Hard Start kits: Supco SPP6 vs. Dometic #3310727.015

[otrfun]

Giving some serious thought to installing a hard-start kit on my 2012 Dometic 13,500 BTU Brisk Air a/c. Quite a few positive reviews on the Supco SPP6. Anybody have any experience using the Dometic Hard-Start Kit (#3310727.015)? Dometic claims their Hard-Start kit (or Starter Assist Kit) will dramatically reduce the LRA for their Brisk Air units. Thanks!

[Wayne_Dohnal]

Notice that I said my EU2000 can start the AC. I did not say that I can run it at those temps and altitude. Alias, I am only able to run the AC with the single generator for about 20 to 30 minutes before the generator gives up.

The eu2000i ran my air conditioner quite reliably and indefinitely below 1,000 feet. What I see at 3,500 ft. is the eu2000i will supply its rated power for 10 to 20 minutes, then it won't supply 1,600 VA any more. I'm assuming it's the generator heating up that leads to the power drop.

[otrfun]

Chris Bryant wrote:
. . . DuoTherm does make a couple of better options- p/n 3102903.006 , which is a true potential relay (unlike the Supco "E" series quasi potential relay) . . .

Chris Bryant wrote:
The best (other than the expensive SmartStart) would be the DuoTherm # 3102903.006- specifically meant for this- actually made for a DuoTherm Penguin running on an Onan 2800, but does the job on any DT air conditioner.

Thank you, Chris! Your last few posts have been a great help! Glad I read this before I placed my order for the PTCR based Dometic Hard-Start Kit (3310727.015).

[SteveAE]

The Sure Start may be a slightly less expensive ($180.00 in 2012) alternative to the Smart Start.
With the Sure Start, my single Honda EU2000 starts the AC every time at 90+ degrees at 3500'.
In the same conditions, the Hard Start was not as reliable starting, but it was "slightly" better than without it.
Another way to start the AC that I played around with before I got the Sure Start was to start the compressor a few seconds before starting the air handler. This worked far better than the Hard Start alone and, with the Hard Start, it was was "almost" (but not quite) as reliable as with the Sure Start.

Notice that I said my EU2000 can start the AC. I did not say that I can run it at those temps and altitude. Alias, I am only able to run the AC with the single generator for about 20 to 30 minutes before the generator gives up. So a starting assist (Hard or Soft) is not a substitute for a generator that is sized to RUN the AC at the temperature and altitude that you wish it to work at.

Hope this helps,
Steve

[Chris_Bryant]

The best (other than the expensive SmartStart) would be the DuoTherm # 3102903.006- specifically meant for this- actually made for a DuoTherm Penguin running on an Onan 2800, but does the job on any DT air conditioner.

[popeyemth]

So which do you recommend I install to help an undersized genny set, Mr Bryant?
TIA, Mike

[Chris_Bryant]

There is virtually no difference between that Dometic part and the Supco SPP6- both are PTCR based start devices. Supco does not recommend the E series for RV applications- because if you shut the compressor and try to restart it right away, the E series will put the start cap in the circuit, a PTCR device will not. My response to that- doesn't short cycle the A/C (most new thermostats will not let you anyway).
DuoTherm does make a couple of better options- p/n 3102903.006 , which is a true potential relay (unlike the Supco "E" series quasi potential relay), and a really good, though very expensive start kit, the SmartStart- unlike anything else on the market (at ~$370, it better be 🙂 ).

Another option I am looking at is the 5-2-1 compressor saver- a true 3 wire potential relay.

Note that the benefit for the non-PTCR type kits is really only in running off an undersized genset- they keep the start capacitor in the circuit until the compressor comes up to 75% of speed, which takes a fraction of a second longer if the genset bogs down.

[otrfun]

Jayco23FB, really glad to hear the Supco SPP6E appears to be working for you. Noticed a bit of chatter online that the SPP6E (vs. SPP6) is supposedly designed for heavier-duty 220 volt applications. Not sure if there's any validity to this, but may be something to keep in mind if you have any issues with the SPP6E down the road.

ernie1, I've heard the Supco/thermal vs. Dometic/electronic comparison before, too. Found some pretty good bargains on both the SPP6 and Dometic (3310727.015), so I've decided to order and try both. Although many folks install the hard-start kits to make an attempt to power their 13,500 BTU a/c's with their smaller generators, I think they're a worthwhile investment for everyone to just reduce the day-to-day strain on the compressor and generator during normal operation.

I'm disappointed a/c manufacturers don't install these things in their OEM units as a matter of practice. Doubt it would cost more than a dollar for them to do so. Get the impression these things have the potential to reduce the LRA (inrush current) on many a/c units up to 50%--that's huge. It may not be much of an issue when powering a/c units with commercial power, but it's certainly a huge deal when using generator power.

[ernie1]

My understanding is that the Supco unit is thermally operated and the Dometic is electronically operated. Translation, the Dometic unit will respond faster and is less strain on the compressor. I'm really happy with my Dometic unit.

[Jayco23FB]

I installed the Supco SPP6E on my Coleman Mack (1350 BTU)last week. It was very easy to install. You can find a great video on Utube by searching for RV AC hard start kit. When talking to the company they suggested the E version as it re-sets faster and is electronic vs mechanical operation ???? it was only a few dollars more. As for operation I bought it so I can run my twin Yamaha 2000's in Eco mode. It is only 50 degrees here in Idaho but in testing the AC system after the install I noticed a huge difference in how much the generators had to work to get the AC unit running. The ultimate test will be in July/August.