Electric towel radiator getting too hot

[joe90]

In our recently finished ( ish) new build we don’t have any heating yet so I thought I would leave the electric towel radiator in the en suite on 24/7 to keep er indoors happy as she feels the cold. It gets very very hot and although we know it, it is still a bit dangerous ( grand daughter is visiting soon and I don’t want an accident). I do have a timer which I will use once the heating is working but is there a way to regulate it but don’t want to dig out buried wiring. Someone has suggested a dimmer to limit the power to it?.

[Jeremy Harris]

I think you can probably just replace the element with a thermostatic one, like this: https://www.nwtdirect.co.uk/86-thermostatic-electric-heating-elements (I'm not recommending them, they were just the first hit on a web search).

 

Our towel rails are both ordinary wet ones, intended for use with a central heating system, but converted to electric power by plugging the unwanted hole, fitting thermostatic elements and filling them with antifreeze and inhibitor (car antifreeze is ideal, as it has inhibitor already).  I'm pretty sure the elements I bought were a fair bit less than the prices on that link above, but I can't quickly find where I got them from (I have a sneaking suspicion it was ebay).

[PeterW]

PTC ones are self regulating - eBay is your friend. 

 

PTC Element

[joe90]

Well done Peter, just the ticket mate. ?

[dpmiller]

Umm, self-regulating perhaps, but still getting to 65c. Might be a touch warmer than you really want? With Jeremy's option you get to choose how burny they are.

[joe90]

Just measured the temp at about 86.5F ?

[Nickfromwales]

1 minute ago, joe90 said:

Just measured the temp at about 86.5F ?

30oC ?

[joe90]

3 minutes ago, Nickfromwales said:

30oC ?

Yup.does not sound so hot in C but could do some damage, especially to an OAP ( like me) or a child.

[dpmiller]

your body is @37 tho?

[Jeremy Harris]

86.5 deg C is enough to burn, whereas 86.5 deg F is just a bit warmer than most swimming pools (I seem to remember they are around 28 deg C usually).  I found that a towel rail at anything over about 55 deg C (131 deg F) is a bit too hot, so that's what ours are set to.

[newhome]

I had lots of practice touching various different bits on my thermal store recently. I burnt my hand on the pump that was 98 deg C, anything in the high 50s to 60s was a bit hot to leave your hand on. Anything in the 30s was fine to hold onto. Can’t see how you could get burnt in the 30s tbh. 

 

 

[joe90]

Huh, I used an infrared thermometer ( not used before); just tried it on other things, walls floors and it seems ok/ accurate but on the chrome of the radiator it’s way off. Just re read the instructions and I am using it correctly. ?

[daiking]

4 minutes ago, joe90 said:

Huh, I used an infrared thermometer ( not used before); just tried it on other things, walls floors and it seems ok/ accurate but on the chrome of the radiator it’s way off. Just re read the instructions and I am using it correctly. ?

 

This has been covered before about how reflective surfaces can fool IR thermometers. Someone like @JSHarris Or @SteamyTea can explain

 

something like this

 

 

Edited May 16, 2018 by daiking

[Jeremy Harris]

Just now, daiking said:

 

This has been covered before about how reflective surfaces can fool IR thermometers. Someone like @JSHarris Or @SteamyTea can explain

 

Non-contact IR thermometers are calibrated for a specific surface emissivity, usually around 0.9, as that's about the emissivity of painted surfaces, concrete, etc.  Something with a very low emissivity, like a shiny pipe, or especially a chrome plated surface, with cause a vary large under-reading.  A chrome-plated surface, for example, will probably have an emissivity of around 0.1, maybe less, so the error will be very large indeed.

 

The fix is to put something like a bit of masking tape on the surface.  That will have an emissivity that's close to 0.9 and will conduct heat well enough to get a more accurate surface temperature reading.

 

Worth noting that something like a matt black surface will cause the opposite effect, and make the IR thermometer over-read slightly, but not by much, as a perfect black body has an emissivity of 1, and a mat black surface is not going to get to this level, so the error is probably only going to be small.

[Nickfromwales]

52 minutes ago, joe90 said:

Yup.does not sound so hot in C but could do some damage, especially to an OAP ( like me) or a child.

KISS.

Touch the rad. 

Can you keep your hand on it without it being uncomfortable. 

Turn your hand over and do the same with the sensitive part of your skin on your wrist / forearm. Thats what a child would feel.

Adjust accordingly.

Pub. 

[joe90]

Where would I be without you guys ? Right, masking tape on a temp of 98.5c measured.( thanks Jeremy) Yes Nick, no way I can keep any part of my hand on the rad. I think I will buy adjustable thermostatic elements.

 

Anyone buying towel rads beware of the mistake i made.

 

all hail the forum.

[PeterW]

Sounds like a fault on the element as they should cut out well below that ..!

[Nickfromwales]

13 minutes ago, joe90 said:

Where would I be without you guys ? Right, masking tape on a temp of 98.5c measured.( thanks Jeremy) Yes Nick, no way I can keep any part of my hand on the rad. I think I will buy adjustable thermostatic elements.

 

Anyone buying towel rads beware of the mistake i made.

 

all hail the forum.

Go add some tags up top then  

[joe90]

1 hour ago, PeterW said:

Sounds like a fault on the element as they should cut out well below that ..!

 

I have an identical one in our other bathroom so I have switched that on to see if it gets as hot.

[CC45]

Hi @joe90,  any update on where you've managed to find some?  Need to get some myself now.

 

Cheers

[joe90]

9 hours ago, CC45 said:

Hi @joe90,  any update on where you've managed to find some?  Need to get some myself now.

 

Cheers

 

Ha, been so busy it’s gone to the bottom of my “to do list “, I will do it this morning and post back ?

[joe90]

Finally got to this job, both were very hot as above, bought PTC ones as per peters suggestion above, still getting very hot but noticed the old ones were 700 watt, these new ones are 300watt so saving money if nothing else. I still think adjustable ones are best especially if children are about.

[Jeremy Harris]

Ours are the same, @joe90, and I'm going to change the elements out (or at least the one in our ensuite) for a thermostatic one, I think.  I went for the lowest power element I could find, but it still gets too hot for comfort.  I have both of them on a time switch, so could play around with the timing settings to try and reduce the temperature, switching the rails on and off every 15 mins during the "on" time.

[Ed Davies]

So, if the function of the towel rail in a well insulated house is mostly to introduce a trickle of heat into the bathroom, the upstairs and, via the MVHR, the whole house then do we want black ones?