Adding a hard start kit to a perfectly good running air conditioner

[Mustwin351]

Just wanted to get thoughts on whether it's worthwhile to add a hard start kit on my own residential ac compressor with the idea of reducing starting current on my unit for the purposes of extending its life. I've read that doing so will extend its lifespan but I'm not sure if that's really talk or just a way to sell more ac parts.

 

[FionaZuppa]

Just wanted to get thoughts on whether it's worthwhile to add a hard start kit on my own residential ac compressor with the idea of reducing starting current on my unit for the purposes of extending its life. I've read that doing so will extend its lifespan but I'm not sure if that's really talk or just a way to sell more ac parts.

i dunno, my 5ton R22 system is abused, compressor (piston) and fan motors (York crud) have been working fine for past 10yrs w/o the need for maintenance or hard start kit. i say dont mess with it. for me though, i have to upgrade to 410a soon.

they are usually installed when needed.

and btw, scroll type compressors should never need a hard start kit. so check which type you have 1st.

 

[Jraef]

Just wanted to get thoughts on whether it's worthwhile to add a hard start kit on my own residential ac compressor with the idea of reducing starting current on my unit for the purposes of extending its life. I've read that doing so will extend its lifespan but I'm not sure if that's really talk or just a way to sell more ac parts.

These things have a place, specifically if you are near the end of a line and the starting of your compressor causes a large voltage drop. But if that's not happening, it isn't really going to do much for you. There are lots of people hawking these as "compressor savers", I think it's BS. It's just another capacitor that boosts the voltage while starting, the same thing the motor start capacitor does, so it basically just "helps" that cap. But if you don't have an issue with the motor's standard cap, then its a waste of money. I've seen some pretty schlocky BS websites on this issue that have the same look and feel as the other "capacitor" energy savers, it's all based on a general misunderstanding of how motors work and how energy is metered. One I looked at a while ago for someone said, LITERALLY, that "Volts x amps = watts and you are billed on watts. So by having this capacitor reduce the amps, you are saving watts." Total BS.

 

[Mustwin351]

Kind of what I was thinking. Even if a hard start kit reduces the starting current it is only for a fraction of a second and not going to make much of a difference in the heat generated in the windings when it first starts. Unless the compressor is struggling to start I would think that would be the only time it would be practical to actually install one.

 

[peter d]

They're only needed on units on their last leg. The compressor is on its way out and you can squeeze a year or three more out of them with a hard start.

 

[GoldDigger]

Just remember firmly the difference between a soft starter and a hard start kit.

A soft starter reduces the motor current by any of several means ranging from reactive voltage reduction to full VFD functionality of variable frequency.
A hard start kit just tries to increase the available starting torque, often at the expense of actually drawing more current.

 

[junkhound]

.

and btw, scroll type compressors should never need a hard start kit. so check which type you have 1st.

+1, AND, since OP just said AC and apparently does not have a HP he needs to start at -20C, I'd even remove the word 'should' from your quote

 

[mbrooke]

Unless you are on a 208 volt supply, or the AC starting is knocking things out via severe dimming, I see no reason. Most AC units do well without a hard start as they are often rated 208-230 volts, ie 197 min 253 max. 197 would produce 98 volts on a 120/240 service, so in that case you would have bigger things to worry about.

 

[mbrooke]

Just remember firmly the difference between a soft starter and a hard start kit.

A soft starter reduces the motor current by any of several means ranging from reactive voltage reduction to full VFD functionality of variable frequency.
A hard start kit just tries to increase the available starting torque, often at the expense of actually drawing more current.

If so I might be wrong above in my reply. I heard somewhere a hard start can reduce peaked locked rotor current but the reduced starting draw carries out over a longer period of time. But again, I could be very wrong.

 

[junkhound]

Many HVAC compressors are just cap run. Most 'hard start' setups are just adding a start cap across the run cap with a potential (or current) relay, so start current (and torque) goes up.

 

[FionaZuppa]

funny how these hard start kits are touted by the sellers. one thing to do if you want to "help" the compressor live a longer life, ditch the mechanical contact relay switch for solid state. its 2017 and the AC makers are still using 1800's technology!

 

[badbanano]

"Inrush" current is a complete misnomer, but if you have a pool pump, a vfd will save you tons of cash.

Sent from my XT1254 using Tapatalk

 

[GoldDigger]

"Inrush" current is a complete misnomer, but if you have a pool pump, a vfd will save you tons of cash.

Sent from my XT1254 using Tapatalk

Starting current is a very small part of the pump power needs.
Unless you are being billed extra for instantaneous peak power, I do not see any effect on the bill.
If the pump will end up cycling on and off a lot, or delivering a higher continuous GPM than required a VFD may save you money by letting you run the pump at reduced speed/output.

Sent from my XT1585 using Tapatalk

 

[Jraef]

A VFD can only save energy on a centrifugal pump or fan if it is replacing some other means of flow control, such as a valve or dampers. That's it.

 

[retirede]

A VFD can only save energy on a centrifugal pump or fan if it is replacing some other means of flow control, such as a valve or dampers. That's it.

Exactly. There's a lot of misinformation out there. I run my 1 hp pool filter pump 12 hours per day on a timer. My pool guy tried to tell me I'd save a ton of money with a vfd. I asked him: so I run it at half flow for 24 hours instead of full flow for 12. How much does that save? He just looked at me.

 

[drcampbell]

A VFD can save energy & money if the motor is oversized for the application, or if it is run at lower speeds during times of lower demand.

 

[Mustwin351]

funny how these hard start kits are touted by the sellers. one thing to do if you want to "help" the compressor live a longer life, ditch the mechanical contact relay switch for solid state. its 2017 and the AC makers are still using 1800's technology!

Not sure a solid solid state would help extend life very much. Especially since when a SSR fails they tend to fail closed....you would have a very cold house though! Well until the evaporator could freeze over.

 

[mtfallsmikey]

Years ago, they had combo run/start caps. Hard start only required if there is a log refrigerant piping run, or high lift. Scrolls don't need em.

 

[mtfallsmikey]

The worse thing IMO is the POJ pull-out discos. They will arc eventually, seen them trash more than one compresssor

 

[kwired]

A hard start kit just tries to increase the available starting torque, often at the expense of actually drawing more current.

Many HVAC compressors are just cap run. Most 'hard start' setups are just adding a start cap across the run cap with a potential (or current) relay, so start current (and torque) goes up.

Exactly the case in most residential type units. That higher value capacitor during starting actually makes the motor draw more current in the attempt to put out more torque to get it started faster. If it is successful then the duration of startup is shorter then without that higher value capacitor.