No

Mainly due to the polystyrene

Being a graduate of the "Brick mausoleum" school, my thought was to lay a 50 mm layer of concrete around a steel reinforcing mesh, to minimise the risk of deflection of the 50 mm of concrete containing the heating elements.

But the increased weight, although a uniformly distributed load, might crush the cells in the polystyrene and so reduce its effectiveness as an insulator.

Maybe the edges of the reinforcing mesh could be turned down to keep the weight off the polystyrene, at a slight expense of the insulation factor.

Howard

Hy shed has actually got 200mm of concrete on top of 100mm of EPS foam (one layer of badly positioned mesh). The specified strength of the foam is more than enough to support the concrete and the machines. Concrete's quite cheap in the grand scheme of things and a good thickness on top of the foam does a wonderful job at keeping the temperature stable.

Would you be bolting down machinery? as a pillar drill or a pedestal grinder defiantly need bolting to the floor which possibly could damaged under floor heating. I would think at least 150mm steel reinforced and fiber mixed concrete would be my minimum. I have a wall mounted electric heater and a dehumidifier which makes it warm and dry in my workshop.

David

Edited By David George 1 on 07/02/2022 07:55:53

I found underfloor heating in a work area to be punishing on my feet and ankles, this was an aircraft hangar and we were in there for a full working day, every day, the underfloor heat makes your feet sweat and ache. I wasn’t alone in complaining about the problem almost everyone who worked in there felt the same. I wouldn’t by choice work again in an area with underfloor heating. With the problems already highlighted with bolting down machines I would go for heating above ground level, if the workshop is well insulated then a small oil filled radiator will work fine, that’s all I have in my workshop, which is well insulated, and I leave it on overnight on a low setting and it keeps the temperature to about 10 degrees, when I am working in there I crank up the thermostat to an acceptable level, this radiator is used in conjunction with a dehumidifier. Dave W

Insulation is most important. Mine has at least 100mm on all sides and top – but not the floor. It would, if it was poured these days, but not 30 years ago as a base for a garage.

Electricity is the most expensive energy source for thermal energy – unless you can generate your own using PV or wind – or use a cheap night-time tariff. I have just installed a chinese diesel hot air heater and it is cheap to run. Ignoring the ridiculously hyped-up claims by the suppliers, they do the job.

We have no details of electrical loads, TOU, etc. My little “claimed” 5kW heater is far more than I need in my workshop, except, perhaps, heating it quickly from a close-to-zero Celsius start. Machines remain cold, lagging far behind air temperature, mind. Once up to workable temp my workshop needs , I would say, likely less than a kW to maintain a reasonable working environment under most conditions.

I have a chinese diesel heater in an insulated garage 20 ft * 12 ft * average 9 ft high & I find it next to useless. I have to use a calor gas radiant heater to suplement it & i find the gas heater far more effective & cheaper. The chinese thing uses lots of fuel ( cost seems to be running double calor gas) & I have tried different temp settings. Having to run it off 12 volts is an issue as well as I have to have a battery charger on the battery at the same time, otherwise the battery goes flat in a short time –

When I had my Joinery works, one of the buildings had 15 electric radiant heaters aimed at each work station. They were very effective & the workforce had no complaints. However, electricity was cheaper then, so I am not sure how they would stack up now with one each aimed at the lathe, mill & work bench.

The wife pays the bills so it might be a massive no no.

As for under floor heating, one only needs to decide where one wants the machinery, Omit the insulation & fill that part in with concrete. There is no point in heating a machine so go round it. . No need to put it under side benches if you are going to stack boxes & tool chests there either. One needs to plan the layout first.

Edited By Sam Longley 1 on 07/02/2022 11:19:32

When installing, one is advised to follow the Webasto or Eberspacher installation details as pipe/duct sizes are important. The chinese instructions often leave a great deal to be desired – either factually, or language problems.

The Eberspacher manual can be found at:

**LINK**

132 pages, of which few are relevant to a simple installation but, nevertheless, useful for those that want to be sure they install the heater correctly.

The advantages of these heaters are: No water vapour is produced, or introduced, within the area heated. They do not need draughts to be sure of proper combustion (ie they are can be completely draught-proofed – my workshop is such, with no windows. Minimum fuel delivery (152ml/h) soon gets my workshop to a reasonable temperature for working, even if the machine temperatures lag behind. Full-chat would soon have been simply too hot in a short time.

I suspect that Sam’s garage is neither fully insulated nor draught-proofed. Also he may be procuring his fuel at inflated cost. He might be drawing in cold air from outside, for all we know.

Gross energy cost for gas oil is currently about 7p/kWh tops? (mine is currently a lot lower than that🙂 ) – unless bought in inappropriate volumes from convenience sources.

I run mine from the mains (practically). The 12 volt battery (needed as the power supply in case there is a power cut) is simply float charged from a lidl battery charger. My battery returns to ‘float’ charge only a few minutes after the heater is turned off, even though the controller is a permanent draw. Electricity draw is, I believe, 36-40W at full output but only around 12-15W at minimum fuelling.

my workshop has 3 to 4 inch concrete floor (no reinforcing) laid on a foot of rubble, with a membrane in between,then 18mm shuttering ply with top layer of 18 mm chipboard,ordinary diy quality. No problems with cold feet and the floor supports a 6 inch Colchester,and in the past has supported a 35 cwt turret mill. In cases with large long bed lathes ie 7.5 ch eg colchester triumph I would use in future 6 to 8 ins of reinforced concrete,and the lathe directly mounted on the concrete,as over a year the concrete will move depending on ground conditions ,my triumph was mounted on 4 ins on concrete over a 9 inches of crushed concrete and the movement in the ground conditions did affect the accuracy,it has now departed as I have got to old as a big lathe can be hard work.If I want my workshop warm I use a 3 kw fan heater,the walls and ceiling are insulated and windows are old double glazing

Thankyou for the link, these heaters are getting some good reports, will be getting one fitted and runner for next winter. Apparently there is quite alot of information on Utube, as usual.

With my new house build, the concrete floor minimum thickness was increased from 50mm for the rest of the house to 100mm for the workshop. I also increased the concrete to 30mpa instead of the std 25mpa, as the higher cement content makes for a slightly nicer finish on the floor as well. The poly styrene under the floor areas that goes down to the base, so makes a concrete rib that is 200mm deep in the workshop and 150mm deep for the rest of the house. The foam is specific for house construction, but I don't know what compressive strength was used. My driveway is cracking and is placed on sand and they did not reinforce it. Not happy about that. The cracks are now happening 2 years latter. It is also only around 75mm thick. Which I think is too thin for an un reinforced structure.