Converting an airing cupboard to a drying room.

In message , Stephen H writes

If you are putting that amount of heat into the cupboard and then extracting to the neighbours garden when the humidity reaches a preset level, double ducting and a heat recovery fan might be worthwhile.

How will you heat the cupboard in the Summer?

regards

Have you seen the groups wiki on the subject, and incorporating a dehumidifier?

this time with the URL

Forget all that and just buy a dehumidifier, perhaps go as far as running a permanent drain to save having to empty the container.

Mike

Yes we have considered the dehumidifier option, we have one in the landing of our house, and SWMBO complains that the noise keeps her awake at night and it also makes the house stuffy as it apparently dries it out too much.

Stephen.

Keep the cupboard sealed, and heat it with a dehumidifier. Use a humidistat (or a dehumidifier with one built in). Use a room thermostat to cut out the dehumidifier at max working temperature (typically 30C).

Don't fit the insulation in the walls.

Use the condensate collected by the dehumidifier for filling the steam iron. (You'll get way more than you need.) I also use it for watering plants which can't take tap water.

You may want to fit vents in the cupboard for occasions when you want things to dry, but there's no urgency, so you don't need to run the dehumidifier. I have thought of using a fan to extract hot air from the loft in the summer, blow that through the cupboard, and then out through a vent. Not got around to it yet though.

I have read the DiY wiki and it mentions that dehumidifying is quicker at 30°C than at 20°C....perhaps using both a dehumidifer and a smaller radiator with a thermostat set 30°C in the airing cupboard?

Regards,

Stephen

That is a great point... I've heard of MHRV (Mechanical Heat recovery ventilation) I could put the humid air outlet in the ceiling and the fresh air inlet through to the bottom of the cuboard as I could put the heat recovery unit in the loft, above the airing cupboard.

Anyone know where I can get a MHRV unit for a single room?

Via the push button timer in the airing cupboard. This would open the zone valve for the two rads, fire up the boiler. When the push button timer runs out, zone valve closes and boiler shuts down. You can see these push button light switches used in communal areas in blocks of flats so people don't leave lights on.

Stephen

The dehumidifier itself supplies more heat into the cupboard than the energy it consumes. You don't need any additional heating. You do need a thermostat to cut it off when the cupboard goes over the dehumidifier's max operating temperature (typically 30C).

Putting it in the cupboard would probably fix both of those complaints then ;-)

I have done this sucessfully without all this work. Put a vent in the door. Insulate the ceiling (so no heat is lost) Fix battens along the sides of the wall. Just put some shelves for storage if required (Blankets, sheets towels ect) Put a selection of cup hooks in the battens and buy the plastic coated expanding curtail wire and you can vary the wiring according to what you have washed after fixing the wire to the hooks. I have a tropical born wife so the healing is on more than off but that means the top half of the airing cupboard is mine!.

Robbie

Really, how does it manage that then!?

Wow! I must get a load of those to heat my house...

You didn't mean to type that did you?

Mike

Folk do, they're called heat pumps in that configuration. ;-)

The dehumidifier probably has a CoP greater than 1, but since the heat source (evaporator) and heat dump (condensor) are in the same room, most of the heat gain will be by converting the latent heat of condensation into sensible heat. The mositure is also being evaporated and condensed in the same room, so there probably isn't much in it.

An brings in dust from Rockwool - if fitted.

To be honest, adding heating is fairly pointless, and an unnecessary complication and cost. Fanned clothing: shirts dry in a day, jeans in

1. I'd use a ceiling fan, with cut down blades if necessary, rather than a little extractor fan. So much more effective. Also heat drying without tumbling causes clothes to go stiff. So all you need is vents and fan.

Re vents, you might find it looks better to simply cut 1-2" off the bottom of the door. Grilles are fairly ugly.

NT

Is anybody able to recommend a decent humidistat dehumidifier, that is nice and quiet?

Meaco DD8L Junior can be had for about =A3120 delivered. Junior just means no ioniser & no silver filter (which looks too lame to do anything).

As a guide 40mm Celotex in a proverbial box-room means 120W tube heater (*) will keep it at about 15oC with the outside at -1oC and the wind blowing a stink, single glazed 1x1m window & empty cavity with slight roof leak, mortar snot laden rotting wall ties and two outside walls.

So you need very little heat input if you insulate. A dessicant dehumidifer kicks out a lot of heat because of the internal heater to dry out the silica gel wheel (120oC+). On normal operation they are about 350W, but laundry mode pushes that to around 800W which is quite a lot of heat - and drying.

Just ensure you have a thermostat that shuts OFF above a certain temperature - you just use a plug in unit with it set to 30oC. The DD8L & DD8L Junior restart in the last mode when power cycled.

BUT you have a problem - the tanks on dessicant dehumidifiers are pitifully small - 3-4L as I recall, a Mitsubish EVX is around 8L which is substantial. So you need to plumb the thing in or have a separate larger capacity tank (10L drum underneath supplied by the hose).

I suspect 12-25mm Celotex or cheaper 25mm Expanded Polystyrene will be quite adequate. I think you will run into the problem of it getting too hot too quickly. So the dessicant type may actually be problematic. You need good airflow around the clothing.

A final note is the fans on these things DO seize at the bearings, so in that respect I suggest at least a heat alarm (58oC trip I recall) in there preferably linked to others in the house. Just because it is not a tumble dryer does not mean it can not catch fire. Likewise dessicant dehumidifiers contain various dire warnings about letting moisture drip into them, I suspect it is the high wattage heater element, water & mains floating around inside. Lots of glass fibre insulated wire.

In the dehumidifier's hot air stream, you also get the latent heat back from condensing out the water. This should exactly compensate for the cooling effect of the wet clothes in the cupboard.