Heaters, what's best and at what watts?

[daemondamian]

Hi folks,
ok so I've finally moved all my orchids into their winter/spring home, a lean-to / attached GH that is roughly 2metres wide, 4 metres long and 2 metres high [it actually varies as the roof slopes down].

I can't believe how dark I was keeping my orchids before but anyway what I'm trying figure out now is what would be the best type of heater to get and at what wattage?

I would like to heat it to about a minimum of 14 degrees celcius - intermediate sort of as I have many masdevallias, plus draculas, pleurothallis etc as well as some vandas, an aerides, arachnis, cattleyas and many things in between miltonia, brassia, oncidium, etc].

I haven't checked after lights out or before dawn but I currently have a 150 watt metal halide light and two 48 watt compact fluros that start at 6am and go to 12am [is that too long?] which extend the light duration and provide some warmth.

I have put up bubble wrap across the ceiling, sealed all gaps with it, and plan on bubble wrapping the other walls and sealing any other gaps with expanding foam.

There is also a 3ft fishtank on the [cement] floor under one of the shelves and several milk containers filled with water to act as solar heat banks and release the heat back at night.

I am wondering if I buy a high wattage heater [say 1000-2500 watts] if it could be damaged in that it will come on more frequently but for shorter periods of time compared to a lower wattage heater that would stay on more often and for longer periods of time?

I have read too that ceramic heaters are good so I was thinking of perhaps a Sunbeam model like Sunbeam >> Micro Furnace >> MF2000
which are small in size and will fit on the shelf at the end of the GH with the fan where I can keep it dry.

Any thoughts reccommendations are welcome Also maybe important is I live in Australia so I may not be able to purchase brands that are available elsewhere in the world and I would prefer not to purchase from a company that is not in Australia.
Thanks

[Gin]

I wish I could be of more help , I use propane in my greenhouse , on the enclosed porch an oil filled heater . Just guessing I would go for a larger size heater rather than 2 smaller ..Sounds like the lights are on for a long time when mine were under artificial light they were on for the normal day length , some are day length sensitive I had Catts. try and bloom on inmature growths when exposed to extended day light .. here is a link I am celcius /metric challenged must be more like me Gin

Conversions, Equivalent Measures, Metric Conversion Table

[Ross]

Not sure what the cost to you per Kilawatt Hour is, but electric may be very expensive. It is here for me. Anything you can do to reduce the escape of heat will be to your economic advantage.

14 degrees C shouldn't be that hard to achieve, and should make lots of orchids very happy if you get to that temp.

As for length of "daylight" with lights, I think you should vary the length based on length of natuarl daylight. I use 10 hours during our winter (this would be your spring) and get up to 16 hours during our summer.

Not sure on heater, but suspect you are underestimating your needs. No you won't damage heater with short cycles. I'd be surprised if cycles are as short as you think, though.

There are some folks here in U.S. that use milk jugs and other containers, painted black and filled with water to hold in the heat of the sunlight. I think this is an excellent idea and I would recommend following this line of reasoning. Even 55 gallon drums (oil drums) filled with water, but painted black, would be excellent heat sinks.

Ceramic heaters aren't really cheaper to run than others. They may be smaller, but still consume watts equiv. to other types. I have tried lots of types and all of them are expensive to run. My recommendations are as follows:

If you have lots of winter sun - install water drums painted black to absorb sunlight and heat the water. These need to be behind the plants, but in the same space.

Use lots of insulation. There are many products that use double wall plastic glazing meant for greenhouses that should be avaialable in your part of the world.

Use dark colored paving for the floor of the greenhouse to absorb the sun and re-radiate later at night.

Try using straw matts (say 2-3 cm thick) to throw over the top of the greenhouse glazing at night. There used to be a company (I can't find reference now) that made a double wall glazing product that used styrofoam beads blown in at night on a timer. That would be the ultimate, in my estimation. Good luck and let us know what you end up with.

[daemondamian]

Originally Posted by Gin

I wish I could be of more help , I use propane in my greenhouse , on the enclosed porch an oil filled heater . Just guessing I would go for a larger size heater rather than 2 smaller ..Sounds like the lights are on for a long time when mine were under artificial light they were on for the normal day length , some are day length sensitive I had Catts. try and bloom on inmature growths when exposed to extended day light .. here is a link I am celcius /metric challenged must be more like me Gin

Conversions, Equivalent Measures, Metric Conversion Table

Thanks Gin, for your reply

I ended up getting a 1000 watt heater rather than a 500W heater.

It is getting dark- night time here at 5pm now..I will look into changing the light duration, for some reason the timers I'm using turn on in the morning but are always slow a few hours so I 've been going out at midnight and turning around past the 12am mark so they will turn off. It is actually kind of annoying

[daemondamian]

Hi Ross, thanks for your reply
the main west facing wall I left alone - it is old corrugated fibreglass that really needs replacing. I'm thinking of replacing it with polyflute which is a doubleskinned acrylic plastic [I think] with a corrugated sheet in the middle [like corrugated cardboard essentially] that would have better insulating properties not to mention would let in more light [the fibreglass is very old].

I'm not sure of the exact sunrise but it is getting dark here at 5pm so I should probably reduce the duration

Do you think it really would make a difference painting the milk bottles black? What about putting in an aquarium heater in the fishtank set on full? I'm hesitant to do that because it will cause lots of condensation.

I guess I am lucky though with a winter average of 8 degrees celcius and the occasional frosts, no freezing ground or snow storms to contend with ...

Will have to wait and see how I go with the 1000watt oil filled heater I ended up getting [I need to get a thermostat to set it at a minimum temperature other wise it's guessing and a whole lot of frequent adjusting ], will sure let you know how it goes! thanks again