Heating an airing cupboard

[Lofty Bob]

I'd like to put a heater in our airing cupboard and would appreciate hearing your thoughts. It's just a small cupboard on the landing that probably used to hold the boiler (the house had a combi boiler in the kitchen when we bought it). The cupboard is approx 60cm by 80cm by 160cm.

I plan to run a fused spur off the ring main and use a 500w convector heater from Dimplex (recommended for airing cupboards).
- Would 3 core 2.5 mm cable be okay?
- Does it matter if you use flexible or non-flexible cable?
- Is a 3 amp fuse enough? (500w = 2.17 amp)
- There's a junction box in the loft for the four bathroom spot lights and extractor fan. The airing cupboard is outside the bathroom so the junction box is in a good location. How can I tell if it's okay to take a spur from that junction box? If it's not okay, how can I be sure whether wires are part of the ring main or part of a spur? I'm new to the house and it's the first time I've looked at the electrics, I haven't got it mapped out in my head.
- will an electrician need to sign off the work?
- is there anything else I need to think about?

Thanks! I'm new to electrics but you've got to start somewhere. I just want to make sure I understand it properly before I attempt anything.

 

[ericmark]

My father insisted in having a radiator fitted in the old airing cupboard when the cistern was removed. It was a total waste of money cupboard now used to store tools. Nothing wrong with the idea but if does need some thought. Air flow is important and unless you have vents it would just be a very humid cupboard.

The use of a radiator is not a problem as the temperature can't exceed the temperature of the water. With with electric some method is required to limit the temperature. Without seeing the heater it is pure guess work. But 500W seems a lot. I would have expected something like 60W not 500W. I heated a whole caravan was a 500W fan heater never mind an airing cupboard.

 

[Lofty Bob]

Hi Ericmark. Thanks for the feedback. Why was it a waste of money? We like the idea for two reasons: finishing off drying clothes (eg when they've dried outside and come in before they're 100% dry), and allowing us to store bedding etc in there. Last winter we had a problem storing bedding because it has an external wall (solid wall - no cavity) so it got damp and mouldy.

Originally I was looking at tubular heaters (eg 80 watt) but I saw mixed comments about whether they kicked out enough heat to be useful. That's when I looked at other options and came across this one that's recommended for the job. It's got a thermostat built in so I planned to set it on a low setting and let it tick over. I would construct some kind of cage around it so clothes wouldn't get too close to it, as per the Dimplex guidelines. Tubular heaters sound better to me though if they might be warm enough, partly because they are quite small.

http://www.dimplex.co.uk/products/d...e_heating/multi_purpose_heaters/mph/index.htm

Thanks for raising the point about ventilation. Dimplex recommends two vents: one about six inches from the bottom of the door, and one six inches from the top.

 

[stem]

I installed an electric towel radiator (or towel warmer as they seem to be called now) connected to room thermostat set at 30 degrees for my mum in her airing cupboard when the cylinder was removed.

It's very handy to drape clothes over, or hook coat hangers on. It was 200 Watts and it's plenty warm enough in there, even when it's covered in clothes. I didn't add any extra ventilation because it's only replicating what the cylinder did, and, because it's a radiator, it doesn't rely on an airflow in the way a convector does.

 

[AndyPRK]

Well if there used to be a hot water cylinder in there, I would be looking at using the old immersion supply.

 

[Steve]

I had a cupboard with 2 external solid walls which suffered with terrible mould once i had the old system boiler removed. I installed 50mm of polystyrene insulation by battening the wall out. Since then, no mould or condensation. And no heat.

The problem with using such a confined space for drying is where does the moisture go? You need to address this. Perhaps by fitting an exhaust fan near the cieling in the cupboard, and a vent at the bottom of the door.

 

[Lofty Bob]

Hi Steve, thanks for the feedback. Good point about the ventilation - will need to consider whether it needs more. Re the polystyrene, I considered doing something similar but a friend who's training to be a chartered surveyor warned against it. He said the warm moist air is likely to penetrate the polystyrene (or find a gap in it) and then condense underneath, making mould that you can't see. That's why I'm going down the heating route instead.

 

[stillp]

Well if there used to be a hot water cylinder in there, I would be looking at using the old immersion supply.

Fused down of course.

 

[winston1]

I plan to run a fused spur off the ring main and use a 500w convector heater from Dimplex (recommended for airing cupboards).
- Would 3 core 2.5 mm cable be okay?
- Does it matter if you use flexible or non-flexible cable?
- Is a 3 amp fuse enough? (500w = 2.17 amp)


- There's a junction box in the loft for the four bathroom spot lights and extractor fan.

Well that is going to be the lighting circuit not a ring final. So don't use it.

 

[ban-all-sheds]

Re the polystyrene, I considered doing something similar but a friend who's training to be a chartered surveyor warned against it. He said the warm moist air is likely to penetrate the polystyrene (or find a gap in it) and then condense underneath, making mould that you can't see. That's why I'm going down the heating route instead.

That is a generic risk with insulating the inside of solid walls, and if the clothes aren't enough you've got all the moist air in a bathroom to contend with.

Your friend is right to point out the risk, but with care and attention to detail you should be able to create a sound vapour control layer.

Without insulation you will be almost literally burning money to heat the space.

 

[ban-all-sheds]

Fused down of course.

Why?

 

[stillp]

Because the designer of the heater probably intended it to be protected by a 13A fuse? My immersion heater is on a 30A circuit, in 6mm. I don't know about the OP's.

 

[ericmark]

Sorry was waste of time as cupboard not accessible by my mother so now used for tools. Nothing to do with idea of heating it. However we seem to over estimate how much heat we need. Depends of course on ventilation but I brew my own beer. I have an old fridge/freezer in the garage no longer powered just use it as an insulated box. Garage at around 10°C yet a 8W CFL globe bulb is enough to keep freezer at 20°C. You clearly have air flow which I don't but I would not expect it would need over 20W to keep everything dry and aired.

 

[PBC_1966]

Originally I was looking at tubular heaters (eg 80 watt) but I saw mixed comments about whether they kicked out enough heat to be useful.

Can't remember the rating, but we had a small tubular heater in the back of our airing cupboard when I was young - That was a 1930's house with the back of the cupboard an outside wall. I remember it being very effective at keeping the cupboard comfortable for drying. But ventilation is definitely essential, if just a couple of vents top and bottom to permit natural convection to set up sufficient airflow.

Because the designer of the heater probably intended it to be protected by a 13A fuse? My immersion heater is on a 30A circuit, in 6mm. I don't know about the OP's.

Kind of high for a U.K. immersion heater isn't it? The majority I've ever seen are 3kW elements on 15 or occasionally 20A circuits. But either way, if there's a now-redundant outlet there it's easy enough to just fit an FCU. It might be worth considering fitting some sort of pilot light outside the cupboard as a reminder that it's on though.

 

[Lofty Bob]

Thanks for the great feedback. I'm starting to favour the tubular heater now, probably either 40 watt or 80 watt. I think 40 watt should be sufficient so I'll buy one to test.

The junction box in the loft is on a 5 amp lighting circuit that runs a total of about 350 watts including lights and an extractor fan. I think it includes an earth but need to check. Is there any reason why I couldn't run a 40/80 watt heater off the lighting circuit on a fused spur? It feels wrong to put it on the lighting circuit, but presumably it would be okay to run a 100 watt lightbulb off that circuit. I don't see much difference! Running it off a ring main would be more invasive.