You know chicks don't always need a heat lamp. In the tropics or desert, no one uses heat lamps because it's naturally warm for chicks. Also, there are alternatives to heat bulbs, such as heat plates and heating pads, which are far safer and less tricky getting the temperature comfortable.
The trickiest period for chicks is during the first couple weeks when they really need to be able to warm up under a source that will put out between 80 and 90 F. Notice the wide range. It's not written in stone that chicks must be kept at such and such a temperature.
It's like us humans being most comfortable around 70F, but we can handle a wide range on either side of that. When our weather is very cold, we like a fireplace or campfire or a nice wall heater to warm ourselves. But we move away from the heat source once we've warmed up. We don't stay there or else we'd start overheating.
The same is true for baby chicks. According to how cool the ambient temp is, they need to warm up more or less frequently, just like us. If you live where it's already the temperature chicks need during those first couple weeks, the chicks probably aren't going to need extra heat. If you see them huddling together, you might just use a 60 or 100 watt incandescent bulb. 250 watts is usually overkill for even cold temps for just two chicks.
Watch your chicks. If they're acting normal, not huddling together for warmth, then they're warm enough.
