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Post by ladybird on Feb 10, 2014 20:18:50 GMT
What width of table are we talking about? well I have a choise of two tables. The smaller one is 127cm X 73cm ( roughly 4 ft X 2 1/2 ft ) and the bigger one is 203cm X 73cm ( roughly 6ft 8" X 2 1/2 ft) |
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Post by daitheplant on Feb 10, 2014 20:34:22 GMT
To cover the largest table, you will need 76ft 9inches plus a little more of cable. Not sure of the cost, but just remember, by using a thermostat, YOU control the cost.
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Post by ladybird on Feb 11, 2014 3:13:30 GMT
Thanks daitheplant so I figure the 24 meter one would do the job for the larger table. If I thought the cost to run would be a lot I would op for a smaller bench with a 12 meter cable with a thermostat .
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Post by ladybird on Feb 11, 2014 13:11:47 GMT
I did a bit of digging on the net and am wondering if I have this right about soil cable heating costs.
1KW of electric costs roughly 15p . Therefor a 100 watt light bulb can burn for 10 hours for 15p.
So a 150 watt soil warming cable ( 12 meters) running at full continuous over 24 hours would be a daily total of 3600 watts ( or 3.6KW ) costing 51p daily or £3.57 a week.
so a 300 watt soil warming cable ( 24 meters)would be double that 7200 watts (7.2 KW )costing £1.02p daily or £7.14 a week
I am assuming the heat can be further reduced via a thermostat.
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Post by daitheplant on Feb 11, 2014 20:16:34 GMT
You don`t want the table hot, just warm. To reduce cost and conserve heat either use propagator lids, or build a polythene "lid" for the bed.
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Post by scrumpy on Feb 12, 2014 11:22:05 GMT
I wouldn't bother with cables but go for an aluminium heat mat with thedrmostat. They are much easier to control and can be removed at the end of the season.
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Post by scrumpy on Feb 12, 2014 11:32:12 GMT
If you want cables I'd recommend a frame at ground level in your greenhouse as they can get very heavy.  |
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Post by ladybird on Feb 12, 2014 13:17:04 GMT
If you want cables I'd recommend a frame at ground level in your greenhouse as they can get very heavy. the mats are more expensive scrumpy but the fact that they can be removed and replaces easily is a bonus and I may rethink that if I make two beds . I can`t have the propagater on the ground , its really cold there but there seems to be a lot of water lying as well after it rains , I havn`t figured why get as the GH is built on the highest past of the garden . I do realize diatheplant that not a lot of heat is needed I have been trying to estimate that the lowest heat on a larger cable isn`t too hot but that the highest heat on a smaller cable is warm enough . I was amazed how warm my previous heated propagater was (a coldframe on the table with just a small paraffin heater ) I have two 4ft long table on either side at the back of the greenhouse and two 6ft table either side at the front of the greenhouse. I now have four options to consider: 1. make one 4 ft bed with a 12 ft cable 2. make two 4ft beds with two cables 3. shuffle the tables and make one 6ft 8" table with a 24 meter cable 4. a new idea ,my Gh is 8Ft wide i could make a long 8ft table running accross the back of the GH , (though there is little support in the middle at the moment ) sorry for going on and on about the details but I`d like to get it right . I have have already sent off for a thermostat a 3 amp one that will do either the 12 or 24 meter cable I see the 6 amp thermostat is for a higher wattage cable. |
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Post by ladybird on Feb 12, 2014 13:28:18 GMT
Thanks for posting your picture as well scrumpy I remember seeing that before great job, giving me more ideas  |
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Post by Tel on Feb 12, 2014 13:38:13 GMT
My bench has a heat mat, it is now 16 years old. I cover it with polythene and fasten it round the edge. Then I do not have to remove the heat mat when I have finished taking cuttings etc.  |
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Post by ladybird on Feb 12, 2014 13:50:28 GMT
My bench has a heat mat, it is now 16 years old. I cover it with polythene and fasten it round the edge. Then I do not have to remove the heat mat when I have finished taking cuttings etc. That has been a good investment tell seems to be a very large on too . No mess no weight . scrumpy suggested the same . I will have a look at the cost of one of those, thanks Tel |
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Post by scrumpy on Feb 13, 2014 12:19:59 GMT
I got mine direct from the manufacturer linkThey can actually make them to any size you want, and it shows the wattages. As to thermostats, you can get them cheaper than the one they advertise. |
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Post by ladybird on Feb 13, 2014 13:23:03 GMT
Thanks for the link scrumpy, 5 meters X 1/2 meter at £169 seems a really good price though the thermostat will be extra. I think for now I`ll stick with the soil warming cables as I am looking forward to the DIY bit and I could get a bigger area heated for less . The mat would be a useful extra especially in spring so I know what to ask for the next presys coming my way. Because of my dithering I have missed out on a good price for a 24 meter cable  it seems better value than a 12 meter . |
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Post by ladybird on Feb 21, 2014 18:50:13 GMT
Ihave now purchased 40 meter cable and thermostat at a resonable price . I see both of the items have a plug, just wondering, I presume I have to remove they plug of the soil cable , thread it through a hole in the box i`ll be making and attach it to the other hole in the thermostat ? the instructions from parasene are dreadful. Another question, in the instructions it says to use only horticultural sharp sand  that will be a bit pricy to fill an 8` X 3` table at £5 98 for 25 kg. I have seen a comment on the net that builders sand cakes like cement in heated benches , is builders sand the same as builders sharp sand ? I`m really confused here . |
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Post by caretaker on Feb 21, 2014 22:27:18 GMT
Just been talking to my brother in law who dose cactus plants, he said he uses heating cable with a thermostat but NO sand, he lays the cable on a sheet of metal and has small wood blocks in-be-tween and then a second metal sheet on top, then his seed plants, he said he has done this for over 5 years.
Now I have been in his greenhouse and he heats the house all through the winter "he must have loads of money".
I have had my 4x2 bench going now for 2 to 3 week and have not noticed if I'm using much more electric but have only set the temp to 10c.
I have only 1 or 2 bits in there so far as it is to cold for me let alone seeds.
I see we was on the tv news as there was 50 homes evacuated last week end with the floods, only 2 miles away, sorry went of track there.
Reg
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it seems better value than a 12 meter .
that will be a bit pricy to fill an 8` X 3` table at £5 98 for 25 kg. I have seen a comment on the net that builders sand cakes like cement in heated benches , is builders sand the same as builders sharp sand ? I`m really confused here . 
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