making a heat mat?

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This section is for discussion on all methods of plant propagation
miketropic

Re: making a heat mat?

Post by miketropic » Fri Oct 19, 2012 1:12 am

came home from work and had a hot box on my hands so I turned the pad off for awhile. I am going to get a timer after work today to set the mat on so Im not cooking seedlings.. any suggestions on time? a 20 on 20 off sounds good to me but I don't have alot of experience with the propagators.

charliepridham

Re: making a heat mat?

Post by charliepridham » Fri Oct 19, 2012 7:50 am

You are better off with a themostat, decent ones can be quite expensive but I guess it saves money as well as making germination easier!

Kristen

Re: making a heat mat?

Post by Kristen » Fri Oct 19, 2012 11:42 am

charliepridham wrote:You are better off with a themostat, decent ones can be quite expensive but I guess it saves money as well as making germination easier!
Definitely saves money IME. A cheap thermostat (well, a low quality one) will overrun the "off" temperature by several degrees, so will have a 5C or even 10C range between On & Off. Costs a lot of extra money to over-heat by that amount, so a quality thermostat with narrow temperature band hysteresis will save money (quality thermostat is not, usually, cheap though ... so can be a balancing act).

Best type of thermostat for a heating pad might be a short "rod" sensor that you can put into a flower-pot of compost similar to that in the other pots on the mat?, then you can tune the temperature based on soil temperature, rather than air or surface-of-mat.

It ought to be possible to get a solid-state thermal sensor that will do this, and they are cheap-as-chips. I bought 50 or so of them to monitor a heating system and just daisy-chained them together (this was a 1-Wire sensor system). They recorded to comfortably more accurate than 0.5C, probably actually accurate to something like 0.1C, but I haven't seen cheap thermostats based on them, more normally its the rod type, or the coil ones (but they are a bit fragile for something that will be packaged up and "put away" for months at a time).

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