Edit on post #39: Should me NOT allowing it to it to heat up to 100F.
Cold Climate Heat Pumps
- Thread starter Snagglefoot
- Start date
I was thinking the same thing and seriously needed some upgrades to insulation and draft elimination.
My parents cape they had blown in insulation added inside all wall cavities and in attic areas. Made a huge difference in comfort and yearly costs.
Generally R40 used to be the standard for attics but R60 is now encouraged up here and is a standard in some locations.
Here is a snap of my power usage. The freezing temps have been here for a few days, testing my heat pump to its limit. Looks like I was staying under 50 kWhrs except one day when we were using the electric oven. I started the week with the 500 gallon propane tank at 70%.
It’s 20 F today and the system switched to the propane automatically. The temp coming out of the hot air register is 82 F, instead of the 75 F I was getting with the heat pump at its limit at 27F outdoor temp.
When I burn propane, I make a fire in the air tight wood stove to reduce the propane consumption.
It’s 20 F today and the system switched to the propane automatically. The temp coming out of the hot air register is 82 F, instead of the 75 F I was getting with the heat pump at its limit at 27F outdoor temp.
When I burn propane, I make a fire in the air tight wood stove to reduce the propane consumption.
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I don't like these freezing temperature heat pump. It does not make sense if you can burn natural gas or wood for cheap, you rely on the carnot cycle after you burn the natural gas then transmit it elsewhere to do heat pump.
In my area (usually won't go below 30F but typically only 45F in winter), even if heat pump is scientifically efficient (i.e. 2x 3x vs resistive heat to get a house to 72F), the natural gas is 5x cheaper than electricity, so a 80% efficient furnace would still be cheaper to run than a heat pump with a grid of natural gas.
Wood burner is typically not allowed during winter spare the air day because everyone burning wood leads to air quality issue. For me if I can get a small multi stage furnace to run continuously it would be the best. Or if someone wants to run a quiet (below 50dB) server in my house in the winter and warm my house up for free while paying for my electricity, it would be great too.
One of my friend just mind crypto in the winter, to break even on heating bill, I guess it works.
In my area (usually won't go below 30F but typically only 45F in winter), even if heat pump is scientifically efficient (i.e. 2x 3x vs resistive heat to get a house to 72F), the natural gas is 5x cheaper than electricity, so a 80% efficient furnace would still be cheaper to run than a heat pump with a grid of natural gas.
Wood burner is typically not allowed during winter spare the air day because everyone burning wood leads to air quality issue. For me if I can get a small multi stage furnace to run continuously it would be the best. Or if someone wants to run a quiet (below 50dB) server in my house in the winter and warm my house up for free while paying for my electricity, it would be great too.
One of my friend just mind crypto in the winter, to break even on heating bill, I guess it works.
Don't forget that in MOST installations, the 80% efficient furnace is drawing it's combustion air from inside the house, which is made up by cold air leaking into the house to replace what the furnace sent up the exhaust flue.
The cost of operation greatly depends on your utility cost. My heat pump is cheaper to run than my natural gas boiler until about freezing (so the math says). But I plan on testing to see how much power it actually uses below freezing. The heat pump brings the house temperature up much faster than the boiler so far. FWIW both my utilities are high. $0.29/kWH and just over 2$ per therm. Or about $22 per MCF of gas.
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Yep. That’s an obsolete furnace. It’s now code up here in new furnaces to have sealed combustion air and a condensing furnace with approx 92-98% efficiency but sometimes I think the condensing feature is not worth it. I’ve seen condensing furnaces that use a pump to move the fluid to a drain. For those unfamiliar with the condensing feature, heat is extracted from the exhaust gas resulting in a small but steady stream of acidic water that needs to be dumped into the sewer drain. If there is no drain nearby, a small pump moves it to the drain.
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Yes, I’m finding anyone with natural gas will typically beat the cost of a low temp heat pump when the temps are below freezing especially when the electric power costs are high, say over $0.20 per kWhr. And yes, the fireplaces add smoke pollution in the cites but are viable in the the rural area. However, there are new subdivisions in the lower mainland where developers are not allowed to bring in natural gas. The price of electricity in BC is $.10 US per kWhr, so heat pumps beat natural gas in the lower mainland. The lower mainland is Vancouver, Surrey, Abbotsford, Langley etc. Also, natural gas is currently cheap but can easily go up as it is a traded commodity.
For me, I don’t pay attention to issues like the Carnot cycle. I go on cost. Some folks go on CO2 but that’s not me.
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Yes it really depends. Mine draw from garage vented to and from outside (with water heater anyways), so it doesn't impact the interior.
With my system switched to propane, and using a modern sealed wood stove with its own fresh air intake for heating in the morning, I’m burning about 4 gallons a day of propane. This is with temps in the 15 F range.
I would switch back to the heat pump!! If it will spit out hot air that is. With temps in the low 40s during the day yesterday and a low of 36 last night I used 19 kWH to my power my whole house for 24 hours with running the heat pump. 4 gallons of propane would be around 20$ here. That would be one hell of a heating bill here for a month.
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The amount of glazing (ie. windows) is a big issue. The double pane glass has an R-value of around 3, triple pane isn't much better at 7-8.
Everyone needs to look at their own situation. My 2012 3-1/2 ton heat pump can run down to 27 F and then switches to propane. Propane is just over $ 2.00 per gallon, so 4 gallons is about $8.00. On a BTU basis, it’s a bit cheaper than electrical heating coils.
I agree with each situation is unique. Propane between 3.50-$4 per gallon here. Thank god I don’t rely on that for fuel.
Yes, those dramatic cathedral ceilings with a wall of glass are bad news.
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I've used mine down to -6C I think, I was going to try it down to -10C, but we didn't get any -10C days after we got it installed, lol. It's good to -30C, but my gas furnace is probably cheaper to run below -5C or -10C. Thing is, I have to manually override it, because it's locked in with a -2C changeover due to how it was programmed by Enbridge and I can't change it until a year has gone by, that was the deal with the $4,500 rebate that was being provided.
Here is a plot from my electric company, BC Hyro. I drew two red arrows on it. The first arrow shows when the temp first started to drop it made the heat pump work more of the time, increasing my power consumption towards 50 kWhrs per day. Then the temps went lower and my heat pump turned off below -3 C and the propane boiler with the heat exchanger kicked it. The power consumption went down as the propane provided the heat and only the water pump consumed electricity as it pumped the hot water from the boiler to the heat exchanger. This is shown by the 2nd red arrow. In both cases the furnace fan also operates. Where the two arrows met was the 50 kWhr per day line. So, I lowered the electrical consumption from 50 to about 30 kWhr per day, worth about $2 and my propane cost was about $8 per day for a net increase of $6 per day, when the temp goes below 27 F. On the coldest days at -30 C, my propane burn is about $14 per day, depending on the cost of my next propane fill.
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That cut-off temperature is adjustable and it's unlikely that whomever set it at 27F put a lot of thought into it.
Actually no, the HVAC guy and I chose -3 C ( 27 F) as the 3-1/2 ton heat pump was running almost full time at that point to keep the house heated. If the unit would have been a modern low temp heat pump I could have run it to at least -18 C (0 F).
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