overcharging 410A heatpump

[thorton]

HI: Recently had my Carrier 38YZA heat pump serviced. It was still cool enough here(south eastern Ontario) that the heat pump was in heating mode. The tech and his apprentice did the usual things like pressure washing out door condensor etc. They hooked up the gauges and to check pressures. They felt it needed a smidgen of 410A. After that I didn't run the system for week and a half until the weather turned much warmer and much more humid. The heat pump went into cooling mode when I fired it up. That's when the problem started. The compressor started to cycle off and on and the unit had trouble bringing the temp down to set point. I believe the compressor was going off on high pressure. Called the company again and they sent a different tech. He said the pressures were not right for cooling. He played with adding more refridgerant, but stated he didn't want to put too much in and would rather have a little less, then too much. He also said he didn't know very much about the system I have Carrier 38YZA and FV4A Fan coil. So they sent a different tech over to check it out. He determined it was the TXV that was shot. They replaced it today and they had the system running for about 20 mins and seemed ok. They charged me 3.5 hours labour to change it. Does this all sound reasonable to you guys?

Thorton

[klyons20]

Since freon amount is so critical in these units the best way to charge the system is by weight. Recover all freon and read the neame tag for how many ounces..

regards
Kelvin

[dave82323]

i agree , recover all 410 and check for leaks with nitro or use existing refrigerant, repair leaks if found. pull vac and have tech weigh in charge compensating for lineset.. I have always totally recharged system with 410 when a leak has occured due to the type of refrigerant [blend]. no leaks great vac no restrictions proper charge..have a nice cool day

[swnoel]

To answer your question... yes, it sounds reasonable.

[ics tech]

3.5 hours sounds fair. He would have had to run and get the part. I doubt he would have that on his truck.

[hvac r us 2]

Sounds right to me also...

Cant understand how a tech can use "I am not familar with 410-A" as an excuse though.

Diagnosing a bad TXV would be the same regardless of the type of refrigerant.

[gha]

This particular unit is well known to me. Carrier has issued a bulletin recently for that TXV. 410 SHOULD NOT be topped up as it is a blended gas and depending on the leak will leak out at different rates causing a host of other problems in the future. The rate he charged to fix the TXV sounds pretty good. As for the tech that was unsure, there are some guys that just don't see heat pumps.The best way to charge it is by subcooling or superheat. Here in Canada we have to account for every ounce of R22 and 410 that we reclaim or use. So it gets weighed either way. In Canada you have to be a licensed HVAC technician with an ODP card to get your hands on 22 or 410, so reclaiming and filling with new 410 (if there was a leak) as a DIY project is not really an option.

[dash]

Can you share the Carrier bulletin number,and content?

[gha]

dash, bulletin #: SMB05-0012, keep in mind this is a Canadian bulletin so you may want to check with Carrier in the U.S. If you want I can scan this and email it to you, just drop me a note at my email address. It is 6 pages long.

[hvac r us 2]

I also have never heard of this bulletin? factory issued SMB05-0012 is in regards to heat pump reversing valve coils?

[thorton]

Originally posted by gha
This particular unit is well known to me. Carrier has issued a bulletin recently for that TXV. 410 SHOULD NOT be topped up as it is a blended gas and depending on the leak will leak out at different rates causing a host of other problems in the future. The rate he charged to fix the TXV sounds pretty good. As for the tech that was unsure, there are some guys that just don't see heat pumps.The best way to charge it is by subcooling or superheat. Here in Canada we have to account for every ounce of R22 and 410 that we reclaim or use. So it gets weighed either way. In Canada you have to be a licensed HVAC technician with an ODP card to get your hands on 22 or 410, so reclaiming and filling with new 410 (if there was a leak) as a DIY project is not really an option.

