Options for adding heat into a tent

[Cajafiesta]

Can anyone make some suggestions for adding heat into a tent?  I hear talk of "tube heaters" but I'm not familiar.  I'm in the states, so some items may be unavailable/unfamiliar to me.

 

 

I need to chuck another couple of degrees into the tent and using the house HVAC to accomplish it certainly isn't the most frugal option.  I've played with the extraction fan to hopefully gain some heat without impacting my C02 levels, but I'm not sure I'm going to be able to get the temp increase I want through that method.

 

 

Anyone have suggestion for heating options?  I'm a fair bit paranoid about a typical "Space heater" sort of idea.  They have a habit of burning houses down.  Ideally, I'd like to have a solution that only chucks out heat that's a couple degrees hotter than the ambient environment in the tent.  My logic says this will reduce the risk of creating extreme hot spots in the tent as well as reducing the risk of ignition inside the tent causing a fire. 

 

I have a heating mat in the tent currently that was intended to raise root temps.  It's also raised ambient temps slightly, which makes sense.  I wonder if the solution could be as simple as hanging a heating mat on one of the walls and letting that warm the environment through radiant heat?

 

 

Anyone have thoughts?

 

Thanks!

 

[Oldbear]

Have a look at greenhouse heating. There are various options. Or underfloor heating, build a thin laminate floor inside the tent / space and heat the space. Just a thought 

[Cajafiesta]

@Oldbear  False floor.  Huh.  That's not a crazy idea.  I hadn't thought of that.  That would, likely, make an excellent solution to even heat dissipation while also warming the roots.  A thin plywood floor with "Feet" to act as stand-offs.  Maybe a 1in (2.5cm) air gap between the tent floor and the bottom of the false floor, with a heating mat living in the air space between the tent floor and false floor.

 

Shit man.  That's a good idea!

 

 

 

Thanks for the clever input!

[Cajafiesta]

It occurs to me, just now, that even changing the material of the proposed false floor would likely impact the movement of temp/rh in the tent. 

 

I have to assume a floor made of sheet aluminum would warm the pots and tent more aggressively than using an insulating material like wood or polycarbonate for the floor. 

 

 

It seems like this could even be a "tune-able" setup if you paid a lot of attention.  hmmmm.  

[Oldbear]

@Cajafiesta

Forgot to mention, get decent insulation boards (cheap ish but really useful) to line the floor before putting in the heating 

Edited November 27, 2021 by Oldbear

[Oldbear]

I'd go for thin wood, gentle and even

[Cajafiesta]

@Oldbear agreed on the wood. Just waxing poetic, so to speak, about other materials’ potential. 
 

 

I think I may be able to get away without insulating material on the floor. The tent floor sits against carpet that has substantial padding under it. Probably over 1” (2.5cm) below the tent before you hit wood sub flooring. Although more insulation is rarely a bad thing. Foam boards are cheap enough. 
 

thanks!

[Oldbear]

Just now, Cajafiesta said:

Although more insulation is rarely a bad thing. Foam boards are cheap enough. 

At the very least it reduces risk and heating costs 

[Head Rose'n'Tail]

+1 for the underfloor heating @Oldbear , put the thin insulation sheets down first (felt like sheets roughly 450mm X 750mm), lay the underfloor heating mesh on top of that, then the thinnest piece of laminate available (8-10mm) as the base for your plants to sit on, brings heat into you tent/area and keeps the roots warm.

[growinggold]

 

+1 for tube heaters, you can see there. I mount them incase I get tropf blumat water leak. I also have heat mate below the garland tray.    Is this is in a insulated space within a 28mm tougue groove shed.  

 

[Dodgee]

My memory of thermodynamics probably not great but from what little I remember I would guess that you wouldn't want heat mat>air gap>floor as that will drastically reduce the efficiency of the heat mat and cost you more in running costs ultimately. 

 

Ideally I think you're better off with air gap>light insulation>heat mat>floor material. 

 

*I think* 

 

Iirc air has a sort of insulating quality as heat won't pass through it as readily as it would a solid material. 

 

Cavity wall insulation is a modern invention and historically it was the cavity itself that was the insulator, stopping or at least reducing heat transfer to the external wall and vice versa. Same principle. 

 

Your heat mats upper surface should be in direct contact with your flooring material in order to ensure the most efficient level of heat transfer.  

 

I'm 90% sure the above is correct but there's always a chance dodgeez misremembered summat so worth double checking yourself

 

Hopefully it help and I haven't just hindered

 

[KingAether]

I second the underfloor heating; i have a thermostat running a 1m ²  underfloor heating mat sandwiched between a thin foam insulation board and laminate slats sat under the tent, it costs very little in the winter to keep the tent a constant heat and can add considerably more than a plant/reptile heat mat. Its fairly adjustable too if you end up with a bigger tent or separate areas in the same room you just add another m ²  inline. Cost more than a space heater up front but the running cost more than makes up for it 

[Cajafiesta]

@Dodgee as I understand it, you’re absolutely correct re insulating properties of air. It’s how sleeping bags, down jackets, really any fiber-filled textile insulates as far I know. 
 

‘course conductivity of air vs solid material depends greatly on the material composition of the solid. For example- air conducts seems to conduct heat better than kaolin bricks used to build kilns/forges. 
 

 

I was actually conceptualizing exactly the effect you’re describing, but as a potential

positive impact.  I’m leaning on the idea that the air gap will indeed act as a buffer (and a hot spot diffuser, in my mind, anyway) to make the heating of the false floor more gentle. 
 

There’s a good chance I’m being way overly cautious and overly complicated. The end goal is this:

 

my heat mat seems to run at about 115f (46c) on its contact surface. I just don’t want the bottom of the pots sitting on a 115f surface. I don’t know, but I assume that would likely cook the hell out of the roots. 
 

 

I think it’ll be easy enough to try it configure both ways, with regard to heat mat location in the “layer cake” of items. I should be able to hit the floor surface with a temp gun, configured both ways, to see what I end up with. 
 

 

some solid thinking in this thread. Thanks for the  ideas, input, alternate suggestions, Fellas!  

[Dodgee]

Does the mat not have a thermostat/probe then? Can you add an inkbird stat maybe? 

 

46c is surely the max surface temp running flat out rather than being ran softer or intermittently (which is what you want really to keep costs down).  

[Boojum]

Do you really not have tube heaters in the US ?

 

Cos I've just added a second tube heater to my tent. It's cold here (not massively cold, not proper cold, it's just above freezing, around the 3-5 degrees c mark - not sure what that is in fahrenheit but that's not warm ) but the two 80 watt tube heaters, plus the heat from my lights are keeping my grow tent lovely and warm (and the exhaust from the tent is keeping my room warm ) and they are only 80 Watts each, so they cost fuck all electric to run 24/7 and they don't need keeping an eye on cos they don't get too hot. I'm sure they must sell them in the US, maybe they are just called something else ?

Edited November 27, 2021 by Boojum