Attention Canadians - time to switch from natural gas heaters to heat pumps?

[wayner]

I was looking up my cost of natural gas as I started heating my pool this past weekend. My all in cost for natural gas ia about $0.43/m^3. The direct cost for gas has come down recently and is about $0.10/m^3. But the carbon tax is now $0.124/m^3. The carbon tax is scheduled to continue to increase and get up to $0.324/m^3 in 2030. (I am not compaining about a carbon tax - that is a separate issue).

At those prices I am wondering when it makes sense to shift to heat pumps to heat your pool. I know that heat pumps are not as good for heating when it is colder and are slower to heat up your pool and I believe that they are more expensive to purchase. But when is it worth it to switch?

Does anyone have a link to a good analysis of the cost/benefit between heat pumps and natural gas heaters at various energy prices?

 

[PoolGate]

I doubt you would ever see an ROI. If the gas heater fails, then work the numbers. Until then, gas would need to be astronomically expensive to make it worthwhile to remove a working heater and replace it with another.

Figure out the cost per BTU I would be interested in that. Keep in mind heat pumps cost more to heat when it is colder and drier. So heat pumps are variable costs. Not to mention if you are extending your season with gas you can't do that with a heat pump.

 

[Newdude]

So heat pumps are variable costs

+1. Imagine a large Air Conditioner in reverse. Using the HP when it's cool out is like using an AC when it's 100+. It is much more expensive when it needs to run continuously.

 

[wayner]

Here is a calculator that I found. It shows a total cost of $1000/yr for a heat pump and $2700/yr for natural gas. That is at today's prices. If I throw in the increase in carbon tax that we will have in Canada then in 2030 the gas cost will be up to $4000/yr. These numbers are likely overstated as they probably assume that you are heating your pool all of the time. I used Buffalo as my location as it is the closest city to me.

The other thing with a heat pump is that I am on a rate plan where I pay very low overnight rates for electricity. So as long as the night time temperature is high enough then I can get pretty cheap operating costs.

In terms of shoulder season - I thought that a heat pump works as long as the air temperature is above 50F? Then why can't you use it to extend your season in September as the air temperature will be well above that during the days.

 

[Newdude]

I thought that a heat pump works as long as the air temperature is above 50F?

Mine didn't do well in the mid 60s or below, also with a large pool. It takes many BTUs to heat 100k liters and the HP has 1/3 the BTUs. There are no two ways about it.

. It shows a total cost of $1000/yr for a heat pump and $2700/yr for natural gas.

Make sure to add your taxes, fees and surcharges to the KW cost. My 'fees' have doubled my electric bill in the past, compared to the actual usage costs which don't look so bad on their own.

Also consider if you have price tiers, that the HP will be added to the electricity you already use, at the highest rate, maybe even bumping you into the next price tier.

 

[wayner]

Also consider if you have price tiers, that the HP will be added to the electricity you already use, at the highest rate, maybe even bumping you into the next price tier.

This is a tricky one. I am on a Time of Use electricity plan and here in Ontario they have just introduced a new plan with ultra low overnight rates. I have switched to this as I have an EV and I only charge my EV overnight. So overnight I pay $0.024 vs $0.24 from 4-9pm, $0.102 from 7am-4pm and 9-11pm and $0.074 on weekend days. On top of that there is about a $0.05 for transmission, distribution, and other tarriffs at all times. So I definitely don't want to run it from 4-9. And running overnight will usually be less efficient for a heat pump as the temperature won't be as high. But then I will be saving on electricity from both the pool pump and heat pump.

 

[wayner]

+1. Imagine a large Air Conditioner in reverse. Using the HP when it's cool out is like using an AC when it's 100+. It is much more expensive when it needs to run continuously.

And this brings up a pet peeve of mine. All summer I am paying to get heat out of my house and I am paying to get heat into my pool. Why not use a heat exchanger to move heat form the house to the pool? There are such products discussed on TFP, but they seem like a bit of a pain to install as you have to cut into your Air Conditioning system. But the concept seems like a no-brainer for anyone with a pool.

 

[Flying Tivo]

Titanium Pool Heat Exchangers | Swimming Pool Heat Exchanger | HotSpot Energy LLC

Go for it.
You can also have an electrical heater and use it at night and keep it covered.

 

[wayner]

Titanium Pool Heat Exchangers | Swimming Pool Heat Exchanger | HotSpot Energy LLC

Go for it.
You can also have an electrical heater and use it at night and keep it covered.

Yep - here is a long thread on this product: Hotspot FPH AC heat reclamation pool heater - a review!

 

[PoolGate]

I've run the numbers on those devices that interconnect your home AC and add the heat to the pool. Long story short, they are a complete joke.

 

[wayner]

I've run the numbers on those devices that interconnect your home AC and add the heat to the pool. Long story short, they are a complete joke.

Why is that? You never recoup the upfront cost with reduced heating costs? But won't that somewhat depend on your gas price, and how warm you like to keep your pool?

 

[PoolGate]

Why is that? You never recoup the upfront cost with reduced heating costs? But won't that somewhat depend on your gas price, and how warm you like to keep your pool?

