A/C hard start kits: are they necessary?

This one explores 2 types of aftermarket hard start kits and what their effect on the compressor starting capabilities are.
How to install the Super Boost compressor starter: • Installing the super b...

[@tacticooldennis]

The 5-2-1 relay is mounted upside down, it might affect its performance..

[@raindogs451]

You’re really informative. I’m a 30 year tech, and I’ve picked up things from you. I appreciate you.

[@thehilltopescape7126]

My unit is about 5-6 years old. The A/C company I have used over the years has tried to convince me to put one of these things on my compressor since the unit was about two years old, the latest being yesterday. They kept telling the unit runs good but since it’s “this old,” it would be good to but one on the unit. After watching this video, I am glad I never did. I appreciate the honesty, and I’ll probably drop this company because they are about nothing but taking money from their customers.

[@condor5635]

Like I posted I just installed a 5-2-1 on my 4 ton today and max start JP went from 110 to 56 amps. Not sure if this video 5-2-1 never kicked in or not since start relay was mounted upside down. I am real happy with it.

[@ethank2466]

@@condor5635It does not reduce the amps it just reduces the time being started, the shortened times leaves a misconception that it lowers the amps due to meters not being able to read the shortened time quick enough

[@fattysgarage1754]

I installed mine on my new unit 10 years and it works perfect. What I had going on is the power would go out, say during a storm, for a split second or two and the compressor would take 2-4 hours to come back on. With the 521 it takes no longer than 5 minutes. Unit is 1pm years old and runs like new.

[@hg2.]

Thank you for again adding to our knowledge in this field. PS: I Just discovered your website - an awesome collection of HVAC information!

[@TexasBuyer2001]

The potential relay on the 5-2-1 is installed upside-down since it is gravity assisted.

[@rogerbeaird3320]

Hey Texas can I use a hard start kit on my amana central air conditioner if the compressor relay is bad will it work we can't find the part for it plans help sos sos sos sos

[@dustsmoke]

Very important detail but you are right. On that particular gravity assisted potential relay it "hangs" from the screw.

[@Militaristics]

delay on break anti short cycle timers can be a better option in some cases, just letting the machine settle down and equalize pressures so it's not starting against a high head can make nuisance service calls go away. and the delay on make still lets the compressor start right away when it has not been running so the customer gets faster response when the system is starting cold vs a delay on make that has to run the clock every time. I enjoy your videos, keep up the good work!

[@grayfurnaceman]

If the unit does not have a TXV control and is not a scroll, these can help. GFM

[@inception727]

Nest thermostat has a delay setting seems

[@markhoffmann5941]

delay on Make.... these will delay the start even if the compressor has been off... Delay on Break... delay starts after load is de-energized.

[@Militaristics]

@@markhoffmann5941 exactly, D O B will let a unit start on demand when it is able to do so and protect a unit from short cycling at the same time. reducing customer complaints about "taking too long to blow cold," and reducing the "it's not blowing cold at all" calls.

[@RSxxx877]

Seeing how to wire both would be much appreciated. I find your videos extremely informative.

[@dipley3771]

Could teach a monkey how to wire em

[@rj.parker]

Hard Starts were more common on recip compressors that start loaded, particularly in normal comfort ac. Scrolls start unloaded in most cases and don't need a boost. The down sides of "optional" hard starts usually outweigh their benefits. First a hard start stuck on will burn up a compressor with its large capacitance in the circuit. They have to drop out quickly and reliably. Second, if a run cap goes bad (never happen right?), then a hard start will start the motor anyway and then drop out. That will cause the motor to overheat, overload and eventually fail if not fixed. In fact, the second problem has led Amrad to add a "compressor protection terminal" on their Turbo 200 and many of their dual run caps to prevent this problem with a hard start and a failed run cap. The Amrad solution breaks the hard start's connection to Common at the run cap when the cap open circuits. Probably the best solution is to avoid a hard start on a scroll and only use them on recips and refrigeration when required by long line sets or hard shutoffs.

[@grayfurnaceman]

Good thoughts. GFM

[@rj.parker]

@Weaver Cattle Company Not saying hard starts are not useful on some recips, long lines, hard shutoff txv/solenoid applications or as a last gasp for a failing compressor. But they have downsides including starting units with failed run caps and potentially staying in the circuit due to low back emf or stuck contacts. If the pick-up voltage generated by the back emf is under the minimum required to open a given potential relay, sometimes caused by miss-application of universal hard starts, the n/c hard start may not open. The start capacitor will stay in the circuit. This causes high amp draw and can open motor protective devices. Short cycling of the compressor caused by repeated triggering of its protection devices can overheat and open windings over a period of time. In a similar manner, the relay contacts can stick or arc in the closed position. Again, the start capacitor is not taken out of the circuit, a rumbling is often present and high amp draws open motor protective devices. Again repeated short cycling can burn a winding.

