Thermostat warm-up

[Old Crow]

All-

Over the weekend I sent an email to White-Rodgers Tech Support regarding our discussion in this thread on the 1E78 thermostat. Basically I said, hey, were having this discussion and wonder if you could comment and/or make recommendations.

I received this response this morning:

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"Thank you for contacting White Rodgers.

In regards to the question on the Discussion Threads. There are a couple of issues when using in a RV application where the thermostat needs to recover from an extreme set back mode.

1- Digital thermostats have, by design, a buffering in the algorithms to recover the displayed set point temperature slowly. The rationale is that if the thermostat were to react in real time to a sudden temperature change the equipment would turn on an off rapidly to this quick temperature change.
a. An example would be if the thermostat is satisfied and holding temperature and someone were to open an outside door for a few seconds and allow a blast of cold air to enter the RV a sudden drop in temperature would initiate a call for space conditioning. The reality is that if the door is only open for a few seconds and then closed it would have little impact on the overall temperature on the RV and the temperature will stabilize with no need for a call for space conditioning. This is why digital thermostats use buffering.

2- Secondly, ensure that the opening in the back of the thermostat where the wires come through has a piece of insulation stuffed in the hole to reduce temperature transfer from the cold walls via air movement into the thermostat.

There is no way to override the buffering built into the thermostat.

Best Regards,

Rae Vincent Balleza | Technical Service Engineer | White Rodgers Division"

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I also called ICM tech support (yesterday) regarding the Frost Sentry FS1500VL garage thermostat we've discussed in this thread. I called because the manual doesn't have ambient-temperature operating specs like we see in the manuals for the 1E78 and for the Honeywell thermostat mentioned above (both of which are 32 degrees on the minimum side). The ICM tech support guy said the FS1500VL is intended to be operated above freezing. He went on to say it will operate (as in turn the furnace on) below that but the display 'starts to go funny' below freezing, adding 'I've only seen it go down to the low-20's and then the display generally gets to the point you can't read it.'

-OC

 

[Stalking Light]

Thanks for the follow up, that's basically what I suspected regarding the buffering.

 

[d2richland]

OC, thanks for the follow-up information; it's very helpful.

 

[RyanOBrian1]

Okay I installed the new thermostat and from the initial test it works much better! After 10 minutes the new thermostat was showing what appeared to be way more accurate then the stock one.

Before I turned on the heater (orig thermostat on left new on right)

Then I left the heater on for 10 min and it showed:

I am going to be camping in some 10 - 20 degree weather this weekend and will report back. For those that are interested here is a link to the themostat and you can put it in "garage mode" so it goes down to 35*

http://www.amazon.com/gp/product/B00H6ARNXO

 

[Stalking Light]

Nice and a pretty inexpensive fix.

 

[DaveL]

I just replaced the WR thermostat with this Honeywell. It is MUCH better. I had the same issue of it not registering the correct temp (didn't know about the reset, but that sounds like a hassle). Now it's within a couple of degrees of my indoor/outdoor gauge. The other thing I like about it is being able to set it at down to 35. The WR only went to 45. We're fine with 35 in our snug bed ;-) Now we'll try leaving the thermostat on if the temps are going into the 20s.
Thanks for the suggestion & link!

Sent from my SM-G900V using Wander The West mobile app

 

[Stalking Light]

I just replaced the WR thermostat with this Honeywell. It is MUCH better. I had the same issue of it not registering the correct temp (didn't know about the reset, but that sounds like a hassle). Now it's within a couple of degrees of my indoor/outdoor gauge. The other thing I like about it is being able to set it at down to 35. The WR only went to 45. We're fine with 35 in our snug bed ;-) Now we'll try leaving the thermostat on if the temps are going into the 20s.
Thanks for the suggestion & link!

Sent from my SM-G900V using Wander The West mobile app

Super, I just ordered one for my Eagle.

 

[XJINTX]

Don't want to Hijack the thread but have a correlating issue. What happens or what are the symptoms of out of propane and the heater is set. I'm pretty new to my Hawk and only been out a couple of longish times. Luckily the first time I ran out of propane I was heating water so just went out and switched.
My question is at night with the heater on... what happens if I run out of propane? Is the heater smart enough to just turn off or not turn on if no propane? Or does it just keep running trying to heat to specified temp?

 

[Stalking Light]

Don't want to Hijack the thread but have a correlating issue. What happens or what are the symptoms of out of propane and the heater is set. I'm pretty new to my Hawk and only been out a couple of longish times. Luckily the first time I ran out of propane I was heating water so just went out and switched.
My question is at night with the heater on... what happens if I run out of propane? Is the heater smart enough to just turn off or not turn on if no propane? Or does it just keep running trying to heat to specified temp?