In a nutshell, yes. But it is a bit more. When I looked at these last year, they put out something like 20k BTUs. That is a joke for a home swimming pool. That is enough for maybe a kiddie pool. So a minimal amount of heat best case scenario. 2nd point they only put out heat when your A/C is running. Your A/C cycles on/off to maintain your set temp. How often does it run? In your climate I suspect your A/C easily gets to your set temp and with minimal cycling maintains it. 3rd point following #1 and #2 this is purely supplemental heat you still need to maintain an actual pool heater. I didn't see any scenario where this would ever make any real difference to the pool. Only real difference is your wallet.

These are basically an afterthought of, "Wow, all this heat we are removing from the house, what can we do with it?". Which is great in theory. But in practice, it just isn't enough heat to matter.

 

[Catanzaro]

Wayner:

The only thing I can tell you from having a heat pump is that it takes quite a long time to heat up your pool. Another problem you are going to have whether you have a heat pump or NG heater is overnight heat loss. In NJ, we are getting very cool nights. The heat pump this week has been struggling to bring the temperate up because of the ambient temperature. The HP is working, but very slowly. I actually have a solar cover and the temperature is remaining at 74 degrees.

I just need 1 hot day to bring it up to 83-85 degrees and then the heat pump will maintain the temperature. My mistake was not using it those few days with the cover in the beginning. IMO, it takes twice as long to heat up a pool with a heat pump vs. the NG heater. This means running the pump twice as long. My single-speed cost about 125 per month in electricity if it runs 6 vs. 12 hours. Now factor in another 6 hours of heat pump usage, and the electricity is probably running at least $125 per month extra for both. Now, the question becomes are you consuming that much more gas?

I would recommend the NG heater with a solar cover. Plus you wrote 100,000-gallon pool (Is this correct in your signature)? And the only reason why I had the heat pump installed is that my clearance away from the house was within inches, and the township could have given me problems. If I failed, they would have to replumb the whole unit costing me thousands.

It is not a total loss, as my pool gets only about 3 months of use. I close the pool early because of the leaves and open up late. I find it saves a lot of time and money. And I never have any issues with algae because I recycle water with chlorine underneath a few times a year, plus I use a solid tarp.

 

[wayner]

Thanks for the info. I haven't had a solar cover on my pool but I think I am going to get one. It took me about 24 hours with my Nat Gas heater to heat my pool up from 62 to 84 last weekend. That cost me about C$90 in gas to heat up and then $10 to keep it there for the next day or so. I realize that a heat pump will take longer, but then I will just start a day or two earlier when I want the pool to heat up. Maintaining the temperature once you are warmed up shouldn't be a big deal, unless it gets cold, or in the fall. But you are correct about having to run the pump more. Currently I run my pump around 18 hours per day, I don't have a proper timer but I am getting one installed and will likely run it around 12 hours per day. My previous heater was a Jandy which had a timer to control the pump - I don't understand why all heaters don't have this. My current heater is a Raypak which doesn't do this and I want to integrate the timer into my home automation system. My electricity pricing scheme has electricity MUCH cheaper at night so I will be running the system more on an overnight basis - likely from 9pm to 9am.

Part of the issue with natural gas heating is that we have a carbon tax in Canada. Currently my all-in gas price is about $0.43/m^2 and $0.124 of that is the carbon tax. The carbon tax is scheduled to increase to $0.324/m^3 in 2030. So all things remaining equal my natural gas costs will increase by 50% in the next seven years, and they could go up by more as gas supply charges are very low right now as gas prices have collapsed after the spike last year due to the war.

My pool is 100,000L or about 25,000 gallons.

 

[wayner]

Interesting, thanks for the info @Catanzaro . I used to have a solar heating system. It wasn't enough to do all of the heating, but it would help increase the temperature by a couple of degrees per day and would reduce the amount of gas that I used. I would see this system the same way, not to replace an existing gas or heat pump heater, but to augment it. Although you don't think of Canada as being that hot, we can get sustained heat. For example over the next few days the temperature will be above 80F for about 8 hours per day, and it is still May, but night time temps will drop to the low/mid 60s.

 

[Catanzaro]

Wayner:

I have no idea why I can see the thread, but can see what you wrote in the e-mail. I guess Gas prices are through the roof in Canada. I am merely stating that you can never heat up the pool in 60-degree weather, maybe even low 70s to 85 degrees in enough time with a heat pump. Gas is Gas.

With us, the way our pool is used, it really does not matter. I am trying to figure out a way to either add a secondary gas heater (really small) that has to be plumbed in. Or I have a waterfall line with a shut-off valve. I can plumb black PVC hoses somewhere and actually recycle the water with a slow heating process. This may work over time and boos that temperature up 2-4 degrees which is all I really need. I will still need to spend money, so I have to figure out if it is cost-effective over this period.

The only time the heat pump struggles is from May 1st until the first week of June, and the last 2 weeks of September into September. This is due to the cold nights and heat loss. The only way to prevent this is the solar cover. And what a PIA to put on and remove as the pool is free form and it is cut in half.