[@grayfurnaceman]

@Weaver Cattle Company I would agree that the start cap is the weak link. However, I have seen compressors (in one case a new one) fail when the potential relay sticks closed. The reason for this type of failure is if the cap shorts inside. A shorted cap and a stuck potential relay will burn out the start winding. GFM

[@jtwags4071]

You can now purchase a Turbo 200 cap that has a Compressor Protector Terminal (CPT) that cuts off the Hard start kit in case of run capacitor failure.

[@trentwilliams3308]

You installed the relay upside down, redo the relay and check your readings you may find that it reduced the start up amps even more.

[@grayfurnaceman]

You are correct. I did change it and it made no difference. GFM

[@stevec8861]

Homeowner, not HVAC pro here. I recently installed a 521 on my 5 ton Trane XB 13 (way too big for my house, but that's another story) because house lights would dim when unit started. 521 fixed my light dimming problem, but maybe I'm going to wear out compressor faster? Surprisingly, a smaller 2.5 ton Trane XB 13 (cools a smaller portion of house) that hardly ever runs already had a start capacitor installed.

[@gilbertmartinez8185]

The 5-2-1 kit is awesome. You won't wear it out. I've been in the HVAC field for 20 years. These are a great addition to any HVAC system in my opinion. Your compressor is already thanking you. I would however recommend that once every 3-4 years you replace both the hard start kit and capacitor together. Or if your capacitor fails then replace with another 5-2-1 kit.

[@stevec8861]

@@gilbertmartinez8185 Thanks. When I added the 521 (3.5 to 5 ton kit), I also replaced the 5mfd fan capacitor and the 80mfd compressor capacitor (with same Genteq brand) because both were very rusty. So you're saying rinse and repeat every 3-4 years with new run capacitors and new 521 kit?

[@leodanryan966]

I am using this kit because I have a backup generator that won't start my a/c condenser. I and most people at this time are installing them to kick the condenser on.

[@bills6946]

The potential relay must be installed arrow up to function correctly. The relay armature drops out by gravity upon power loss. If not oriented arrow up, the armature COULD hang up and cause the 5-2-1 to stay on after startup and destroy the 5-2-1.

[@franciscocastellanos9157]

In some air conditioning and heat pump units, the SC* starter capacitor or also named SR* starter relay they are included in the system wiring schematic (in dot segments ) as field option to install. I usually recommend to homeowners to add on to a failed dual run capacitor on old reciprocal compressor motors or a blown fuse on the incoming power disconnect box ( after checking for arching or grounded connections of course ) . Always a pleasure to learn from your videos

[@philstover2422]

I sure appreciate you taking time to explain this.

[@throttlebottle5906]

need a second video of the same, but with undersized wiring gauge ( simulated by using proper gauge at long length's so there's a big voltage drop and actual hard time starting (maintain head pressure on non scroll)

[@averyalexander2303]

I don't really see a hard start doing any damage, but I don't really see it doing much good on a properly functioning unit either under most conditions. I don't see the high amp draw for a fraction of a second on startup heating the motor up much because it just doesn't last that long, but I'm no engineer. Plenty of units make it 20+ years no problem with just the factory installed capacitor

[@grayfurnaceman]

Pretty much my thoughts also. GFM

[@TheWilferch]

Add this..... the power factor issue is often not discussed.....but plays a part. Especially on arguments over the amount of inrush current. Consider.....example.... if your 230V motor draws 10A when running, and the PF = 80%, the watts used is 230 x 10 x 0.8 or *1840W*. On starting though, the power factor doesn't stay at 0.8, but goes down to maybe 0.2 . So the watts are *2760*, not *12,000+* as some would claim without the hard start kit ( this assumes 6x or 7x increase during starting).

[@andygalindo8978]

Yes a step by step on how to wire those things. Thank you

[@daveerrington5166]

In any electrical motor more power is always better on initial start up. Even on a brand new factory installed unit. It’s a good idea.

[@condor5635]

Not sure what is different from your but mine went from 110 amps to 56 amps using 5-2-1. Definitely happy here. Using a Fluke 410i and a 87V

[@grayfurnaceman]

No it did not. Your meter just could not read the inrush effectively. GFM

[@condor5635]

@@grayfurnaceman . Can you expand on that a little bit? I had it on high resolution and it measures maximum minimum and average. You mentioned in your video you wish you could have used a more expensive meter that was more accurate. What are you suggesting then? Thanks for clarifying

[@grayfurnaceman]

@@condor5635 The start kit will increase amp draw upon startup. What it does is start the compressor faster and keep the high amperage from being on as long as without the kit. GFM

[@condor5635]

@@grayfurnaceman still don’t understand why you indicated my meter did not read the amps correctly. Max amps clearly dropped almost 50% after I installed it.

