New condensor

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mggray87

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I have a 2 story 2485sq foot home 3bd 3bath house with formal ceiling at 20feet.

I currently have a carrier 38ckc048-371

It actually works pretty good. I'm relocating the condensor location since they put it on my patio where our furniture is. It's worst location. And it's loud. So I'm thinking to remove and relocate this old thing might not be worth it. Since I'm disconnecting and relocating. Might as well put a new condensors. But not sure what brands to look at
 

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Dana

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R22 will be going out of production in 2020, and though it's still legal to sell "dry" R22 replacement condensers, are sure you really want to invest in an R22 future with a new condenser? A replacement condenser would have a minimum SEER rating of 13 (up from 10 for your older unit), but it's unlikely to ever "pay off" in the short life time that R22 equipment will be able to be fully supported.

Also note, a 4 ton split AC system would usually be substantially oversized for the true cooling loads of a 2 story ~2500' house (even a house with a 20' ceilings for part of the house.) Most homes that size would come in under 3 tons, many under 2 tons with the low latent loads of CA.

An Atlanta GA area HVAC guru who lives & dies by Manual-J load calculations came up with this plot of square feet per ton vs. house size on projects he's worked on, most in the steamy gulf coast states (with high latent loads, unlike your mostly negative latent loads.) If you look at the cluster of houses between 2000-4000 square feet you'll note the middle range is about 1400-1500 feet per ton, and NONE are as low as your (2500'/4 tons =) 625 feet per ton:

square-feet-per-ton-air-conditioner-sizing.png


So your real load is probably on the order of 1.8 tons, to maybe 2.5 tons at the high end. Oversizing the equipment by that much costs more up front, and leads to lower operating efficiency & lower comfort.

It's probably better to keep the equipment you already have and move it, then next summer see if you can get a handle on the actual cooling loads by datalogging the duty cycle of the compressor on the hotter days when afternoon temperatures at or near your 1% outside design temperature , (about 97F same as Stockton or Concord.) By using the unit itself as the measuring tool the parasitic loads of duct gains, duct leakage etc, are already built-in, but you'll then have hard data on what would be a better size for the eventual replacement.

Right now R410A is the favored refrigerant, but like R22 it's a powerful greenhouse gas (but doesn't eat the ozone layer the way R22 does.) It's possible that by the time you really NEED a replacement R410A may be on the way out, being replaced by HFO1234yf equipment or something. In your location it probably makes sense to pay the up-charge for a heat pump rather than straight AC, given California's ambitious green house emissions targets. At some point within the lifecycle of HVAC equipment it's likely that fossil fuel heating in California will be heavily taxed in one form or another, if not outright banned.

In areas with high latent loads high SEER isn't always going to be your friend, since it results in generally lower moisture removal rates, but in CA it's really the way to go. A lot of houses your size could even be cooled and heated with a 1.5- 2-ton modulating ducted mini-split with an SEER north of 20, using half the power use of your current system or less if right-sized. Carrier makes a very efficient modulating split heat pump that can be had as small as 2 tons, but it's pretty pricey compared to some of the mini-split solutions, and even the 2-tonner may be too oversized for your heating & cooling loads to really max out the comfort & efficiency. (The turn-down ratio on their Infinity Greenspeed is only 2.5:1, which is much range compared to the better mini-split options.)

Typical 99% heat loads for houses your size in CA run around 20,000 BTU/hr @ 30F, but if it's air-leaky with a lot of single pane windows it could be over 25,000 BTU/hr. If it's pretty tight without a lot of window area design heat loads under 20K are likely. Given the oversize factor of your AC I wouldn't be surprised if your existing heating equipment has output in the 60-100,000 BTU/hr range. Since you're coming in to the heating season you can sort that out with a fuel use against heating degree-days heat load calculation this winter, with adjustments for other uses if the same fuel is being used for hot water, etc.

Most people err to the conservative side and tend to want to oversize (usually by way too much) out of fear they'll be too hot or too cold, and HVAC contractors support that, since they don't want the headache of a call-back in the event that the equipment can't keep up (which almost never happens.) If you're going to live in a place long enough to take some rudimentary measurements it's possible to get to more reasonable oversizing factors, say 1.2-1.4x rather than the more typical 2-4x. Title 24 requires that load calculations be performed, but the load calculations are often fudged by the contractors, and rarely challenged.
 
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WorthFlorida

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Go with Dana's suggestion, replace the unit. R22 is now going for about $500 for a 30 lb bottle and service companies are charging a lot. $60 and more a lb. It's getting so expensive that most techs now carry scales to measure what is used to service a unit.

I searched your model and it was built in the late 1990's to early 2k. That makes it about a SEER 12 at best. Minimum SEER required by law is SEER 14 and to up it to SEER 15 or 16 is only a little more $$. As an example, my son's home in Altamonte Springs, FL had an R22 compressor built in 1992 and the entire system was replaced with a heat pump model at SEER 16. This past summer his electric built was around $200 a month from $350 a month the previous year, plus from Duke energy he was credited a $400 rebate. Also, most new units are very quite and you may find db ratings in the specifications. Check you electric company's web site and search for rebates.
 

