Hi Cedric,

The first thing I would do is insulate the walls. This can either be a rigid foam board glued to the wall with a few screws to hold it in place, or build a timber framework to create an internal wall with insulation, more choice with the method, and finish it of with a board. You have a choice of boards depending on how tough you need the walls to be. Plasterboard, chipboard or stirling board would do the job. You will probably have to include a vapour membrane in the constructio. Then you can think about heat.

Lee

^^^^ This. The better you can insulate it, the easier and cheaper it is to heat. Insulating the ceiling is important too. And some kind of floor covering or even a false floor with insulation between it and the cold concrete is good too. And put your main work area up against the wall that adjoins the house. That will be the warmest part of the workshop.

For your climate in the UK you will need to look at humidity/moisture control too. Not just to stop corrosion of machines and tools etc but if you can knock the relative humidity down to 50 per cent or so, it takes less heat to achieve a comfortable temperature. Too much humidity and you will need to heat the shop to a higher temperature to feel comfortable. (Likewise, too little humidity and the perspiration drying off your skin will make you feel colder and so again more heat will be needed.) It is worth installing a wall thermometer with relative humidity gauge to monitor it. And dehumidifiers seem to be a thing in some UK workshops from what I see on the forum.

The first thing to do is to read all the posts on this forum for the last 3 months, We have covered this topic every week, over and over again. You can do this in the warm of your house thus saving 3 days of heating in the garage.

Yes, nice one

It is quite easy to make one if you have access to welding equipment..

But not legal. New wood burner installations are required to be "EcoDesign compliant" & EcoDesign stoves are not inexpensive.

Heat treated pallet wood is probably OK, but not chemically treated wood. Even the heat treated stuff is probably not legal, as solid fuels are supposed to be "Ready to Burn" certified now.

Having said that, my vehicle diesel air heater is probably of dubious legality – though red diesel is an approved heating fuel.

As your gagrage is attached to the house, i would go with "insulate, insulate some more & add a radiator off the house CH" – assuming that you have a wet CH system in the house.

Nigel B.

If it is open to the roof, install a plasterboard ceiling with insulation.

For the floor, I have bought some interlocking rubber mats from Halfords – they are about 10mm thick. They provide some insulation and are more comfortable than standing on bare concrete.

If you can, install a radiator fed from the house CH system. I have just done this and fitted a motorised radiator thermostat to it. I can control the temperature using an app on my phone so it only needs to be on when I want it and can be set to heat up in advance of going to the workshop. I have them on all the radiators ( it is the ‘Wiser home’ system from Schneider). For this particular system you need to replace your traditional CH timer with the Wiser one, but you can buy other brands that are free standing.

Stuart

I did a thorough job insulating doors, walls, ceiling. I didn't do the concrete floor yet but place is very cozy without it so I would say it isn't essential.

A self closing door is a good idea but at least a door that slams shut with draught exclusion.

I use a mini fan heater to take the edge off quickly, and an infrared to make me feel warm while waiting. It is a detatched double garage – half an hour of heat lasts all day for a weekend like we just had.

I also have a FLIR infrared camera to identify weak spots in insulation. Very useful once or twice a year (also good for electicals and finding the next thing that might let the smoke out.)

Edited By jaCK Hobson on 16/01/2023 12:19:51

How good is the existing insulation? My garage/workshop is part of the house, with bedroom over. This means it has a double cavity wall which has been foam insulated inside, and the floor is damp-proofed. Unless it's very cold, I don't heat at all. Instead, heavy coat until the lights take the chill off. Brightly lit, 6x fluorescent tubes.

Wouldn't work in a thin-skinned lean-to type garage sat on a concrete pad, or a simple shed. These are diabolically poor.

My advice, don't start by heating. Minor reason is the cost, because lots of energy is wasted because most of the heat escapes uselessly. But the major reason is repeatedly heating and cooling a workshop is the very best way quickly rusting tools! Cycling the air temperature causes condensation. Instead, start by insulating as much as possible, plus everything you can think of to exclude damp.

Then heat as necessary for comfort. Choices:

• Electric for clean easy convenience. For cheapness, wood burner or similar, but remember the installation cost is higher than an electric heater, and they have to be stoked and maintained. Not good if you pop in and out of the workshop rather than work long hours in one
• avoid portable electric fan heaters and free-standing paraffin heaters – fire and trip hazard
• oil-filled electric OK, but they tend to warm the workshop top down. Hot air rises, so it takes a while for heat to reach floor level, which it might never do if the roof is poorly insulated
• radiant electric heaters emit radiation that warms solid objects rather than air. These feel warmer, but a good part of the energy is soaked up by the walls and equipment. My gut feel though is these are good for workshops. Safe, easy install, the benefit is felt instantly, and condensation is less likely because air is warmed last, not first.
• Never heat by combustion unless there's an external chimney!
• A combustion heater fed by air inside the room is inefficient because it pulls cold air in from outside. May not matter if fuel is cheap.
• Diesel heaters have become popular for heating workshops, but although oil is cheap, installation isn't. They require an external air intake and outlet, plus a 12V power supply. They blow room air over a heat-exchanger, and the distribution pipework can be aimed to maximise benefit. Fuel efficient, but more likely to cause condensation than a radiant electric heater. Again, much more suitable for long sessions in cold weather than short ones. Installation advice is shaky: aimed mainly at vehicles, the instructions provided vary from extremely basic, to good, but many are indifferent. Lots of youtube installation examples, but it's up to you to filter these! Most youtube technical videos are produced by amateurs, who don't have their efforts checked before publication. Consequently an uncomfortably high proportion contain errors, bad practice, or miss important details. Not a problem when shortcomings are obvious, but potentially nasty when they go unnoticed. Treat anything on youtube with suspicion, remembering that it's your problem if taking their advice burns the house down. The people who publish duff advice on the internet have no responsibility.

Dave

For the last couple of weeks, my well-insulated and draught-free workshop has been mostly heated by the dehumidifier (375W) which has been run on a timer, for one hour during the night, on E7 power. The temperature had dropped below 10 Celsius this last couple of days, so the diesel air heater was fired up for an hour yesterday evening. Not yet checked the temperature today. The heater had been used for a few minutes on a couple of occasions this year, so far, to warm it sufficiently while working in there.

Apart from the temperature being adequate, the humidity has been around 70%, or less, during this time.

Cost, so far this year, is about £1.30 for leccy and less than a litre of diesel. Diesel usage was rather more during the cold spell, but not excessive, IMO.

Is anyone using a stand alone 'window fitting' air conditioner in their workshop? They have both heat and cool modes (plus often a dehumidify mode) so would seem an advantage as we move to a continental climate and they provide COP > 1 too.

They are not as good a proper split system but better than the ones that use a vent hoses.
Certainly better than a simple electric heater.
Not sure how prices compare to one of the "self install" split systems with pre-charged hoses and one-time mate fittings.

I've had air-air heat pumps in my last tow homes (over 20 years total) and higly reccomment them.
For any type of heat pump it's worth getting a "inverter" type. These basically use a VFD to controll the speed of the compressor instead of turning it on and off at full speed. This is more efficent, quieter and less wear on the compressor.

Robert G8RPI.