[@TheWilferch]

@@condor5635 ...have seen that confirmed too by many other HVAC pro vids.

[@condor5635]

Strange that the manufacturer offers essentially the 521 as an OEM option for an additional price. Can’t imagine they offer this as a temporary fix to extend the life of a unit. If they offer it as some thing you can immediately put on a new unit. It seems to me that it would be something that would improve the longevity. But I’m just guessing. I put a 521 on my unit a year ago after matching the capacitor exactly to the OEM capacitor. I don’t know if the relay matches the OEM relay but I have to think it’s pretty close. Thanks for the test.

[@grayfurnaceman]

The manufacturers offer a hard start system to match the expansion device. Equipment may be matched to a fixed orifice device and the unit will not need a hard start. Other matches may be used with a TXV. Then the start kit will be necessary. GFM

[@condor5635]

@@grayfurnaceman - thanks for that info. On a sidenote, if my 4 ton unit compressor typically runs 4 minutes for every 12 minutes (1/3 running ratio) during Texas heat (mid to high 90’s) does that tell you anything in and of itself? Seems like ratio is a good figure to know on ACs but you never really hear people reference it. Would love your insight.

[@Jon-hx7pe]

they aren't just for failing compressors though - required for a recip when there's a non-bleed txv. useful also when starting off a generator.

[@grayfurnaceman]

If you are setting up a system with a non bleed TXV, a factory hard start is by far the best. GFM

[@edbouhl3100]

I’ve seen them in discussions about home batteries also. Sounds like a soft start comes at the price of seriously hard usage on the motor.

[@faststang85]

I have a brand new lennox xp16 that is having a hard start condition when it gets over say 80 degrees out. I just ordered a factory hard start kit for it.

[@Jon-hx7pe]

@@faststang85 may want to check the voltage

[@faststang85]

@@Jon-hx7pe i will, i guess i should say what i ordered they consider a "soft start" not sure if its exactly different than a hard start im seeing mixed writings on it. It is however a oem lennox part number though, (10j42). The reason for it the heat pump is buzzing loud on start up

[@watermanone7567]

Good video. I used to put them on remote country houses that had borderline voltage. New equipment would sometimes not start with lower voltage, ie: 105-110 volts. Sometimes after the until would run for awhile I would remove them to see if they would start when broke in. Please show the wiring. Thanks for the video.

[@throttlebottle5906]

you got it on low voltage and current starvation is the key to needing them.. poor upstream wiring/utility supply needs fixed! hard start kits are a band aid over top a bad wound :) but still better to have the hard start, than sit there lock rotor until off on thermal overload or fuse/breaker trip, which is even harder on winding's in the long run. locked rotor = high force winding vibration, rapid heating and major stress, in comparison to a jolt each start up. the best way would be an unloader valve and soft step starting up to speed, then apply load, yeah not going to happen lol. although a scroll is close to that with the mechanical unloader after pressure drops

[@dido1803]

I really enjoyed seeing this video. Was very insightful. I would love to see how you would install it in an ac unit.

[@Rinebo]

This really confirmed what I have been thinking, thanks!

[@Mabalzitch2024]

So much great information and wisdom. Thank you for sharing your knowledge and insight.

[@grayfurnaceman]

Welcome GFM

[@highpwr]

Another vote for a more in-depth video on the wiring and installation of these hard start kits please...

[@mikec555555]

Temporary fix? Really? Let me tell you my story. Bought a house in 2000 (built in 1985). Had a 2.5 ton Lennox HVAC system ( already 15 years old at the time). Five years later it just wasn't cooling good enough. Could not afford a new system. A HVAC guy put in an old used 3 ton Fedders condenser/compressor (how old was it. I don't know). He put it in with a hard start cap ( this was now 2005). From 2005 to the present (2023). All I have done is replace the dual run cap once and replace the condenser fan. So, this used Fedders condenser/compressor has been running for 18 years with the same hard start cap ( I measured hard start cap capacitance and it is still at what is listed on the cap). The HVAC guy did give me a two year warranty which was up in 2007. This old used condenser/compressor has now been running with the same hard start cap for 18 years.

[@markhoffmann5941]

My costumer run cap failed... The 521 would start the compressor, after the potential relays contacts opened the compressor would run without the run cap working... but at 9 amps higher than normal and noisy...

[@LucianoJuly]

Appreciate your honesty and work

[@dgaz3057]

521 has to be matched to the tonnage of the compressor, if its undersized it will read less, if its correct it should read 50 amps +/-, Hard to believe this.

[@McmM-cv9sb]

I have a 20-year-old system I was thinking about adding a hard start , but I'm going to do like you suggest wait for it to start acting up it seems to be firing okay so I'm not going in to disturb The Beehive right now thanks for your help...😅😅

[@PorkGrinder71]

By now I’m sure you realize the 521 relay is installed improperly that can affect its operation.

