R290 refrigerant
For my fellow nerds:
I’ve read that the EPA is on the verge of approving more widespread use of r290 refrigerant. You may be familiar with R290 under its more common name, propane. This is part of a broader push to phase out high GWP refrigerants like R410A by the EPA.
This article had an interesting bit of information:
First, according to the EPA’s GreenChill Partnership, a typical supermarket’s refrigeration system holds an HFC refrigerant charge of about 3,500 liquid pounds. Unfortunately, the average store also has an annual leak rate of about 25 percent.
That means, on average, refrigerant leaks cause a single supermarket to emit about 875 pounds of refrigerant, mostly HFCs, into the atmosphere every year.
With more than 236,000 food retail outlets in the U.S. alone, one can quickly see that as much as 206.5 million pounds of HFC refrigerants escape from store merchandisers annually, evaporating into the atmosphere and contributing to the problem of global warming and climate change.
HFCs, unlike propane R290, have a GWP ratinggreater than 1,300versus R290, a natural, non-toxic refrigerant, which has a tiny GWP rating of just three (3). And, R290’s ozone depletion potential (ODP) is zero. Zero!
(From https://www.winsightgrocerybusiness.com/equipment-design/propane-r290-here-stay ).
First, Holy Cow! Supermarkets are leaking 200 million pounds of CFC’s into the atmosphere every year? That sounds really bad.
A couple of interesting things I’ve found reading about this. First, since propane has no ozone-depleting chemicals, you don’t have to have an EPA license to handle it. I could see that opening up all sorts of DIY possibilities.
Compressors have to be designed to the refrigerant, so existing equipment can’t be retrofitted. Compressors designed for propane seem to have very similar performance to ones with R410A.
The EPA is limiting propane compressors to charges of about a pound, 500g. This is out of concern for fire safety as propane is flammable. (Although homeowners regularly use 20-lb propane cylinders and we’ve been running natural gas pipes into houses for 150 years. But I digress). Because of the small charge allowed, most designs have a package configuration where the evaporator and condenser are close to each other and another medium — typically water — is used to transport heat or cooling to where it is needed. So we should expect to see propane first appearing in applications like air-to-water heat pumps.
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The European and Chinese versions of the R290 pumps seem to have a higher temperature output rating than the R410A versions. They all claim around 75C or roughly 170F. It might be something that will start to enable direct replacement of gas burners, etc for the houses that use radiators. In Europe this is a big deal as most homes are heated with radiators.
500g is not much refrigerant. Only the 2ton units have that small a charge on the European and Chinese markets. The 3ton and up have closer to 1 or 1.5kg. And those are all A2W with no lines, I don't see a charge of 500g being feasible for A2A systems.
The 500g is what is currently allowed, my fridge is R290 since it need very little refrigerant, so it is bellow the limit.
The change I believe is to allow for larger amounts for residential purposes. If you are talking about monoblock A2W units where all the refrigerant is outside the building, the bit of extra refrigerant seems much less of an issue.
Lot of the flammability of refrigerant has never made sense to me. The car manufacturers didn't want to replace r134a since the new stuff was slightly flammable yet it is fine to drive around with 20 or 30 gallons of gas in the tank.
>The change I believe is to allow for larger amounts for residential purposes.
The previous limit was 100g.
> If you are talking about monoblock A2W units where all the refrigerant is outside the building, the bit of extra refrigerant seems much less of an issue.
Yeah, you're allowed to have a 20lb propane tank on the deck next to the compressor.
propane in lines in your house is like 2 psi
as refrigerant it is hundreds of psi
Possibilities of problems with a leak are much more significant
Not saying it should not be used, but caution is not uncalled for.
Why would manufacturers introduce an R290 product to the US residential market if you can only target air-to-water customers? The few customers who have hydronic systems mostly either have cast iron steam radiators or fin-tube baseboard, neither of which are suitable for low-temp A2W systems (140F)
That's not even counting extremely conservative building codes and the extra worry around wood framed residential homes. I don't see R290 being approved or expanded much anytime soon in the residential market.
In theory, a manufacturer could create an A2W monoblock connected to a single fan coil unit via water lines instead of refrigerant lines. Cost to manufacture would probably be within a few percent of the current R410a minisplits with refrigerant connections. As R410A is phased out, manufacturers may not have a choice but to develop this path. I don't know if other refrigerants are being looked at.
