Workshop/Garage Insulation/Space Heating

All,

Just wondering what folks use for heating the workshop in winter?

I've got a double garage, with a small central heating radiator in it - really to keep things above freezing in very bad weather, drying painted components or drying wet bikes out.

I have already put some floor mounted draught excluders under the doors, and am thinking about sealing the outside frames and the large metal panels. However I don't want to 'seal' it completely for fear of condensation issues.

So what's an economical method of quickly heating a large space like this (and avoiding condentastion)? It's not like I'd be spending all day in there at this time of year, maybe 3 hours at a time.

Thanks!

You probably expect 101 answers. Mine, for shortish periods in a garage workshop, is a simple electric fan heater. Instant warmth without water vapour, and I find the moving air also helps.

I've got a small ceramic fan heater, but I end up moving it around to either the lathe or mill; it's only effective at short range. Obviously a bigger one is one answer, but not sure about relative cost vs gas. But then there's the potential condensation issue.

I wonder if some kind of floor covering would help too, to keep feet warm?

I have an electric wall fan heater Dimplex PFHE 3kW Installed Garage Fan and also a dehumidifier which I run occasionally to keep down the damp. The wall heater has a thermostat built in so comes on and off and seems to work well and the dehumidifier I switch on and leave on and it collects water till the tank is full and I empty it next time I go in or if I am in there for an extended time I may just empty it and switch it off. I don't seem to get any problem with corrosion etc.

David

‘Drying wet bikes out’ is the first problem you need to solve. Every bit of moisture you carry into the workshop has the potential to become condensation on any cold surface. Machines are big heavy things that take a long time to warm up so are the first places for condensation to form. The British climate tends to be pretty soggy too so keeping it outside is best for most of the year. Insulation can only be a good thing,not only to keep the heat in but also to prevent sudden temperature increases,as when a warm (ie wet) front comes along.

I used to have an unheated,uninsulated and badly sealed workshop in one of the wettest bits of Britain so have given the matter some consideration. Dehumidifiers are great but you must do a good job of draghtproofing,otherwise you’re trying to dry out the entire planet.

I use a small oil-filled electric radiator in my double garage workshop, 600w I think. And it's toasty.

But I've insulated it well. Walls, ceiling and up & over car doors, which are sealed and secondary insulated doors added. They only ever open, which takes half an hour, when I need some nice shiny new (to me) machine wheeled in.

The floors are just painted concrete.

This year I have not needed to put the heat on yet as it's still at 60f - the sun warms it through south facing double glazed windows, but when required, which will be shortly, I keep the heating on 24/7 during the cold months.

No rust at all, but I don't bring wet bikes into it, let alone a car.

Cheers - Will

If you still have bare rafters, put up a ceiling then insulate it.

Glue 1" foam to the up and overs.

Duck boards help with cold feet and also reduce the bounce and vanish range of dropped items.

I had a similar problem with a detached Marshalite block built double garage & only came up with a workable solution to heating last winter. A 2Kw converctor heater hardly made any difference, apart from having something to stand over to warm up & meant I had little enthusiasm for working in the garage-cum-workshop over winter.

My solution was a diesel fuelled lorry "night heater" rated at 5kw. These are a self contained unit that burn diesel in a closed combustion chamber & blow the room air over a heat exchanger. The combustion by products are exhausted outside the building (AND MUST BE EXHAUSTED OUTSIDE !), which required a roughly 20mm diameter hole through the wall for the exhaust pipe. I take the combustion air from inside the building, as I think there is enough of a gap around the up-and-over doors to supply this, but this air could be sourced from outside the building if required as an inlet air hose and filter are supplied.

Fuel consumption is around 0.5 litres an hour flat out - I can buy red dilesel at a local filling station pump for around 80p per litre, so it is not expensive to run. They also operate on paraffin if you can get it - some say that paraffin is preferable, as it burns a bit hotter & generates less carbon build-up in the combustion chamber tan diesel. A complete kit for a unit to build in to a vehicle is around £100, plus you will need a 12v power supply at around 15A for the supply to the unit. I made an angle iron frame for mine & draw the fuel from a 25 litre oil drum, though if I were to do this again I would buy a version that comes in a case with a built-in 5 litre tank. Mine came from Ebay - search for "diesel air heater" for the various options (outputs range from 2 to 8 KW). My unit can get the garage to a comfortable working temperature & I have the warm air outlets attached to workbench frame using 3D printed brackets.

