot water, is vastly more efficient than a 100 year old copper tank heated indirectly by a typically very inefficent gas or oil fired boiler

While all of the above may not be the primary driving factor behind new installations of electric showers, it's certainly how they caught on in the first place!

[This message has been edited by djk (edited 01-06-2007).]

How is the chemistry of the water? You would be surprised how effective a coating of calcium and lime on an element can be at insulating the water from the heat being generated by the element. I have seen this as the cause of similar issues many times on rural installations. Might be worth a look see.

Great post Dave!!,
I hadn't thought of the Bath/Shower angle.
I remember the English guy that used to work at the PoCo and would have a bath once a week.
In our climate here, that doesn't work that well.
Saturday night was bath night, by the next Friday you couldn't get near him.
Is it any wonder they lost the Ashes!.

Trumpy,

Things have changed a lot since those days. There are *very* few people who don't shower at least once daily thesedays. Attitudes to that kind of thing are similar to those in the US/Canada etc. You may have just met a smelly guy The climate probabally had something to do with it. It's a bit like living in a very well air conditioned building at all times.

But, in the past thing definitely were different. You have to remember too that pre WWII showering wasn't too common anywhere in the world until a considerable way into the 20th century. Western Europe's development was very badly held up by WWI and more particularly, WWII which pretty much obliterated the entire European consumer economy. Manufacturing capacity was entirely focused on war supplies and a lot of the industrial base was destroyed by bombing on both sides. The electrical infrastructure, particularly in contenental europe was largely wiped out too. It took a couple of decades for things to return to normal and catch back up. So, you start seeing major improvements in standards of living in the post-war boom period which, for Europe, was in the 1960s, not the 1950s.

While the US, Canada and probabaly Australia and NZ were having fairly prosperous 1950s Europeans were generally still just putting the place back together.

Bare in mind the UK had food rationing from 1940 until 1954 !
Clothing was rationed - as there was nothing but very basic fabrics.
Furnature sales were restricted to only newly weds, new homes and those who had been "bombed out".
Petrol (gasoline) was rationed so severely that people simply stopped buying cars and many were put into storage for the duration of the period.
Fuel for heating was also seriously limited.

While the Republic of Ireland had declared itself neutral, largely to avoid being bombed/invaded, during WWII it also pretty much had no ability to import/export during the period so rationing applied here too. In some cases far more severely as we didn't have the manufacturing base to survive without imports. E.g. there was a period when there was almost no coal, oil or gas. The railways had to re-instate modified 1920s steam locomotives buring dried turf. ESB had to look at generation of power from turf and to squeeze what it could out of hydro. Delivery of goods went from diesel trucks back to horse and cart!

I'm not 100% sure of the details of what happened in continental in the aftermath of WWII, but if anything it was a lot more extreme than the situation on the British isles.

In general that period did hold up european consumer society for a considerable period of time. Some places recovered more quickly than others too.

If it hadn't been for aid from the US and Canada in the form of major loans and the establishment of the forerunners of the European union which pooled resources and focused developement on the continent. There was a serious risk that Europe could have spiraled into a total mess. Although, there was a major industrial, financial and technological base to build upon. It was just a matter of picking up the pieces.

As for the water chemistry, it varies substantially from area to area. The water in Ireland is generally soft to very soft with a few exceptions where there's a lot of limestone (however it may be artificially softened during the treatment programme to prevent pipe damage.)

I know there are certain parts of England where, due to the prevailance of limestone (they don't have the white cliffs of dover for nothing) you end up with extremely hard water which can cause big problems for heating systems, kettles etc.

I think in general it reduces the lifespan of electric showers fairly drastically. They just clog up within a few years of operation.



[This message has been edited by djk (edited 01-07-2007).]

I think Dave has covered everything quite extensively, but I'll just add my "tuppence worth" that I grew up in homes with no shower until the 1980s. At one time hardware stores, Woolworth, etc. used to carry cheap "shower kits" which consisted of just a simple shower head with a Y-splitter hose and rubber cups which you pushed onto the hot and cold bath (or basin) taps when needed. Their effectiveness was variable at best, particularly in those homes where the cold taps in the bathroom came straight off the mains supply rather than from the cistern in the attic.

Regarding the water chemistry, the west country and some northern parts of England have soft water, but many central areas and almost all of the London/southern/eastern region has hard. It's especially hard water here in East Anglia, which does cause problems.

In this case of the shower though, it seems odd that the unit was working fine until a short while ago and then "suddenly" starting producing barely-warm water. If it were a build-up of scale, I'd have expected some sort of more gradual decline in performance.

Limescale deposits can sometimes occur very quickly though. Once some scale takes hold on the smooth surface of the heating chamber, it becomes much easier for more scale to attach because the surface is rougher but also because it has a greater surface area.

