Gas greenhouse heaters

Intresting thread, never thought of using an independant thermostat switch, and agree that ones in the heaters are poor.

 

"... independant thermostat switch ..."

... plus you can put it where the plants are, which may be different to the zone close to the heater itself.

 

Hi Pete
Thats a bit of a problem.. it wont be a lot of use to mobile pots unless you use sand perhaps so you could bury them
Winter veg should grow ok with the short daylength especially with some extra bottom heat.

 

Bob, if the pots are in a greenhouse, I think it would be simpler and more effective to bubblewrap the inside of the greenhouse rather than individual pots.

However if the pots are outside, there could be an arguement for bubble wrapping the pot, but it would be a lot of work. It is true that a plant that is perfectly hardy in the ground may be less hardy in a pot, as the cold can encroach in on the roots from all sides. I would certainly push outside pots together for mutual protection. But the best thing is probably to put them next to the house. The house will always give off a small amount of heat, and they will get the benefit of not getting so wet sheltering under the eaves. Winter wet can be just as much a killer as winter cold.

 

Peter, I have brought an electric meter (guage thingie) from Maplins.
I have plugged it into my heater and it says that my heater is using 11.89kw/h
My electric price is 8.85p per KW/h so does that then mean that it is costing me 97.35 p per hour to run my heater?

I only ask as I am a little confused with the meter and want to make sure I am working it out correctly! lol.

 

Doesn't sound right. 11.89kW would melt the cable! A 3kW fan heater is (I think) the maximum you can put on a 13Amp socket. So I reckon if you had an 11kW device that would need some special, heavy duty, cable. (If I've calculated it correct 11 kW at 240 volts = 45 Amps!)

 

To get a reading like that you`d have to be measuring a shower or an electric cooker :wink:
Maybe the decimal is in the wrong place or perhaps its reading (totting up) the total power usage over several hours?

 

After putting up my post, I thought to myself, surly that cant be right so I revisited the instructions and the unit to see if I could make any more sense from it. From what I can see, (The instructions are not clear at all!) is that the KWH button is a dual button which also tells you how many hours the unit has been running so therefore, I deduce that the KWH figure needs to be divided by the hour figure to give you the actual KWH per Hour.

I'll have a play with it later and see what I come up with but if anyone uses the Maplins meter and has a better idea than me, please share.

 

"is that the KWH button is a dual button which also tells you how many hours the unit has been running so therefore, I deduce that the KWH figure needs to be divided by the hour figure to give you the actual KWH per Hour"

Errmmm ... not quite, you are mixing your units a bit! I'm not sure I can accurately describe it, but I'll have a go, no doubt someone will be along shortly to correct me if I get it wrong.

A device will be rated at X kW. That's the maximum - and if it is not adjustable it will run at that power. If you run it, flat out, for one hour it will use X kWh. If you run it flat out for two hours it will use 2X kWh.

If it is on a thermostat, or it is adjustable and you turn it down, and you run it for several hours, and measure it with your meter, then it will use Y kWh. If you have run it for, say, 5 hours then it will have used Y/5 kW per hour on average.

So I'm afraid all that will tell you is that for the 5 hours that you ran it (i.e. in Autumn) it used Y kWh. In Winter it is going to use more, because it will be colder.

However, it is correct to say that for the 5 hours (say) it used 11.89kWh, and if your electricity is 8.85p per KW/h then it cost 97.35 p for the 5 hours - i.e. 19.45 p / hour (again, for Autumn temperatures)

 

Thanks Kristen,
I know that it will only give me an average but that's fine, it's all I'm after really just to give me an idea of what it costs. I could run it for an hour flat out and see the difference this makes but that is for a later time.

OK. so, so far the meter has been running for 92 hours and the KWH figure was 20.92
So if I divide 20.92 by 92 it gives me an aveage of .2273913. If I then multiply this figure by 8.85p this gives me a figure of 2p an hour to run (average)
If I then multiply that by 24 (hours) makes it 48p a day. Multiply that by 365 (days in the year) = £176 a year to run!

That seems like an awful lot. Ok, I know the heater is not going to be running the same in summer as in winter but I am just trying to get my head around working this meter thing out as I want to use it on other things that do work all year.

So, could someone please look at my math above and let me know if I have done it right and if the heater was running the same all year would that infact mean that it would cost £175 a year to run or have I got a decimal in the wrong place somewhere! lol

 

I reckon you will run it Nov through March and Dec through February will need more than Nov and Mar. You won't need much during the day, most days.

Your average of 0.22 kW per hour is pretty low - by comparison with a standard fan heater which has three settings for 1kW, 2kW and 3kW - so I reckon it was off far more than it was on.

I reckon you will use maybe 4 times as much during Dec - Feb.

So lets say

Nov + Mar = 61 days * 24 hours * 0.22kw
Dec - Feb = 90 days * 24 hours * 0.22kw * 4 times as much

that's about 2,200 kWh which at 8.85p = £190

If its only twice as much, not 4 x as much, during Dec - Feb then that would reduce to about £110