I have also just purchased a motorcycle dryer to get round the "putting bikes away wet" problem. I hadn't known about these until I came upon a review on Youtube by an initially very skeptical reviewer. His intial view was much as mine was when I heard of the devices - a solution looking for a problem. But by the end he had concluded that it was a worthwhile device that worked well & was a great improvement on the tradition chammy leather approach. The unit I bought (also from Ebay) is marketed as a "pet dryer" - the same unit marketed as a "motorcycle dryer" is several 10s of pounds more - mine was £47 delivered. It looks like a small cylinder vac, but blows rather than sucks through a flexible hose with interchangeable nozzles. Mine is 2 speed (25 & 50 metres/sec airflow) & it has a switcheable heating element to warm the air if required. After finishing this message I am going to give the Interceptor an overdue wash & try it out.

HTH,

Nigel B.

I use a desiccant dehumidifier - it warms as it dries.🙂 Approx 375W for a couple of hours a night (at the moment). Volume is now close to 30 cubic meters (before machinery, etc take up space, of course) as I have just moved one internal wall back by about 650mm - only nearly completely draught-proofed yesterday, so still w.i.p.

All but 1 1/2 square metres of the structure has at least 100mm of insulation. I’ve added more insulation as I get round to it - one section has 125mm of celotex + a layer of aluminised air cell plastic sheeting + at least 100mm of usual loft insulation. I expect to eventually add another 100-150mm of rock-wool and some of the insulated sheet to the 6 1/2 square metres of ceiling currently with only 100mm of celotex.

Temperature was 10-11 degrees Celsius this morning - about 4 hours after the dehumidifier turned off). I’m not going to add any more heat today and will see how it goes in the coming days.🙂

This is a workshop constructed within an existing pre-cast sectional garage. It clearly demonstrates the value of insulation - it is also cooler in the summer - unless the door is left open! Most insulation has cost ‘peanuts’ - picked up second hand from various origins over a period of time.

My workshop is around 35ftx25ft and is part of house extension so the roof is covered by the upper floor and one side is attached to the house. The brick wall is single skin with support pillars for the upper floor.

The two garage doors are a pair of insulated roller shutters. These made a significant difference as they completely prevent draughts. The windows are also double glazed It is quite a large area to heat. I have approached it two ways.

I have A 5Kw 3 phase electric fan heater, which warms things up but appears to take quite a time. It is rather weird because feels cold and then suddenly it doesn't. If I'm not happy with that speed of heating I have a Machine Mart propane gas blow heater which I bring into use. I tend to use this for around 1/2 to 1 hour to bring the temperature up quickly and then turn it off and use the electric heater. If it is very cold I occasionally leave an oil filled electric radiator on all night. I do have a central heating radiator out there but this sucks the heat out of the boiler rapidly.

I have never suffered from any condensation issues.

Keeping the workshop warn has the added benefit of assisting with the heating of the floors above it.

When I used to do car repairs in my dads garage many years ago I used to have a paraffin fueled Salamander. These were amazing things with 10 gallons or thereabouts of paraffin in the base, the lid had a 4ft chimney with a cone shaped cover over it. You opened the air flap on the base and threw some burning rag or paper inside. The paraffin caught fire. The base of the chimney had a about 50 small louvres in it around the circumference spread over 10 rows. Flames would spit out of these slots. As the flame went up the chimney it came to a cast iron 'U' bend which channeled some of the flames and heat back down to the surface of the paraffin. Gradually it would get hotter and hotter and hotter and make a lovely roaring noise. Great for warming pasties or sausage rolls on the top of the base. Totally lethal things which left a big ring of soot on the ceiling. It had a fair few years use before I decided things should be bit safer.

Colin

I'm the same as Nigel (mgnbuk),I bought a night heater as sold for campers and motorhomes from Ebay for (I think) £120, been running it for 3 years now with no problems at all.

It's used about 60 litres over the three years but I run mine on kerosene @39.9p per litre, half the price of red diesel.

My workshop is 7 x 5 metres, built in shiplap with 100mm insulation in the roof and 50mm in the walls and lined with ply

Regards

Roger

Three almost incompatible requirements!

