Heating a workshop/garage

In article , Donwill writes Don,
When I expanded from my small workshop a year or so ago to annexe the garage, I had the same issue. The workshop is not heated but is open to the house and reasonably warm; the garage was unusable in winter as it was.
I decided the first need was to insulate. I fitted fibreglass insulation and plasterboard to the roof. An estimate of heat loss (Googling "heat loss calculator" will show up dozens of pro-formas, though not many cover steel doors) showed that most was lost through the steel un-and-over door, but the manufacturer did not supply insulation panels for it (sidebar - should it not be a requirement to make these available? - the heat lost through these things can be enormous). I am still working on this, something cobbled up from polystyrene or polyurethane sheets seems probable.
Then I fitted heaters. It seemed to me that electrical heating was the only sensible option, and I fitted a couple of ceramic panel heaters from Machine Mart:
and wired them up through a cheap wall-mounted thermostat from Screwfix. A little experimentation is required to get the desired temperature, as (certainly in my experience) the temperature achieved fell rather short of the marked figures.
My experience is that I need to improve the insulation or crank up the heat to make the garage habitable first thing in the current weather - it improves once I have opened the door connecting it to the house for a couple of hours, though still a bit nippy. However, it has, so far, meant that I have seen no signs of corrosion on the machinery and tooling stored there.
David

Thanks for that David, I'm thinking of removing the garage door and replacing with an insulated stud wall and an used pedestrian access 3ft wide fire door which I picked up cheaply for £10. I have a car port which abuts directly on to the existing garage door and I have another 2 off road parking places so I don't think that planning will be interested "I hope". A friend told me about a method of keeping the dreaded rust away by attaching low voltage power resistors to the machines which seems to be quite successful in his case. I haven't done it myself yet but the time will come as I am collecting resistors to put it into practice. Don

erm - you may as well extend your domestic heating system into the workshop and use a controller/timer/thermostat device to operate a motorised valve and leave the door through to the house closed. That way you can apply a bit of background heat to the garage without venting all of the cold air into your house. The ceramic heaterrs can operate via a cheap mechanical timer and your screfix thermostat to provide a bit of heat when your CH isn't running - in the middle of the night for example.
just my 10p worth
regards
dudley

Tubular heating of the sort sold for greenhouses for background heating.
Run a dehumidifier, which as well as sucking out the moisture will also add a little background heating effect.

I had exactly the same problem. I cosidered replacing the door with a stud wall but decided that access in the future was important if I ever get a "proper mill". In the end I got a builder friend to get me two sheets of 8 x 4 Celotex 70mm thick. Cut these to suit the width of the door frame and cut wedges of the same to fill in the edges out to the wall. I glued a length of 75 x 19 "treated" board to the floor first to stop any water coming through under the door getting into the shop. Taped all of the edges of the Celotex with Aluminised tape and put a length of EPDM seal between the lower panel and the floor board.
Reading the above it sounds like a cobble but it actually looks good and seems to be working. Cost £46 for the two panels, tape in stock, EPDM seal from Screwfix. Advantages Easily removable, low cost, quick to do Disadvantages Cannot hang anything on the new "wall".
I also had a problem with the rooflight in the garage. Even though double glazed I could feel the cold "falling down". Fitted a piece of 1000 x 700 5mm polycarbonate sheet into the cavity and supported it with a batten "picture frame". The polycarb has been kicking arround for years so zero cost. Left the protective sheet on it so if needed for a job is recoverable. That has definitely made a difference.
Yet to insulate the roof once I get rid of a load of stuff hung from it!
Then I need to bite the bullet and put some "controlled" heating and maybe de-humidification in.
Also need to check neighbors garden as I feel that their soil line is higher than my garage floor and that is why that end of the garage seems a bit damp!
Richard

I am doing the same with mine. The ceiling has been boarded (one panel twice) and I am half way through doing doing the fibreglass. The rest will have to wait another week or so while I recover. Two of the 3 up-and over doors I have bolted shut, taken the mechanism off, and lined the inside with 50mm rigid insulation (Kingspan type stuff) glued in with polyurethane foam. I am thinking of putting a proper door in the 3rd hole, and in the meantime I think a brush at the bottom and several layers of cardboard might not be a bad insulator, if I can figure out a reasonable way to fix it. Don't forget the floor. I have covered this with loft boarding chipboard which is warmer, better to walk on, and does not ruin jobs and tools dropped on it.