It could explain the sudden loss of heating power.

It can be a very effective thermal insulator too!

One way to avoid it is to use an ion-exchange filter on the water intake of the house. Pricey enough, but it can protect the pipework for years.

All European dishwashers have such a filter as part of their standard design. It reduces the need for large doses of phosphates / other water softeners.



[This message has been edited by djk (edited 01-07-2007).]

djk. The Triton people should be able to tell you if the ion exchange filter is necessary for your area.

Paul
Did you ever resolve this problem?

Kenny

Not yet, but the shower is used only rarely so we haven't rushed to do anything about it. I've not been able to track down replacement parts at a sensible price, so we'll just replace the whole unit.

I'm curious to investigate further though, so once the old shower is out I'm going to break open the canister for a closer inspection.

Paul,
If it's not used that often.
Disconnect it, take it home and dismantle it.
It sounds like an Electrode Boiler unit that is all scaled up.
Scale will kill an Electrode Boiler, as in more resistance.
Hence cooler water.
Get Emery paper on the probes.

Scary South American approach to instantaneous electric showers:





Very safe use of wire nuts!

{ Images copied to ECN server }

[This message has been edited by pauluk (edited 01-23-2007).]

They seem to be quite popular

[This message has been edited by pauluk (edited 01-23-2007).]

The last picture is clearly one of the "And I thought I've seen it all!" type!

Tex. Wait till you see the chemical WC full of battery acid!

I see one of those units is set to "Hot" -- In more ways than one!

Here's another similar pic that I found some time ago. It was Central America -- Guatamala or Honduras if I recall correctly.

DJK. O.M.G

Same attitude as in France, just a different accent!

"Senor, the shower she is working, no? Esta bueno!"

Well you wouldn't catch me in that shower!

Finally got around to stripping down the offending unit:









The element assembly looks remarkably clean for this area (very hard water), but I know the shower has only seen occasional use.

I can't see anything obviously wrong, no excessive scale, the elements are showing 13.1 and 13.6 ohms, and even on the 1kV range of my megger I'm reading insulation resistances in the hundreds of megohms range.

Seeing the inside would really make you wonder how they were ever allowed to go in the shower cubical. Even with RCD protection!

Were they ever installed pre-RCD days?

Their IP rating doesn't look great..

[This message has been edited by djk (edited 03-06-2007).]

Sure. In fact there is still nothing in BS7671 today which requires them to be on an RCD-protected circuit.

Makes for a stark contrast with the "no sockets in the bathroom" stance, doesn't it?

If the proposed changes for the 2008 revisions go through though, showers will need to be on RCD circuits, as will even lights in a bathroom. Talk about going from one extreme to the other!



[This message has been edited by pauluk (edited 03-06-2007).]

Yeiks, they're specifically required to be on an RCD here, as is the immersion / any shower pumps etc.

Paul, what is the unthread line for? I assume the bottom threaded line with the thermoswitch or flow switch is the cold water inlet. The other threaded line is the discharge. Is there no mixing valve or anti-scald valve?

No, the threaded coupling on the right is the cold inlet. The left-hand one is the outlet to which the shower hose attaches; the device with the blue wires is the protective thermostat. There's another 'stat mounted on top of the heating canister which acts as a main thermal cutout.

The other tube running from the bottom of the canister is just a pressure-relief outlet should there be both a blockage and a main cutout failure.
http://www.shower-spares.co.uk/triton/tx7000i_and_tx7500i.htm

If you think that's scary you should look inside a Dolphin one. Some friends bought a house where the previous owner had had an expensive bathroom refit. I looked inside the shower unit, which was leaking internally, to find that the heating elements are uninsulated wire spirals within a plastic enclosure. Didn't have much difficulty persuading them to be rid of it! You can see the sort of assembly sketched quite well at : http://www.showerdoc.co.uk/shower-spares/dolphin/heater.html

Thankfully I have a normal shower

Quite frankly, the idea of having any type of electrical device in the shower with me is scary. Especially if it's 240. Wouldn't it be just as easy (and safer) to mount one of those small 5-10 gallon electric water heaters in the attic, above the shower?

[This message has been edited by noderaser (edited 03-08-2007).]

My "favourite" are electric tankless water heaters... *shudder*
400V 3x35A, 21kW...

A pressurized electric storage tank would probably the most comfortable option where gas is not available.
The classoc 5 or 10l open electric tanks (the ones that go in our hardware stores for €27.90) are pretty useless for a shower and the matching faucets pretty much even out any price difference.
We have one of those on our workshop sink... I still want to strangle the unknown person who replaced the old gas-fired Ascot with that electric trash! (Not to mention the gas pipes were brand new whereas the electrical wiring was some 80 years old and scary as could be)...