Dana

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If you're going to replace the system before being able measure the load by duty-cycling, have a competent third party (not an HVAC contractor) run the Manual-J load calculations, using aggressive rather than conservative assumptions. This can be either a certified professional engineer or a HERS / RESNET rater, etc., but make sure it's somebody whose primary product is their numbers, not somebody making a margin on the equipment and installation labor. In my area it costs $400-600 for that service (but I've seen folks charging more than 2x that in some gold-plated communities).

I don't know anything about the quality of their work or pricing, but this company offers independent Manual-J & Manual -D services in your area. I'm sure there are others.

You usually save more than fees charged for a good Manual-J just in lower equipment costs. That gets multiplied by lower utility costs over the lifetime of the system.

CA Title 24 2016 still allows for a minimum SEER of 13 for air conditioning, and minimum HSPF 7.7 for air source heat pumps. Somewhat higher efficiency than "the crummiest efficiency still legal to install" is of course better, and doesn't have to be radically more expensive.
 

mggray87

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R22 will be going out of production in 2020, and though it's still legal to sell "dry" R22 replacement condensers, are sure you really want to invest in an R22 future with a new condenser? A replacement condenser would have a minimum SEER rating of 13 (up from 10 for your older unit), but it's unlikely to ever "pay off" in the short life time that R22 equipment will be able to be fully supported.

Also note, a 4 ton split AC system would usually be substantially oversized for the true cooling loads of a 2 story ~2500' house (even a house with a 20' ceilings for part of the house.) Most homes that size would come in under 3 tons, many under 2 tons with the low latent loads of CA.

An Atlanta GA area HVAC guru who lives & dies by Manual-J load calculations came up with this plot of square feet per ton vs. house size on projects he's worked on, most in the steamy gulf coast states (with high latent loads, unlike your mostly negative latent loads.) If you look at the cluster of houses between 2000-4000 square feet you'll note the middle range is about 1400-1500 feet per ton, and NONE are as low as your (2500'/4 tons =) 625 feet per ton:

square-feet-per-ton-air-conditioner-sizing.png


So your real load is probably on the order of 1.8 tons, to maybe 2.5 tons at the high end. Oversizing the equipment by that much costs more up front, and leads to lower operating efficiency & lower comfort.

It's probably better to keep the equipment you already have and move it, then next summer see if you can get a handle on the actual cooling loads by datalogging the duty cycle of the compressor on the hotter days when afternoon temperatures at or near your 1% outside design temperature , (about 97F same as Stockton or Concord.) By using the unit itself as the measuring tool the parasitic loads of duct gains, duct leakage etc, are already built-in, but you'll then have hard data on what would be a better size for the eventual replacement.

Right now R410A is the favored refrigerant, but like R22 it's a powerful greenhouse gas (but doesn't eat the ozone layer the way R22 does.) It's possible that by the time you really NEED a replacement R410A may be on the way out, being replaced by HFO1234yf equipment or something. In your location it probably makes sense to pay the up-charge for a heat pump rather than straight AC, given California's ambitious green house emissions targets. At some point within the lifecycle of HVAC equipment it's likely that fossil fuel heating in California will be heavily taxed in one form or another, if not outright banned.

In areas with high latent loads high SEER isn't always going to be your friend, since it results in generally lower moisture removal rates, but in CA it's really the way to go. A lot of houses your size could even be cooled and heated with a 1.5- 2-ton modulating ducted mini-split with an SEER north of 20, using half the power use of your current system or less if right-sized. Carrier makes a very efficient modulating split heat pump that can be had as small as 2 tons, but it's pretty pricey compared to some of the mini-split solutions, and even the 2-tonner may be too oversized for your heating & cooling loads to really max out the comfort & efficiency. (The turn-down ratio on their Infinity Greenspeed is only 2.5:1, which is much range compared to the better mini-split options.)

Typical 99% heat loads for houses your size in CA run around 20,000 BTU/hr @ 30F, but if it's air-leaky with a lot of single pane windows it could be over 25,000 BTU/hr. If it's pretty tight without a lot of window area design heat loads under 20K are likely. Given the oversize factor of your AC I wouldn't be surprised if your existing heating equipment has output in the 60-100,000 BTU/hr range. Since you're coming in to the heating season you can sort that out with a fuel use against heating degree-days heat load calculation this winter, with adjustments for other uses if the same fuel is being used for hot water, etc.

Most people err to the conservative side and tend to want to oversize (usually by way too much) out of fear they'll be too hot or too cold, and HVAC contractors support that, since they don't want the headache of a call-back in the event that the equipment can't keep up (which almost never happens.) If you're going to live in a place long enough to take some rudimentary measurements it's possible to get to more reasonable oversizing factors, say 1.2-1.4x rather than the more typical 2-4x. Title 24 requires that load calculations be performed, but the load calculations are often fudged by the contractors, and rarely challenged.

