Keeping workshop warm and dry.

[BraithwaiteA]

Hi everyone. As is traditional with first posts: please move this if it's in the wrong place.

I had a detached block workshop built towards the end of the summer, and it got thoroughly soaked before the roof went on. It then got more exciting water ingress through faulty render. This has now been repaired, but it's winter and the place never got dry. Cardboard wilts, there's mildew on my plywood and I've had to oil all my metal to stop it rusting. I'm going to insulate the roof, which will hopefully stop me being dripped on all the time from the condensation, and when the electrician comes next week there will also be an extractor fan.

I'm wondering if anyone has any recommendations for electric heating which can be left on unattended for long periods? Obviously, there aren't lots of soft furnishings, but I'm worried about leaving a heater in there 24/7 which is really what it needs to dry out properly. I've run a fan heater when I'm in there and then flung open the door and window to 'vent', but it's still very damp.

Also, if anyone has any tips for cleaning off mildew without adding more water to the situation, that would be very much appreciated! I tried wiping down with bleach-water and it seems to be worse.

 

[Myfordman]

Run a dehumidifier until it is properly dried out

 

[BraithwaiteA]

That's a good idea, thanks! I have two of those passive ones that slowly make blue water, but we have a 'proper' one inside I can move out. I'm SO excited to have power out there next week.

 

[Stanleymonkey]

Greenhouse heaters are good for being left unnattended - but probably too weak to make much difference to the damp.

Have you considered a 1kw heater on a suitable timer switch? On for an hour or two in the morning and afternoon each day? Might make a bit of a difference.

 

[BraithwaiteA]

Oh, I'll look into greenhouse heaters - that might be good for keeping the chill off once it's dry.

The timer is a good idea! Thank you!

 

[cammy9r]

Hi, Cilitbang black mould remover is pretty good at mould removal. Its a bit stronger than the regular bleach. Oiled filled radiators are good for keeping rooms warm and seem safe enough as are tube heaters. It will be difficult to dry anywhere out in winter.

 

[BraithwaiteA]

Yeah, I think it's going to be like this until the summer, but I want to try and stabilise it a bit if I can. The original plan was to have it done around April 2020, but that didn't happen for obvious reasons.

 

[sploo]

Dettol do a mould and mildew remover; which I find works well. The older "formula" smelled really bad, but it now seems to be much better.

Assuming the workshop is reasonably well insulated (otherwise you're just trying to pee into a hurricane) then a dehumidifier will keep the interior at a safe humidity level (safe as in no mould, and for your tools, no rust), and an oil filled radiator can be left on all the time.

I have an Delonghi radiator (from memory I think it's an older version of the Dragon4 TRD40820E). It's set to 12C and on the most "eco" mode.

For the dehumidifier I use an Eco Air DD1 Mk5 Classic 7L; with the drain hose running out of the workshop (rather than water collecting in the internal tray). It's a desiccant dehumidifier (vs refrigerant type) as they're more suited to outdoor spaces. However, it's only really when you get down to <10C that the refrigerant type dehumidifiers struggle, so given the heater keeps the space at 12C a refrigerant unit may have been a better choice (they also use slightly less electricity).

I find I can pop the dehumidifier on (using the timer) for 2-4hrs when I finish up in an evening. I don't leave it running all the time.

 

[Jelly]

Oil-Filled Radiators are your friend for unattended to always-on heating. My experience is that somewhat paradoxically running a small one (500W or 1.2kW on half power) constantly set to it's highest temperature will generally be more efficient for space heating than having a more powerful one on a lower temperature setting.

You need to maintain at least 12°C, ideally >15°C for electrical dehumidifiers to work effectively, Chemical (calcium chloride based) dehumidifiers of the type which are sold for caravans etc. will work at lower temperature.

For practical purposes, it's generally more effective to raise the air temperature (and thus decrease relative humidity) and ventilate the space than to use a dehumidifier if you have serious amounts of moisture to remove in a hurry.

 

[sploo]

For practical purposes, it's generally more effective to raise the air temperature (and thus decrease relative humidity) and ventilate the space than to use a dehumidifier if you have serious amounts of moisture to remove in a hurry.

Yep - though (at least in the winter) isn't raising the air temperature and ventilation somewhat mutually exclusive? Unless you can either heat incoming air really quickly, or you're meaning recirculation rather than changing the air?

 

[Jelly]

Yep - though (at least in the winter) isn't raising the air temperature and ventilation somewhat mutually exclusive? Unless you can either heat incoming air really quickly, or you're meaning recirculation rather than changing the air?

Yeah, I suppose the best approach ultimately depends what you're looking to achieve...



