Garage Heater

[Colin Symonds]

I have just recently moved house, in my old place the garage was part of the house and had a radiator from the house central heating system.  In my new place the garage is separate so before winter I want to install an electric thermostat controlled heating system.  I obviously don't want to keep it like a sauna, just maintain a reasonable frost free temperature.  There seem to be two main options, either a radiator with a built in thermostat or a separate thermostat and heater.  Does anyone have any recommendations please.

 

 

[keith1948]

Hello Colin

Initially I was thinking of suggesting a small electric greenhouse fan heater or a convector heater with a frost guard setting. However it occurred to me that these would not be very good where there might be petrol fumes. Take care that any thermostat switch or heater cannot spark and cause you to have a really warm garage! I guess this goes for light fittings and switches as well. First step might be to upgrade any insulation.

I will be interested to see what our electrical experts in the Register recommend where petrol fumes might be an issue.

Sorry I can't be of more help.

Keith

 

[boxofbits]

I use a Igenix oil filled electric radiator.

No exposed elements, flame  or fanned heat, but is thermostatically controlled with a range of heat settings and a 24 timer with several time settings.

They are a good price and has worked out ideal for me.

Kevin

[Hamish]

Do you go for sealing up the garage and heat and dehumidify or allow ventilation ?

it will also depend on the type of build of the garage 

 

[RobH]

Do bear in mind that a slight smell of petrol doesn't mean there is danger from a spark, and unless the garage is very well sealed, normal ventilation should be enough to keep things safe.  Petrol/air is flammable over the range 1.4% to 7.6% by volume. That means in each litre of air you would need at least 14ml of petrol vapour for it to be flammable.        If your garage is 6M x 3M x 4M that is 72,000 litres and would need 1008 litres of petrol vapour to reach 1.4% concentration.  One litre of liquid petrol produces approximately 157 litres of vapour so you would have to vaporise about 6.4litres of petrol  (getting on for 1.5 gallons) to reach the lower limit of flammability - and retain it all in the garage.  Barring a major leak from the fuel tank I suggest that is unlikely.

( petrol vapour is heavier than air so it would tend to have higher concentration nearer the floor level but that is where the gap under the door is..... )

 

I expect the garage will have lighting installed already?  There is no requirement under current regulations for that nor any switches or socket outlets to be flameproof, in a domestic garage in the UK.

If you are really concerned then sealed tubular heaters with no thermostat are probably the safest, wired permanently to a fused switched outlet, not plugged in. (The oil filled one in Kevin's picture has a normal thermostat contact open to the air, and could spark as it turns on and off). 

 

[DaveB66]

Hi,

An alternative would be to use a Carcoon or similar.

Dave

[boxofbits]

2 hours ago, RobH said:

Do bear in mind that a slight smell of petrol doesn't mean there is danger from a spark, and unless the garage is very well sealed, normal ventilation should be enough to keep things safe.  Petrol/air is flammable over the range 1.4% to 7.6% by volume. That means in each litre of air you would need at least 14ml of petrol vapour for it to be flammable.        If your garage is 6M x 3M x 4M that is 72,000 litres and would need 1008 litres of petrol vapour to reach 1.4% concentration.  One litre of liquid petrol produces approximately 157 litres of vapour so you would have to vaporise about 6.4litres of petrol  (getting on for 1.5 gallons) to reach the lower limit of flammability - and retain it all in the garage.  Barring a major leak from the fuel tank I suggest that is unlikely.

( petrol vapour is heavier than air so it would tend to have higher concentration nearer the floor level but that is where the gap under the door is..... )

 

I expect the garage will have lighting installed already?  There is no requirement under current regulations for that nor any switches or socket outlets to be flameproof, in a domestic garage in the UK.

If you are really concerned then sealed tubular heaters with no thermostat are probably the safest, wired permanently to a fused switched outlet, not plugged in. (The oil filled one in Kevin's picture has a normal thermostat contact open to the air, and could spark as it turns on and off). 

 

‘Tis possible Rob, though I have tested it in pitch blackness by turning it on and off and at least visually cannot see any evidence of a spark, nor from the timer. That would be ironic if my garage exploded instead when it switched itself on.

There are a number of sources in a garage which might produce a spark, including drill, grinding and power tool commutators, MIG & spot welders, plugs being pulled out and not least a sTRay spark from a TR when started ! Probably best not to saturate the air with fuel!

Liked the theory about the air/petrol ratio btw!

Kevin

Edited September 6, 2020 by boxofbits

[john.r.davies]

While not wanting/needing to keep my garage warm, It gets bloody cold in winter.

I'm probably nearer the North Pole than you, Colin, and keep the garage well ventilated to deter condensation.   So working in there in winter is a bit on the chilly side.

