Due to these factors you may require more or less warmth depending on your choice of bed and comfort preference.
Other factors may also be contributing to the bed feeling warm. Your sheets, quilt/duvet, blankets, clothing and room temperature can also affect your warmth as they arealso key regulators of temperature during sleep.
The type of material in the sheets you are sleeping on will alter the warmth of the bed. Flannelette and polyester blend sheets will be warmer than 100% cotton or bamboo sheeting. Remember when you tested the bed in-store there were no sheets on the mattress so it will feel different.
As well as needing a different weight duvet between Winter & Summer, you may also find that the weight of your old duvet may not provide the right level of warmth on your new mattress.
Woolrest, electric blankets, overlays or protectors
An additional layer between the mattress and the sheeting can also have an impact on the warmth of your mattress. Wool and some foams are naturally warm. TENCEL protectors allow mattresses to breathe whilst protecting from external moisture and so are cooler than plastic protectors. Electric blankets, whilst in use, will also make the sleeping environment warmer.
The ambient temperature in the room will also affect the temperature of the mattress. Many types of foam layers respond to heat and are cooler and firmer in cooler temperatures and warmer and softer in warmer temperatures. You may find that your mattress warms up and becomes softer as the bed responds to the heat from your body.