After several of the cheapest I could find and after the human heating pads had to be made with regulations requiring they shut off after an hour or two, went with a heat mat that had a thermostat. More expensive but it has lasted four years so far where the cheap-os lasted a max of two before just quitting.

The very best solution was a heating pad made for the waterbed my boys had in the 90s. It has a thermostat but can get so hot it melts the plastic seed trays so care must be taken. It is the heater for my peppers. So long as there is a wooden spacer a couple inches thick it is perfect and is fifteen years in use as a plant mat and counting.

[QUOTE=PaulF;722016]After several of the cheapest I could find and after the human heating pads had to be made with regulations requiring they shut off after an hour or two, went with a heat mat that had a thermostat. More expensive but it has lasted four years so far where the cheap-os lasted a max of two before just quitting.

The very best solution was a heating pad made for the waterbed my boys had in the 90s. It has a thermostat but can get so hot it melts the plastic seed trays so care must be taken. It is the heater for my peppers. So long as there is a wooden spacer a couple inches thick it is perfect and is fifteen years in use as a plant mat and counting.[/QUOTE]


I suppose a person could chop out the safety shut off rheostat and put in a regular rheostat.
But without calculations you would end up burning the house down.
Calculations by meaning get one that wont go up to full power like a light dimmer.

A rheostat is a variable resistor use to control higher currant/power than a potentiometer.

[SIZE=3][FONT=Garamond][B]I use an old heating pad from the '60s... it doesn't shut off automatically and it was already sitting unused in the closet.
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[SIZE=3][FONT=Garamond][B]The only issue is the lowest temperature is too hot to be used without some sort of a barrier between the pad and the seeds. I just put a few towels on top of it, monitor the temperature with my Thermopen (instant read cooking thermometer), and adjust the amount of towels as necessary.[/B][/FONT][/SIZE]
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:lol:

I use lights for heat. Even CFLs put off a decent amount of heat if you have enough of them in a small space.

Just go to the greenhouse megastar and look up PR-HMC commercial propagation mat,they are the best,they last for many years,and give even all across the mat. They come in 3 different sizes.please don't waste your time dinking around with unsafe alternatives, it's not worth it!

Megastore,arg!

I knew someone who buried a waterbed heater in a few inches of sand on top of a greenhouse bench. It worked well.

I've been using a couple of Root Radiance heat mats (10''x20.75''), that I bought from Amazon, and they have worked well for several years. They're just the right size for a single flat, and are moderately priced.
Initially I didn't use a thermostat, but the starter mix was getting up over 90F.
Once I put a thermostat on them, and set to 80F, the germination rates of my finicky pepper seeds improved greatly. The down side is the cost of the thermostats (about $35).

[QUOTE=biscuitridge;722104]Just go to the greenhouse megastar and look up PR-HMC commercial propagation mat,they are the best,they last for many years,and give even all across the mat. They come in 3 different sizes.please don't waste your time dinking around with unsafe alternatives, it's not worth it![/QUOTE]

Good advice...I’ve been looking at those.

[QUOTE=mike5953;722125]I've been using a couple of Root Radiance heat mats (10''x20.75''), that I bought from Amazon, and they have worked well for several years. They're just the right size for a single flat, and are moderately priced.
Initially I didn't use a thermostat, but the starter mix was getting up over 90F.
Once I put a thermostat on them, and set to 80F, the germination rates of my finicky pepper seeds improved greatly. The down side is the cost of the thermostats (about $35).[/QUOTE]

Thanks for that ... I certainly don’t want to cook the pepper seeds I just received from Vertiloom in Belgium.

[QUOTE=GrowingCoastal;722109]I knew someone who buried a waterbed heater in a few inches of sand on top of a greenhouse bench. It worked well.[/QUOTE]

Wow. Now there’s a re-use recycle kind of person.

I just use the common/inexpensive 10 x 20 inch ones, but I put a 1 x 2 foot floor tile between it and the seed tray to diffuse the heat, and then plug it in to the light timer, so it goes off at night in synch with the lights. This seems to ameliorate the overheating issue and I typically get north of 90% germination.

[QUOTE=Koala Doug;722087][SIZE=3][FONT=Garamond][B]I use an old heating pad from the '60s... it doesn't shut off automatically and it was already sitting unused in the closet.
[/B][/FONT][/SIZE]
[SIZE=3][FONT=Garamond][/FONT][/SIZE]
[SIZE=3][FONT=Garamond][B]The only issue is the lowest temperature is too hot to be used without some sort of a barrier between the pad and the seeds. I just put a few towels on top of it, monitor the temperature with my Thermopen (instant read cooking thermometer), and adjust the amount of towels as necessary.[/B][/FONT][/SIZE]
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:lol:[/QUOTE]

That was my first thought, but when I went scrounging for an older heating pad I realized we must have gotten rid of them in one of the moves. Dang!

[QUOTE=Cole_Robbie;722088]I use lights for heat. Even CFLs put off a decent amount of heat if you have enough of them in a small space.[/QUOTE]

So you don’t bother with bottom heat for things like peppers?

[QUOTE=Canehdian;722131]I just use the common/inexpensive 10 x 20 inch ones, but I put a 1 x 2 foot floor tile between it and the seed tray to diffuse the heat, and then plug it in to the light timer, so it goes off at night in synch with the lights. This seems to ameliorate the overheating issue and I typically get north of 90% germination.[/QUOTE]

Now that’s a good idea - plugging the heat into the light timer. I would have left the heat on constantly.
And the tile diffuser ... I’m sure we have tile kicking around the garage.
Thanks!