[@andresbarragan8595]

FROM CHICAGO I REALLY YOUR VIDEO YOU WHENT WHIT VERY DETALS

[@andresbarragan8595]

THANK YOU SO MUCH

[@GUILLERMOJGARZON]

Thanks for sharing your knowledge

[@fernandofhernandez899]

well explained but you need a meter that reads INRUSH CURRENT, the way you manually starting the compressor contactor with your meter reading Aac doesnt have the nanosecond to catch the Inrush current...good video

[@eddiecalder5436]

His meter says “inrush” right on there.

[@gentrylabarda8576]

My understanding of a hard start kit is similar to a spare tire. Once the original existing dual capacitor takes a dump due to whatever reason, the hard start kit will apply. Like riding on a doughnut tire, you wouldn’t want to drive on that spare tire forever because it can potentially cause issues and you will want to replace the dual capacitor as soon as possible. Basically a trade off for the unwanted breakdown… but it will still cause damage to the compressor overtime if the dual cap is not replaced and is only using the hard start. I only recommend the on older compressors that is already “hard starting” or “short cycling”. Surge protection is the answer for the newer compressors and soft starts to diminish inrush amps, soft start also come with a built in start cap if I did my research correct. Sum it all up, it’s a back up auxiliary capacitor for when you have that flat dual capacitor. Hoped this helped!

[@demoll78]

Some videos are showing a big difference you sure you have the right one for the size unit🤔🤔🤔

[@grayfurnaceman]

I would have to ask: What difference are they showing? A hard start kit increases amp draw in order to start the compressor against unequalized pressures between high and low side. The unit does not use less power, it just is in the start mode for a shorter time. Soft start jerks the windings with less force, so it may be easier on the compressor. I would be interested in any demonstrations of the difference. GFM

[@Eddy63]

Great vid G F M ... Good to see ya back ...

[@grayfurnaceman]

Thanks GFM

[@xelaju8]

Great advice. Thank you.

[@grayfurnaceman]

Welcome GFM

[@Eric-ul9rm]

You have Great Videos but I noticed the 521 Potential Relay is installed upside down, instructions state the screw hole needs to on top.

[@grayfurnaceman]

You are correct. GFM

[@PH-md8xp]

This is not a valid test, the 521 relay is installed upside down. Install it correctly and measure the inrush.

[@snookysnax]

some higher price units come from the factory with a start cap and potential relay.

[@grayfurnaceman]

Generally, the only time you will see hard start kits on units is if they use a non bleed TXV for an expansion device. GFM

[@MacMcCabe2456]

The relay is mounted upside down, screw goes on top........

[@MsFishingdog]

Great video.

[@u2ooberboober]

The 5-2-1 unit is good for rapid restarts since the PTC doesn’t have to cool down for the next cycle.

[@hg2.]

? Could you elaborate on?

[@u2ooberboober]

hg2 my understanding is the PTC is a positive temp coefficient device which breaks connection after a certain amount of time elapses upon voltage being applied due to heat. That takes the start cap out of circuit. The potential relay depends on motor speed which creates back emf to open the contacts when speed of the motor is 75% of rated rpm. Since the potential relay doesn’t have to cool down it can be triggered again in a short period of time unlike the ptc. Same applies for a current relay device. But there should at least a 4 minute anti short cycle delay in the t-stat to prevent rapid restarts to give the system time to equalize in pressure so the compressor doesn’t have to start against high head pressure.

[@u2ooberboober]

In my original comment it should have stated the potential relay doesn’t have to cool down where the PTC does....

[@stevengao8345]

with all due respect, i do not agree with you. It improves the efficiency of the AC by enabling the compressor to turn on faster. Since the compressor has to work the hardest in the first couple of seconds, a hard start kit can alleviate much of that effort. The improved efficiency also reduces wear and tear on AC components other than the compressor. yes, maybe like you said initial hard push will wear out the fan motor a bit more faster, but it is ok, the compressor is saved, the fan motor is much much easier to replace than compressor. i do x20 fan motor replacements == x1 compressor replacement

[@emiliohidalgo4648]

How about it I have a generator that I like to use?

[@dreadrechsler8278]

Another property of the 'hard start' capacitor is it's spreads start current out over a longer time period so it seems to me it's not exactly pushing the motor harder but pushing the motor longer. I've also seen where they are recommended to help with older house wiriing when lights dim as the compressor kicks in even when it's fully up-to-code and properly maintained.

[@grayfurnaceman]

Hard starts do not lengthen start time, they reduce it. The current running thru the compressor windings is higher to overcome pressure difference between high side and low side. Yes, they do help with light dimming because the compressor is in start mode for less time. GFM

[@Z-Ack]

What if my lights flicker every time the things starts? Got a 3 ton train from 2013, so almost 9 years old.. works fine.. has a cap marked 2019 thats a 10,20,30,50 μf.. is 20.5 rla and 109fla.. figure the caps probably good, wire feed is 10ga so sized fine.. dedicated circuit with a 200a service so shouldnt cause flicker but it has been for past few years….

