Brian in a recent reply to a post brought up a interesting topic, efficiency and cost of heating a coach..Most have already decided this..I chose heat pumps with elect heat back up at low temps and run generator when not hooked up to shore power..I my case I do very little dry camping (almost none).so generator time is cost effective.Use bus heat when running down road but Air is supplied thru the heat pump and generator combination when needed. my math for my life style..others please share! Bob
First, I need to say we spend the cold weather months in Fl where it rarely gets cold, EXCEPT LAST WINTER!!. We purchased a used ProHeat 40,000 BTU diesel fired boiler and designed our one system. We have one large heat exchanger in the living room area and a toe kick exchangers in kitchen area and bathroom. Our coach has 2" of spray foam and additional foam sheets in ceiling. We are happy with our design and it works for us. We have never had any different system, so I can't make any comparison. We do use a small 120 volt cube heater as a morning "chill chaser". Jack
Like Jack we are rarely in cold weather. We use a 10,000 Blue Flame down to the mid 20s and below that we supplement with Generator and electric heat. Works for us.
I don't winter camp. but late fall and early spring invariably requires several nights at below freezing. I use a typical Suburban 35K btu or thereabouts RV propane furnace. It was free, the cost benefit of anything else ain't gonna happen anytime soon, it is ducted throughout the coach, it keeps the water bay warm as well. It costs maybe a 30lb tank of propane a week if I was using it for a solid week of nights, and that is $25. I use cube heaters if I have electricity for daytime and to supplement.
Brian
I have and use a heat pump when in RV park and paying for elect but when free I use cube heaters and when dry camping I use diesel fired hot air heaters that draw very little current from the 24 volt system. Jerry
Quote from: Jerry32 on October 16, 2010, 12:41:12 PM
I have and use a heat pump when in RV park and paying for elect but when free I use cube heaters and when dry camping I use diesel fired hot air heaters that draw very little current from the 24 volt system. Jerry
I'm curious why you don't use the heat pump any time you have electricity? Do the cube heaters heat better?
Heat pumps need to take heat from the ambient air, and once you get to 40 degrees or so, the heat available in the air is not enough to provide a lot of heat to the bus. Other heaters use resistance elements for heat, therefore act independently of air temp.
chuckd
spend as little time as possible in weather below 40 when camping..then elect heat takes over... Bob
That restriction to operation above 40 degrees only comes from two things. One is the use of R22 refrigerant and the other is due to a lack of defrost capability.
With the newer heat pumps, R410A operates right on down to -4 F because there really is enough heat in that cold air. The tier two units are rated to produce fully 2/3 of the BTU at 17 F that they produce at 47 F. This is without using any supplemental heat source, such as strip heaters.
The worst of it is that R22 units will cost you nearly as much to buy as R410A units.
Sometime in the future, we will get to try out CO2 heat pumps. Some early designs are reported to continue producing heat down to -30 F. Mitsubishi is reported to have done the engineering work.
We are currently using eight of the R410A heat pumps and plan to install at least another dozen. They go right through the winter and produce, on average, about three times as much heat as resistance heaters for a given amount of power.
The only reason for using resistance heaters is low initial cost, and then, you get to keep paying for them as long as you use them.
For what it's worth.
Tom Caffrey
thanks Tom for the reply.I had forgoten how low my R410A were good to..I don't plan on being there( 17 deg) un less it is when I'm leaving home for the race to the sun. Bob sell my box heaters
Tom, I don't understand what it is that you have. You say that you have 8 of these and are adding more. I had pictured a basement unit, but obviously that is not what you have.
Jim
What brand and where are you using them? Any pictures? Thanks Rod
Awhile back I was deciding what to use for heating and airconditioning and researched Mini-split heat pumps.Tom said he used them in Alaska and said to get with the R-410A refrigerant.That it was more efficient.I Decided on 2ea 12000 btu units for my coach.A local friend and busnut board member is a hvac guy and put them in his mci 8 and has had great results. Tom can tell you which brands to avoid. Bob Ps Apartment buildings I think was his use.
We have a new system at home with the 410 I do notice a difference in the cooling temps coming out of it is around 7 degrees warmer than the old unit with the r22 haven't had the chance to check the heat pump part yet with 90+ temps we are having.
So far I am not happy with the unit running longer than the old one but the AC guys and the power co say it will be cheaper on power we will wait and see
good luck
The heat pumps that I mentioned are being used in apartments in Ketchikan. The 18,000 BTU units cover up to an 800 square foot apartment. They use about 1 KWH per ton of heating. That works out to less than 15 cents per compressor hour here. It would cost about 50 cents per hour for the same amount of resistance heating.
The brand isn't important because many different brand names have been stuck on these machines. We already have three brands and are looking to order more with yet another brand name. They all seem to be the same. The specs are what is important, and the class of machine.
The 13 SEER units are what we are using, and they are only rated down to 19 F. However, we have used them down to 11 F without any of them quitting. We have kept the existing heating equipment for backup heating in case the weather tries to set some records.
The newer inverter designs are rated are rated variously from 19 F down to -4 F. They do ask more money for the better ratings. I don't buy Soleus branded units because they are not rated to perform below 23 F without supplemental heat. There are a lot of Soleus units on the market.
If you want to check them out, just go to ebay or use google and search for "mini-split heat pump". You will find a whole pile of them, with pictures.
I don't buy anything that doesn't have the specs right in the offer to sell. And I try to buy only from sellers with 99% feedback to reduce the risk of BS. So far, no failures.
I hope this answers most of your questions.
Tom Caffrey