<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-09-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000874482</issuerCik>
        <issuerName>UNION NATIONAL FINANCIAL CORP / PA</issuerName>
        <issuerTradingSymbol>unnf</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001406825</rptOwnerCik>
            <rptOwnerName>Staman Stephen D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>860 WESTMINSTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LANCASTER</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>17601</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series A Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-09-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1000</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2009-09-23</value>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11275</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Series A Convertible Preferred Stock is convertible into UNFC common stock at step-up prices of:
    Sept 15, 2009 - Sept 14, 2010 at $4.00 per share
    Sept 15, 2010 - Sept 14, 2011 at $6.25 per share
    Sept 15, 2011 - Sept 14, 2012 at $7.50 per share
    Sept 15, 2012 - Sept 14, 2013 at $8.75 per share
    On or after Sept 15, 2013 of $10.00 per share</footnote>
        <footnote id="F2">The Series A Convertible Preferred Stock has no expiration date.</footnote>
        <footnote id="F3">Based on the step-up conversion prices in footnote (1) above:
    Sept 15, 2009 - Sept 14, 2010 - 6,250
    Sept 15, 2010 - Sept 14, 2011 - 4,000
    Sept 15, 2011 - Sept 14, 2012 - 3,333
    Sept 15, 2012 - Sept 14, 2013 - 2,857
    On or after Sept 15, 2013     - 2,500</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Charles R Starr, AIF</signatureName>
        <signatureDate>2009-09-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