As Don's "friend" I've taken some pictures of my machine heaters
Myford ML7R Lathe 2 x 5 ohm in series on 16v VMC Mill 4 x 39 ohm in parallel also on 16 v About 25 watts into each machine.
Has kept rust away for 30 years in an unheated single skin brick workshop. The only other 'precaution' is not cleaning up any oil splashes from normal use.
Bob

This is true, but a major worry if you intend doing any serious angle grinding or welding work, the potential fire risk makes it a bit of a no no in my eyes.
Returning to the OP's question. I'd forget trying to heat the workshop unless you spend ages in winter in it, invest in an (wall mounted or portable) infra-red heater and provided you position yourself in front of it you'll be OK - don't forget the thermal underwear! Heating is expensive these days :-(
Regarding rusting machinery - I have a lathe, saw and mill and all I do is liberally spray the bare steel with oil every so often, nothing shows signs of rusting and everything slides freely! I use some old thick gear oil (SAE220?) that I cut back with some kerosene so that it'll spray with one of those plant mister bottles - simples.
Julian.

In article , Richard Edwards writes Richard,
That sounds like a great idea; unfortunately the garage door is required to open fairly frequently for access for window cleaners etc. (my wife insists...). When I built the garage it took up the whole space at the side of the house and it's now the only access to the back. Don't forget to put all the lights you might want up first - it's much harder afterwards. You may need to dig it away and paint on a bitumen damp proof coat down to below the existing DPC. Alternatively, you could use a product called "Bituthene" - a heavy gauge polythene sheet coated with bitumen, which also protects the damp-proof bitumen and also keeps it away from your neighbours legs.
David

If you are contemplating electric heating then start by installing one or more dehumidifiers. Firstly they (obviously) dry the air but secondly they recover the latent heat of evaporation so are slightly more efficient than a 100% efficient radiant heater (you get more heat out than electric energy equivalent put in).
Another alternative which is much cheaper to run than resistive heating is an inverter split unit air conditioner. This is an air source heat pump with air drying. DIY fit versions are available. Look for the coefficient of performance figure. In heat pump mode these types of systems typically have a coefficient of performance (CoP) of about 3. This means that a 3 KW air conditioner uses about 1 KW of power. Conversely a heat pump provides about 3 KW of heat while using about 1 KW of power.

That sounds like the way to go, having done a quick search LG and Toshiba seem to be eminent in the field, do you have any experience with them that you can share? To keep the humidity down AND heat the wksp cheaply seems to be great. :-) Generally speaking, the air passing through the unit needs to be cooled to remove moisture, how does the unit apply heat to warm it up to working temp, is this where the so called "split" system comes in? To cool and then heat the air in principle seems wasteful ? Any info gratefully received. Don

The split is simply the two units, external and internal which are separated by the refrigerant pipes (compared with the old window fitting combined unit where the two were in the same big box).
The one I have when operated in dehumidifier mode the unit is switched automatically so the indoor unit alternates between having hot pipes for heating and short periods where the refrigerant is reversed to cool them to condense moisture out. If the room temperature is at the temperature set on the thermostat it runs in dehumidifier mode.
Most have timer functions built in so you can have them turn on and off by themselves - they often can't easily be controlled by a separate time switch.
is a company specialising in DIY units. There are some useful documents on installation at I've used them a few years ago and they were very helpful when I talked to them about what was needed.
Many units meant for DIY now come with "easy fit" sealed pipe runs with snap fit connectors which makes installation easier.

In article , Donwill writes Don,
Warming the air automatically reduces its relative humidity, so it does not need to be cooled first.
David

Donwill schreef op 13-1-2010 : Hi, Recently extended the shed, used 70mmm aerated concrete blocks to make inner walls and floor heating. Now experimenting with Mother Earth's Waste Oil Heater. Made it from old 12 kg propane bottles. Google for the plans. Works fine with wood and lamp oil, but not - yet - on discarded frying oil as planned. It does not seem to get hot enough to ignite. Best regards, Dirk

You need to reduce the dewpoint temp of the air below the temperature of the machines in the wksp. e.g air at 22degC and 60% RH, will condense out at the DP of approx 14degC. If you can reduce the RH of the air to say 48% then the DP will be reduced to approx 11degC so if the machines are above 11deg C then water will not condense out on them. Don

Hence the efficacy of heating the machines.
One undesirable result of heating the air intermittently is that the warmer air will pick up any excess moisture and then deposit it on surfaces -such as machines- that don't heat up so quickly. Continuous space heating above the dewpoint is good but can hurt the wallet somewhat.
Bob

If it's using any combustion air from inside the workshop then such an approach is guaranteed to promote massive swings in humidity resulting in huge condensation problems.
Run them 24 hours a day round the clock with the door open to the outside and they *might* be ok. But no one wants a workshop that hot or draughty and that's the reason wood fired stoves, gas burning hot air blowers or paraffin heaters are a pile of poo for a workshop.

Surely it is not drawing combustion air from the shop but exhausting combustion products containing water into it that is the problem. I don't see why a stove, having an external flue outlet, would be a problem.

Mike had uiteengezet : Right! Exterior air intake will be added later on.