I just installed an Earthlinked DX system with the air handler and compressor unit in the basement.  The county inspector passed the mechanicals but said a freon alarm is needed in the basement in case of a refrigerant leak.  Is this a common requirement or is my county just being a "you know what"?  These alarms are mega$$$.

FYI, this is a 4-ton system with eight 75-foot vertical loops in moist clay.  R-407C charge is about 28 pounds.

I smell an idgit. I would definately inquire and question why your dx system needs an alarm. Do they require the same for package units and or splits that are not dx? I would also want to know what is the harmfull effect they are trying to prevent. What are you supposed to do to help or fix anything if the alarm goes off? My .02

Posted By waterpirate on 04 Jun 2010 06:09 AM
I would also want to know what is the harmfull effect they are trying to prevent.

I 'spect 28 pounds (!) of refrigerant in the basement might
induce them wimpy oxygens to run for higher ground.

I'd like to know what the inspector is citing specifically. He may be citing refrigeration code or fire code.
The question is worth asking however as we get into such high volumes of refrigerant (" about 28 pounds").
My Michigan amended mechanical code for instance suggests only 18 pounds of R-407C are permissable to 1,000 cuft. So a small furnace room that does not freely communicate with other areas of the home could arguably make this installation improper. Add a standard gas water heater (with standing pilot) to the mix and we have a "Danger Will Robinson" scenario.
Further with a fan coil present, an inspector could determine the smallest room served by the ducts as the indicator of permissable refrigerant quantity, ergo a 30SF half bath could disqualify this system.
If the permissable refrigerant level is exceeded in the furnace room, it then must be in a "machinery room". A machinery room among other things activates fire code requirement for refrigerant detector.
BTW, listed and labled products (factory assembled) may have up to 6.6 lbs of refrigerant without triggering the code, so most water source heat pumps will not run into this.

One of the old criticisms of DX systems is the amount of refrigerant that could leak and "harm the soil". I don't think much of that criticism, but a leak in a home.....
.... think of 28 lbs of refrigerant released into a small home, rapidly (obviously worst case scenario), it could be extremely dangerous to occupants. I've been in a service van with a can of R-22 that didn't close all the way and was overcome in just a few blocks, fortunately I was awake and able to discern that something was wrong. I think morally a contractor has to consider providing the protection of a HFC detector in some circumstances.
I also think it is time for DX manufacturers to get the code up to date with their systems...."Ground Source Heat Pump System Loop Piping: The assembled loop system shall be pressure tested with water at 100 PSI......", sound like a good idea for DX loops? Its the code! Of course it's under "hydronic piping" but there isn't much in the code about GSHPs and no definition whatsoever of DX systems.
Sometimes we think it's good to fall off the radar in the writing of the code, but in this case, a resourceful inspector has defined the equipment himself; " refrigeration" - and the rest as they say........
You should involve your Earthlinked rep in this and suggest that if it is code and not in the manufacturer's installation instructions, perhaps they could apologize by bearing some of the expense of the HFC detector. Of course if it is not code, they can assisst you with a defense for future installations.
Shop outside of your regular suppliers for the HFC detector (on line). You might find an aftermarket version for much less.
Keep us posted and good luck,
Joe

Shouldn't the installer have quoted a code compliant job?  If this detector is indeed required by code, then I would ask the installer to pay for the entire detector, but be nice about it.

If I contract with a general contractor to build me a house, I would expect the job to include necessary smoke detectors per code even though they may not specifically be listed in the details of the contract.

Posted By geome on 04 Jun 2010 11:34 AM
Shouldn't the installer have quoted a code compliant job?  If this detector is indeed required by code, then I would ask the installer to pay for the entire detector, but be nice about it.

If my hunch about the inspector's posistion is correct;
The detector is required for a "refrigeration machinery room". Is that what we have here? Or is that what the inspector is calling it for lack of a better description?

I'm an inspector myself and un aware of this posistion being taken before, but it is defensible and may be sensible.
Either way I'm not going to hang the installer for what is a relatively uncommon enforcement practice.
Some things are left to inspector interpretation. My electrician who is also an electrical inspector was red tagged recently for using romex in liquid tight in what that inspector percieved as a "wet" location. The call was chicken$h!+ but defensible.
 
The Code is a work in progress that is sometimes uncommonly adapted, sometimes ignored (like not putting water in DX tubes for pressure test), sometimes over enforced or dangerously under-enforced. The book has things that don't make sense in it (i.e. my warm air duct must be an inch from floor joists but my 90% furnace exhaust pipe can touch them).
I maintain that the DX manufacturers are way behind at getting their product recognized by the code. It took the CSST boys (Wardflex et al), about 10 years to get code writers to define their fittings as other than "mechanical joints" (like unions) so that they could be installed in concealed spaces. It takes time and money.
The DX makers are going to have to spend that time and money or continue to be thought of as abnormalities subject to code officials' interpretation. That's why I'm suggesting the installer get with the rep.

I'm certified in 2 different DX systems. I like the technology. I make my points as a proponent of a system that I would like to see elevate it's game to where a mainstream equipment should be.

Joe

Maybe I shot my mouth off to soon.  I gave no thought to a gas displacing 02.  Is that flavor gas any different from the gas in a split unit or package unit geo?  Also volume is an issue?  Due to the refrigerant being a DX more total pipe volume?  How tight would a house have to be for this to be an issue?  Is this gas heavy or light compared to 21% 02? 
Education please.

R-407c is a mixture of three components -- all heavier than air,
with the two major components 3x to 4x heavier than air.

The 28 lb charge is much larger than a non-DX residential heat pump --
but the volume (at atmospheric pressure) is only about 117 cubic feet.
That's much less than I would have guessed.

Can't imagine it displacing the O2 in anything larger than a phone booth.

