high efficiency propane unit heater

[littleboss]

Anybody running one of the high efficiency hanging shop heaters? They are 93+ % efficient vs 80% for a standard Hot Dawg or similar? They vent with pvc.
The Modine Effinity 85k btu is about $2500 while a standard 80k unit is about $1300
Looking at what you save in fuel the higher efficient unit shows about $500 per 100 million BTU in savings vs the 80% unit (propane $2.69) The question is how long does 100 million BTU last? If you divide 80k into 100 million you get 1250 hours. If the heater ran 3 hours a day for 200 days that's 600 hours. So I would save $250 a year in fuel. The heater cost an extra $1000 so it would take me 4 years to break even? Thoughts?

 

[mike93lx]

You also have the condensate to deal with along with higher maintenance.

Where do you live?

 

[Bert_]

The big issue is the condensate. Has to drain somewhere and it will freeze if you don't to keep the building heated.

I'd be more concerned with getting it properly sized heater. Most end up with something grossly oversized. I've got an 80% furnace in my house and would install another one.

 

[Jackfre]

The condensate can be a real pain to deal with a can/will freeze if not handled carefully. Any advise on H&C here is best given if we know at least which state you live in. Minot or Miami? As you are considering long term savings you should also be looking at a mini-split. In an occasionally heated building I’d go 80%.

 

[Dagny]

All true mine is up high on the mezzanine and drains out the back wall with a self regulating heat tape inside you get a large ice cone outside by spring. The mandate for ecm fan motors jacked all the 95 % furnaces up by about a thousand dollars. The more you burn the more you save. I always price jobs both ways 8 out of ten shops here have the reznor cause you can just shut them off and let the shop freeze. where high eff. will have damage if it freezes.

 

[PoorUB]

The difference between the two heaters is about 10%, so if you spend $500 a year on heat you will save roughly $50. If you spend $1,000 it would be $100.

My heating bill is close to the $500 per year so it will never pay back.

 

[littleboss]

Shop is in southern Colorado. So the problem is the condensate will freeze inside the heater if the building isn't heated all of the time?

Thanks

 

[littleboss]

All true mine is up high on the mezzanine and drains out the back wall with a self regulating heat tape inside you get a large ice cone outside by spring. The mandate for ecm fan motors jacked all the 95 % furnaces up by about a thousand dollars. The more you burn the more you save. I always price jobs both ways 8 out of ten shops here have the reznor cause you can just shut them off and let the shop freeze. where high eff. will have damage if it freezes.

Thanks for the reply. So you put a heat tape inside the unit?

 

[littleboss]

The condensate can be a real pain to deal with a can/will freeze if not handled carefully. Any advise on H&C here is best given if we know at least which state you live in. Minot or Miami? As you are considering long term savings you should also be looking at a mini-split. In an occasionally heated building I’d go 80%.

It gets cold in our part of Colorado. A hyper heat would work for part of the time but would still need propane. I am probably better off doing the 80% and maybe down the road add a mini split

 

[Dagny]

No just in the drain where it goes thru the wall . keep the shop at 58. Also with an 80% the warmer you keep it the longer the heat exchanger will last.

 

[pcmeiners]

It gets cold in our part of Colorado. A hyper heat would work for part of the time but would still need propane.

The low temp units below can heat at 100% rated output at -15° F before the capacity starts to fall.

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

 

[fitter30]

80k 80%. = 64k usable heat run time per gallon 68.6 minutes
85k 93% = 79k usable heat. 64.6
65k 93% = 60,450 usable heat. 84.46
Gallon of lp 91,500 btu's

 

[littleboss]

The low temp units below can heat at 100% rated output at -15° F before the capacity starts to fall.

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

Efficiency is low at those temps so propane is cheaper

The low temp units below can heat at 100% rated output at -15° F before the capacity starts to fall.

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

I will have to take a look at those. I have looked before and not only does heat output drop but COP drops. Electricity is .19 and propane $2.69 currently. Thanks

 

[pcmeiners]

With a standard efficiency unit, propane run at nearly twice the cost. With a high efficiency minisplit it is more.