I use a gas powered fan heater, a Little Devil, that lights up and runs with a roar and a blue flame inside.    I suppose if there ever had been a problem, I wouldn't be here, but I am and it is.   And it heats the garage up to comfortable in 15 mins, although the metalwork stays cold for much longer.

John

[Lebro]

I also use a gas powered "space heater", very effective, if a little smelly.

Bob

[John Morrison]

Hi Colin,

 

I use a 3kw fan heater to take the chill off the air in the garage in the depths of winter, (Expensive but rapid, pop it on, make a coffee and we are away) plus an eclosed 500W heater left on, or  near the bench.

As others have said, sparking of heaters or switching, is not an issue, and without your TR pooling fuel, on the floor, cannot see it could ever be one.

 

John.

[Chris1966]

I use a desiccant dehumidifier in the garage and find the heat provided as a byproduct to be fine most of the time. In really cold condition I'd go with a fan heater if I had to work in there. I have insulated the inside of the garage (including the door) to keep running costs down, did try condensing type first but they don't work in low temperatures.

Chris

 

[john.r.davies]

Ah, Chris, the operant words there are "Insulated the inside of the garage"!     You have also, I presume sealed it, draught excluders as good as your home has?     If you brought a large metal object into the living room and breathed around it, it would soon be covered in condensation.      That's where the humidity you expensively remove comes from.    Allow the air to circulate in the garage, remove the draught excluders, ensure a gap under the door, and at the soffits under the eaves, and the atmosphere will take away the moisture, at no cost to you!

I do know whereof I speak - the wettest part of the Uk where I live has a reputation for chilly dampness, yet my unheated garage, save for the occasional gas heater blast (which generates lots of water vapour!), gets no condensation and my tools and car do not rust!

JOhn

[Richardtr3a]

My single garage was used by the previous occupier to grow Marijuana. They insulated the walls and roof . It is not draught proof and the door does not fit well. The contents have remained rust free over the last 4 years.  That is the car and the tools.

As you get older working on the car on a cold damp day is less appealing. I am keen to go out there if the sun is out at any time of the year. Thanks to Covid there are no deadlines for finishing the work in hand so I just carry on at my own pace. No garage heater for me..

Richard & B

[SeanF]

I have a pair of quartz wall heaters in my garage, similar to these

https://www.screwfix.com/p/mh-10-1-wall-mounted-quartz-heater-600-1200w/1238P?tc=WB4&ds_kid=92700055281954496&ds_rl=1249404&gclid=CjwKCAjw19z6BRAYEiwAmo64LRumFF-sDXO2g0_JoWKaRCfHQmHOoYxJb1FVjex_ky3qa2t5P6SIeRoCyJYQAvD_BwE&gclsrc=aw.ds#

I don't have a need to keep my garage temp controlled as it is dry and well ventilated as discussed above, but they are very effective for warming the space up quickly when I want to work in there in the colder months

[keith1948]

Here is a link to East Sussex Fire Brigade cautionary tale re petrol vapour.

https://www.esfrs.org/black-museum/all-the-black-museum-cases/petrol-vapour/

I am sure people will do their own risk assessments but personally naked flames and sparks are things I try to avoid in the garage just in case I get a leak of fuel when I am not in there to see what is happening.

I used to have a mouse problem in the garage until I made the doors fit really well at the bottom. The roof is reasonably well ventilated so it is quite cold in the winter. As long as I have antifreeze in the car then can't see a problem except for working in the cold. I use a small fan heater when I am in there but wouldn't use it if I was working on the fuel system and would have the doors open as well. I have one of the quartz heaters as mentioned by Sean in my workshop but with a trip switch that does not reset automatically after a power cut. (Most seem to reset). I don't want it coming on by mistake.

Keith

[Chris1966]

Further to the merits or not of running a desiccant dehumidifier. In the past I have been fortunate to have a garage that kept dry all the time due to good construction/positioning. At the property that I'm at now that was not the case from the beginning. The TR was away being restored when I moved, and I expected it to return within a few months (actually much longer) so I needed to sort things quickly. The garage is built into a slope on top of a heavy clay soil, with the rear around 4 inches below ground level, after heavy rain water would pool at the far end.

To remedy this I fixed the blocked soak-away rainwater drain, applied tanking slurry to the lower parts of the walls and floor, dug way the top soil to the one accessible length outside and filled with gravel to aid drainage.  Although this reduced the problems the relative humidity was still high, so that is when I stated using the dehumidifier. 

Yes I could have tried the ventilation route, given the circumstances I don't think it would work - maybe in summer it would have been okay. At first it removed a lot of water - as per the use in flooded areas - and then settled to a maintenance amount. It is set at 50% RH as that is supposedly the border between rust/no rust so it does not run all the time and on dry cold days it may not run.

It would indeed be a bad idea if I took the car out each day, especially in humid conditions, as the ratio of time in the garage is much larger for me that does not come into the equation.

