Control Unit For Towel Rail Immersion Heater

[Oriole]

My bathroom’s central heating towel rail has an immersion heater with an on/off switch, wired from a switched fused spur in an adjacent cupboard. I’m forever forgetting to switch it off, after having intended leaving it on for an hour only. It needs a time switch

The on/off switch is a short tubular unit that connects to the bottom inlet of the towel rail via a tee connector. The ideal solution would be to be able to replace it with a simple time controller, if such a thing exists. I suspect thought that the switch unit and the immersion heater are one composite item, so I would have to replace the lot.

I’ve come across another option: A Horstmann Electricsaver or a Kudox Wall Controller.

• Does anyone have experience of either? Are there good reasons to choose one rather than the other?

• Either of them could be conveniently installed in the back box that houses the existing switched fused spur, though that would leave nowhere for the fused spur. Both instructions say a fused spur is necessary on the supply side, one preferring in addition a separate supply from the consumer unit.

My existing fused spur is on a power ring from an RCD protected breaker.

Does that mean I could do without the fused spur?

 

[ProDave]

the hosrtman unit is intended for immersion heaters but would do what you want with the towel heater.

Forget trying to change the switch on the heater itself.  Is there another switch, usually outside the bathroom that allows you to turn it on or off? if so the horstman could go there.

 

[HandySparks]

A timer with integral switch and fuse would do if fitted outside the bathroom in place of the fused connection unit.

tlc-direct .co .uk item SM FBT4 or similar.

(Can't post a link due to forum restrictions.)

https://www.tlc-direct.co.uk/Products/SMFBT4.html

 

[Lurch]

Is there another switch, usually outside the bathroom that allows you to turn it on or off?

Did you not manage to read any further than the first half of the first sentence?

My bathroom’s central heating towel rail has an immersion heater with an on/off switch, wired from a switched fused spur in an adjacent cupboard.

My existing fused spur is on a power ring from an RCD protected breaker.

Does that mean I could do without the fused spur?

Nope, replace the existing fused spur with the item linked to in the post above. I tend to use the FST24 for towel rails, the boost controller looks handy though, obviously I've not paid enough attention to the Smiths newsletter that keeps getting sent to me!

 

[Oriole]

Thanks very much for your advice, Handysparks and Lurch. Sorry for my delayed response.

Yes, the Timeguard units are just what I need.

 

[Oriole]

Hello again Handysparks,

A slight snag . . .

I was about to order an FBT4 on Amazon (I'm in the same boat as yourself "due to forum restrictions") when I noticed the following review from "JJ Greenwall":

"the wiring diagram is wrong; for some very odd reason, the fused isolator switch is wired after the time-switch, so even when the fused switch is set to OFF, the boost LEDs still light up when you press the boost button.

The boost does not work if you wire it the other way round, i.e., putting the supply onto L-out and the load onto L-in to put the fused switch first in the circuit.

This means that you will always have an active (and unfused) circuit in the time-switch rather than a properly isolated one”.

Does this tally with your experience?

I've emailed the comment to Timeguard as well to see what they might have to say.

Not being an electrician myself I would appreciate your comment also.

 

[Doc Hudson]

The internal schematic from Timeguard's instruction sheet  https://www.tlc-direct.co.uk/Technical/DataSheets/Timeguard/SMFBT4-5_Instructions.pdf (page 3) suggest that the Amazon reviewer is wrong. I have not seen this particular item, but I would tend to have more confidence in the Timeguard sheet rather than this JJ Greenwall.

Doc H.

 

[Rob_the_rich]

Is the towel rail also connected to the central heating, as suggested in first post? if so, are both isolating valves open? This means that when the CH is switched on, any electrically heated water in the rad is pumped around the system and the benefit is lost. you might consider timing the "immersion heater" not to coincide with the CH (some combi boilers cycle the pump once a day too I think)

You could just use it as an electric-only towel rail by turning off one of the valves, I wouldn't turn off both, so as to allow expansion of the hot water within the rail, though not sure if this is necessary. Is a TRV fitted?

 

[Lurch]

Rob, if the CH is on the water entering the rad will be a lot hotter than the tiny heater can get it so the heater will be off anyway. If the CH is off the pump will be off, so the heated water in it won't leave.

 

[Rob_the_rich]

Rob, if the CH is on the water entering the rad will be a lot hotter than the tiny heater can get it so the heater will be off anyway. If the CH is off the pump will be off, so the heated water in it won't leave.

yes, good point, the thermostat in the rad heater should kick in. 

 

[Oriole]

Thanks Doc Hudson.

As you say, the FBT4 schematic clearly shows the opposite to JJ Greenwall's contention. In any case, it's hard to believe that an experienced manufacturer would have got such an elementary thing wrong.

Having said that, Timeguard's response to my enquiry was not quite what I had expected; ie, "We do not get heavily involved in the wiring as the helpline team are not electricians, however I can confirm that if you want to isolate it, you have to supply the supply feed to (Live in) and the exit feed to (Live out). When you press the boost button, the LEDs are meant to flash because they are indicators that the boost is at either 30 mins, 1 hour, 2 hour, etc."

Thank you also Lurch (again) and Rob-the-Rich for the your enlightening fact about the thermostat's over-riding control. However, since I do only intend using the immersion heater when the central heating is off, it's now a purely academic point.