Good question, I've never had that happen.

 

[dakozicki]

When you run out of propane with the WR Thermostat, the heater fan will run for a short time and then shut off. The same with the water heater. I am curious to know if the Honeywell thermostat behave the same way. It may not even be controlled by the thermostat. It may be a sensor in the heater itself that shuts it off when no propane is detected.

 

[Wallowa]

Good question.. Safe bet is that the appliance has an automatic shut down if propane or electrical power [ igniter ] is not available at the valve. Like most modern home appliances.

Otherwise the liability would be enormous.

Not having taken delivery of our Hawk, I have no idea of how the propane bottles are connected, nor disconnected. I was planning on a bottle gauge but that may not be needed or possible.

Devils advocate; if the WR goes to 45 degrees but the Honeywell goes to 35 degrees is that alone sufficient to change thermostats? If my intent is to prevent freezing of water in lines and fixtures my guess is that 45 degrees might do the trick but that 35 degrees might not.

I realize that propane is a limiter for extended camping off the grid; but will the Honeywell save significant propane and battery electrical?

Not adverse to changing out a new thermostat and will do so if it makes sense.

Thanks for all the input!

Phil

 

[ckent323]

Phil,

Water must get to and stay at 32 degrees to freeze. IF the thermostat keeps the temp above 32 degrees (i.e. 35) then the water will not freeze. The question is what is the temp at the water vs the thermostat.

To make an extreme point if the water tank is steel and the tank is sitting on steel (or some other conducting surface) even in a room at 45 degrees it could freeze IF the surface area and cold sides offset the heat influx from the warm sides and allow the tank to get to 32 degree or less. Possible.

In reality the water tank in the campers is usually some kind of polyethelene (not a great thermal conductor) and it is within the heated envelope of the camper. Further it sits on top of a wood floor (modest insulator) and is enclosed by thin wood sides (weak insulators) with one side typically adjacent to the camper side wall (potential for significant heat loss). Depending on camper model and year the tank may have more or less heat loss through the side wall and floor.

Why not use a thermostat and measure the temp in the water compartment near the back and bottom of the tank (it is important to do this with it empty) while also measuring the temp inside the camper - at the same time. Do this for several temps above and below 40 degrees after the temp has soaked (or dwelled) to be at a stable temp. The wider the temp range the better. The more data the better, Plot the data and draw a line (if more then 3 date points fit a curve to it). You will have a first order idea if keeping the camper at 35 or 40 or 45 degrees is enough to keep the water tank compartment above freezing.

This involves some time and effort but it is better than guessing.

But if you want to guess I think guessing that keeping the inside of the camper at 45 degrees will likely do the trick (however, 35 or 40 degrees may do the trick too). ;-)

Regards,

Craig

 

[Wallowa]

Craig,

Kinda new that water freezes at 32 F.. But my thought was that the thermostat and heater work in concert to heat inside box of the camper to the set temp and the areas with the plumbing and storage outside that box are subject to much less insulation and therms from the heater. In short form, at 35 F inside the living area, the -5 F ambient outside may well lower the areas outside that cozy 35F inner box living area to well below 32 F.

Good idea on measuring temp differential in differing sections of the camper and then setting the thermostat at whatever is needed to keep water from freezing in the camper's "outer shell area". So many variables and so little consistence in temps, how and when heat is distributed and how, when and where heat is lost. In the final hour before dawn the difference in frozen lines and ruptured fixtures may only be the difference in cloud cover or wind velocity changes with variance in back radiation and ambient temps.

Proof of the pudding is in the eating; so when in doubt crank up the heat and open access doors and then hope that is enough.

Or play it smart and remove all the water from the camper systems. Carboy inside = coffee in the morning!

Phil

 

[Stalking Light]

Swapped out my White Rodgers for the Honeywell and will see how it works next week, although the real test will probably be in mid Feb when I go to Reelfoot Lake to photograph eagles.

Just taking the unit from inside the house into the 40 degree camper showed that the temp reading is more sensitive to quick changes, so I am cautiously optimistic.

 

[Stalking Light]

Just an update, we're camping in 20 degree weather and freezing rain and the Honeywell thermostat is performing admirably and very little latency when warming up the camper from cold. Well worth the few coins.

 

[melcooke]

I think I might try mounting the thermostat with some 1/4" or 1/2" spacers allowing air behind the thermostat.

I'm liking this idea to allow for air circulation and a thermal break from the cabinet. We are certainly living with this issue and plan to continue our stays in resort parking lots with the combination of blankets, window coverings, under bed insulation and the right combination of clothing and bedding layers.