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Posted By Topic: removing a heat pump. what's involved?

rarrar
Aug 07 2019 19:47

electrically it's simple but what's involved with the gas etc, both to remove for re use and for disposal ?
   

ppaw1965
Aug 07 2019 22:25

If it’s still working you can shut off the outlet and pump the gas back into the unit then shut off the inlet. This will only work if it didn’t have extra pipe and gas added.
If not working will need to attach an email external pump and storage.
Any fridgie should be able to do it easily enough.
   

mazdaman
Aug 07 2019 22:42

For re-use of the heat pump: From a Daikin manual (with extras):

1) Remove the valve cap from liquid stop valve and gas stop valve.
2) Carry out forced cooling operation. (Or just use the remote to put it in cooling mode. If the air temp inside is too cold, use a hair drier, heat gun on low near the temperature sensor (right hand side of inside unit) to simulate a warm inside temperature)
3) After five to ten minutes, close the liquid stop valve with a hexagonal wrench.
4) After two to three minutes, close the gas stop valve and stop forced cooling operation.

(Ideally use a Low Pressure gauge to watch the pressure - it usually only takes a minute or so to get to zero. Close the larger valve, switch off the isolator. The refrigerant is now back in the compressor just like it was when the unit was new.

For disposal, use a recovery pump to suck out the refrigerant into a cylinder which is then taken to a collection depot (such as Pattons) where it is transferred into a larger cylinder and sent overseas. There is no charge at the depot.
   

Someone
Aug 07 2019 23:19

The issue with the above procedure is quite often the unit will declare a fault, open the valves back up, and shut off the compressor - releasing the gas back into the system.

You need the gauge to be able to close the valve once the pressure reaches atmospheric, so that you close it up before it decides there's a fault.
   

rarrar
Aug 08 2019 09:38

what qualifications must the remover have, if any?
   

AlecK
Aug 08 2019 11:19

Disconnection of electrical fittings is PEW, so a PL that authorises disconnection.

Not sure about licencing for removal / disposal of refrigerants; but there will be Regs governing that.

-------------

The problem with pulling the system down only to atmosphere is that still leaves some refrigerant in the pipes, which will escape to environment. Needs to be pulled down to vacuum.
   

Someone
Aug 08 2019 21:49

There's basically no licensing requirements for working with refrigerants here. Some places won't sell to people without an 'approved filler' ticket, which is I think mostly a safety thing.

You can pull down below atmospheric, but there are diminishing returns; you are down to the last few grams as there is no liquid refrigerant left (it will all have boiled off) and you risk contaminating the system if there are any leaks, as sometimes gear can leak under vacuum but not while pressurised.

A rough back-of-the-envelope calc says there's around 2 litres of space in the pipes (being generous), and 410A gas at atmospheric pressure (whether the -52C boiling point or room temperature) is about 4 grams per litre. 8 grams total is not really worth worrying about.
   

AlecK
Aug 09 2019 08:52

I'd be happy to accept that if you backed it with documentation. It's a long time since I worked in this area, the refrigerants have changed and so have the rules.

From EPA website:
Under the Climate Change Response Act 2002​ (CCRA), New Zealand has banned the knowing release of SGGs from particular sources and activities. This is restricted to penalising anyone who knowingly, and without lawful justification or excuse, releases SGGs into the atmosphere while installing, operating, servicing, modifying or dismantling any electrical switchgear, refrigeration or air-conditioning equipment or other heat-transfer medium.
We have enforcement powers under CCRA and offenders can be fined up to $50,000 for wilfully releasing SGG into the atmosphere.

The wilful release offence captures everyone who is aware they are releasing SGGs while performing specified activities. The reasonableness test will then provide a defence for those people who are using best practice in their industry.