...any of you wippersnappers ever heard of a phone booth?

Geezer Looby

Posted By Looby on 04 Jun 2010 06:07 PM
...any of you wippersnappers ever heard of a phone booth?

Kind of like a little Tardis, right?

Thanx looby, if 28# equals 117 cubic feet I can now see the volume. It would have to be an awefully small and tight house for this to be an issue, I would think. The fact that it is heavier than 02 would mean that a leak would occur and flood the room from the floor up. The unit would cease to work immediately signalling a problem and potential leak?
Geome? A tardis refferance? really?
I am a huge fan! I had a 1926 penguin sail boat all varnish bright work amidst a sea of white fiberglass. Her name?
Tardis of course.

Posted By waterpirate on 04 Jun 2010 07:33 PM
Thanx looby, if 28# equals 117 cubic feet I can now see the volume. It would have to be an awefully small and tight house for this to be an issue, I would think. The fact that it is heavier than 02 would mean that a leak would occur and flood the room from the floor up. The unit would cease to work immediately signalling a problem and potential leak?
Geome? A tardis refferance? really?

We're dealing with two things here. Code and actual threat to safety.
Regarding safety, " heavier than air matters less if the fan coil leaks and it is mixed with air delivered around the house. If it doesn't leak into the ducts, it may leak into the mechanical room where a pilot light may be present on a gas water heater. Lots of ifs, but isn't that what code and safety regs gaurd against?
Regarding code, it doesn't specify the amount of threat, it specifies the amount of refrigerant allowed in certain situations. It appears this install may be contrary to that in this circumstance.
New code also requires CO detectors in homes with any fuel burning appliance (including a clothes dryer or stove). Is the risk remote? Sure. Is the code still boss? Yep.
I'm not saying I agree with the particular inspectors interpretation. In fact I still don't know what he's hanging his hat on. However, it does beg clarification in my mind.
Perhaps my inspector hat is the problem. Does no one else see a conflict with code here?
Joe

Hi Joe,
Not bucking the code.  I am just seeking understanding on my part.  I work and weave my way through at least three different code books almost daily. lol  That gas being contained in a mechanical space/room could obviously be a risk.  I also did not know it was flamable?  If the code iinspector is confusing two issues, gas volume being one the installer should be defending his install to the best of his ability.  If the detector is required in the end, a shared cost home owner and installer would be fair.

 

 

It would be nice if OP offered specific reference inspector wrote up.......
We (inspectors included) agree that the code and some inspectors are a little crazy sometimes. Main point is that if this guy has a defensible-enforceable point then our DX colleagues better start costing in HFC detectors.
J

Posted By waterpirate on 04 Jun 2010 07:33 PM
Geome? A tardis refferance? really?
I am a huge fan! I had a 1926 penguin sail boat all varnish bright work amidst a sea of white fiberglass. Her name?
Tardis of course.

Hey WP,  me too, starting with Tom Baker.  I think Ona and stuart.wyss are fans too. 

Thanks for all the informative discussion!

I also did the R-407C volume calculation and was surprised it was less than 120 cubic feet. That seemed to take oxygen displacement out of the argument. The compressor unit and air handler are both in a walk-out basement with about 800 square feet in the room. With an 8-foot ceiling, that gives 6400 cubic feet of air to mix that 120 c.f. of R-407C into. So it is conceivable that the concentration could get to about 2% if all the stuff vented into the room. So the inspector's concern must be the 20,000 ppm concentration in the room, not oxygen displacement. 1000 ppm appears to be the limit for 8-hour occupational exposure. This would be exceeded even if the stuff was mixed throughout the entire house. DX installers may indeed want to start looking at refrigerant alarms.

My contractor found an HFC alarm for about $725 that we are still waiting on the inspector to approve. It's a SHERLOCK 102 Refrigerant Gas Monitoring System. The first alarm he found was more like $2000 and he asked if I would go 50/50 on the cost of that one. I think he is willing to pay for the cheaper alarm as part of the contract of supplying an approved system.

I'll let you know what I hear from the inspector.

O2 displacement was never a suspect of mine for triggering the code. Volume V cubic feet of smallest room served by duct on the other hand......that's code lingo. Is there anyway you could find out what the specific reference was for the red tag?
BTW anyone else smile at the "heavier than air" description of HFC that simultaneously are alledgedly climbing into the atmosphere and blowing holes in the ozone layer???? I know, I know, 407C is supposed to be non- depleting, but we could have had this same conversation last year with an Earthlinked R-22 system.
Personally I still believe the 70 year old technology of the water source geos and 30 year old DX systems are a tad archaic. I hope something can upstage them. Will it be new low ambient air source technology? I would say the smart money is on anything that doesn't tear up the lawn. Currently however ground loops are the best horse in the race (IMHO).
Joe

Posted By joe.ami on 08 Jun 2010 12:45 AM
BTW anyone else smile at the "heavier than air" description of HFC that
simultaneously are alledgedly climbing into the atmosphere and blowing
holes in the ozone layer????

Not even a grin. An escaping slug of high density gas will initially flow into
the low spots -- but it won't stay there very long. Gasses mix. If they didn't,
we'd all be most sincerely dead. Carbon dioxide is heavier than oxygen or
nitrogen, but the lowest 5% of the atmosphere ain't pure CO2, is it?

...physics and chemistry don't give a rat's rump about what humans "believe,"

Looby

Well then, I guess we need that HFC alarm.....

Just an update here. I am still waiting on the county inspector to make a decision on the HFC detector. He is looking into an alternative solution, installing a sealed door and closer between the utility room where the compressor is installed and the rest of the basement.

These county guys seem to be in no hurry to do anything!

Did he share with you a specific code # he's hanging his hat on?
J