If you don't like heat lamps get them a brooder plate.
No I don't. I'd go by the manufacturer recommendations. I personally use a heat lamp and will always use one. I find them cheap and easy. I do brood out in a shed. I tend to brood 15 plus chicks at a time. I only use a 125 watt bulb. The 250 bulbs can be too hot unless you are brooding in cooler temperatures.I've never used a brooder plate or heating pad. Any idea how big of a brooder plate you might need for 20 chicks? A few years back Beekissed did a pros and cons of heat lamps versus heating pads. One of her Pro's for heat lamps was that they could handle larger numbers of chicks. Bee broods outside in her coop with those temperature swings. I'd think if you brood in a climate controlled house it would be easier with a plate or pad and higher numbers of chicks.
@LittleRedCoopLady I agree that a grow light doesn't give off that much heat. I would not try using one. If you can get one big enough, heating pads or heat plates work really well.
I'm not sure what your concern is with a heat lamp. They do use more electricity than the other methods so your electric bill will be higher. Anything electric has a fire risk if you don't set it up right. In my opinion if you throw away that clamp that comes with it and use wire to hold the heat lamp in place you greatly reduce your fire risk. Wire, not string that will burn or plastic that will melt.
You do not want to overheat your chicks. With 20 chicks your brooder should be big enough that you can heat one end and the other end can cool off to a much lower temperature. Even straight out of the incubator mine are really good about finding the temperature area they like. You can lower the temperature the heat lamp is causing by putting a dimmer in the circuit, moving the lamp further away, or do what I do, use a lower wattage bulb to lower heat output.
An alternative to the heat lamp is a hover. It's basically a shallow box with the open side down that traps heat. If you do an internet search on "chicken hover" you'll get some hits. Those are generally intended for brooding outside and a lot more than 20 chicks but it can be a cost effective way to brood them.