Condensation is most likely when temperature changes, up or down, and especially when it changes quickly. Problem is cold metal takes longer to warm up than air, and warmer wet air will condense water on any cold surface it meets. Natural and man-made temperature changes are equally bad. A poorly insulated workshop will warm up rapidly during the day and quickly cool during the night, and the change causes rust. In the same way, quickly raising the air temperature of a cold damp workshop with a powerful heater is asking for trouble. Insulation is a better answer than heat.

First step, get rid of the water. Porous roofs and walls, rising damp, leaks, tumble driers, free-standing paraffin heaters, dripping bikes are all banned. Seal, improve ventilation, pump, drain and fit a dehumidifier as necessary.

Second step, slow down temperature changes. Insulate and then control heating. The pro's fit chillers and heaters plus dehumidifiers, pricey! A cheaper wheeze is to keep big metal tools just warmer than air with a bolted on thermostatically controlled black heater. Another is to not heat the workshop at all. This works in mine because it warms up slowly on the electric lighting and motors; on cold days I wear more coats and suffer for my art! However, my workshop is well-insulated and never freezes: my English shed is too cold for this, and it certainly wouldn't be do in mid-winter Canada!

Third step, protect. Keep tools boxed and cover lathes etc with a blanket to keep damp air away from the metal. Oil surfaces.

A dehumidifier will deal economically with an ordinarily damp small workshop and only run when the air is wet. Provided it keeps the air dry it should be reasonably safe to warm the workshop quickly for comfort on cold days.

I don't believe there's a cheap sure-fire way of dealing with condensation in all circumstances. The answer has to be bespoke to the local problem. What works in north facing Aberdeen will be wrong for south facing Dorset, let alone Alice Springs or Darwin. And vice versa.

Dave

Thanks guys. I've not read all the replies in detail - I will later on.

A bit more info that I guess is relevant:

It's a garage that's attached to the house on one side, with an office above it, so the cieling is fully insulated with a foil blanket and rockwool. The front is two large up-and-over doors. As I mentioned, the lower gaps are sorted, but the panels themselves aren't, nor are the surrounds.

The "wet" bike drying isn't an issue; it happens infrequently, but is very handy when needed.

I have plastic covers for the lathe and mill, and most other tools are in cabinets. Never had any issue at all with condensation, but this may be due to the un-sealed nature of the space.

I would like to seal it, becasue as someone mentioned, it would probably make the room above warmer. It's the coldest part of the house, despite it being fully insulated with cavity wall insulation on the gable, and it being basically wrapped in a huge insulated foil blanket all around.

I suppose the two large steel doors are conducting a load of heat out, and I wonder if I fully insulated them, and eliminated draughts from the surrounds, I might even get away with turning the small central heating radiator up to 5 for an hour might do the job?

Thanks.

On a slightly different topic, but may be interesting:

Re. the cold room above the garage: it's got a large radiator in it, which had to be on for an age before the room got warm, and often it was only one end and towards the ceiling that got warm.

I decided to roll the dice on one of those cheap radiator fan/deflector arrays from Amazon. I was almost sure it was money down the drain, but in fact it's made a massive difference. It seems like slightly increasing the speed of the air coming off the top of the radiator has done something disproportionate to the overall circulation of the hot air in the room. It's got a thermostat, so fit and forget.

Now, when the fans kick in, you can feel warm air at the other end of the room in a few minutes. Not like a draught, more like a warm current. Might get one for the garage, or at least move the original to try it.

A thought about metal doors. I fitted an insulated roller door, and immediately missed the radiated heat caused by the morning sun (door is SE facing). Very noticeable that in the winter, the garage is always cold until I apply heat. Overall I suppose I am better off, but an effect I didn't anticipate. I do my work mostly early in the day, and now often open the door for direct sun.

+1 for an electric fan heater.

+1 for something to insulate the feet from the concrete

+ 1 Dry the bikes before entering workshop.

Possibly partition one side of the garage into 2 areas. One for bikes & lawnmowers the other as a workshop area.

regards

All good advice from folk above. I see you already have a central heating radiator fitted in the garage, when my house was being built I requested the same - much to the confusion of the plumbers who happened to be fitting it on April 1st and were convinced it was a wind up!

