best place to put 20k for 3 years

Was wondering what would be the best thing to do with 20k. I won't need it for at least 3 years. From reading previous posts, 3 years seems too short a time frame for thinking of investing, while from my understanding fixed term deposit accounts seem to have low or similar return compared to demand deposit accounts. Just wondering what my best options would be.

Re: best palce to put 20k for 3 years

How flexible would you be in terms of extending the investment timeframe if, after 3 years, your investment was not performing as well as hoped? What is your attitude to risk/volatility? What other savings, investments, debts do you have?

No other debts except mortgage, which will be paid off in about 10 years. Other savings, would include 5k, in a credit union account. Planning on having another child, within next year or two, and I intend to give up work for at least a year. We can survive on one wage, but would like to put that 20k, aside for 3-5 years, where it cannot be dipped into, and be used later, when I return to work, if we decide to trade up, to pay for stamp duty, fees etc. If that makes sense.