Dear All,

Our proposed design is providing hot water for space heating and domestic purposed through a central fossil fuel boiler system. The system has primary and secondary pump which are variable. The baseline in this case will have separate system for space heating and domestic hot water purposes. In that regards, I have two questions?

1. The efficiency of baseline boiler is modeled on the basis of Table 7.8 while matching the fuel type to proposed. What type of boiler should we model condensing or non condensing, natural draft or force draft?

2. There are two set of pumps which are primary and secondary. As the baseline does not explicitly states modeling of DHW pumps, should I model domestic hot water efficiency i.e. W/L/s by combining primary and secondary pumps power? for instance if primary pump is 1000 W/L/s and secondary is 600 W/L/s, how would you model it for DHW pumps?

3. I have assumed baseline pumps will also be variable for DHW. Is that ok?