[@garrythompson4132]

We are thinking of installing a stand alone backup generator. Our central air conditioner is 8 years old, would this be something that would benefit the start up of the A/C when on generator power so it wouldn't take such a rush on the generator? If not, could you please recommend a procedure that would ease the compressor into start up amps? Thanks, Garry.

[@grayfurnaceman]

The hard start is probably your best option. GFM

[@eddiecalder5436]

Micro Air Easy Start is a better option for your situation that probably wasn’t available when your comment was originally replied to.

[@lsternhagen6188]

Shouldn't potential relay be mounted with tab up because of gravity switch- according to my HVAC installer who put mine in?

[@grayfurnaceman]

A number of them were position sensitive. However, this one does not seem to be so. GFM

[@AP-514]

@@grayfurnaceman is says so on the instructions look at the Diagram Screw hole UP

[@h2macm]

Good stuff. Thanks!

[@u2ooberboober]

Good stuff

[@josephescamilla562]

Great vid..

[@Darton-ok5xt]

how do i know which hard start kit fit or compatible with my lennox 5 tons AC residential

[@grayfurnaceman]

First, why are you installing the hard start? You will need one if you have changed expansion devices from a fixed orifice to a non bleed TXV. Also if the compressor has been having problems starting that is traced to blown fuses or other indication that the compressor has not reliably started you can use one. If you are installing one because you think it is easier on the compressor, consider this: Its called a hard start because it hits the compressor with a large jolt of power to increase starting torque. These units jerk the windings very hard. I would argue this is harder on the compressor than the much softer starting torque with the the run cap alone. If you still want one get it from the manufacturer, it is designed for your unit. GFM

[@Darton-ok5xt]

@@grayfurnaceman During the startup, your compressor draws 8 times more current than it needs for regular operation. All that extra power translates into a lot of heat. The heat rapidly wears out your compressor and other components, such as belts or motors. When critical parts burn out, you have a unit that doesn't cool your home. Not to mention that the compressor is often the most expensive and important part of the system, making it costly to repair. A hard start kit makes kicking on a lot easier for your air conditioner. Increasing the starting torque minimizes the power needed to start the unit and makes starting faster and smoother. Startup efficiency increases from 50% to 98% with a hard start kit. A hard start kit can prolong the life of your AC unit if the compressor is the source of the problem. If you have a newer unit that's otherwise in great condition, installing a hard start kit is a solid choice. However, with older compressors, a hard start kit may not be worth installing. While these kits can help coax a bit more life out of your compressor, they're more of a Band-Aid than a long-term fix.

[@zekenzy6486]

Great Video. Could you make video how to wiring A/C hard start kits ? Thank you for sharing. Could I ask you what reason relief valve boiler water leaking ? Thank you.

[@grayfurnaceman]

Its coming. The most common reason for boiler relief valve leaking is a leaking by auto fill valve. I would be looking for boiler pressure above 25# on a single story structure. Could also have a waterlogged/failed expansion tank. Look for normal pressure until the unit starts, with an increase in pressure as it warms. GFM

[@johnmgriffin3060]

Thanks for a great video! (Is the mounting tab "up" on that 521 potential relay?) Question: On a 5 ton Rheem classic with existing comp start cap and potential relay, would a 521 setup replace the existing components, or be installed in conjunction with them?) (Really appreciate that you are sharing your knowledga and experience)

[@grayfurnaceman]

It is down. It should be up. I would replace the manufacturer's start controls with a factory part. At no time should you have 2 start kits installed. GFM

[@TheWilferch]

BTW...at timeline 8:14....where the 5-2-1 components are added.....it SEEMS you have the relay installed upside down....the tab being on the bottom. As these seem to be gravity-assist for proper operation, the orientation is critical and almost ALL units I've seen like this tell you to install tab-side-up. Right? Could this be the reason your inrush did not go down much......other vids like this show almost 1/2 value of inrush after installing 5-2-1.

[@cashion556]

If Copeland specs a start cap for a particular compressor but the condenser manufacturer never installed one, and the unit has run 23 years without one with no problems. What are your thoughts on installing a factory start cap and potential relay at this time?

[@grayfurnaceman]

Don't bother. Even though the manufacturer specked it, often the equipment manufacturer will not use one and the compressor manufacturer is just fine with it. GFM

[@daveerrington5166]

The 8 amp that you claim ,I think you have the wrong size hard start

[@papitosabe]

Does the 521 only help the compressor or does it help the compressor fan motor as well??