Holy cow what a response. Slot to take in. I was only going to replace it because it' so old it didn' make sense to disconnect. Move it on side of house. Reconnect. Plus charge with r22. And then disconnect when something happens to it. So we figured buy a newer one now. But I wasn' going to replace the coil. But I think I may have too if I get the new stuff and not r22. Also if 4 ton is to much. I can always get a 3ton or 2. It' funny my dad got a.c. put in his home. Like 1100 square foot. They put in a 2 ton.

But if I bought one. I don' know what brand to look at. I mean. Just to recharge my old one. After I move it might be cost of a new condenser.
 

Dana

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Don't guess on the sizing when replacing equipment. Either measure the duty cycle of the existing system under design conditions, or get a third party's (not HVAC contractor's) Manual-J. Otherwise you're likely to end up as ridiculously oversized as your dad's new system probably is.

It's worth getting some quotes for moving the condenser as well as quotes for replacing it with a right sized R410A refrigerant system that'a also a heat pump. It could still be cheaper to move it, re-using the R22 they pumped out of your system for the bulk of the re-charge. But there's not much sense in buying a new "dry" R22 condenser.
 

mggray87

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Buying a correct size 410 condensor do I need to buy a new coil too or just new 410 condensor and furnace and coil are still usable?
 

Dana

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You almost always have to buy new coils & refrigerant lines when changing over to R410A, due to incompatible contaminates in R22 refrigerant mixes (particularly the lubricants.) The coil pressures are also higher with R410A , and the old coil isn't necessarily designed for it. There are some HVAC folks who will punt, just flush & hope, but is it worth the risk?

This was a hot topic 8-10 years ago, with lots of searchable information still online. Try searching on the terms flushing + r22 + r410a you'll get the gist.
 

mggray87

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ok... ill just look at pricing... and see what the correct size condenser would actually fit my house best.. ill try to get someone out that knows what the heck they are doing..
 

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Any reputable tech will not use a R410A compressor with a R22 coil even with flushing it. The efficiencies come with both components compatible with each other and warranty requirements will come into play. If you ever change your system to R410a you'll be amazed on how fast the system will cool down, reduction of humidity and the air will smell better. You have 20 plus years of dirt and mold inside your air handler. One thing to check on that the lines between the compressor and air handler are sized correctly. If you can afford it you also would want to replace the lines. Copper lines can last a long time but R410a systems do have higher pressures that could cause a line to leak. You find that some tech say leave it and others say replace it. On my last house I had to replace a R22 with a R410a system and since the lines were replaced about ten years ago we left them in place. We blew them out with compressed air and there was nothing in them. The lubricants do not stay in the lines.
 

mggray87

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id have to replace lines regardless. the lines are in the wall of 2 story... so wed put new lines out the side of the wall at attic and straight down the wall to side of my house where we want to move it too. ok so hopefully I can find someone to size it correct for me so I can start shopping for a condenser with right tonnage. and a new coil to match.
 

Dana

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Seriously, have a qualified third party (not an HVAC contractor) size it for you, and spring for a heat pump, not cooling only! A 2 stage heat pump sized for the cooling load should be able to heat at fairly high efficiency at low stage, and still cover your weather extremes at high stage.

I posted a link to one such third party in your area in response #4, but I'm sure there are others. It all starts with calculating the load numbers...
 

Dj2

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You need all new equipment. You can't use an old coil (R22) with a new condenser (R410).

Get multiple offers. The unit in the picture is 4 ton if I'm not mistaken.

I like Rheem equipment.

You mentioned noise: choose higher SEER. It will cost a little more but will be a lot quieter.
 
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mggray87

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anyone ve experience with lineset covers.. I see nice looking ones.. all similar.. no experience or haven't seen any in person.. any experience with any that you like? its going to be straight out wall of attic and straight down.. except I have a little "foam trim" that its going to have to go over like 2" off wall. decorative trim. not sure if it can make that little bend.
 

Dj2

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Are you asking about the casing for the copper refrigerant tubing from the condenser?

It's normal practice to cover the refrigerant tubing with sheet metal casing/cover. You can paint it to match your exterior paint.
The other option is to put it inside the wall.
 

mggray87

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yea.. ive seen online plastic ones... fortress makes them. not sure what a sheetmetal one looks like.. id think plastic would last longer and not bent etc.
 

mggray87

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Another question. While relocating this on other side of house. It' on its own bdedicated 50a breaker. The current service disconnect on it now is a disconnect with a 60a breaker in it. My question is. When I run power to new location off that 50a main breaker. Do I have to have a say 60a fused disconnect. With 50a fuse in it since condenser says 50a max. Or can I simply just put a non fused disconnect for service. Just pull the power. ??
 

Dj2

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I wouldn't use any plastic products outdoors, use metal only. It won't get bent if you don't hit it.

I prefer a fused disconnect, as it's double protection. If your A/C been running fine with 50A breakers, then use 50A fuses.

A word of caution: State law requires a licensed A/C tech to evacuate the system, recharge the new condenser and do all the soldering/welding.
Have him check all the electrical too.
Don't attempt to do it yourself.
 
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