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.
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.
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.
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.
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.
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.
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?
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?
Those Triton water heaters only deliver cool water if they are located too far from the outlet. Was it delivering hot water previously ?
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.
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.
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.