I had a Myson blown air radiator fitted - plumbs into the CH system but has a twin fan pack and this distributes the warm air around the garage despite all the 'bits' in the way. It is thermostatically controlled so I can leave it on over night in 'frost mode' (allied to a outside air temp sensor set at -5C on a north facing wall).

The garage had a metal framed double width but timber clad door which I fitted draught excluder strips to top and bottom. Then glued in expanded polystyrene insulation. The garage is single story with a ceiling and loft space, insulated in the loft with 6" of fibreglass. The result is a draught free workshop which keeps a good level of heat in and is a pleasure to open the door and walk into in the middle of winter. On the far side (the North facing side) of the garage I noticed it was slightly chillier, so when I shut down for the night i switch on an oil filled electric heater set at minimum setting. It makes an appreciable difference.

The object is to keep the garage temp above the 'dew point' to prevent condensation. The 'dew point' varies according to ambient temp and humidity. It is interesting to find that as temperatures fall below about - 15C the humidity becomes almost zero as all water vapour freezes out of the air. This protects everything from condensation but the transition temperature of heavy metal objects lags way behind the ambient.

I just use a 2000W radiator.

Jim

Thanks guys.

I can't partition the garage, because I've got 2 cars and 2 push bikes in it, as well as all my workshop equipment. It's not exactly cramped, but I do like free space to work on large bits of car. I suppose it could be considered a triple garage, but with only two large doors. I designed the house myself, and since I was done with working in crap conditions, I gave myself plenty of workshop space. It's probably not a standard size. And yes, the plumber did question the radiator in the garage, and the insulation folks had to come back (after an arguement) becasue they didn't bother with the cavity wall insulation in the garage - said it wasn't necessary.

What type of polystyrene do you put on the doors, and how do you fix it? Presumably something fireproof. I thought I'd seen a kit on EBay, but can't find any now. That's where I got the floor seals from. I wonder if self-adhesive Velcro would do it, or double-sided Gorilla tape? If it looks a complete balls-up, or I end up not wanting it for some other reason, Ideally I want to be able to remove it without having glue smeared all over the panels.

Thanks.

Re Sealing the doors.

Leave the bottom of the door unsealed, so that moist air can escape. By all means seal the sides and top, and then insulate the face of the doors, to prevent heat loss.

The ceiling is already insulated, but it is worth insulating the walls with 50 mm of glass fibre, or rockwool, and cladding them with 12 mm ply or plaster board. If you can get already well insulated board, this will save effort..

Heating should not be by any form of combustion heater, because one of the products is water vapour, cueing the entry of then rust fairy. Plus, any leak could put you at risk of carbon monoxide poisoning.

So, dry heating, which implies a fan heater for rapid warm up, preferably thermostatically controlled. A convector heater, tubular heater (s) or oil filled radiator can provide background heat, A radiant heater will provide instant warmth for you, when you are in the beam, but a lot less for the whole shop.

I am located in East Anglia, so in a temperate climate, with little rain.

My shop, located in East Anglia, in a temperate climate with little rainfall, small, is 10'9" x 6'9" external, with 19 mm cladding on 50 mm frames with 12 mm ply internal cladding.

The rubber covered flat roof slopes from 8' at the front to 7'6" at the back, and has the same 50 mm of glass fibre as in the walls. The door end framing, is actually 100 mm to carry the weight of the fire door with its 6 lever lock!

The floor is 18 mm ply carried on four 8 x 2 bearers, with thick plastic matting in the central aisle where feet move. The back wall is protected by a high fence, and the front by a low patio wall, as is the non door end wall, so there is some protection from the weather.

There are no windows. Ventilation is by two small fixed vents at floor level, and by a 6" intake fan, (with rainproof cowl ) set in the back wall.

Heating is by a 2 Kw fan heater with thermostatic control. Normally, it runs for about ten minutes and then only cuts in for a couple of minutes every 30 minutes or so.

When frost is expected, ie, from now on, a 60W tubular heater under the bench is switched on, and left on continuously. After a couple of days the steel benches no longer feel cold, and entering, one is aware that the place is not cold.

If you live in the Highlands of Scotland, or on the 49th parallel, you may well need more insulation and heating

On the equator, the need for insulation may be as great, but to keep out the heat, and the need for heating possibly replaced by air conditioning.

HTH

Howard