Combi vs system vs heat-only
Combi boilers heat water on demand — ideal for 1–2 bathroom homes with mains pressure above 1.5 bar. System boilers (with an unvented cylinder) suit 3+ bathroom homes and households drawing two showers simultaneously. Heat-only (regular) boilers keep the existing tank and feed and are usually fitted in older properties where pipework can't be reasonably reconfigured. We size all three from a measured heat-loss survey, not a guess from photographs.



