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Comment on Oxford study proves heat pumps triumph over fossil fuels in the cold

The Oxford study is really good. But I can’t say the same about this article.

A COP of ~2 is not great for a heat pump, calling this a triumph is really weird. But from a journalist saying that a COP above 1 means the heat pump “creates energy”, I am not sure I should have expected more.

But what’s great is that this COP of 2, while bad, is not catastrophic. That’s still in territory where gas boiler are more cost efficient that a heat pump, but unless you are living in a place that is consistently under -10C for several months, then a heat pump has lower running costs than a gas boiler. And you are starting to hit pretty northern territories with this.

What’s important is also to be able to store heat during the day so that the heat pump runs at its most efficient time. But that can unfortunately coincide with the higher consumption time, so the timing needs to be adjusted properly to avoid using it during consumption peaks.

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CountVon@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

a journalist saying that a COP above 1 means the heat pump “creates energy” In this house, we obey the laws of thermodynamics!

But what’s great is that this COP of 2, while bad, is not catastrophic. That’s still in territory where gas boilers are more cost efficient that a heat pump, but unless you are living in a place that is consistently under -10C for several months, then a heat pump has overall lower running costs than a gas boiler. And you are starting to hit pretty northern territories with this.

I actually have a hybrid furnace/heat pump system, and I live in southern Ontario, Canada. The furnace is the auxiliary heat source and it only kicks in when the outdoor temp is below -6C. I’ve only had this system through one winter so far, but I think I could count the number of days the furnace ran without running out of fingers. My electricity bill went up some of course, but my winter gas bill went down a lot.

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- CoolMatt@lemmy.world ⁨1⁩ ⁨year⁩ ago
  I’m a 4th year AC/R mechanic born and raise in Southern Ontario, currently in BC.
  
  You mebtioned your hydro was up but gas was down. Out of curiosity, can you tell me how your total cost of heating changed before/after your first winter with your heatpump? Did you end up saving money?
  
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- ikidd@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Was there are brand/seer rating restriction with the GHGrant? I just applied and will be going this route, but I don’t want to be paying $15000 for a specific brand or something if I can get similiar equipment that might not be on a list.
  
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  - CountVon@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
    
    Was there any specifig brand/seer rating restriction with the GHGrant?
    
    It’s more complicated than that. The major components of the system all have to be qualified for the rebate, down to the component model numbers. There’s a lookup tool to see which model numbers qualify. For a hybrid setup like mine, there are three parts:
    
    Outside model number: this is the actual heat pump component that gets installed outside
    
    Inside model number: this is the condenser coil that gets installed on top of the furnace
    
    Furnace model number: this is the model number of the furnace itself
    
    A ductless system would only have two part numbers involved, the outside heat pump unit and the inside wall unit. No furnace for a ductless system of course.
    
    Every HVAC company I talked to was pretty knowledgeable about the GH program, so if you tell them you’re an applicant for the program then they should put together a quote that qualifies. Multiple HVAC reps advised me to make sure that all rebate-covered part numbers were listed clearly on the invoice. Apparently if that info is missing it can derail the rebate until the invoice is updated with full info.
    
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    ikidd@lemmy.world ⁨1⁩ ⁨year⁩ ago
    That’s a useful tool, thanks for linking that. How much did your hybrid system end up costing?
    
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p03locke@lemmy.dbzer0.com ⁨1⁩ ⁨year⁩ ago
Even the study could have used some better clarification on geothermal HVACs, which is the direction we should all be heading towards:

Ground-source heat pumps typically provide a very high level of efficiency, even during cold weather. The reason is that soil temperature does not change significantly between seasons, resulting in a higher—and more constan—COP. In addition, ground-source heat pumps do not need to expend energy on defrosting.

This commentary focuses on the performance of air-source heat pumps in mild European winters with average January temperatures above −10°C. We refer to these heating conditions as “mild cold climates”, whereas those with average temperatures below −10°C in the coldest month are designated “extreme cold climates”.

No, why?! Gimme the COP on geothermal. Google tells me it’s 3 to 5, but I would have liked a better source.

Regardless, while I understand that we should spread out our solutions, I don’t understand why we’re not talking more about geothermal HVAC systems. Household solar is all the rage, but my gas company is still charging me $25 a month just to have the gas on, never mind the winter costs.

If we’re talking about $5K a hole to dig for geothermal, that seems like a hell of a lot more cost-effective solution than either gas-based HVACs, or these air-based heat pumps. If it’s an area with only mild winters, you probably only need the one hole, which will last for 100 years at least. At most, we’re talking about 3-4 holes for a large house in Canada, and that’s going to pay for itself in 10-15 years.

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- alvvayson@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Geothermal has advantages, but air source is getting so good that it’s really becoming a niche.
  
  Spending $5K on insulation or heat recovery ventilation will be more effective than spending it on a hole.
  
  I saw an awesome home refurbishment in Montreal, they just went all-in on insulation. The heating was just done with a 500W resistive heating coil, just for the coldest days. They didn’t even have a heat pump, except for the heat pump boiler. The heat recovery ventilation did the rest.
  
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  - p03locke@lemmy.dbzer0.com ⁨1⁩ ⁨year⁩ ago
    What if you already have good insulation? It’s already well-known that old houses have shit insulation, so of course it’s worth investing money into that if you already need it. But, even heating a new house can be expensive.
    
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    alvvayson@lemmy.world ⁨1⁩ ⁨year⁩ ago
    If you have good insulation then the weakest link is usually heat lost through ventilation, or an inefficient heating system.
    
    Ground source heat pumps have their place, but it’s really a niche. It is possible to cheaply heat a home without them.
    
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  - DarthBueller@lemmy.world ⁨1⁩ ⁨year⁩ ago
    What is HRV? I thought it meant a ground loop heat exchanger. I’ve heard about it in the passivhaus model but don’t understand it.
    
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    alvvayson@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Houses need fresh air and need to expel dirty air.
    
    The dirty air is warm, while the outside fresh air is cold. With heat recovery ventilation, the heat is transferred into the incoming air and the exhaust air becomes cold. This warms up the air in a very efficient manner.
    
    It can also be combined with a heat pump to extract even more heat out of the exhaust.
    
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tony@lemmy.hoyle.me.uk ⁨1⁩ ⁨year⁩ ago

That’s still in territory where gas boilers are more cost efficient that a heat pump… a heat pump has overall lower running costs than a gas boiler

You just contradicted yourself… what did you mean here?

Electricity is 3x the cost of gas, so unless the heat pump has the COP of 3 or above it is more expensive to run. Once you factor in the high cost of installation people aren’t installing these things to save money.

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- marsokod@lemmy.world ⁨1⁩ ⁨year⁩ ago
  It’s not a contradiction if you put my whole sentence. When it is really cold, a heat pump will be more expensive than a gas boiler. But over a full winter (hence “overall”), the period where it is more efficient make up for it, especially since that when it is bad, it is not that bad.
  
  But you are right to mention the high cost of heat pumps. I would not advise anyone to get a heat pump with a goal of saving money, the return on investment is slow and rather small.
  
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  - pedalmore@lemmy.world ⁨1⁩ ⁨year⁩ ago
    I don’t agree with generalizing that ROI is slow and small. There are too many variables here specific to each market, location, and home. Someone with an old propane or oil boiler that is already planning to buy a new AC will absolutely see massive ROI going with a heat pump. In the US, federal standards will make furnaces more expensive (condensing only soon) and heat pump costs can be heavily subsidized. I bought a new HP that was cheaper than my neighbors new AC/furnace after incentives, and my running costs will be lower.
    
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