If you want to dry out a damp space, having a ventilation path which draws cool air past a heater and then through the space and out again will maximize the amount of moisture removed in absolute terms...

Because the energy you put in is effectively doing work (by being carried off as latent heat in the water you're vapourising), rather than increasing the sensible heat in the environment the space may not feel any warmer for it, but you will dry it out faster.


By contrast if you want to maintain a low level of relative humidity in a space which is already dry then heating it to a temperature which is above the be external temperature and minimising the air ingress from the outside will generally be sufficient

 

[sploo]

Yeah, I suppose the best approach ultimately depends what you're looking to achieve...



If you want to dry out a damp space, having a ventilation path which draws cool air past a heater and then through the space and out again will maximize the amount of moisture removed in absolute terms...

Because the energy you put in is effectively doing work (by being carried off as latent heat in the water you're vapourising), rather than increasing the sensible heat in the environment the space may not feel any warmer for it, but you will dry it out faster.


By contrast if you want to maintain a low level of relative humidity in a space which is already dry then heating it to a temperature which is above the be external temperature and minimising the air ingress from the outside will generally be sufficient

I was lucky enough to be fixing the problems with my shop over a summer - so kept the door open as much as possible during the day, but then made heavy use of the dehumidifier overnight for a few days. Now that it's down to something reasonable, the combination of the oil heater and occasional dehumidifier does seem to work well.

For the OP (considering it's winter); I'd definitely recommend getting a dehumidifier asap - as pulling the moisture out of the contents of the workshop will make a big difference.

Slightly off topic - but I understand some large (commercial) sites vent their dust extraction outside - accepting it means they need to heat or cool new incoming air (depending on the ambient temperature) as it's considered easier/cheaper/safer to just process new fresh air than to try to adequately filter and recirculate the extracted air.

 

[Cabinetman]

Dettol do a mould and mildew remover; which I find works well. The older "formula" smelled really bad, but it now seems to be much better.

Assuming the workshop is reasonably well insulated (otherwise you're just trying to pee into a hurricane) then a dehumidifier will keep the interior at a safe humidity level (safe as in no mould, and for your tools, no rust), and an oil filled radiator can be left on all the time.

I have an Delonghi radiator (from memory I think it's an older version of the Dragon4 TRD40820E). It's set to 12C and on the most "eco" mode.

For the dehumidifier I use an Eco Air DD1 Mk5 Classic 7L; with the drain hose running out of the workshop (rather than water collecting in the internal tray). It's a desiccant dehumidifier (vs refrigerant type) as they're more suited to outdoor spaces. However, it's only really when you get down to <10C that the refrigerant type dehumidifiers struggle, so given the heater keeps the space at 12C a refrigerant unit may have been a better choice (they also use slightly less electricity).

I find I can pop the dehumidifier on (using the timer) for 2-4hrs when I finish up in an evening. I don't leave it running all the time.

Plus what Jelly, said, what you have said here is exactly what I have. But without insulation I really think I would give up and take my tools indoors with me. Ian

 

[Jelly]

Slightly off topic - but I understand some large (commercial) sites vent their dust extraction outside - accepting it means they need to heat or cool new incoming air (depending on the ambient temperature) as it's considered easier/cheaper/safer to just process new fresh air than to try to adequately filter and recirculate the extracted air.

When I worked in sawmilling, the extraction system would remove around two articulated lorry loads of chips and dust per day during a busy week.

There's absolutely no way to economically clean and recirculate the amount of air required to convey that volume of chips; given that the mill was a building around 10,000m² with 40' ceilings, and had eight 15'×30' roller shutter doors which were constantly opening for the sideloaders... Even without the negative pressure from the extraction system there was not a hope in hell of heating that building.

The workstations all had infrared heaters for staff comfort in the winter, and the machines were protected from rust by the heat output of their own motors being captured in the sound cabs (sound insulation also tends to act as heat insulation) but it was otherwise effectively the outside.

But without insulation I really think I would give up and take my tools indoors with me. Ian

Agreed, that's what I did for years.

 

[Skydivermel]

In my shop/shed I've insulated floor, ceiling, walls, doors with 50mm rigid insulation with a 25mm airgap. (Shed frame is 75mm) I then screwed 9mm osb boards to walls and ceiling. Painted it all white. When weather dictates I have a dehumidifier set on a humidstat which kicks in when required. For heating I have a 1.2kW oil filled radiator which I leave on all the time during winter which is set on a thermostat. Workshop never goes below 60deg F. Warm in the winter, cool in the summer. Dehumidifier and radiator are most important items IMHO. My workshop is 16' X 8' so calculate your heating requirements according to your floor space.