Fitting a dual electric/central heating towel rail

[DarrenSL]

Following on from an earlier thread ...
//www.diynot.com/forums/viewtopic.php?t=52788


May seem like a stupid question but ... how are the electrical elements fitted on towel radiators? From what I can see on the pictures of the product there seems to be some sort of T adapter with the water inlet on the side which means I would have the water inlet horizontal and the outlet on the radiator vertical. Seeing as the valves are sold in pairs either vertical or angled I can't work out how to plumb these in?

I raised this question on the plumbing forum but to no avail.

 

[RF Lighting]

Screwfix sell the valves singularly in normal finish, polished chrome, TRV etc. Click Here

This is how I did mine:

 

[Steve]

How did you do the other side RF? That side looks pretty neat, but I expect you'd be hard pushed to make it symmetrical without having 2 heaters

My uncle fitted our towel rad, without electric element, and he just used standard rad valves on their sides, and bent the 8mm pipework down into the floor.

 

[DarrenSL]

Thanks for that RF. It gives me an idea ...
I'll buy angled valves, both going into the wall albeit one will be horizontal and the other vertical so won't be symmetrical. Not sure how that'll look but can't think of any other way.

(ps. like the idea of chrome flexplate. Blends in well with the rad).

 

[RF Lighting]

I did the other side like this:

Screwfix now do valves that will allow the pipe to connect straight into the back of them, instead of having to use a knuckle like I did.

 

[jpbamford]

This looks really neat; however, I've plumbed mine in, then realised I need the electric element in the summer! Rather than get the blow torch out again, I thought I'd pop an element in at the top (my rad has the bleed valve one side and a blanking plate the other). Obviously heat rises and all that - might not be as efficient - but does anyone see any real problems with doing it this way? Thanks, Paul.

 

[TicklyT]

If you fit the element in the top it will only heat the top rail.

As you say, heat rises. Water is actually a pretty poor conductor of heat. Radiators rely on convection to work. There won't be any convection currents created in the radiator below the heater to heat the rest of the rad.
It might even overheat the top rail.

 

[jpbamford]

Thanks TicklyT. My towel rail is not very tall - 800mm (by 600mm) with cross-pipes in groups (7 at the bottom, 5 in the middle and 4 at the top). I thought that as these heater elements are about 400mm long, I might get a convection current set up between the middle and top cross-pipes - the end of the element will be in the same place whether fitted from the top or the bottom, but I do see that only half the water in the rad might be persuaded to move if I put it in the top! Am I deluding myself? Also, do these heaters come with a thermal cut-out? Paul.

 

[Taylortwocities]

The heaters some with a thermostat so the element will switch off when it gets to temperature.

I would advise against fitting the element at the top. Several reasons

• It is not desinged to be there, The cable seal is designed to be at the bottom so water may get into the electrical connections.
  
  As already stated, it will not heat up the rad properly so will be inefficient = costs you money
  
  If air enters the system it will be at the top of the rad. The element will then heat up in free air and not in water. It will probably then over heat and the element will fail.

 

[jpbamford]

Fair points Taylortwocities, especially re. the air. Looks like I'll just have to do it properly then won't I!

 

[Taylortwocities]

As Ban-All-Sheds says: If you're going to do it, do it right, right!

 

[jpbamford]

OK; so I've got the plumbing done right, now for the electrics - Hope I'm not making any fundamental errors here:
What I'm planning is to take the towel heater (150w) to a simple felx plate on the wall (its in zone 2 - 1.1m from the bath) where I'll take it to a double cut fused neon switch outside the bathroom. I'm planning to feed that from the central heating control. The CH control I have has an unused terminal marked CH OFF - I don't want the Towel Heater on at the same time as the CH. However, I do want the TH on when the CH is on, but the room stat has reached temperature. So, I'm planning to replace the room stat with a gas filled two-wire one, that's SPDT, and connect the "cooling" side to the TH too. Assuming that the Ch control is no more complex than a timer and two SPDT relays, and won't object to being back-fed, I think that I will get a truth table thus:
C - Central heating relay 0 = CH off, 1 = CH on.
R - Room stat relay 0 = "cooling" 1 = "heating"
T - Towel Rad heater
M - Mid position zone valve (the only item directly connected to the room stat currently).

C R ¦ T M
0 0 ¦ 1 0
0 1 ¦ 1 0
1 0 ¦ 1 0
1 1 ¦ 0 1

Sorry for the long post, but can anyone see any problems here, and do I need to run the CH control through an RCD too?

Thanks.