Plan the heating system as a whole
Hydronic heating carries heat through water to radiators, radiant floors or other emitters. The boiler, piping, pumps and controls need to suit the building and the temperatures required by those emitters. An existing radiator system and a new heated floor may need different design arrangements.
Renovating? Discuss future zones early
If you hope to add in-floor heating later, mention it before equipment is selected. Ask whether the planned system can support the extra load and what space or connections should be allowed for. Future expansion is a design question, not a feature that every boiler automatically provides. Floor construction and the chosen floor covering also affect the plan.
Look at space and hot water together
Some coordinated heating and domestic-hot-water designs can make better use of a mechanical room. The final footprint includes service access, piping and every required component, not just the appliance cabinet. Ask Comfort Nest about suitable compact options, including whether an NTI GF150-based arrangement is appropriate. Bring a mechanical-room photo and your renovation plan so the discussion starts with the space available.