GHA: Would you mind making sure that this is the correct bulletin # from Carrier. I would love to discuss this with the dealer who worked on my heat pump. When I went over to pay him for replacing the TXV, I said to him that the heat pump worked fine until they came to do the general maintenance on it. Like I said in my post they washed the condenser and added a smidgen of 410A. Next time I turned on the heat pump it didn't work properly anymore. Also when I went to pay him he said that I should have got the extended warranty and it wouldn't have cost me a cent to fix the TXV. I said that I guess I should have, although, being a Carrier I thought I was getting the best, and being assured it would be installed properly, I didn't think I would have any problems for a long time.After all, I have owned three refridgerators in my life and never had any problems, and I have a 1989 Olds Touring sedan and the air conditioner has neve been touched.The heat pump is only 3 years old. What I think is going on is, the dealers anticipalte that most buyers will purchase the extended warranty and then they don't have to worry about a real good installation as Carrier will pay on the extended warranty for any problems down the road. Would a poor install have showed up before 3 years?
GHA if you would like to email me, please do dkirkham2@cogeco.ca

Thanks, Thorton

[Gunnery Sergeant Hartman]

Anything that is man made WILL break.

The question is when?

[airworx]

subcooling is used to check the charge on any expansion valve system. type of refrigerant has nothing to due with it. subcooling tells you how much refrigerant is in the system. if charge is low subcooling will be low if charge is high subcooling will be high.

[thorton]

Originally posted by airworx
subcooling is used to check the charge on any expansion valve system. type of refrigerant has nothing to due with it. subcooling tells you how much refrigerant is in the system. if charge is low subcooling will be low if charge is high subcooling will be high.

Hi Airworx: Would you mind explaining to me how tech's check the subcooling.

Thanx--Thorton

[dpatty]

Originally posted by thorton
Hi Airworx: Would you mind explaining to me how tech's check the subcooling.

Thanx--Thorton [/B]

Per site rules we are not allowed to give instruction on how to do this, sorry

[beenthere]

Originally posted by dpatty

Originally posted by thorton
Hi Airworx: Would you mind explaining to me how tech's check the subcooling.

Thanx--Thorton

Per site rules we are not allowed to give instruction on how to do this, sorry [/B]

All he has to do is a search, and he'll find the for your interest, and a whole bunch of other post that tells anybody how to do it.

[dpatty]

Yea thats true, That does seem to contradict the site rules doesn't it. Maybe Boss needs to look into that.

[thorton]

beenthere & dpatty--I'm not looking to try and fix the heat pump myself. What I'm trying to do is become more informed when my equipment is being serviced. You two may be very good refridgeration mechanics, nevertheless, there are some in the business that are not that great. This leaves consumers at the mercy of these not great contractors. So I try to become informed about things that I'm buying or having serviced. Hope you understand.

Thorton

[dpatty]

When a unit is serviced the tech should hook up some kind of temp probe to the lines comming from the unit, Thats how they get superheat and subcooling numbers. If they are not checking these temps then they are not doing there job. If the tech just wraps his hands on the lines then you know your not dealing with a good company and your unit will suffer.

Most companies that cannot figure out whats wrong with a unit do not even have the tools to do this.

[Edited by dpatty on 07-16-2005 at 02:05 PM]

[hvac r us 2]

Thorton you have the right approach, as a homeowner myself I understand where you are coming from.

TXV’s can go bad, a lot more TXV’s have failed due to foreign material, overheating, or just plan old miss-diagnosed in my opinion.

Non-condensable can shut a TXV down right now; of course changing the TXV will correct the problem after the system has been cleaned up properly. But it probably would not have failed in the first place if a proper evacuation and start was performed during installation.

Puron can be “topped off” so to speak. It is a 50/50 blend with an even leak rate. But the bigger question is why should it have to be topped off? Don’t let anybody kid you when they say, “better to be a little low” that is just as damaging to the compressor.

When you’re low on refrigerant there is not enough suction gas to properly cool down the compressor.

A little high, a little low…here’s a novel idea, how about being right on?

Sorry, you caught me monologing…sore subject with me (refrigerant charging)

Anyhow, checking sub cooling would be to complicated to explain to somebody with no refrigeration knowledge. But it would not hurt to ask you’re dealer how they determined if the charge is right, guys that respond with “the pressures looked good” are scary.

In your case the answer would be they charged by sub cooling, probably for that unit in the range of 12-14 degree’s of sub cooling.

Another thing to look for, did they change the liquid line drier? If the answer is no I would worry about their workmanship…insist on a new drier since they have been into the system.

Good luck, there are lots of great HVAC guys out there. Protect yourself by educating yourself on the subject.


One thing I did not see mention was the serial number? There were some units that got out with contaminated accumulators. I believe without looking most was in the 04 range.

There is a policy for that which gives the dealer the ability to change out the unit and labor.

Something you might want to look into.