heating electrically a "back yard" report

[pianotuna]

Hi,

This is a test of a cold soaked RV, ambient temperature -31 C (-23.8 f) The test started at 2:00 but I had difficulty getting the cords "run". I'm plugged into one 30 amp and two 15 amp outlets. The inside of the RV started at -21 c (-5.8 f)--a testiment to solar gain--through the front window. I am running between 4500 and 5500 watts of electric heat, or 15354 to 18766 btu's.

The bedroom area is closed off by a sliding fabric door, with about 2300 watts of electric heat, or 7847 btu's. (This number is NOT in addition to the total above.)

The unit is a 2004 28'5" class C with many cold weather modifications.

The date is 2013 12 07 and the location is: 50.448487,-104.50848

inside rv; bed room; ambient temperature; time

-20. C (-4 f); -20 C (-4 f);;;;;; -31 C (-23.8 f); 15:00

5.70 C (42.3 f); no data;;;;;;;;;;-26 C (-14.8 f); 17:00

7.70 C (45.9 f); 14 C (57.2 f) ;-26 C (-14.8 f); 18:00

11.2 C (52.2 f); 16 C (60.8 f); -26 C (-14.8 f); 19:00 {door open from 18:00 to 19:00}

10.3 C (50.6 f); 23 C (73.4 f) ; -26 C (-14.8 f); 20:00 {door closed}

12.4 C (54.4 f); 24 C (75.2 f); -26.6 C (-15.8 f); 21:00

13.6 C (56.5 F); 25 c (77 f);;;; -26.8 C (-16.2 f); 22:00 {cracking door open}

15.1 C (59.2 F); 23 C (73.4 f); -26 C (-14.8 f);; 23:00 {door still open}

15.6 C (60.1 f); 22 C (71.6 f); -25.5 C (-13.9 f); 24:00 {door fully open}

time to sleep

[SWD]

Hey Don.......I thought you were heading South not East! You must have upset the politburo and they decided to exile you. Buriyatka should be nice this time of year!

[pianotuna]

LOL SWD,

You know very well that it is colder here than in Siberia.

[SWD]

gandude wrote:
LOL, when I put your coordinates into googlemaps, it says you are in Russia next to Mongolia. Yea, it does get cold there!

Yuup! Seems about right to me! I'm just a bit west of Pianotuna!

[pianotuna]

Hi Mark,

My location is actually Regina, Sk, about 104 miles north of the USA border.

[pianotuna]

Hi Phil,

It's good to know that heat pumps have evolved so that they will work down to -7 C. If my air conditioner dies I might upgrade. For now I'll stick with resistance heaters.

And, yes, it is much more efficient to run a heat pump than resistance heaters.

[greenrvgreen]

Well, I think a lot of money is being spent trying to heat 45 degree interior walls up to 50 degrees. Most RVs are poorly insulated and coated in highly heat-conductive materials. In the winter my windows drain heat to the outdoors, and in the summer my corrugated aluminum skin radiates heat inward through the evening and much of the night. This is why I gave up trying to heat (or cool) my TT and focused on heating/cooling me.

Tuna mentioned radiant heat earlier, and I am a big fan of this. I have a pair of heat lamps under my desk, and I have run reflectix all around the footwell of the desk. With a jacket on, 250w on my legs takes care of me in most lower-48 weather. (I get the part that Tuna's in a much more formidable climate.)

In that environment there could easily be a 10-20 degree difference between the insulated/reflective wall my seat backs up against, and the wall on the far side of the TT, near the door. BTW, "far" is relative, my cabin is less than 15 feet long.

In the mornings with temps in the teens, the interior cabin temp is in the low forties. I have spent a very comfortable night under layered open sleeping bags used as thermal blankets, but it's time to heat up the cabin, so I use a single 1500w space heater set on my bench seat six inches from my torso while I fire up my computer.

In minutes I am hot and the cabin is "getting warmer", and I turn the heat down to 1000w. I might let it run an hour at 1000w before turning it down to 500w, while still running 250w of heat lamps. I don't use ANY thermostat regulation, but simply use less heat than I "need", and more clothing. It is far easier and quicker to take off a jacket than to turn down a thermostat.