It has to be acknowledged that a desiccant dehumidifier is not cheap to run, especially in comparison to a low wattage type heater. The one I have is rated at 660 watts max, remember that it does not run all the time or at the maximum rate. I reckon a rough cost of £300 per year, if you look at having a 100 watt heater you could run that all the time for less than £140.

The heat provided is about plus 5 degrees F., depending on outside temperature, which is useful for cooler months - but it may not be running exactly when you want to be in the garage, although it tends to start fairly quickly due respiration.

If you already have a dry garage then you are probably best going for background heating in winter, rather than letting it freeze and then heating it up quickly.

If you have a damp garage and additional ventilation does not work a desiccant dehumidifier is a cheap to buy easy solution against rebuilding costs / storing your TR elsewhere. 

 

Chris

 

 

 

[Rob Salisbury]

Hi Colin, If the garage is not too separate from the house consider laying insulated pipes to it and have radiators like before, then no worries about sparks or flames.

Cheers Rob

[Colin Symonds]

5 hours ago, Rob Salisbury said:

Hi Colin, If the garage is not too separate from the house consider laying insulated pipes to it and have radiators like before, then no worries about sparks or flames.

Cheers Rob

Yes I'm exploring that option.

[boxofbits]

On 9/9/2020 at 2:01 PM, Rob Salisbury said:

Hi Colin, If the garage is not too separate from the house consider laying insulated pipes to it and have radiators like before, then no worries about sparks or flames.

Cheers Rob

You might have to check/upgrade your boiler and pump rating if coming off your household heating. I did look at this option but was told I would need to upgrade so didn’t bother.

Kevin

[Waldi]

Has anyone considered a pump?

I have the house central heating warming one radiator of my garage, but that is what I would consider too.

It can be basically a air/air heat pump. It will have an “efficiency” of 200-500%, depending on your climate. So for 1kWh current draw it supplies 2-5 kWh heat.

Anyone using more electricity than say 150-200 pound/year could consider this.

Waldi

[stuart]

4 hours ago, Waldi said:

Has anyone considered a pump?

I have the house central heating warming one radiator of my garage, but that is what I would consider too.

It can be basically a air/air heat pump. It will have an “efficiency” of 200-500%, depending on your climate. So for 1kWh current draw it supplies 2-5 kWh heat.

Anyone using more electricity than say 150-200 pound/year could consider this.

Waldi

I would have thought that was a physical impossibility as the laws of physics dictate you cant get more out than you put in.

Stuart.

[Hawk]

As above, oil powered radiators set on frost setting have served me well for years .... 

[RobH]

Air source heat pumps do work Stuart. It is akin to a refrigerator working backwards. It converts a large amount of low heat in the ambient air to a smaller amount of higher heat for the house.

As for the physics, the electrical input is not providing the heat output -  that is coming from the ambient air outside. All the electricity is doing is moving that energy from one place to another, so conservation of energy is satisfied.

The apparent 'efficiency' depends on the type as Waldi says. It's the sort of thing everyone will need for heating if they ever turn off the domestic gas as threatened.   

 

 

Edited September 11, 2020 by RobH

[Hawk]

I has an air source heat pump at my previous house and ran it for 9 years ... and they do work and are capable of producing very efficient heat in the right condiitons.    And it undeniably reduced my heating costs (but that was versus a very inefficient oil powered boiler).

However, they are not without limitations ... notably the efficiency is very poor when the ambient temperature is below freezing and they only heat the water to circa 55 / 60c so you need to boil kettles for washing up and baths and / or use an immersion heater to top up (which it is recommended you do every day to kill harmful germs).  And leave the heating on 24/7 as letting the house get cold results in long waits for warmth.  

I qualified for grants and quarterly incentives which paid for most of my instillation but I still woudln't have another one.  

And did I mention that I had 2 catastrophic failures in that period.  Once entire unit was replaced under warranty by DeLonghi and second time the heater matrix failed.

The new owner then told me, about 3 months after we moved out that the electrics had all given up!  

[Waldi]

Heat pumps are considered “the future” and all energy-neutral houses in NL are fitted with them. We are used to water heated radiators overhere, and natural gas fired HE boilers.

Possibilities are W to W, A to W, or, like with an airco, A to A.

They are cheaper to operate overhere than Gas fired units, but ONLY if your required water temperature is low, say 30-40C throughout the year. So on existing (older, pre 2000) houses it starts with improving insulation.

The A to A (“airco”) units are typically split units, they come in an abundance of sizes, qualities.

Daikin is considered best quality overhere.

Back to the OP (Colin) question:
If I had no heating device in my garage and I would not have moving plans (in a couple of years) and was planning to heat the space throughout the winter  I would definitely insulate it first and then install an A To A unit. 

If not, I would install an electric heater and accept the couple of hundred euro’s. 

Make sure the electric wiring is properly rated for extended high currents.

Regards,

Waldi