Greenhouse frost protection

[ash_s3]

I have a customer who would like their new greenhouse to have some degree of frost protection.

In previous years they have used a plug in fan heater hung from the ceiling with an extension lead from the house! I told them I can come up with something better than that...
Starting with a new SWA supply being taken into the greenhouse.

Initially I thought of a tubular heater, with built in thermostat, atleast they're splash proof so should be safe around a watering can. The wattages of tubular heaters seem pretty low (4ft around 160w), will they be enough to keep the frost off? Has anyone used anything similar?

Cheers

 

[Leesparkykent]

A fan heater would probably be better as it distributes the heat better and should prevent cold spots within the green house.

 

[Andy78]

I have a customer who would like their new greenhouse to have some degree of frost protection.

In previous years they have used a plug in fan heater hung from the ceiling with an extension lead from the house! I told them I can come up with something better than that...
Starting with a new SWA supply being taken into the greenhouse.

Initially I thought of a tubular heater, with built in thermostat, atleast they're splash proof so should be safe around a watering can. The wattages of tubular heaters seem pretty low (4ft around 160w), will they be enough to keep the frost off? Has anyone used anything similar?

Cheers

Tubular heaters work very well in small areas coupled with a frost stat. No idea how well they would work in a greenhouse though. They would be my first thought too due to, as you say, the robust construction and low wattage. I would say they would be sufficient to keep the frost off, but not "heat" the greenhouse as such.

 

[ash_s3]

Thanks chaps, the dimplex website suggests them for use in greenhouses.

Not looking to heat the greenhouse, but just take the chill off to keep it above freezing when it's very cold.

 

[Dave OCD]

I've used them on several occasions in greenhouses and they work fine, as Andy said just wire it through a frost stat [set to around 5 degrees I'd say]. Generally tubular heaters are rated at 60w per foot so a 3 foot one would probably be ok assuming the greenhouse isn't huge.

 

[ash_s3]

Cheers Dave, it's 10ft x 6ft so a pretty normal sized greenhouse.

Did you mount them on the floor? As the frame of the greenhouse is pretty thin

 

[davesparks]

Garden centres used to sell clips, a bit like caddy clips, which go onto the greenhouse framework and allow you to fix lightweight things.

The problem with heating a greenhouse is that there is nothing to stop the heat escaping, it pretty much all escapes into the atmosphere.

 

[Marvo]

A tube type heater will be convective only so you're going to have to mount it at low level for it to be most effective. Obviously this will leave it likely to get wet and dirty so I'd suggest finding one that the manufacturers say is fit for purpose.

 

[Dave OCD]

Cheers Dave, it's 10ft x 6ft so a pretty normal sized greenhouse.

Did you mount them on the floor? As the frame of the greenhouse is pretty thin

Yes I mounted them on the concrete floor [under benches] but also fitted wire guards as that protects them from falling bits and pieces and stray hands as they do get a bit hot to touch.

 

[ash_s3]

Cheers Dave, how many did you use?

 

[telectrix]

paraffin heaters. they give the tomatoes such a lovely flavour.

 

[ash_s3]

You'll do me out of a job Tel!

 

[Guest77]

A fan heater would probably be better as it distributes the heat better and should prevent cold spots within the green house.

Well if you are a millionaire yes, other wise for us normal folk a tubular heater the answer pmsl.

 

[Dave OCD]

Cheers Dave, how many did you use?

Sorry mate just seen your post, I used 2 x 3 foot heaters and the last greenhouse was roughly the size you mentioned, maybe a touch smaller. In my case I put a short piece of duct from one side to the other [and another duct for the supply cable] before the concrete base was laid.