In this paper, a load reduction Aggregator participating on the Swedish Peak Power Reserve (PPR) market was analyzed. The load reduction was provided by electric heating systems in larger dwellings (e.g., office buildings). Two simulation models were developed to assess the market performance of the Aggregator. From the simulation results it was concluded that the PPR market was not optimal for the proposed Aggregator. Among other things, the market was too inflexible and the profits were just a small subvention of the larger day-ahead electricity purchases. Also, it was concluded that the Aggregator was exposed to several risks by participating on the market, e.g. situations of shortage in available power capacity. A number of countermeasures to mitigate these risks were presented.