When I first put in electric heat, I went with a 1500w baseboard unit, thermostatically controlled. For starters, the 1500 watt inrush current was the biggest drain in my RV, and unpredictable. Secondly, the warm air coming out of the baseboard seemed to be carried straight to the far side of the TT where it was cooled by the walls or simply escaping through cracks in the door.

I used to use an electric blanket, but found it was way too powerful. For somebody in the frosty north, it might be just the thing to keep humans at 75-80 degrees and the bedroom at 40 degrees. If there is no plumbing in there, there is no sense in paying to heat the walls.

While I realize that most people on a "camping" website have no interest in wearing a coat indoors, I myself cannot imagine sitting in a camper in -30 degree weather, so I suggest that desparate times call for desparate measures.

[pnichols]

pianotuna wrote:
The cost of running the compressor compared to the watts of heat extracted is about 100% more than running plain electric resistance heat at the lowest operating temperature for the "pump".

Don, I'm not sure that your comment above came out as clearly as you intended it to.

Here's my way of talking about heat pumps:

It's much less expensive to get heat from a pure air-to-air heat pump system than from a pure resistance heat system -> when outside temperatures are such that an air-to-air heat pump system can deliver heat. That's of course because heat pumps merely transfer heat that already exists, versus creating new heat as resistance heaters do.

We have had a couple of heat pump systems for about 37 years in our all electric powered residence. Our newest heat pump is a state-of-the-art high efficiency (Trane XL16C) air-to-air one with complete computer control of it's variable speed compressor and variable speed circulation fan. Even though it uses auxiliary resistance heat strips for fast warmups if you want it, in it's fully automatic compressor-only mode it can still deliver heat and keep our interior warm (71 degrees F) with outside temperatures in only the high 20 degrees F range - as a matter of fact it had to do this again this past Sunday evening.

So .... in an RV park with pay-as-you-go electric and outside temperatures not much lower than the 40-45 degree F range - a heat pump roof unit (without heat strips) set to heat mode should result in lower electric charges from the park than what would result from use of a resistance heater in the RV.

[NinerBikes]

W 104 or -104. +104 or 104 is east of Greenwich.

[greenrvgreen]

More good info. At an hourly average of 3.33 kwh, your daytime usage is likely well under 3 kwh. Shut down the heater in the bedroom until evening, and I bet your daytime use could be easily handled by a single 3000-class gennie (2600 watts).

Additionally, you now have a "daily rate" you can reimburse when "backyarding". IMO, this is the real future of your biz plan, hooking up overnite to your customers.

[mena661]

gandude wrote:
LOL, when I put your coordinates into googlemaps, it says you are in Russia next to Mongolia. Yea, it does get cold there!

You missed the - symbol on the 104 coordinate. 🙂

[MNtundraRet]

gandude:

The error most likely occurred from your entry. There is a difference from using a decimal entry versus a coordinate entry. Also there a more than one type of coordinate entries accepted by GPS's.

His location is somewhere south of Calgary closer to the US border where he is covering his customers.

[gandude]

LOL, when I put your coordinates into googlemaps, it says you are in Russia next to Mongolia. Yea, it does get cold there!

[pianotuna]

Hi,

I found a daily average. It suggests I'm using 80 kwh per day.

That number is somewhat skewed because I use the inverter to do my cooking electrically. The meter is set to monitor all 120 feeds--so cooking more or less doubles that part of the number.

It would be about 2 kwhs too high I think.

Where I live propane is $1.41 per liter. ($5.34 per US gallon)

79 x 0.12 for electric is $9.48.

I'm using about 269559 btu's per day.

Propane does 24,603 btu's per liter, and the furnace might be 80% efficient so I'd be using 13.7 liters per day or $19.31 per day. At 80% full my tank only holds 57 liters, so I'd have to fill up every 3 days to prevent running out. That would be a royal pain.

Even if power were metered, in Canada I'd be better off heating electrically. As it is--there is no charge for power where I am staying.

[pianotuna]

I know I promised a kwh reading--but I can't figure the darn meter out. It won't reset.

I'm going to resort to (gasp) pencil and paper.