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Posted: 8/21/2017 1:39:48 PM EDT
[#1]
Why do you have a 100,000 btu furnace for 1300 square feet? I agree with everyone else, I bet the fan speed is set to "high" which will cause your symptoms. By the way, for a 3/8" liquid line, you only add roughly .6 ounces per foot of R410A over the factory charge. So 10 extra feet will only take 6 ounces extra.
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Posted: 8/21/2017 2:09:02 PM EDT
[#2]
Quote HistoryQuoted:
looks like that air handler can push up to 2000 cfm. you have a 3 ton coil and a 2 ton condenser which only needs 800 cfm you have too much cfm to get a delta t. you can't transfer enough heat into the coil at that cfm. 4 tons of air cfm on a 2 ton CU Unfortunately that's what you get for DIY. I guarantee you that the flex return duct is too small for the furnace. What he needs to do is run the heat full blast and see what his temperature rise is. That will tell him what his CFM is. His furnace should have a temp rise of 65F if he has 1000 cfm going through it and 35F with 2000 cfm. My bet is 35F or less. |
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Posted: 8/21/2017 2:25:17 PM EDT
[#3]
Contact the manufacturer of the evap coil. Guaranteed they will have a pressure drop for the required CFM. Using a manometer set the pressure drop across the coil, airflow done. As others have mentioned, without correct airflow everything else is moot.
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Posted: 8/21/2017 2:45:04 PM EDT
[#4]
Quote HistoryQuoted:
Why do you have a 100,000 btu furnace for 1300 square feet? I agree with everyone else, I bet the fan speed is set to "high" which will cause your symptoms. By the way, for a 3/8" liquid line, you only add roughly .6 ounces per foot of R410A over the factory charge. So 10 extra feet will only take 6 ounces extra. The supply company knew what furnace was in place. I don't know why it seem some are assuming I just hodge podged some shit together I found at the local fleamarket. The outside unit and coil were supplied by a large HVAC supply company that knew what unit I had. Had they said "that won't work" I wouldn't be where I'm at. The ductwork was also supplied by a duct manufacturer in the area that had my floor plans. The only thing we can say I shortcut was placing the equipment myself. As a professional tradesmen in another field I do not see how this was unreasonable. When it came to the technical stuff I paid what I thought where skilled HVAC techs in there own right. At this point I'm not against figuring it out myself and acquiring the tools to do so. I'm not just tying to save a buck. Back on topic...I will be looking into what setting my handler speed is on tonight. Any chance my TXV may just need adjusted to get my superheat down? (Obviously after making sure I don't have to much air). I had even opened up the cutout between the V of the coil and superheat didn't really change. Coil was still only cold about half way up. Would it hurt to play with it before I go down the road of pulling the system down and charging it properly? |
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Posted: 8/21/2017 2:53:45 PM EDT
[#5]
Quote HistoryQuoted:
The Furnace was there when I moved in. I removed the ductwork and installed new (atleast what I have done so far). The supply company knew what furnace was in place. I don't know why it seem some are assuming I just hodge podged some shit together I found at the local fleamarket. The outside unit and coil were supplied by a large HVAC supply company that knew what unit I had. Had they said "that won't work" I wouldn't be where I'm at. The ductwork was also supplied by a duct manufacturer in the area that had my floor plans. The only thing we can say I shortcut was placing the equipment myself. As a professional tradesmen in another field I do not see how this was unreasonable. When it came to the technical stuff I paid what I thought where skilled HVAC techs in there own right. At this point I'm not against figuring it out myself and acquiring the tools to do so. I'm not just tying to save a buck. Back on topic...I will be looking into what setting my handler speed is on tonight. Any chance my TXV may just need adjusted to get my superheat down? (Obviously after making sure I don't have to much air). I had even opened up the cutout between the V of the coil and superheat didn't really change. Coil was still only cold about half way up. Would it hurt to play with it before I go down the road of pulling the system down and charging it properly? Edit: By the way, your evaporator is probably fine for your condensing unit. It is probably rated for 2 to 3 tons and whoever sold it to you picked a bigger one to allow more air through it when heating. |
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Posted: 8/21/2017 3:13:51 PM EDT
[#6]
Quote HistoryQuoted:
The Furnace was there when I moved in. I removed the ductwork and installed new (atleast what I have done so far). The supply company knew what furnace was in place. I don't know why it seem some are assuming I just hodge podged some shit together I found at the local fleamarket. The outside unit and coil were supplied by a large HVAC supply company that knew what unit I had. Had they said "that won't work" I wouldn't be where I'm at. The ductwork was also supplied by a duct manufacturer in the area that had my floor plans. The only thing we can say I shortcut was placing the equipment myself. As a professional tradesmen in another field I do not see how this was unreasonable. When it came to the technical stuff I paid what I thought where skilled HVAC techs in there own right. At this point I'm not against figuring it out myself and acquiring the tools to do so. I'm not just tying to save a buck. Back on topic...I will be looking into what setting my handler speed is on tonight. Any chance my TXV may just need adjusted to get my superheat down? (Obviously after making sure I don't have to much air). I had even opened up the cutout between the V of the coil and superheat didn't really change. Coil was still only cold about