Question about the Helix thermostat...

[heatherhead42]

So, we bought the Helix DBS1000 proportional thermostat to maintain the most stable possible temps. And it's working pretty well, but with one thing that's puzzling: When the temps are around 91.7-92.0 during the day, they go down as far as 88 degrees at night.

Here's the set-up:

Flexwatt taped with foil tape directly to the bottom of the tub, which is raised about an inch off the surface below. The thermostat probe goes through a little hole in the bottom of the tub and is wired securely against the bottom of the tub inside the warm-side hide. (Yes, I know, everyone says to put it outside the tub between the flexwatt and the tub, but I could *not* for the life of me convince Carey, so we compromised and wired it securely, with the cord leading through a hole in the bottom.)

The thermometer is an Accu-rite with the temp probe set under a thin layer of aspen substrate against the floor of the warm-side hide (held in place by the weight of the rather heavy hide).

The tub sits in a rather warm room of the house that gets very warm (84-86 on the warmest day) on sunny days due to south-facing windows. It can get down to around 75 degrees at night in the same room.

So temps in the room fluctuate quite a lot, but they do not get above 84-86 on the warmest winter day. I thought that the point of the thermostat is that it would compensate for the room temperature fluctuations. And it's not that the thermostat *can't* keep it warm enough at night, because we've tried raising the set temperature and can get the night-time temps up to 90 easily, but then the daytime temps top 93-94.

Am I missing something?

What's going on? And should I worry about it?

Thanks!

Heather

[Reediculous]

i was having the same problem..............when you use back heat, it's really tuff to get the temps where you want........if the temp in the room your snakes are in drops below 80 your going to have these problems............i ended up getting an oil filled heater for my bedroom

hope this helps

[heatherhead42]

Okay, I can see that. But here's what I don't understand: Since the heat tape is quite capable of keeping the temps above 90 even at night, why doesn't it just up the power at night and do it? Although they are on opposite sides of the warm-side hide, both the thermostat probe and the thermometer probe are under the substrate under the warm hide against the tub bottom.

I thought stabilizing the temps by changing the power input was what the thermostat was supposed to do. I understand needing to change the room temps if the problem were ambient temps--but it's not. It's the warm-side bottom surface temp, right where the heat tape is.

Can someone tell me, if this is a normal fluctuation for these conditions, what is the advantage of a $130 thermostat and a space heater over a cheap rheostat and a space heater?

[kavmon]

tape the helix probe directly to the flexwatt! then you will be controlling the temp of the flexwatt directly. adjust the temp setting on the helix until the temps are right in the tub. can you post a pic of the setup? is the tub an inch above the flexwatt or is this back heat?



vaughn

[kavmon]

Can someone tell me, if this is a normal fluctuation for these conditions, what is the advantage of a $130 thermostat and a space heater over a cheap rheostat and a space heater?
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one advantage is that if something goes wrong or fails with the helix, it will shut off and not fry your animals! cheaper thermostats can and will stick in the on position and kill animals.


vaughn

[heatherhead42]

Thanks for the feedback. I don't have a pic handy, nor the energy to get one right now (it's been a long day). I'll try to do that later, but I'm plain tuckered at the moment. But to answer your question, no, the inch of space is between the tub and the dresser the tub sits on. The flexwatt is attached directly to the tub. And I'm sorry for the newbie question but what is "back heat"?

And yes, I know everyone says to tape the probe to the flexwatt. But to be honest, I don't see how that would fix this particular problem--it seems to me that the thermostat should be sensing the fluctuating temp inside the enclosure and adjusting the power to the flexwatt accordingly. If I attached the probe to the flexwatt, then it seems like the Helix would be even less likely to sense fluctuations in the room temperature and adjust accordingly, since it would be sensing ONLY the temp of the flexwatt and not the temp of the tub. I don't mean to be oppositional on the matter, but I am just not seeing the reasoning here. If you were setting the thermostat for your house, would you put the sensor directly on the heat element? No, because then when temps outside fluctuate, the heat element wouldn't know to get hotter. It would stay the same temp and the house would get colder. I am having a hard time understanding how it is different in this case.

Now, I *do* understand the rationale that says the probe should *not* be where the snake can move it. And for that Carey and I have, as I said, compromised and wired it securely to the bottom of the tub (so that the only thing between it, by the way, and the heat tape is the thin plastic of the tub bottom).

Thank you for the answer to my "what is the advantage" question. :p I had not considered that possibility, and I'm glad to know I'm protected against that at least!

I'm sorry if I sound a bit abrasive tonight. I don't mean to be. I really do appreciate the dialog and feedback. It helps to clarify the situation, even if I'm not understanding everything just yet. :p

Thanks,

Heather

[kavmon]

what size tub? and what size/wattage flexwatt? is this tub in a rack? a pic would really help!


houses normally use a type of forced air to heat/cool, with the exception of boilers. totally different kind of heat than flexwatt, which is radiant heat.

taping the probe to the flex insures constant even heat output and the flex never gets too hot.

putting the probe inside the tub can ask for few problems(spilled water bowls, snake on probe, feces/urine on probe, etc)

back heat refers to the heat source being behind the tub (back wall) in a rack setup. belly heat is on the bottom of the tub. belly heat is more efficient in most racks.


vaughn

[heatherhead42]

Thanks for the quick feedback again. I'll try to get some pics tomorrow and put them up. It's a 96 quart tub, equivalent roughly to a 20 gallon L. One foot of 11" flexwatt, not in a rack. It's heavily insulated on three sides and the top (two layers of polyester fleece).

Hadn't thought about spilled water, urine, feces, etc. Food for thought (and to pass on to Carey). Thanks!

Heather