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Hi All,

I am planning to upgrade my aging furnace (probably over 30 years old) and possibly my hot water tank (maybe 10 years) at home and take advantage some of the rebates the governments are offering right now. I came across the heat pump technology for heating/cooling and am very interested. I’ve already contacted a couple of local HVAC contractors but I feel I am not getting the honest opinion and planning from my point of view. The reason why I said that was they both suggested to get a heat pump system (as I showed interested) and also the new high efficiency gas furnace as a backup. This setup is really expensive as they are for two brand new space heating system. With the average temperature in my area, the backup gas furnace would hardly ever be needed.

Temperature near my area.
https://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?searchType=stnProv&lstProvince=BC&txtCentralLatMin=0&txtCentralLatSec=0&txtCentralLongMin=0&txtCentralLongSec=0&stnID=876&dispBack=0

Questions:
1) For the central air heat pump system, are there systems that would work by themselves without an air handler to work? Or perhaps the air handlers that’s already built in? one of the things I get from HVAC contractor is I need an air handler anyways for the heat pump system and might as well go for a gas furnace and use their blower to complete the system.
2) Am I right in saying, in my area that rarely see any sub-zero Celsius days, I would not necessarily need a “backup”? There are quite a few “cold climate” heat pump out there that seem to work quite well at near zero degree C.
3) I’ve heard a combination system for heat pump that will do both space and hot water heating. Is that also a hot water tank system but heated by the heat from the heat pump system as well? is this kind of system efficient? Or I am better off staying with a gas water tank.
4) In my area (near Vancouver, BC), I was told by the HVAC contractors that gas heating is 3 times cheaper than electricity. Which I roughly translate into if I can get a heat pump that operates at 3 COP or above at most days of the year, I am not only helping the environment but also saving money.

A few notes on where I stand now. I would like to help the environment by switching to electric heating since our grid is fairly clean and should only get cleaner going forward. I don’t mind paying some higher upfront cost, but it has to be within reasons. That goes with the operating cost as well.

Thanks,
Andy
 

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Central heatpumps are either installed with a furnace or air handler.

To do all electric, you would get an air handler. A 200 amp service is a must if backup heat is installed.

In vancouver with reasonably priced electricity and not a lot of very cold weather, dual fuel with a furnace is probably not worth the money.

When the heatpump can no longer keep up, the furnace usually takes over completely even if you only need a little supplemental heat. Heatpump and furnace can't work at the same time because the furnace is upstream of the heatpump coil.


When an air handler is installed, the backup heating elements are put downstream of the coil and can work to supplement the heatpump if it falls a little short.

It probably won't be cheaper to run an all electric system than gas due to how cheap gas is right now, but it's certainly better in that you're not burning limited fossil fuels to heat. BC as u probably know is mostly hydro so it's renewable and heatpumps can be very efficient.

(it is possible to do dual fuel with an air handler and hydronic coil off a gas water heater)

It's easy to calculate comparative operation costs if you know the delivered hydro and gas rates.

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To do a heatpump, you need a really competent contractor. Furnaces often heat okay even when they're hacked in, not set up properly and incorrectly sized.

Heatpumps are extremely installation sensitive. They don't heat anything like furnaces - which usually supply far more heat than needed. Capacity loss due to improper charge, mismatched components and incorrect airflow can render a heatpump garbage.

A load calculation needs to be done to see how much heat the house needs and how low a heatpump can heat to without supplemental heat.

The air ducts need to be evaluated see how much airflow they can take - ideally, should include a direct cfm measurement and static pressure test.

Heatpumps need to move more air than furnaces to provide enough heat.

In your climate, the unit should be sized to minimize or eliminate the need for backup heat. This is not always possible due to air duct constraints.

Heating capacity drops as it gets colder outside - if a heatpump is 3 ton/36 000 btu/hr, it only provides that at 47F outside.

At 25F, it may be more like 24k btu.

Heatpump output and heat loss get plotted on a graph to determine below what out-door temp supplemental heat is required.

There are heatpumps with inverter technology which can maintain full capacity down to like -20C or lower but they're very expensive to purchase and repair. They're more suited for climates with real winters.

Edit: electric elements are required in all electic applications even if there's enough capacity to temper the air during defrost cycles.
 
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3) I’ve heard a combination system for heat pump that will do both space and hot water heating. Is that also a hot water tank system but heated by the heat from the heat pump system as well? is this kind of system efficient? Or I am better off staying with a gas water tank.
Stay with mainstream equipment.

There may be a couple of small manufacturers that make combo air-source units that heat water both for space heating and dhw, but if they're uncommon in your area support/repairs will be a nightmare.

It's important to get equipment that most techs in your area know how to service and parts are readily available.

It may make sense to get a straight electric water heater if you pull the plug on gas for heating. While gas may be a lot cheaper, you have to consider the monthly cost to have a gas meter as it may offset any savings.

You can look at a gas water heater that is approved for space heating, get an air handler and put a hydronic coil in there for backup instead of heating elements needed for defrosts and supplemental heat.

Can save you from having to upgrade to a 200 amp service.

Dual fuel that allows the heatpump to continue to run when it's still efficient but just doesn't supply enough heat.

The COP of a decent HP can still be 2.5 below freezing.
 
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