Mystery - Electric radiator only partially warm

[ClearClaire]

Hello, I have joined in the hope someone can help me with this mystery!

I have 2 electric liquid-filled radiators in my extension, same brand/style but different dimensions (pics below). Both are heated with a 1200w element (both elements are the same brand as each other) which came with them and recommended by the website which sold them, attached to a plug, plugged into the wall (different sockets) One rad is narrower, taller (236x1780mm), placed against party wall and gets nicely hot. The other is wider, horizontal (635x1180mm), placed under the window, and only heats up directly along the bottom where the element is inserted. The rest of it is lukewarm or still cold to the touch, even when it has been on for a couple of hours on full whack. The elements have in both cases been installed correctly, facing the right way up as recommended by the manufacturer. Both radiators were delivered pre-filled with glycol.

I have bled the cooler radiator in case that was the issue, and that has not resolved it (hardly any air came out). I just don't understand why one heats up well and the other doesn't. I even replaced the element in the cooler rad with a brand new one of the same brand to see if that was the issue, and got the same result. (The taller rad is a beast to get on/off the wall so didn't want to remove it as it is working perfectly).

If anyone can shed any light on this, it would be much appreciated! I measured the BTU requirement for the room before purchasing but the room is never quite warm enough as one radiator is not pulling its weight. I've looked at all the installation guides over and over and have followed them to the letter.

 

[Murdochcat]

I suspect that the wider one will take far longer to heat up as it needs the water to naturally move around inside the radiator, whereas the taller one the water will heat up and push the warmer water up faster.

How long did you leave it on ?

 

[ClearClaire]

Hello for sorry not replying sooner. I kept wondering if I had been an idiot and not left it on long enough, but I tried it a few times, left it on overnight and still in the morning only about 1/4 of it was hot, 1/2 was warm-ish and the other 1/4 was just room temperature. I unplugged the other appliance (just a reading lamp) from the same wall socket and that has not changed anything so I don't think the socket is overloaded.

I connected it to the Hive app and even though it has a 1200w element, the app says it is only drawing around 400w of power - is that usual?

 

[Taylortwocities]

Unless I misunderstand the situation, the radiator is stand alone and not connected to the water/heating supply?

If that is the case, then there is no point in bleeding the radiator. It is not suprising that

hardly any air came out

as that can only happen if water/coolant is put in to push out the air!

If my assumption above is correct, and as the bottom gets hot, but the upper does not, then the radiator is not filled up with water/glycol or whatever. Hopefully it is under warranty and you can get it replaced.

 

[foxhole]

The horizontal rad may be designed to work vertically as well as horizontal in which case there are sometimes internal knock outs which have to be removed to allow it to work correctly , seller may not know this and hasn’t adjusted .?

 

[ClearClaire]

That could be possible, I will look into that, thank you foxhole.

There definitely is liquid in it, Taylortwocities! It is an electric radiator, the liquid is heated via an element which is inserted directly into the radiator and plugged in. The mystery is why the heated liquid is not moving around the whole radiator.

 

[Taylortwocities]

There definitely is liquid in it, Taylortwocities! It is an electric radiator, the liquid is heated via an element which is inserted directly into the radiator and plugged in. The mystery is why the heated liquid is not moving around the whole radiator.

Yes, I know. But if the radiator is not COMPLETELY FULL of LIQUID then the whole of the radiator cannot heat up.
Say the radiator is only a third full, the bottom third will heat up, the next few inches will only be warm, as the metal of the radiator will conduct some heat, the rest of the radiator will be cold.
That is exactly what you are experiencing, isn't it?

If there is a filling point at the top of the radiator, then remove that and put a long rod in. You can then gauge how full the RAD is.

 

[ClearClaire]

The coolest part is the area of the radiator furthest away from the element horizontally, not vertically. If it was only partially filled (and otherwise working normally), there should be consistent heat all along the bottom and consistent coolness all along the top. The element is horizontal, at the bottom left hand side of the radiator. The hottest part is around where the element is, it is warm (but not hot) to the top directly above it, and it is coolest at the right hand side, the opposite end of where the element is installed. The radiator is definitely full of liquid - some spilled out when the element was inserted - and when I bled it, more liquid dripped out pretty quickly (i.e. there was next to no air to escape before the liquid started seeping out).

It is using 1264W, so there is plenty of power to it. I will stick something else longer down the inside to see if there is something jammed inside preventing the heated liquid from circulating properly.

 

[JohnW2]

The coolest part is the area of the radiator furthest away from the element horizontally, not vertically. .... The element is horizontal, at the bottom left hand side of the radiator. The hottest part is around where the element is, it is warm (but not hot) to the top directly above it, and it is coolest at the right hand side, the opposite end of where the element is installed. The radiator is definitely full of liquid ...

I presume that the 'tubes' of the radiator contain a vertical column of liquid, right to the top if the radiator is 'full'.

That being the case,and by virtue of convection, one would expect that the place to become hottest most quickly would be the top of the tubes immediately above the element. The heat would then gradually spread downwards (towards the element) in those tubes and then subsequently sideways (to the right), again with the top of the tubes getting hot before it spread downwards. In fact, in all situations, one would always expect it to be hottest (and most quickly hot) at the tops of the tubes than lower down.

The only thing that could stop that convection would be 'blockages' in the vertical tubes,and it would seem incredibly unlikely that such could be occurring in multiple tubes - unless something is going on such as plugwash suggested (internal baffles/knock-outs that need to be removed) - but the instructions would surely mention anything like that?(

It is using 1264W, so there is plenty of power to it.

You previously said that it was only drawing 400W. Has that changed?

However, physics is physics, and if it's now using 1,246 kW of power,then 1,264 kW's worth of heat must be being generated, and must be going somewhere.

Kind Regards, John

 

[ClearClaire]

Thanks JohnW2, there was nothing in the instructions (it came pretty much ready to plug in, once the element had been inserted). In fact, there was only instructions for the element itself!

Yes that power must be going somewhere. The Hive app was saying 400w but I re-set it and the figure changed (currently says 1070W - I think it must be fluctuating to maintain what it believes to be an even temperature).

I've searched some other forums and people have had a similar issue with this design of radiator to do with the orientation of flow, so tomorrow it is coming off the wall and I will try turning it over and putting the element in the other end, see if that makes a difference!

 

[JohnW2]

Thanks JohnW2, there was nothing in the instructions (it came pretty much ready to plug in, once the element had been inserted). In fact, there was only instructions for the element itself!

If any 'adjustments' anything like as fundamental as plugwash mentioned might be necessary, the instructions would surely explain?

Yes that power must be going somewhere. The Hive app was saying 400w but I re-set it and the figure changed (currently says 1070W - I think it must be fluctuating to maintain what it believes to be an even temperature).

Yes, it presumably will be under thermostatic control, so will vary. It may just switch the element on/ff (completely) as required, or may have the ability to change between two or more power levels (as well as 'off').

Around 1 kW of heat is a fair bit, but not massive - corresponding to the 'low setting' of most standard fan heaters. It would not be enough to reliably heat anything other than a pretty small room.

I've searched some other forums and people have had a similar issue with this design of radiator to do with the orientation of flow, so tomorrow it is coming off the wall and I will try turning it over and putting the element in the other end, see if that makes a difference!

Changing the orientation and/or the location of the element will probably make some difference - it will be interesting to hear what - keep us posted

Kind Regards, John