Electric shower overheating - question about heat exchangers

[mikej2005]

My Gainsborough Energy 2000x electric shower has suddenly started to run extremely hot - too hot even on the medium power setting with the temperature control at the coldest setting. The shower sounds rather like a boiling kettle and you can hear it subside, even after the water has stopped flowing. It never used to make this noise.

Water pressure is OK, the shower head is not scaled up and the problem has developed so suddenly and so severely that I'm happy that the seasonal variation in mains water temp is not to blame.

The previous owners of the house left me a brand new, unused heat exchanger which indicates to me that they intended to replace it at some stage for some reason.

My question is - does a heat exchanger have some kind of built-in thermostat that might be faulty in this case ?

Also - if the heat exchanger was scaled-up, would that explain the overheating ? After searching this forum, I've read a few comments about limescale causing problems with electric showers, although my overheating problem appears to have happened almost overnight.

If the answer to either of these is yes, then presumably getting it replaced would be the first thing to try ?

The shower will be replaced with a thermostatic shower next year, so I'm only interested in keeping the shower going at this stage and don't want to replace it with another electric shower.

2000x diagrams here : http://www.showerdoc.co.uk/shower-spares/gainsborough/energy-2000x.html

Any thoughts or comments would be appreciated - cheers.

 

[breezer]

My question is - does a heat exchanger have some kind of built-in thermostat that might be faulty in this case ?

you tell us, you have it, we don't

The previous owners of the house left me a brand new, unused heat exchanger which indicates to me that they intended to replace it at some stage for some reason.

now you know why

Also - if the heat exchanger was scaled-up, would that explain the overheating ? After searching this forum, I've read a few comments about limescale causing problems with electric showers

 

[mikej2005]

you tell us, you have it, we don't

I don't know because I don't know what I'm looking for on the new unit.

I guess it was a general question regarding how heat exchangers work - ie. is there a temperature sensor built in to them or is the temperature monitored elsewhere ?

 

[breezer]

depends on brand etc

change it anyway

 

[bernardgreen]

The lead from the mians in terminal block will almost certainly be going to a thermal cut out in the heat exchanger and looking at the diagram that would appear to be the case.


SAFETY

If the water is too hot that thermal cutout should have operated and cut all power to the unit. As it appears it didn't then the thermal cutout may be faulty or thermally insulated from the water by limescale. Need to fix that,

Why has it gone very hot all of a sudden, suggests a short circuit connecting up all of the heaters at once, maybe the control switch has failed and internally shorted all heaters to be on. What do the indicator lamps show when set to low ?

 

[mikej2005]

Thanks for your comments.

It doesn't look like the heat exchanger was the problem, as changing it has made no difference.

Indicator lamps light up as expected when low, medium or high power are selected.

If the control switch had failed and caused a short circuit, would some or all of those lamps light at once ?

Water is at a reasonable temperature when on the low setting (the flow rate is poor of course) but almost scolding on medium or high, even with the temperature control set to the minimum.

Interestingly - if you increase the temperature setting beyond half way (on low, med or high power), the 'reduce temp' light comes on and the flow almost stops.

Any further thoughts ?

 

[viewer]

I've one of these bought new and fitted by myself. At first I several times considered changing it as it is very difficult to set up. The large water flow control seemed to have a mind of it's own and is not intuitive. There is a huge difference between low setting and medium. The overtemperature switch works well, but to avoid overhot water I start on low and then if too cold turn to medium. Starting on medium always trips the overtemperature. Even in winter it is too hot to run on medium for any length of time.
Not sure that this helps, but it does suggest that there may be nothing wrong with your shower.
Best of luck
V

 

[mikej2005]

Just thought I'd conclude my thread...

The cause of the problem was the mains water filter, which is located at the 15mm compression fitting where the mains water enters the shower.

It was almost completely blocked with sediment and gunge, which was limiting the flow and causing the water to be unusually hot.

Once this was cleaned out, the shower worked perfectly !

 

[Softus]

My question is - does a heat exchanger have some kind of built-in thermostat that might be faulty in this case ?

you tell us, you have it, we don't

Just noticed this topic, and I'm glad the OP has solved the problem, but the above contribution was utterly opposed to the intent of the site.

Given that it was devoid of all useful content, I fail to see the point of it.

 

[Patty636]

My shower problem is undoubtedly the same as this post below.

Could some kind person please tell me where to find the mains water filter so as I can try and clean it?

I'm a single mum and unable to afford a plumber at present.

Many Thanks

Patty636

==================

Just thought I'd conclude my thread...

The cause of the problem was the mains water filter, which is located at the 15mm compression fitting where the mains water enters the shower.

It was almost completely blocked with sediment and gunge, which was limiting the flow and causing the water to be unusually hot.

Once this was cleaned out, the shower worked perfectly !

 

[jj4091]

marked inlet spigot on this drawing http://www.showerdoc.co.uk/shower-spares/gainsborough/energy-2000x.html