Therefore, the offence would not be triggered where:

- SGG is leaked into the atmosphere slowly over the natural course of a product’s life
- SGG is released during servicing where the best industry practice was being exercised.
----------
From CCRA:
265 Defence for release of synthetic greenhouse gas

The circumstances in which a person described in section 264(1) may have a lawful justification or excuse for releasing any hydrofluorocarbon, perfluorocarbon, or sulphur hexafluoride into the atmosphere include (but are not limited to) circumstances where the release could not reasonably have been avoided.
--------------------
So where is "industry best practice" documented these days?
And does it allow this small amount, or does it call for vacuum?
In the context of a decommissioning, I would have thought that the risk of contamination from pulling a vacuum (which in my day was standard procedure for eliminating contaminants such as air and moisture; on basis that a properly-installed system shouldn't leak) couldn't outweigh the prohibition on release.




   

MitchB
Aug 09 2019 10:07

I have read that a small amount of refrigerant release is tolerable, i.e. it is unavoidable when connecting/disconnecting gauges to a pressurized line.
I seem to remember reading this in the coursework one of my guys did for the Split Systems AC course run by MIT, will have to see where it's cited as being from.
   

AlecK
Aug 09 2019 10:32

The problem is, with all this sort of thing, that it only takes one disgruntled busybody to make a complaint, and suddenly the council / MBIE / EPA / whoever mounts an investigation =- and they seem to mostly be very anal about how they interpret rules. Especially if the relevant rule has any weasel-words like "minor", "small", "adequate" or 'reasonable"; that give them room to move the goalposts so we can be found to have transgressed.

So the days of "just don't worry about it" have gone, and we need to be absolutely sure our bums are covered. Or at least know whether they are.

Just look at the shit-storm that began with a lazy sparky not cleaning up after drilling a switchboard; and the homeowner wondering what the black dust actually was.
   

Someone
Aug 09 2019 19:16

Your quote:

So where is "industry best practice" documented these days?
And does it allow this small amount, or does it call for vacuum?
In the context of a decommissioning, I would have thought that the risk of contamination from pulling a vacuum (which in my day was standard procedure for eliminating contaminants such as air and moisture; on basis that a properly-installed system shouldn't leak) couldn't outweigh the prohibition on release.

My quote:

Pulling a vacuum with a vacuum pump dumps everything in the system (air, moisture, refrigerant) to atmosphere - this does not help contain refrigerants already in the system.

Leaks can develop over time. While a new system has hopefully just been pressure tested and is totally clear, a 10 year old system being moved because of e.g. earthquake damage to the house - that has a much higher chance of a leak.

Using the AC compressor to pump down will take it quite near vacuum, with an increased risk of compressor damage due to lack of lubrication and cooling, though that's not too bad as you theoretically do it very infrequently. And the previously mentioned risk of sucking in things that you don't want.

You could also use a recovery machine, which pumps the refrigerant into an external tank, e.g. for destruction or to re-use (such as if you're replacing a part in the machine, then want to re-charge it).

Many refrigerant recovery machines have a low pressure cutout; a search finds that this seems to be around 10-13 inches of mercury vacuum, or about 2/3 of an atmosphere. They do not pull down to a near-pure vacuum like a vacuum pump.


   

SymonS
Aug 09 2019 21:05

"I'd be happy to accept that if you backed it with documentation. It's a long time since I worked in this area, the refrigerants have changed and so have the rules."

There are No restrictions on who can fill or recover refrigerants in this country !!

Their was an attempt a few years ago by the EPA, formerly ERMA, and IRHACE to introduce a voluntary code which introduced the "No Loss" card, but this largely went ignored by all and sundry, especially those in the Electrical Trade once radcliffes and the like started selling heatpumps to contractors.

Those of in the refrigeration trade that actually cared back then went and got a dangerous goods, compressed gas filler and recovery, licence. A two day, NZQA course run by ERMA, but the only thing that actually meant was that some wholesalers would only sell refrigerant to licence holders.

Not all wholesalers got on board, and has largely been dropped these days.

While there are rules around knowingly releasing, and disposal, there are No restrictions on who can work with it, Unlike Australia, who is pretty strict on its requirements.

Bit of a farce really.

Code of practice is below.
https://www.irhace.org.nz/uploads/COP_Refrigerant_handling_2007_Part_1.pdf
   

SymonS
Aug 09 2019 21:09

And for what its worth, I had more than a little bit to do with developing that COP.