Electric underfloor heating in Greenhouse?

Alliumali

I'm trying to work out whether it would be more economical to install electrical underfloor heating in a single glazed lean too greenhouse or just to rely on plug in oil fired radiators. Greenhouse is 12 square metres and have been quoted £350 to install the heating but over a number of years (we plan to live there forevermore) I think the running costs might offset this. I would only really need to keep it frost free during the winter so could keep it on a low setting. Any ideas gratefully received!

Cardew

Alliumali wrote: »

I'm trying to work out whether it would be more economical to install electrical underfloor heating in a single glazed lean too greenhouse or just to rely on plug in oil fired radiators. Greenhouse is 12 square metres and have been quoted £350 to install the heating but over a number of years (we plan to live there forevermore) I think the running costs might offset this. I would only really need to keep it frost free during the winter so could keep it on a low setting. Any ideas gratefully received!

Live in a greenhouse forevermore! That is a bit drastic;)

Seriously, the cheapest electrical heater - costing about £20 - will cost EXACTLY the same amount to run - for the same heat output - as any other electrical heating.

This gives an idea of available heaters

http://www.greenhousepeople.co.uk/accessories/heaters/electric-heaters/

If you work on the principle that each 100watts output will cost about 1.2pence per hour to run.(asuming you are not on an Economy 7 tariff.

The more powerful heaters - say the 2kW fan heater - will have a thermostat so turned down to its lowest setting will be turning off and on.

sheffield_lad

Alliumali wrote: »

I'm trying to work out whether it would be more economical to install electrical underfloor heating in a single glazed lean too greenhouse or just to rely on plug in oil fired radiators. Greenhouse is 12 square metres and have been quoted £350 to install the heating but over a number of years (we plan to live there forevermore) I think the running costs might offset this. I would only really need to keep it frost free during the winter so could keep it on a low setting. Any ideas gratefully received!

Are you already heating the greenhouse? Seriously electric is a very expensive fuel to use and as greenhouses have zero insulation if you stick a convector heater with a stat on I doubt the stat would ever kick in meaning you could be running it 24hrs a day! = £6.72 (£201.60 a month),(depending on tariff).

Oil filled radiator with lowest possible setting (say 500w), 24hrs a day = £1.68 per day (£50 per month). Might be cheapest way to go but you need to realise how expensive this is going to be.

Richie-from-the-Boro

Alliumali wrote: »

I'm trying to work out whether it would be more economical to install electrical underfloor heating in a single glazed lean too greenhouse or just to rely on plug in oil fired radiators. Greenhouse is 12 square metres and have been quoted £350 to install the heating but over a number of years (we plan to live there forevermore) I think the running costs might offset this. I would only really need to keep it frost free during the winter so could keep it on a low setting. Any ideas gratefully received!

- either way, doing it without investing in insulation above as well as below will make it very costly
- using commercial or even domestic bubblewrap can save a fortune, and if your careful can last for years
- in fact ensuring is is 'bubbled' might be the very key to making your plan marginally economic in the first place

Alliumali

Many thanks for your replies. It is beginning to sound very expensive to heat it with electric. The greenhouse isn't built yet so I might ask for an alternative quote using double rather than single glazing. It is a lean to against the house so the house wall, which is south west facing will provide some insulation. I am a professional gardener so being able to keep the space frost free would really make a difference to the kind of plants I could grow.

LesU

Here are some numbers and ideas for you to consider. I have a larger but standalone aluminium greenhouse which is approx 21m2.
When I built it, I substituted the glass for twin skin polycarbonate sheets on the non-sun side and roof. I also put up large bubble insulation wrap inside during the winter months. We heat using a proper professional thermostatically controlled fan heater to maintain a minimum 6C during the winter.
I monitor the whole environment using data collection devices (well, I was an instrumentation engineer in another life!).
Last year over the period mid-Nov to mid-March we experienced several very cold snaps down to -4C and -6C on a few occasions. Average nighttime temperatures over the whole period was 1.7C.
We use economy 7 electricity and we are in the East of England.
Total heating bill for the period mentioned was £80. That will translate to about £95 this year with price increases coming through. Of course it may be warmer this year (not so far though!).
Remember this is for a standalone greenhouse twice the size of the one you are planning, but with some insulation.
It could be that you could go to a lower temperature, we keep it a little higher to keep some of our more fussy plants happy.

Richie-from-the-Boro

LesU wrote: »

Here are some numbers and ideas for you to consider. I have a larger but standalone aluminium greenhouse which is approx 21m2.
When I built it, I substituted the glass for twin skin polycarbonate sheets on the non-sun side and roof. I also put up large bubble insulation wrap inside during the winter months. We heat using a proper professional thermostatically controlled fan heater to maintain a minimum 6C during the winter.
I monitor the whole environment using data collection devices (well, I was an instrumentation engineer in another life!).
Last year over the period mid-Nov to mid-March we experienced several very cold snaps down to -4C and -6C on a few occasions. Average night-time temperatures over the whole period was 1.7C.
We use economy 7 electricity and we are in the East of England.
Total heating bill for the period mentioned was £80. That will translate to about £95 this year with price increases coming through. Of course it may be warmer this year (not so far though!).
Remember this is for a standalone greenhouse twice the size of the one you are planning, but with some insulation.
It could be that you could go to a lower temperature, we keep it a little higher to keep some of our more fussy plants happy.

In a lifetime of E7 usage, it never occurred to me, that's one more major E7 tariff only benefit @ 26p per day today's prices if electric is the chosen option. Congratulations.