Underfloor heating vs Electric Oil Radiator?

[rmwebs]

Hi all,

As you may have seen from my many threads with questions (Sorry!!) I'm building a garden office, by converting a log cabin (using celotex insulation, 50mm on walls, 100mm on floor/ceiling).

I'm trying to decide what route to take for heating.

Originally my options were underfloor, electric (oil filled?) radiator or a wood burner. I've ruled out the wood burner as its simply not practical. They take up too much room, and after getting the heating requirements back for my room at 1kw, the smallest log burner I can find is a 2kw output, which will be major overkill.

So I'm back to underfloor (electric) heating and oil-filled electric radiators.

Now, I've not got electric sorted out yet, I'm having an electrician round once the structure is in place, from what I understand the oil-filled radiators need a lot more power (e.g most are 2kw). The underfloor heating is 140w per square meter, and will be covering 8 square meters, so that comes in at 1.12kw - this is for one of the newer style underfloor heating systems that heats up in 3 minutes, not one of the old ones that takes an hour.

What would you go for, and why? I'm leaning towards underfloor as the biggest complaint people seem to have with garden offices is that the lower half of the building stays cold all the time, underfloor heating would obviously tackle this, but I dont know if it'll be powerful enough to warm the whole room.

The structure size is 12x8, however it'll have internal walls/insulation added so this size on the inside will be reduced a bit.

Many thanks!

 

[stem]

I would go with the underfloor (I'm assuming it's safe in a wooden building) It will prevent the cold feet problem you mention. Also you will probably feel comfortable at a lower room temperature because of this. I would then include a 2KW wall mounted convector heater. They are cheap to buy and often come with inbuilt timer & thermostat which you can use in very cold weather, or for a fast initial warm up when you need to use the building unexpectedly.

The only other way to be sure is to carry out calculations using data specifically related to your building and work out the energy required to reach and maintain a temperature and the time available for doing so. Whilst this can be done easily for brick built homes using online calculators, that ask if you have cavity or solid walls, whether or not they are insulated, how much glass there is and if it's double glazed or not etc., etc., It may be difficult to find this for a log cabin.

I don't know where you got the 1kw figure from, however, sometimes the figure quoted is the energy required to maintain an internal temperature of say 20 degrees when it is 0 degrees outside. This is different from the energy required to get it to 20 degrees from say 5 degrees in the first place. Also what if it's -10 degrees outside.

 

[big-all]

a 2kw wood burner will be useless a 2kw stove will only give out 2 kw maximum the likely average is going to be nearer 0.5-0.75kw
if i keep filling my 4kw stove it takes 40 mins to raise the temperature from around 6 to 16 degrees in my fairly well insulated shed thats 27 cubic metres

i also agree that an electric fan heater will be the most economic as you aim the warmth where you want it
underfloor is designed to be left on all the time so expensive

low wattage doesn't mean cheap to run it just means longer to do the same job and in this case less efficient as quick warm up rather than continuouse running will be required

 

[rmwebs]

Thanks for the help guys

Here's what I think I'll do. Once I've got everything done (e.g absoluely everything including decorating) I'll pick up a fan heater and oil-filled radiator. The oil-filled radiator can go on a timer and come on at around 1am on a frost-only setting (obviously if I really need it during the day I can click the timer to on). Then the fan heater can be used in the morning when I go in first thing just to warm the place up.

Once the room is occupied and the computer is running, it shouldn't loose much heat. I'm having 100mm celotex on the floor/ceiling and 50mm on the walls, and its got double glazing and a solid wood door with a pretty decent looking seal.

If this proves to not be enough in the depths of winter I can look at maybe a more beefy log burner as an option further down the line.

I think it'll just be a case of trial and error. I know I'll need an oil radiator either way just to have it on frost setting as I dont want the temperature dropping below zero.

Does this sound pretty reasonable?

 

[big-all]

Thanks for the help guys

Here's what I think I'll do. Once I've got everything done (e.g absoluely everything including decorating) I'll pick up a fan heater and oil-filled radiator. The oil-filled radiator can go on a timer and come on at around 1am on a frost-only setting (obviously if I really need it during the day I can click the timer to on). Then the fan heater can be used in the morning when I go in first thing just to warm the place up.

Once the room is occupied and the computer is running, it shouldn't loose much heat. I'm having 100mm celotex on the floor/ceiling and 50mm on the walls, and its got double glazing and a solid wood door with a pretty decent looking seal.

If this proves to not be enough in the depths of winter I can look at maybe a more beefy log burner as an option further down the line.

I think it'll just be a case of trial and error. I know I'll need an oil radiator either way just to have it on frost setting as I dont want the temperature dropping below zero.

Does this sound pretty reasonable?

an oil filled will of course have a delay but might be safer than a fan heater as in a faulty fan heater can catch fire but a oil fed should be safer for un attended heating i assume

 

[rmwebs]

an oil filled will of course have a delay but might be safer than a fan heater as in a faulty fan heater can catch fire but a oil fed should be safer for un attended heating i assume

Yeah that was my thinking too. I'm going to go with the oil-filled rad, one that I can set to come on at a certain time. If I find in the winter its way too cold, I'll get a log burner put in (wont do it myself, will get a professional in to make sure its done correctly).

I was told by a friend that they had a home office on display yesterday at the Chelsea flower show and that it was using a cool little log burner. He wrote down the name so I'll have to take a look, apparently they install them and do safety checkes. At least thats an option if the oil-rad really cant do the job. Wood for it should be pretty easy to come by too as we've got a bridal path running down the side of our house, lined with 50+ year old trees which are regularly trimmed back, leaving lots of thick logs at the side for anyone to take.

 

[stem]

Oil Radiators are good but very slow. I've got one of these in my conseravtory, it comprises a 2KW convector and a 1KW fan heater that can each can be used on their own, or together to give 3KW.

Untitled

• stem
• 24 May 2012
• 1

With both on, you can feel the heat in seconds and from being unheated in sub zero temperatures, the conservatory (3m x 3.5m) will be warm enough to sit comfortably in about 15 minutes. It also has a useful built in thermostat and time switch. I took the option to take the legs off and wall mount it. Complete flexibility for about £40. The version without the time switch is about £10 less.

If a fast warm up is not an issue, an oil radiator will be fine. The time lag at start up is reversed when you switch it off, it will take a while to cool.