half way up. Would it hurt to play with it before I go down the road of pulling the system down and charging it properly? Many technicians do not know how to calculate duct sizing. Unfortunately DIY doesn't come with a warranty regardless of who gave you the advice. If I were to come to your home my first job would be to figure out what your needs for heating and cooling are by doing a Manual J load calculation. That will determine what capacity equipment you need. The next step would be to calculate the duct sizing. If you look on page 5 of the manual you provided you will see your model number and beside it it says 3, 3.5, 4 ton. Did they size the ductwork for the furnace or for the 2 ton unit that was sold to you? Please provide the dimensions of the supply trunk and return duct so we can figure out where you are heading. As the other poster is saying the furnace is way too big so is the ductwork sized for the furnace or the A/C. |
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Posted: 8/21/2017 3:23:46 PM EDT
[#7]
Quote HistoryQuoted:
The Furnace was there when I moved in. I removed the ductwork and installed new (atleast what I have done so far). The supply company knew what furnace was in place. I don't know why it seem some are assuming I just hodge podged some shit together I found at the local fleamarket. The outside unit and coil were supplied by a large HVAC supply company that knew what unit I had. Had they said "that won't work" I wouldn't be where I'm at. The ductwork was also supplied by a duct manufacturer in the area that had my floor plans. The only thing we can say I shortcut was placing the equipment myself. As a professional tradesmen in another field I do not see how this was unreasonable. When it came to the technical stuff I paid what I thought where skilled HVAC techs in there own right. At this point I'm not against figuring it out myself and acquiring the tools to do so. I'm not just tying to save a buck. Back on topic...I will be looking into what setting my handler speed is on tonight. Any chance my TXV may just need adjusted to get my superheat down? (Obviously after making sure I don't have to much air). I had even opened up the cutout between the V of the coil and superheat didn't really change. Coil was still only cold about half way up. Would it hurt to play with it before I go down the road of pulling the system down and charging it properly? I understand your wish to do things at low cost and 'experimentally' and applaud you for doing so. You will become very strong technically... 
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Posted: 8/21/2017 3:35:44 PM EDT
[#8]
Quote HistoryQuoted:
OP, does the air handler have a multi speed motor, what is it wired for? I understand your wish to do things at low cost and 'experimentally' and applaud you for doing so. You will become very strong technically... [:) |
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Posted: 8/21/2017 3:45:12 PM EDT
[#9]
Since it looks like I'm going this way.
Recommendation on natural gas furnace? I need a direct vent unit anyway. |
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Posted: 8/21/2017 3:50:50 PM EDT
[#10]
Quote HistoryQuoted:
even if the air handler was wired for 3 tons on cooling he only has a 2 ton condenser. now if he squeezes the duct work down so the system will only push 800 cfm than the velocity of the air going through the coil will high enough to pickup the moisture off the coil and fling it into the ducts It will end up performing like dogs hit no matter what you do if you don't have a matched system. I would be able to live with a 2.5 ton coil on a 2 ton condensing unit. We do that with heat pumps for better heat transfer in the winter. The airflow and duct sizing is what scares me. That furnace would require the low setting and 1.0" wc of external static pressure to get it working at the bottom of its curve. |
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Posted: 8/21/2017 3:52:17 PM EDT
[#11]
need to do a heat load to determine that
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Posted: 8/21/2017 4:19:53 PM EDT
[#12]
1. If blower motor is on high speed, drop down to at least medium.
2. Fix this airflow issue of the ducts still being open or whatever else was posted. 3. I am still wondering if there might possibly be a restriction in the A coil from someone not flowing nitrogen. But hey, if 1 and 2 work, who cares. |
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Posted: 8/21/2017 4:40:05 PM EDT
[#13]
Quote HistoryQuoted:
need to do a heat load to determine that I meant brand preferences. Units you guys like. That's all. You know 9mm vs .45 |
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Posted: 8/21/2017 6:12:30 PM EDT
[#14]
Could I temporarily block some of the return to restrict airflow? If my superheat goes down it would instantly verify too much air correct?
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Posted: 8/21/2017 6:13:39 PM EDT
[#15]
Quote HistoryQuoted:
even if the air handler was wired for 3 tons on cooling he only has a 2 ton condenser. now if he squeezes the duct work down so the system will only push 800 cfm than the velocity of the air going through the coil will high enough to pickup the moisture off the coil and fling it into the ducts |
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Posted: 8/21/2017 6:25:05 PM EDT
[#16]
Yeah, can't he put the cooling fan on a lower tap on the motor to approximate the desired airflow?
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Posted: 8/21/2017 6:32:27 PM EDT
[#17]
I think he's saying even at my units lowest setting it's too fast.
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Posted: 8/21/2017 7:03:48 PM EDT
[#18]
Quote HistoryQuoted:
Not if he slows the fan... There's one of those issues us trained guys understand. 
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Posted: 8/21/2017 7:28:43 PM EDT
[#19]
I think one of those trained guys helped him put the units together.
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Posted: 8/21/2017 7:38:16 PM EDT
[#20]
Higher a reputable pro to redue/fix/direct/consult.
