Triplex With Assumable Mortgage

[Jason Reider]

Hi everyone – first time poster here. There's a triplex in West Hartford that just came on the market – it's the perfect location I'm looking for to house hack my second property. The listing offers an assumable FHA loan at 2.625%. I'm trying to run the numbers, but I'm having trouble since the rental property calculator only factors in one mortgage.

The house is listed for $550K and the existing mortgage balance is $392K with $3,149 monthly payments.

The mortgage company will allow for a secondary loan up to 80% of the current equity in the property (about $157K). 

Can anyone offer any advice on how to calculate the numbers between assuming the FHA loan plus a secondary mortgage to get an accurate look at what the total monthly costs would be. Any other advice on how to approach this property? Thanks!