A quick caution/tip if you are going to do this, particularly if the value of the house has appreciated significantly since you bought it - you could be setting yourself up for an unnecessary tax hit when you eventually sell it. If you sell your primary residence - defined as having been your residence for at least two years out of the five years prior to the sale - the first $250k of gain is not taxable ($500k for a married couple). If you rent it for too long, then sell it, you'll end up paying tax on the entire gain. So say you bought it for $200k, lived in it for 10 years, and now it's worth $400k. You buy a new place & move. If you sell within the window of time to exclude the gain, no tax. If you wait 3 years & a day, then sell, $200k taxable gain.
There's a way around it that, if the appreciation is sufficient, is well worth the cost & paperwork shuffle. Form an S Corp, sell the old house to it at current market value. You exclude the gain (up to the $250k/$500k limit). Now the S Corp owns the rental house, you own the S Corp. The S Corp rents the house, and as an added bonus gets to depreciate it at the purchase price when you sold it to the corporation. If you still owe on a mortgage, it can be a bit more complicated (because the bank might want/expect to be paid off when you sell it to the corporation), but there are ways around that. If you go this route, do the paperwork by the book & spend a little money to get an appraisal to document the market value of the house.