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Posted: 8/21/2017 7:51:08 PM EDT
[#21]
Quote HistoryQuoted:
I think one of those trained guys helped him put the units together. |
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Posted: 8/21/2017 8:07:19 PM EDT
[#22]
Quote HistoryQuoted:
I don't consider the warehouse monkeys "trained help" The only thing the sales guys didn't do is say that my air handler might be way too strong. Actually feedback here says that the sales guys provided items that arnt really far off from what I need. So far it's the techs that are the monkeys 
New update here. I choked the return duct pretty good. Almost covering the thing just to see if superheat would drop. It did...but not enough. Saturated temp dropped to aprox 36-38 degrees which sounds good but superheat didn't come down enough I don't think. I measured as close to the evaporator as possible. Just outside the unit with the cover on and only dropped to about 68 in 30 minutes. 30 superheat still seams high. Coldness to the touch definitely moved up the coil but tops still not cold. So I checked the TXV. Removed from line and put into an insulated cup of ice and water. Line temp increased. Then held in my hand. Line temp dropped back down. I hate to ask but...restriction? |
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Posted: 8/21/2017 8:08:54 PM EDT
[#23]
Quote HistoryQuoted:
Higher a reputable pro to redue/fix/direct/consult. There are a lot more qualified people then I will ever be guiding me, here and elsewhere, and I'm learning a ton of information. Plus acquiring all kinds of cool tools. Thanks to everyone who's provided there input. 
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Posted: 8/21/2017 8:13:42 PM EDT
[#24]
Quote HistoryQuoted:
Yeah, except a 5ton AHU won't slow down enough. There's one of those issues us trained guys understand. |
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Posted: 8/21/2017 8:27:14 PM EDT
[#25]
Quote HistoryQuoted:
I understand what they are just was under the impression superheat was not used with a TXV. I will record it anyway. Quote HistoryQuoted:
Quoted:
Subcooling is the point at which saturated vapor turns to a liquid at the condenser. Superheat is the point at which liquid turns to a vapor in the coil. I will record it anyway. |
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Posted: 8/21/2017 9:32:55 PM EDT
[#26]
Quote HistoryQuoted:
Yeah, except a 5ton AHU won't slow down enough. There's one of those issues us trained guys understand. |
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Posted: 8/21/2017 9:51:36 PM EDT
[#27]
Been a design build contractor for 30 years. Advice here has been good to idiotic.
Superheat is hyper important with a txv. Don't adjust it until everything else is in spec. You really should find someone locally to help you. If you insist, running the heat to get a Delta t to calculate airflow is a good idea. It should be close enough to run with. |
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Posted: 8/21/2017 10:12:18 PM EDT
[#28]
So what kind of subcoling do you get with a partially restricted drier?
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Posted: 8/22/2017 6:40:17 AM EDT
[#29]
Quote HistoryQuoted:
So what kind of subcoling do you get with a partially restricted drier? At this point I'm most likely going to run as is. It's actually cooling pretty good and not running all the time. I'm going to replace the handler/furnace because even with out the cfm issue I need a direct vent unit so I can abandon a chimney. Also going to get the ductwork done and redo the lines with nitrogen. Make sure the microns are down. Replace the filter drier. Also probably replace the TXV just because it's down. Anything else I should do? |
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Posted: 8/22/2017 6:43:44 AM EDT
[#30]
Should the refrigerant go back in after I do the work? Or new?
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Posted: 8/22/2017 8:08:57 AM EDT
[#31]
Quote HistoryQuoted:
Should the refrigerant go back in after I do the work? Or new? |
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Posted: 8/22/2017 11:15:50 AM EDT
[#32]
Quote HistoryQuoted:
Should the refrigerant go back in after I do the work? Or new? |
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Posted: 8/22/2017 6:20:02 PM EDT
[#33]
Quote HistoryQuoted:
with as many problems as you have had I would use all virgin. plus york systems like you have are on the bottom of the builders grade for systems |
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Posted: 8/22/2017 6:23:00 PM EDT
[#34]
Quote History |
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Posted: 8/22/2017 6:25:05 PM EDT
[#35]
Quote HistoryQuoted:
So what kind of subcoling do you get with a partially restricted drier? |
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Posted: 8/22/2017 6:37:22 PM EDT
[#36]
Quote HistoryQuoted:
If there was a restricted dryer you would see a temperature drop across the dryer. Great point! |
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Posted: 8/22/2017 6:40:12 PM EDT
[#37]
Quote HistoryQuoted:
So what kind of subcoling do you get with a partially restricted drier? As stated above, you test a filter drier based on temp drop (if your don't have gauge ports). |
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Posted: 8/22/2017 6:43:49 PM EDT
[#38]
Quote HistoryQuoted:
Meh, he can trim the blades or cut a couple off... 
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Posted: 8/22/2017 7:55:26 PM EDT
[#39]
Quote HistoryQuoted:
There is no limits to hackiness.... http://hvac-hacks.com/wp-content/uploads/2014/01/hvac-hacks.com-LuMVpOW6mv5ia5eQS57EP.jpg |
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