DV Advice Requested

[Snakebit12]

I am looking to heat an 800 sq ft basement apartment here in Virginia. Well-insulated with only one 40' southern exposure wall exposed to the elements (the other walls are either below ground or shared with an unheated part of the basement).

I found that I could effectively heat the room to 70F with outside temps below 30F with 2 space heaters running at 1,250 and 1,400 watts, respectively. Assuming 100% efficiency on electrical space heaters, that is a combined 2,650 watts x 3.1412 BTU/watt = approx 8,300 BTU. I assume that my math is correct?

With electricity @ $.125/w here, I suspect that an direct-vented LP wall heater might be more cost-effective...but I am not positive. Just filled my LP tank @ $1.89/g.

Been talking to sales people from both Empire and Rinnai - they keep suggesting units in the 30k-35k BTU range...which makes no sense to me. Assuming 80% efficiency, they are talking 24k-28k of BTU output.

Yet, I did it with 8k BTU output albeit at a cost of 2,650 w x 24 /1000 = 63.6 kWh @ $.125 = $7.95/day. Too expensive.

My questions:
1. Is my 8k BTU calculation correct?
2. If yes, why do I seriously need a 30k BTU DV wall heater?
3. Any guesstimates on how much LP I would burn per day with a unit that size?
4. Any reasons to decide between Rinnai vs Empire?

Thank you in advance.

John (aka Snakebit12)

 

[Mainely Saws]

Hello John , sorry that I can't answer your questions about your calculations but I can share my opinion on the Rinnai products . I heat 3 1000 SQ FT apartments with average insulation with Rinnai heaters in Maine. The units are very well made , very low in maintenance ( an easily removable screen needs cleaned every so often) and perform quite well . One distinguishing factor about the Rinnai is that they modulate both the heat output and the blower fan which means that if a small amount of heat is needed, only a small amount of BTU's are produced , if the room has been cold and needs a lot of BTU's to bring it up to temp quickly then all of the heater's full BTU's are available for that purpose . A number of other DV heaters are all or nothing when it comes to heat output . I have three of these units in different apartments that are fueled with LP . I pay about the same as you for LP . I have had these units for many years and would highly recommend them .

Bob

 

[Snakebit12]

Bob - Thank you for the feedback. Unfortunately, my FPX44 cannot reach this room.

1. Can you tell me which size Rinnai units you used for your 1,000 sq ft apartments?
2. Any estimates of the annual LP usage per unit?

 

[Mainely Saws]

PS - I forgot to add that two of the 1000 sq ft apartments just had deliveries yesterday . One used 66 gals of Lp and the other used 55 gals for a 5 week period. At 1.89 per gallon that would be $124.74 and $103.95 respectively at your prices . There are many variables here but the previous deliveries were on Nov.7th . The last week up here has been pretty cold ........ The heaters are both model 1004 ( the largest units at the time of purchase )............. hope this helps .......

Bob

 

[Snakebit12]

Great info - helps alot. The 1004 has been replaced by the ES38...38,000 BTU's (which I think is still the largest DV model).

Sounds like you are using (an average) about 50 gallons per 30-day period...under $100 per month.

I still wonder if I need that many BTUs for an 800 sq ft open room...

 

[Mainely Saws]

If you heat it 24/7 all winter , you may not need the extra BTU's but if you heat occasionally it might be nice to have the power when and if you need it . The units that I have run almost continually but at a very low output . Last night it dropped down to 0 degrees F and I noticed that the unit bumped up it's output and fan speed . I know these wall furnaces aren't the cheapest but over the long haul I can't say enough good about them . They do require electricity to run .If you do a search on Rinnai you will find numerous positive reviews on them . I must sound like a salesman for Rinnai which I am not, but it's not all that often that I find something that works well, is easy to maintain and lasts a long time . Good luck with what ever you decide John ................

Bob