R290 pumps claim an output of 170F, so they actually would work for older systems. This is why they are such a big deal in Europe where most homes are heated by radiators.
Because they can keep the high pressure propane outside the house
Because when you retrofit an old baseboard house, you end up with a lot more baseboard than is required, allowing you to lower water temps. I keep the aquastat on my boiler at about 165 degrees and it has never failed to heat the house. It is an outdoor reset system which runs the water down to like 110 degrees in warmer weather.
I'll start here by saying I don't believe their "annual leak rate of 25%" even a little bit. I work with very large refrigeration systems at work, we use these systems to keep large datacenters cool. Typical systems can be up over 1,000 tons of cooling capacity, with large amounts of refrigerant in the chillers. We typically lose around zero pounds of refrigerant per year. Older systems may have some need to recharge after leaks, but that's rarely more than 10-20 pounds on a system with up around 500-1,000 pounds or so of refrigerant, so around 2%. I can't see any facility losing 25% year over year -- refrigerant is VERY EXPENSIVE, and there is a HUGE incentive to keep it from leaking out. Typical maintenance will use "wands", which are electronic sniffer probes, to locate leaks. When leaks are found, they are repaired, typically by brazing (a sort of in-between better than soldering but not quite the level of welding). Very slow, small leaks don't usually show up, so we put a dye in the lines that shows up under UV light (blacklight). This lets those little leaks build up over time and become visible for checks.
Typically if you have a big leak, you fix it before recharging, and don't have to recharge that system again for years, if ever. I think the linked article is exaggerating here to push something that won't make as big a difference as they claim.
The problem with propane is that it is very flammable. It's been known for a long time that propane can work in old automotive R12 systems, but it's dangerous if you have a leak or get in a crash. Refrigerants are tradeoffs between operating temperature ranges over which they can work, efficiency (which is part of the GWP metric), ozone depletion potential (the ODP metric not mentioned here), toxicity, and flammability. The idea refrigerant would work over a large temperature range, have zero GWP and zero ODP, be non-toxic, and be non-flammable. I don't think such a refrigerant exists though.
In reality, everything is a tradeoff. At work, I like to spec R123 for large chillers, because it's very efficient, which keeps energy consumption down (which reduces both GWP and operating costs for the facility). The downside for that one is it is somewhat toxic, and requires monitors in the mechanical spaces to alert to any leaks. That's the tradeoff there.
In a residential application, toxicity and flammability become big concerns, since you spend a lot of time there and you are usually in a wood-framed structuch which much lower fire resistance compared to a typical commercial building. I'm not a big fan of using propane here due to the risk of what it can do if it leaks. R410A is fine here, and I really wish they'd stop constantly pushing to phase out refrigerants, which is hugely disruptive to the industry, and imposes large cost burdens on everyone for ongoing system maintenance over time -- often for little or no actual green benefit, which is probably the case here. Remember that back when R410A came out, it was all about ODP, and R410A was supposed to solve that so that we wouldn't need to phase it out at some point. People are chasing smaller and smaller gains nowadays, which often means greater cost than the resulting benefit.
Bill
Bill --
Thanks for the sanity check, my eyes popped when I read 200 million pounds of leakage a year -- just from supermarkets.
Thanks for the insight Bill!
FWIW, I did some digging and this EPA report from 2005 seems to be the source of the 25% leakage figure https://www.epa.gov/sites/default/files/documents/EPASupermarketReport_PUBLIC_30Nov05.pdf
I agree that a centrifugal chiller is unlikely to leak much refrigerant. However, a supermarket system pushes refrigerant around the building to serve display freezers and refrigerators, along with the walk-ins. They have racks with dozens of small compressors. There are hundreds, if not thousands of copper joints on small lines. The 25 percent is well-documented.
I dunno is it?
If they leaked that much then there would pretty much be a guy with a bottle of refrigerant in the store every day. Systems do not all leak a the same rate or cease functioning at the same time. If they were that unreliable they would go back to ice.
I cannot recall seeing a refrigeration tech at a supermarket. I did see the drain guy last week.