Decisions? Decisions? (Heat Pump, Propane?) - Canadian TV, Computing and Home Theatre Forums
 
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post #1 of 15 (permalink) Old 2018-03-19, 02:55 PM Thread Starter
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Decisions? Decisions? (Heat Pump, Propane?)

Last 3 months of heating/hydro costs: $550, $450, $300

Considering moving off my HP with aux electric to HP with propane aux.

Every new home ion my area is going with propane, yet every calculator I use says electricity is almost the same price.


Approx energy costs:
Electricity $0.12 kw/hr
Propane: $0.69/ litre or $2.69 gallon

Current set-up: Installed 2009
Heat Pump with electric back up (20,000 Watt)

Should I:
1. Wait until existing unit needs replacing? then decide.
2. Keep Heat pump and install propane furnace for backup? dual fuel
3. Convert heat pump to A/C alone and install new propane furnace for all heating needs

I've had 4 contractors come out:
1 voted for option 1
1 voted for option 2 (price from $8000-10,000)
2 voted for option 3 (price from $5500-$8,000) depending on furnace AFUE).

Since there was no real consensus from the contractors, I'm at a loss. Looking for the best long-term solution based and shortest pay-back period.

thanks
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post #2 of 15 (permalink) Old 2018-03-19, 05:05 PM
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Is that gross charges for the months. If so what are the "fixed" hydro costs if any, that you won't be eliminating by a conversion?

quote online:1 Gallon of Propane = 27 kWh (Kilowatt Hours) of electricity - This means that one gallon of propane contains the same amount of usable energy as 27 Kilowatt Hours. Or we can say that 27 kWh equals approximately 91,500 BTU.
A 100 watt light bulb left on for a full day (24 hours) will consume 2.4 kWh. If propane were to power the same light bulb (hypothetically- remember, we're comparing energy content) for 24 hours, it would use .09 gallons of propane....unquote

.12/kwh
2.69/27 - .10/kwh with propane.

.12 or .10 doesn't seem to be a reason to convert

without fixed cost $430 average would be 430/.12 3600kwh so saving $72 with propane but there must be fixed costs in the 430. $72 for 6 months?? $400/yr Seems like I would leave things as they are but give us more info.


What age of home. What state is the insulation? Maybe an upgrade there would be more effective.

We are in BC with a 18 year old home and we only see -20C for a couple days per year but our bill(natural gas) is about half yours. The home is extremely well insulated.
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post #3 of 15 (permalink) Old 2018-03-19, 05:40 PM
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The calculations in post 2 seem to assume 100% efficiency. High Efficiency Propane (furnace) would be slightly less than 100% and a heat pump (the portion of heat associated with the heat pump) could be significantly higher than 100%, sometimes going to 200% or 300% at higher temperatures in the winter, depending on the device. Of course the portion associated with electrical radiant heat (backup) is 100%. One item is not clear to me, is the heat pump currently electric?

Looks to me like you should stick with what you have until you need a change and then can do the calculation again.

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post #4 of 15 (permalink) Old 2018-03-19, 09:18 PM
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Have you looked into offsetting hydro costs with solar panels? It won't help with night time heating but prices in Ontario are relatively low at that time anyway. The savings for daytime use and A/C could be substantial. It doen't need to be a big ugly panel in the yard. It's estimated that solar panels on the roof can provide up to 40% of electricity requirements in Ontario. Costs for solar have never been lower. It may also be possible to lease solar panels with a pay back for electricity sold to the grid.
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post #5 of 15 (permalink) Old 2018-03-19, 11:03 PM
 
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A 2009 heatpump should have a lot of life left.

The issue is the lack of capacity in winter weather, leading to use of electric backup.

I would seriously look into getting the electric elements replaced with a hydronic coil. Your air handler may be able to take a hydronic coil, otherwise it may be possible to install one upstream of it.

You get a propane water heater designed for domestic hot water and heating - could be tankless or tank.