[@grayfurnaceman]

It is only for the compressor. GFM

[@papitosabe]

@@grayfurnaceman darn. My fan is over amping and was hoping this would help. Thank you!!!

[@ScottDLR]

Thanks for this vid! I read someplace on the interweb that one of these can kill a compressor if the run cap dies while the compressor is running. After watching your video, it sounds like these devices remove themselves from the circuit so that can't happen. Does that make sense to you? My compressor (25+ y/o) seems to be making the lights dim slightly these days when it starts so maybe that's a sign that it's getting worn? I live in Western Washington state so it hasn't lived a hard life. The cap just died (4 y/o) too..

[@grayfurnaceman]

It does. If the run cap fails, the motor won't start. The customer will know he needs to get repair. If the unit has a start kit, the motor will start, but if the cap has failed, the comp will run inefficiently and over draw power. GFM

[@ScottDLR]

@@grayfurnaceman Thanks for the response!

[@chuckb4375]

@@grayfurnaceman I stumbled across AmRad run caps that have an extra Compressor Protector Terminal to break the circuit between start cap and compressor, if the run cap goes bad. Any experience with those?

[@grayfurnaceman]

@@chuckb4375 I can't say I have. GFM

[@jtwags4071]

You can purchase a Turbo 200 cap that has a special Compressor Protection Terminal to drop the start capacitor if the run capacitor has failed.

[@mattheebz8017]

Climate master/carrier Water source heat pumps come with the superboost sp6 Hardstart Kits from the factory. Is it in order for the compressor to start back up while the pressures from the 410a may be potentially high? From the unit running not to long before it goes to start back up? Or is carrier just utter garbage lol

[@jeffm2787]

Just because a cap measures good doesn't mean it is good. Lot more to a capacitor then just capacitance. Change the cap to a new one, still doesn't work perhaps the run cap will help. My background is in electronics.

[@rogerbeaird3320]

If my amana central air conditioner compressor relay is bad we can't find the part can we use this hard start kit instead

[@grayfurnaceman]

I would use the 5-2-1. Not the best, but usable. GFM

[@geraldc.37]

Thanks for the valuable info. Btw what was the maximum inrush rating on the compressor you demonstrated these devices on? Thanks for posting

[@grayfurnaceman]

That compressor is rated at 95 amps inrush. GFM

[@coldfinger459sub0]

The turbo easy start two wire universal. Part# TES5. Would you happen to have one of these lying around perform an amp draw a comparison.

[@grayfurnaceman]

The one I used was a super boost. Probably the same thing. GFM

[@bridgetevans2188]

Why would a AC Technician suggest adding this if your Unit is only 2 years old? He was just doing routine maintenance on the unit...

[@grayfurnaceman]

Some techs are into selling things you do not need or they just think its a better way to start a compressor. There is no studies that I know of that has proved that the unit lasts any longer. GFM

[@JorgeRodriguez-hm1ym]

Good video. Question: my unit runs fine but when the compressor stops it make a knocking noise really hard. Do I need this? The A/C guy said yes I don’t think I need it since my issue is when stop not when start. My unit is 10 years old well kept, never an issue in the 10 years. It is a Rheem 5 tons. They said is wear and tear. Let me know please. Thank you

[@grayfurnaceman]

If its a scroll compressor (most Rheem units are), the discharge valve may have failed. This will not cause an immediate compressor failure but may lower the life of the compressor. The reason the tech wants to install a hard start may be because the discharge valve separates high side from low side. I don't think the hard start will help, but it probably won't hurt. GFM

[@JorgeRodriguez-hm1ym]

@@grayfurnaceman thank you Sir.

[@gerardomireles122]

Cool thanks for the video Grayfurnaceman What is the Model number Of the Amp meter

[@grayfurnaceman]

Its an Ames CM1000A (Harbor Freight). I will be doing a video on how it works. GFM

[@ronnyoo9371]

Gfm. I ran. Into a situation that has both a meter device inside a piston and Txv outdoor which do I charge with / primarily check charge with kinda stupid question checking charge with a/c its a heat pump

[@grayfurnaceman]

Most heat pumps are charged in A/C as the cold weather needs less charge. That said, manufacturer instructions should always be the guide. GFM

[@June-of8iu]

I have a six-year old 1.5 ton unit with a rotary compressor. I replaced the piston metering device with a non-bleed TXV. The unit started fine after installing the TXV, but I thought it would be good to add a hard start kit, due to presence of the non-bleed TXV. I noticed that the hard start kit causes to unit to start quite "hard", such that the line set now rattles during starting. Consequently, I am wondering whether the hard start kit is perhaps doing more harm than good. Any thoughts? Many thanks, Philip.