As far as your statement the low temp minisplits are inefficient at low temperatures, this link is just for the first AHRI cert I found on the Internet, not the most efficient......

https://images.greenbuildingadvisor.com/app/uploads/2023/04/22095707/44313_1682171826_ASHP-NEEP-Fujitsu-AOUH36LMAH1.pdf

 

[littleboss]

With a standard efficiency unit, propane run at nearly twice the cost. With a high efficiency minisplit it is more.



As far as your statement the low temp minisplits are inefficient at low temperatures, this link is just for the first AHRI cert I found on the Internet, not the most efficient......

https://images.greenbuildingadvisor.com/app/uploads/2023/04/22095707/44313_1682171826_ASHP-NEEP-Fujitsu-AOUH36LMAH1.pdf

Not sure how you would calculate for the whole season though. On the days and times that the temp was really cold COP is less than 2. I guess I need to see if I can find a chart showing how many hours at each temp for our location. The Pioneer WYF-25 that I am looking at starts dropping at 5 degrees. At -13 it's down its down over 10,000 BTU Thanks very much

 

[pcmeiners]

Forget about calculating for the whole season, that would being dealing with a boat load of variables.
The spread sheet make it simple by showing the cost of each fuel per million of BTUs. ( and if flue gases exist for the fuel) , that is all that is needed to calculate. The cost to run an efficient minisplit beats every fuel, considering flue venting, using the national average fuel costs. Yes a few lucky percent of fuel users have great fuel costs and can beat the running costs of a mini split.

"The Pioneer WYF-25 that I am looking at starts dropping at 5 degrees. At -13 it's down its down over 10,000 BTU Thanks very much"

All manufacturers vary as to efficiency, Fujitsu and Mitsubishi are the most efficient at the moment; there are others which claim higher efficiency but have no verifiable data to back it up or use false data.

 

[Bert_]

Probably have to buy 2 mini splits for the life of one gas furnace.

 

[American Locomotive]

Forget about calculating for the whole season, that would being dealing with a boat load of variables.
The spread sheet make it simple by showing the cost of each fuel per million of BTUs. ( and if flue gases exist for the fuel) , that is all that is needed to calculate. The cost to run an efficient minisplit beats every fuel, considering flue venting, using the national average fuel costs.

Well he does make a good point, that the COP of most minisplits is not fixed. It's stable to a certain point, and then starts to decrease. My buddy's Mitsubishi hyperheat has a COP of ~4.5 at 47°F, but a COP of 2 at -13°F.

Not sure how you would calculate for the whole season though. On the days and times that the temp was really cold COP is less than 2. I guess I need to see if I can find a chart showing how many hours at each temp for our location. The Pioneer WYF-25 that I am looking at starts dropping at 5 degrees. At -13 it's down its down over 10,000 BTU Thanks very much

The thing is, propane is so expensive that even operating at a COP of 2, it's still cheaper to run a minisplit in your area than propane heat.

Propane is only makes sense as a primary heating fuel in the midwest. For whatever reason it's absurdly expensive everywhere else in the country - like 2-3x the price it is in the midwest.[/B]

 

[pcmeiners]

Well he does make a good point, that the COP of most minisplits is not fixed. It's stable to a certain point, and then starts to decrease. My buddy's Mitsubishi hyperheat has a COP of ~4.5 at 47°F, but a COP of 2 at -13°F.

He has a point, minisplit COP varies over all temperature ranges.
It is a given the efficiency drops at very low or very high temperatures for minisplits, it is also a given an efficient minisplit is extremely efficient at the mean temperature for most of us in the USA. At extreme cold temperatures the only fuels which can possibly beat minisplit operating costs are NG, wood, coal and pellets, which is for very short time periods for most of us, Alaska being noteable exception.

Average operating cost of of efficent mini can't be beat, but as Bert points out the cost of the units and mostly the cost of installation are the negatives.

" The average lifespan of a mini split air conditioner is 10–15 years, but it can last as long as 20 years or more."

 

[Jackfre]

The thing is that you need look at the number of hours per season that you are at that -15% temp. Yes, it is cold in CO but design temp is only a couple percent of heating hours thru the year. I used to have a report of all the main weather stations that recorded that info. They were Binn hours. I have searched for it but not been successful. Someone here more savvy that I may be able to dig it up.