Reason to do it this way is, when you put a propane furnace, the heatpump gets disabled below the temp at which it can't keep up. Heatpump heat in your case is probably cheaper than propane heat, so it's best to keep running the heatpump and supplement with propane rather than go 100% propane.

gzink posted propane cost of 10 cents per kwh, converted. The heatpump at 12 cents per kwh will supply heat at 6 cents until it get bitterly cold and the cop, energy out vs energy in drops below 2.

I'm not sure if it's worth replacing strip heat with propane to save 10%. It certainly makes zero sense to install a propane burning furnace, any savings of not running strip heat will be offset by burning 100% propane.

As far a solar pv goes, forget about using it for heating applications, the amount of electricity produced vs what's needed for heat is minimal and even a grid connected system costs thousands to install.

A better case can be made for solar thermal to heat water, that could knock 10kwh per day or more off the bill in the right area.

I'm betting your electric usage is well above 50 kwh per day.

The only economical source of heat left is natural gas.
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post #6 of 15 (permalink) Old 2018-03-19, 11:06 PM
 
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Quote:
Since there was no real consensus from the contractors, I'm at a loss. Looking for the best long-term solution based and shortest pay-back period.
Nothing will have a short payback period at the energy prices you posted.

Contractors want to make money first, not do what's in your best interest.
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post #7 of 15 (permalink) Old 2018-03-19, 11:28 PM
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As far a solar pv goes, forget about using it for heating applications
That's not what I said. Solar will produce electricity when rates are high, offsetting costs for heat. It will also produce electricity for A/C during peak times. Excess sold back to the grid would be sold during peak times and purchased back at off-peak rates. The savings are not directly for heat but will lower hydro bills. It would be better to also find a cheap source of heat but NG isn't available in this case or we're looking at more expensive systems like a geothermal heat pump or solar hot water with storage. A case could even be made for heating hot water with solar electricity for heating at night. Don't know what the cost benefits would be for that though.
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post #8 of 15 (permalink) Old 2018-03-19, 11:43 PM
 
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Using solar pv for domestic water heating never made sense, it's better to use heat from the sun. Both PV and solar water heating systems are very expensive, solar water heater would probably supply more kwh per day with of hot water than a pv array.

I'm not sure what area the op is in, certainly not ontario with the rates posted and the electricity rate may very well be flat.

The electricity production from a pv setup is minimal compared to what's being consumed and that was my point. A pv system at 12 cents per kwh could take like 10 years to pay off, after that even a very large (for residential) system won't make more than 10-15kwh per day.

Don't actually have to put in geothermal to really save, there are air source heatpumps now that, if the heat loss is low enough don't require any strip heat down to -20 and can maintain full capacity.

problem is, very pricey up front, only second to geothermal in costs. Mitsubishi makes one.

Best strategy is to lower the heat loss as much as possible to begin with, then less strip heat is needed, which also costs a lot of money.

Can't win.
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post #9 of 15 (permalink) Old 2018-03-20, 07:16 PM Thread Starter
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Ill try and anwer all the questions. Thanks for the input

Located in Ontario.
We manager our TOU pretty well and have averaged $0.12 kWh (induced all extras, taxes, distribution etc)
House is 40 years old with new windows, doors and R50 in the attic.
Current heat pump is air-source electric.
I believe we were well over 100 kWh a day in Jan.

So consensus is that keeping these heat pump with electric aux is better than switching th aux to propane.

Why would ALL the new homes in our area be going with what appears to be 100% propane furnaces? Not electric furnaces with/without heat pumps? All these people were scrambling for propane when we had a cold spell around Christmas.
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post #10 of 15 (permalink) Old 2018-03-20, 07:20 PM Thread Starter
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Oh...hard for me to calculate the fixed costs? I assume youre asking for all the non-heat related hydro use? Im guessing $150 month? I guess Ill know that in late April/may when Im not running heat or A/C.
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post #11 of 15 (permalink) Old 2018-03-20, 07:22 PM Thread Starter
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Id also be interested in any speri necks running a heat pump. Ive read the traditional turn-down overnight might not be useful in saving money. Only means the electric aux will come on for sure to raise it back up 2 degrees. Wondering if I should experiment keeping the temp constant for 48 hours and see what happens. I can track electric usage by the hour from our utility co.
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post #12 of 15 (permalink) Old 2018-03-20, 08:06 PM
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Quote:
Both PV and solar water heating systems are very expensive
Solar panel generation has fallen rapidly recently. It's close to par with most other means of generating electricity. Ontario residents got burned severely because solar was adopted too soon. It's about 1/10 that price now. Generating your own electricity is even better in Ontario because it avoids all the extra taxes and levies placed on it. Solar generation peaks when the cost in Ontario is close to or over $0.20/Kwh so that's a better figure to use.

