Mr Heater heating thru external vent duct

[StarEcho]

7x7x12 or thereabouts

 

[Canine]

VERY poorly insulated 12f trailer with a Wave 3 heater.  The temps were around 0 degrees F with blowing wind and snow.  The heater was on high and kept the trailer at around 65 degrees.  So in a poorly insulated trailer, the Wave 3 on high could keep it at 65F in 0F temps with wind.  Not too bad I think.

That is a great example. Very helpful. I like how the Wave 3 has a couple different settings and the price is right for sure; perhaps not the best choice, but you sure wouldn't go wrong with a Wave. The PlatCat has a thermostat, but you pay for it.

 

[ascii_man]

At this point I'm leaning toward the big one anyway, since it's thermostatically controlled and is about 1500 W (less than a hair dryer) and I'd like to be prepared or extreme conditions. I have asked Vented Cat whether there is a minimum cycle time or problems with "short cycling" (gasoline-powered heaters like Espar & Webasto build up soot when short-cycled). Knowing the minimum cycle time will allow me to calculate the minimum temperature rise per cycle (I guess I'd just do it based on the thermal mass of the air volume, even though that's very conservative). If it seems reasonable, I'll go big.

 

[Canine]

... and is about 1500 W (less than a hair dryer)

I believe it takes 60 watts over two minutes to start it. That is a rating of 1800 watts/hour. That is kind of a lot. I'm surprised I overlooked that; I should've maybe asked about that when I bought mine. Will have to connect a dedicated watt meter to mine when I hook it up to see real world numbers. Over the course of a 24 day, if the temperature caused the heater to cycle frequently, that would mean a lot of juice. May need to manually turn it off and on if cycling is an issue.

My understanding is that this heater is either on or off. Maybe the heat output varies, though. That would avoid cycling to a great extent. I guess we'll see when I use mine.

 

[ascii_man]

I believe it takes 60 watts over two minutes to start it. That is a rating of 1800 watts/hour.

Do you have a Wave or a Vented Cat? I have no idea what you're doing with your math. If you continuously restarted, you'd use 60 W, also known as 60 Watt*hours per hour.

If it's DC, 60 W / 12 V = 5 A
5 A * 2 min * ( 1 h / 60 min) = 0.17 A*h per start from your battery.

So if you start 10 times per hour for 24 hours, that's 40 Ah per day. So yeah, you do want to keep an eye on the cycles. But if you have a Wave, you have to manually start it anyway, so you'll know how much you're cycling it.

 

[Canine]

I have the PlatCat vented heater.

I derped out. Am misreading the product specs. It says:

"Current Draw...start -- 5 amp (for 2 minutes)"

I took that to mean 5 amps (60 watt) used in a two minute period. I then extended that 5 amps at 2 minutes to an hour to get 1800 watts. If I took that 1800 watt rating and had the heater cycle only 4 times an hour over a 24 hour period, that would be 5760 watts! Hahahahaha! A 400 watt solar set up running at peak efficiency would take 14.4 hours to power that. If the heater cycled 10 times per hour, a 400 watt solar set up would take 36 hours.

Now that I read it again, he means that is 5 amps/hour, but that rating is only used for 2 minutes. So you take that 60 watts and divide it by 30 then you are getting 2 watts being used for every two minute start. Even at the extreme of 10 cycles per hour, that is only 480 w/h or 40 ah total per day just like you said.

Do you think 10 ah a day would be a more realistic high estimate? If so, that would be about 40 watts of solar and 40 ah of battery.

If you think 10 cycles an hour could be a realistic expectation during the most extreme of circumstances, a 150 ah battery and a 150 watt solar panel would easily handle that.

 

[ascii_man]

I have the PlatCat vented heater.

Wow. An actual owner! This is exciting to me after thinking about having one for about a year.

I derped out. Am misreading the product specs. It says:

I think you need to clarify that amps and watts are a rate (like "miles per hour"), and Amp*hours and Watt*hours are nonstandard (but commonly-encountered) units which express quantity. So it's never "amps per hour", but always amp*hours or (kilo)watts*hours. As an EE major ("Can't spell geek with out double-E"), this pisses me off. It's like saying "I live 300 mph*hours from Cleveland".

"Current Draw...start -- 5 amp (for 2 minutes)"
...
Do you think 10 ah a day would be a more realistic high estimate? If so, that would be about 40 watts of solar and 40 ah of battery.

You also have 0.5 A when your heater is running.

Since you have your RV and heater, if you'll do some experiments, I'd like to see the data and help you interpret it. More details to follow.

 

[Canine]

I don't really understand the mph*h thing, but that's OK. Is that like saying, "What's the VIN number?" That is saying, "What's the Vehicle Identification Number Number?" Will work on it.

Will get you some real world numbers on the PlatCat when I get the build done. Am looking to rent a heated garage if not cost prohibitive. I'm not working right now and am super anxious to get it done.