[@grayfurnaceman]

What I like to compare it to is starting your car from a dead stop by floor boarding the accelerator. GFM

[@June-of8iu]

@@grayfurnaceman Thanks

[@summerforever6736]

Get a soft start

[@SuperRobkar]

Would it be possible for you to set your meter to record max amps , and then try the test again with the 5-2-1 connected? From what I’ve been told is that the 5-2-1 just shortens the duration of the Inrush, thus fooling a lot of meters when set the the “inrush” setting.

[@grayfurnaceman]

I believe that is what I did. I believe you are correct that the start time is very short with the 521. I would like to try this with a high end meter that could give a more accurate reading but my budget does not allow it. GFM

[@matt_in_maine]

What are the typical signs that a compressor would need a booster?

[@mitchdenner9743]

Not starting would be one.

[@Militaristics]

tripped breakers, tripped compressor protection, the compressor protection can reset itself so it may seem like a very long delay before any cooling is felt.

[@u2ooberboober]

More than 5 times LRA to FLA.

[@grayfurnaceman]

The answers that have come in so far are accurate. GFM

[@matt_in_maine]

@@u2ooberboober great advise. Thanks

[@Kief_]

My Goodman 3.5ton is a year old. Do I need a hard start kit for any reason?

[@grayfurnaceman]

I would leave it alone GFM

[@TheLawIX]

More up to date video on when to use these: kzbin.info/www/bejne/m3nQlH1jaNSbZsU

[@grayfurnaceman]

I would not call that updated. This reasoning has been around for a long time. A hard start kit is not necessary for a properly operating compressor unless it is used with a non bleed TXV. The difference is very low on start time. Kind of splitting hairs here. They put a lot of pressure on the windings of the compressor due to the large "kick" upon startup. This could reduce life of the windings. GFM

[@TheLawIX]

@@grayfurnaceman My unit came with a factory hard start kit. I'd worry less about the initial kick on a modern unit. My OEM capacitor also has a failsafe built-in that stops the hard start kit from functioning if the capacitor fails.

[@grayfurnaceman]

@@TheLawIX You probably have a non bleed TXV. GFM

[@TheWilferch]

Just asking about the design of the 5-2-1 pieces. You say the relay is normally closed, and back-EMF of the compressor motor during its starting period.....then drops out this relay and opens its contacts. Question: is your term "normally-closed" meaning while sitting there and installed ( connected to power ) ....OR....is that the "shelf position" of the relay? I'm trying to understand the possible failure mode of the 5-2-1 kit...and understand if the relay can "fail-closed" and thereby ruin the compressor by not dropping out when it should. Am I making sense here?..... or does the "failure mode" of the relay cause it to go open?

[@grayfurnaceman]

On the shelf it is closed. BTW, the upside down relay is true. A lot of commenters noticed that. GFM

[@TheWilferch]

@@grayfurnaceman ...thanks. What is the risk (probability) of the contact failing "stay-closed" or the failure of the additional hard-start capacitor?...as they introduce more pieces into the system and they too can fail.....do they fail "safe" or if they fail, can they fail to damage equipment?....I guess they can, as a relay contact failing closed can ruin the compressor.....what have you seen here as to reliability history?

[@harunaral2932]

5 2 1 I can't find anywhere from this relay. Can a standard relay or contactor be used instead?

[@grayfurnaceman]

Absolutely not. The relay is specialized for this application. GFM

[@GuruMN]

What's wearing out inside a compressor that starts for 20 years just fine and then wears out and needs a start capacitor to limp along? Are there winding issues, are bearings getting rough, or it is something else?

[@grayfurnaceman]

The bearings in compressors are bronze bushings. When they wear, the clearance between the rotor and the stator reduces and the rotor drags on the stator. That friction stops the motor from starting in some cases. GFM

[@lightloving683]

Are you familiar with the ICM805 kit? It’s noted as ‘current sensing’; I don’t know how it compares with the kits you’re testing.

[@grayfurnaceman]

It works on the same principal as the fractional HP refrigeration compressors that used a current relay. The problem I see with it is it is a "one size fits all" sort of thing. Many of the factory start kits are designed for a specific size of compressor. I would trust them more than the ICM. GFM

[@wauzdancer1556]

Good video. After your explanation it confirmed no need for these hard start kits. I have a 25 year old 4 ton AC unit. It starts, loud for a second or two on the startup but starts right up and cools well. I do replace the main motor contactor every couple of years as the contacts look pitted at that time by that time. It does make a noticeable momentary buzz at the main circuit breaker during the startup. Is that normal? Confirmed the breaker is well seated , wiring is tight and bus bar is in good condition. Even swapped out the breaker with a known good one, no difference. Wondering if the wiring is the right gauge. 40 amp breaker with #10 romex running about 45 foot. Wondering if that is a bit under sized for the length of the run. Original wiring from 1972.

