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Carrier 15,000 BTU Heat Pump Required Voltage


Ski

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Voltage measured in the 5th wheel without AC  is 118 volts, with AC on it is  112 to 114 volts. Would it harm the AC unit to operate a couple volts under the required 115 volts?

Thanks,

Al

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Normal voltage is usually 120. It won't hurt to run it at that voltage.

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10 hours ago, Mntom said:

Generally a 10% variation is acceptable meaning if you stay above 108 volts or below 132 volts it shouldn't be a problem.

That is the standard that modern 120v-AC equipment is designed to and yours is no exception. Even at 112V, you are well above the minimum so there should be no problem at all.  What you are dealing with is the very reason that so many of us use a line monitoring device such as those from Progressive or TRC-Surge Guard . Where the potential problem comes is that if more RVs arrive and power up their air conditioners, or when you use something like your microwave, the supply voltage should drop to under the minimum 108v, then motor damage will start to take place.  You can read more about the power issues here, should you be interested. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
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    FWIW I agree with the fine gents above, only a couple volts under 115, or 113 per your question, shouldn't cause undue harm to your AC, it might run just a tad warmer as voltage drops but shouldn't pose any serious problem. In many years or RV park experience I've seen too many under designed parks when its extremely hot and several RV's park (and run AC) voltage falls to unacceptable levels.  Trouble is unless you're closely monitoring voltage levels or utilize a protective device, voltage can gradually creep down below acceptable levels which can, if left uncorrected, cause some harm. No easy runs or free lunches out there lol.

 

John T

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The OP said that he was measuring the voltage "in the 5th wheel".  If he's measuring it at a socket inside the RV the measured voltage can be one or two volts less due to voltage drop.  Even though his A/C was off there could be other items running, for example, microwave, electric hot water, even the inverter/charger, that could drop the voltage a bit.  Even with a very small current load there are so many connections inside the RV that small voltage drops are probably almost inevitable unless you are very careful to keep all key connections torqued up.

As an example, I have a Progressive EMS and the voltage it shows on L1 and L2 were within a volt of what the power company measured recently when they had to do some work on my pedestal.  But those voltages are often a volt or two higher than what I get with the plug-in digital meter I have in the kitchen.  The power company was there because the Progessive had detected a fairly significant difference between L1 and L2 (~3-4V) which disappeared after the technician tightened all the connections from the pedestal back to the 7kV step-down transformer.

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Doc, good points. Indeed there's V = I x R Voltage Drop in each inch of the circuit from the utility transformer all the way to the end load and the more the current and the smaller the wire (plus often the more connections/splices) the more line voltage drop. In our huge Naval industrial complex where I practiced when 120/240 volt single phase three wire circuits exhibited different voltage levels my first instinct was to check all the connections. A simple visual inspection often revealed off color or brown or burns at the connections.

John T

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On 6/22/2017 at 6:40 PM, Ski said:

Would it harm the AC unit to operate a couple volts under the required 115 volts?

 

The short answer to this is, no. While I would check the voltage at the power pedestal as well, it is good to know both locations since it does tell you quite a bit about your RV connections. The other thing that I concern myself with is the amount that voltage falls when a larger load is first applied. I would monitor the voltage inside while turning on first the a/c and then with it running, add in the microwave. If that combination stays well above the 110V mark I would not be concerned but would continue to occasionally check to see what voltage is. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

            images?q=tbn:ANd9GcQqFswi_bvvojaMvanTWAI

 

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Kirk, using a digital VOM I took some readings. At the outlet we are plugged in to, it reads 121 volts. Inside RV  at an electrical outlet reads 121 volts with everything turned off. . With A/C on reads 114 volts. With A/C and with fridge on electric reads 111 volts. When A/C is on we run the fridge on propane and do not use a toaster, microwave etc. We just run the A/C at night. Currently in VaBeach (warm and humid at night) at a relatives plugged in to an outside receptacle using a new 10 gauge extension cord with a 20amp to 50amp adapter to the RV.

From the replies, sounds as it we'll be okay. 

Thank you.

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25 minutes ago, Ski said:

to an outside receptacle using a new 10 gauge extension cord with a 20amp to 50amp adapter to the RV.

 

The readings that you have taken demonstrate that you have a somewhat soft power supply, as I would expect from the source you describe. But the circuit you are connected to clearly is a very solid one or the drops would be worse than they are. Since the voltage threshold we are concerned about is 108V, it does seem to me that you should have no problems doing as you are. Most of that voltage drop is probably happening at the connection to the outlet it's self so I would suggest you check to make sure that the outlet you are connected to isn't getting hot while the a/c is running. Warm to the touch is OK but it should not be so hot that you can't hold your hand against it for a long period of time. Your a/c probably draws about 12 - 13a when running with a start current peaking near the trip setting of the outlet's circuit breaker. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

            images?q=tbn:ANd9GcQqFswi_bvvojaMvanTWAI

 

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On ‎6‎/‎25‎/‎2017 at 9:30 AM, Ski said:

At the outlet we are plugged in to, it reads 121 volts. Inside RV  at an electrical outlet reads 121 volts with everything turned off. . With A/C on reads 114 volts. With A/C and with fridge on electric reads 111 volts.

 Ski, that 7 volt drop with the AC on is higher then Id prefer, although 114 volts (If present at the pump ??) should power your 15,000 BTU heat pump fine. HOWEVER unless you take the time and trouble to measure the actual voltage input at the AC when its running I cant say how much if any problematic it is. That 121 volts open and 114 when the AC is on "at the outlet" is subject to the homes branch circuit wiring and while its typically 12 gauge wire, if it were only 14 gauge and/or the distance from the panel is excessive and/or there's a loose resistive connection/splice in the circuit, such could account for that 7 volt drop. Obviously there's a V = I x R drop in the branch circuit to that outlet and the longer the wire and the smaller the wire and the more current THE GREATER THE VOLTAGE DROP. I don't have the specs on your 15,000 BTU Heat Pump (not the same as a typical 13,500 BTU around 12/13 amp rooftop AC) but guess its at least 11 to 14+ amps ??

I think most above agree the 113 volts you originally asked about (or perhaps even lower) should power your heat pump, but if you're only seeing 114 "at" the outlet due to voltage drop "to" the outlet there's less room for error especially when you don't know how much more voltage is being dropped from the outlet to your heat pump WHICH IS WHY THE ACTUAL VOLTAGE GETTING TO THE HEAT PUMP IS IMPORTANT TO KNOW. In addition to the RV's internal circuit to the heat pump, those dogbone adapters and RV plugs and receptacles may pose a voltage drop. Check them for tightness and evidence of heating and keep the male pins/blades bright n shiny.

 PS there's likely a good chance you're fine due in part to the fact there's a shorter wire run inside the RV versus from the homes main panel to that outlet (less line drop)  but there can be the possibility of voltage drop in the dogbone and plug and receptacle etc downstream of the homes outlet ?? 

 John T Tooooooooo long retired Electrical Engineer and rusty on this so NO warranty  

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