Propane heaters - a good idea??

[annew]

I'm thinking of buying one of these for a new greenhouse to keep it frost free:
http://www.twowests.co.uk/product/lifestyle-eden-propane-gas-heater
Has anyone any experience of using one of these in an alpine/ bulb house? I'm a little concerned about possible condensation problems. Thank you.

[johnw]

Anne  - My old propane furnace required a chimney but after a few years I disconnected it and let it vent into the greenhouse. I did have to run a dehumidifier which cost more to run than the heat saved.  The new ones vent directly out the wall with no chimney so condensation is not much of an issuee.  Mine must be 20 odd years old now & still works fine. A replacement here is $700-$1000 which is shockingly pricey.  Just get yourself a good thermostat that goes as low as 3-5c.

johnw

[Anthony Darby]

I used a propane heater at the start. The first time I switched it on all the flowers on my Hoya dropped off.

[annew]

Ouch!

[annew]

The one I'm looking at doesn't vent to the outside.

[Martinr]

Burning any gas heater which isn't 'chimney'ed' (is that a word) to outside will create a significant amount of water which will condense on the glass. OK if you have no threat of fungal diseases but otherwise 

Any way you can get an electricity supply to the greenhouse?

[johnw]

Anne - True, when mine was unvented I could never see through the glass in winter.  The de-humidifier worked well to alleviate that until the temp got around 5c and then the coils would ice up and the glass condensation return.  Then I would have to spray for botrytis every 3-4 weeks.

Have you looked into one with a direct vent?  t would save a lot of headaches aside form the wallet one.

Here's arather cheap one with pic of simple venting.

http://www.northerntool.com/shop/tools/product_200362081_200362081

johnw - +19c & brilliant blue skies.

[Yann]

Anne if you use gas heater inside of greenhouse or coldframe you'll have more water which will condense on the glass panes.
Last winter changing my main greenhouse i had to use a gas heater 1 week, humidity was almost around 95% during nights.

For 10 years I used  an electric fan heater like this one

it's made in Poland, it has strong metal armature, doesn't fear water projections, you can buy it in a 2KW-12KW range. Price is cheap compared to other electric heaters dedicated to greenhouse.

If use a 3Kw for 20m²

In the 90's i used a HeatBox, usefull if you want to fix it on the edge of the greenhouse. I'm tall and every weeks i knocked my head in it 

[annew]

I have power down to 2 of my 4 greenhouses (they all have electric fan heaters) but it will only take a 4kw load, enough for 2 of the heaters so I have to run an extension lead from the house out to the third . I was hoping to avoid having a second cable to trip over!

[annew]

Thank you to everyone for helping out with advice, by the way 

[LucS]

I use an air-heater with petrol switched on/off with a thermostat a few meter away from the heater.
This works perfectly for me and is in use a lot cheaper than electric fans. Further the temperature in the greenhouse is more even than with a fan.
Of course you have to invest some 350€ for a heater of 25 kW at first.

[brianw]

I don't know your setup Anne but do you need 2kw for each greenhouse for "frost free"? Would smaller heaters be sufficient and allow you to use the current  wiring? I use a 2kw heater to keep an 8'x8' at 7C min, although I do now use partial double glazing to save money.

[johnw]

I'd use electric as a back-up but never as primary source.  They work well indeed but only when there's electricity and electricity has a nasty habit of failing during winter storms and ice.  Then what?

johnw

[Martinr]

True John but our climate is a little less extreme and power cuts are more likely to due to metal thieves at substations or builders cutting lines with mechanical diggers. The big advantage with electric heaters and thermostatic control is that they are, in our climate, just about fit and forget........till the bill comes in

[johnw]

Martin - We too have the copper thieves.  Yes the bill is killer even for our 7x10ft lean to.  A tank of propane is about £400 and luckily we got away with one tank for the entire season and the same the year before.  In the past we've had to be reilled in early March, only needing 1/10 of it until frost free.  If I had the ambition I'd dig a trench from the house to the greenhouse to hook onto natural gas but that would require a new stove and a good long run of copper pipe.

johnw