[@grayfurnaceman]

Some concern about the wire size. If the unit ampacity (on the model plate) is more than 30 amps, the wiring should be increased to #8. I am not too concerned with the buzzing. GFM

[@NorCal-refrigeration]

Enjoyed the video.

[@1martinontherocks]

i have found brand new units with after market hard starts. extra up selling?

[@grayfurnaceman]

Probably GFM

[@burakokumus6040]

Hello sir, On my brand new old tech r22 compressor's manual it says motor type CSR, should I build a CSR starting system with a 5-2-1 or is it okay to use the compressor as a PSC with only a run cap. Thank you.

[@grayfurnaceman]

If the system did not come with a start kit, I would not install one. GFM

[@burakokumus6040]

@@grayfurnaceman understood, thank you Sir.

[@armandom.5299]

I hereby, propose a demonstration on how to connect a Jump Start. All in favor say AYE! ✋🏼

[@dido1803]

✋✋

[@pontiffury9451]

What about so-called "soft starters"?

[@grayfurnaceman]

Soft start controls were a PTC similar to the Super boost, but without the start cap. Just a wire that bypassed the run cap to put more power to the start winding. Have not seen them used for a long time. GFM

[@pontiffury9451]

@@grayfurnaceman well i have one made by Emerson for my Copland scroll. It claims to extend compressor life. Saves me money on my light bill tho.

[@pontiffury9451]

@@grayfurnaceman went from drawing 75amps down to 27 amps at starting.

[@grayfurnaceman]

@@pontiffury9451 The most inaccurate measure of energy savings is the utility bill. There are far too many variables. Besides, starting amperage is present for less than a second. GFM

[@pontiffury9451]

@@grayfurnaceman but based on my utility company's explanation, they charge for highest amp draw within a 15 min interval. So, they use that highest amperage and applies it the the whole 15 min interval. That second of 75amps can be pretty expensive based on that. $50 less per month. Just hope that the soft start can actually extend the compressor life.

[@raymondj8768]

Will these help start the a/c with a genorater ?

[@grayfurnaceman]

I would not guarantee a start kit would help. GFM

[@raymondj8768]

@@grayfurnaceman thanks bud :)

[@mitchdenner9743]

How does the inrush current not trip the breaker on the circuit? How long would it take at that current to trip a breaker.

[@ronnyoo9371]

They are designed like that it depends. Because. If u pull that kinda amps on a. 20 amp won’t last as long as a 30 Usally they have to pull that amount about a solid minute prior to it being tripped or super large amounts of current aka faulted

[@u2ooberboober]

Time delay fuses and breaker design. Breaker doesn’t get a chance to thermal off and it doesn’t detect a short circuit so it doesn’t magnetically trip.

[@grayfurnaceman]

The answers so far have been accurate. I will add that breakers are, by design, time delay circuit protection. Also, the HACR breakers that are required for A/C systems are a higher level of time delay. If there is a dead short all protection will immediately open. GFM

[@mitchdenner9743]

Thank you all.

[@cinnamonisawesome]

Hi there, I was wanting to ask you if by any chance you used to be an instructor at Inland Northwest HVAC Association?

[@grayfurnaceman]

I plead guilty. 2003 to 2012. GFM

[@burnsm2012]

Capacitors have a direct relationship with current, where, if you increase the capacitance of a circuit, you increase the AC current. What U are reading is not the inrush. Your meters samples per second are not adequate. When your meter takes a reading the capacitor has already reached max current and is falling off. Please, argue. I don’t card what Jim bob and his three friends think. Show me your formulas, theory. Not what your meter or what u heard. Also this is exactly why they work on dying compressors/motors. They are boosting amps. Since the voltage remains the same then amps have to go up to produce the kick. Using to many amps without a counter or back EMF will burn your compressor/motor.

[@z06rcr]

If you recommend not putting one on a new unit, why do some manufacturers install them at the factory?

[@grayfurnaceman]

If a unit has a non bleed TXV expansion device, it will not equalize pressures in the off cycle. That high pressure on the discharge of the compressor will not allow the compressor to start as a PSC low starting torque compressor. Thus the hard start kit added to the unit. GFM

[@z06rcr]

grayfurnaceman That makes sense.

[@obobobobobi]

Trane compressors come equipped with hard start from factory.

[@armandom.5299]

Disagree. Never seen that.

[@obobobobobi]

@@armandom.5299 You must be blind then. Google it.

[@armandom.5299]

@@obobobobobi on this video, the unit being worked on is a Trane. The only jump starters are those installed by GFM

[@grayfurnaceman]

The answers so far have been correct. I will add, the Trane unit shown in this video is a scroll compressor with a TXV. On a piston compressor, the TXV would require a hard start. But scroll compressors will start without use of the hard start. GFM

[@bymarkhvac64]

grayfurnaceman can you replace a factory hard start w/relay with a 2 wire super boost if that’s all you have on the truck or is this harmful?