Quote:
Why would ALL the new homes in our area be going with what appears to be 100% propane furnaces?
New homes are a different scenario than retrofitting existing homes. Propane may be the cheapest choice for builders and contractors. It says little about long term costs. If NG was available a conversion would be very cost effective. Otherwise, it's probably better to wait until the current equipment needs to be replaced.
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post #13 of 15 (permalink) Old 2018-03-20, 10:57 PM
 
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Quote:
Located in Ontario.
We manager our TOU pretty well and have averaged $0.12 kWh (induced all extras, taxes, distribution etc)
House is 40 years old with new windows, doors and R50 in the attic.
Current heat pump is air-source electric.
I believe we were well over 100 kWh a day in Jan.

So consensus is that keeping these heat pump with electric aux is better than switching th aux to propane.

Why would ALL the new homes in our area be going with what appears to be 100% propane furnaces? Not electric furnaces with/without heat pumps? All these people were scrambling for propane when we had a cold spell around Christmas.
Electricity in ontario has a distribution component that's also per kwh which adds quite a bit to the bill. You have to go to your utility's website to calculate the true variable rate.

It could be an extra 2.5 to 5 cents per kwh.

Our electricity is super expensive which is why we don't use heatpumps much. The use of strip heat offsets savings compared to propane only.

They don't have enough capacity to begin with, being sized for a/c and it drops as it gets colder outside. Most traditional air source heatpumps may start needing supplemental heat from between 25 to 40f outdoor.

There are heatpumps out there which can maintain full capacity down to -20c or so and almost completely eliminate the use of aux heat. In canadian studies, the effective efficiency has been shown to be around 200% over the entire heating season, so cheaper than propane despite the high cost of electricity.

A traditional air source heatpump relying on aux heat may be 120 to 150% over the entire heating season.

The problem is, they're extremely expensive.

The one I know of is made by Mitsubishi; it's call "zuba".

---------------------------
You're right in that use of a programmable thermostat with heatpumps raises consumption - set it and forget it.

---------
Check your actual kwh per day on the bill. At 100kwh, unless your heat loss is really high, your heatpump may not be working right.

What size and shape is the house? What's the tonnage of the heatpump?
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post #14 of 15 (permalink) Old 2018-03-21, 11:13 AM Thread Starter
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House is a raised bungalow. About 2400 sq ft on the main floor. The basement is below grade at the front and at grade in the rear. Main living areas face south. Sun all day.

I think the HP is working fine. The high kw usage occurs when the 20,000 watt aux furnace kicks in (when temps are below 0 C or when the temp diff is more than 2 degrees.).

Im paying a lot but it seems my setup should be better than a standalone propane furnace without a HP. I guess folks here are avoiding the HP due to the initial costs.
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post #15 of 15 (permalink) Old 2018-03-21, 12:21 PM
 
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What's the tonnage of the heatpump?

If you add in all the variable costs, the propane would be cheaper than strip heat.

When the heatpump is small due to being sized for cooling, you use a lot of strip heat, especially with the house being 40 years old. This is the problem. The bungalow also uses more energy per sq ft than a two story.

if you can find a willing contractor, you can use a hydronic coil supplied by a propane condensing water heater for strip heat.

You can also spend a lot of money, doing something like adding insulation to the outside of the house, stuccoing over it to reduce the balance point and strip heat use.

No retrofit will come cheap.
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