mhrv efficiency

selfbuildsoon

Comparing mhrv systems at the minute. They all have different efficencies- 86%, 92%, 95% and 97%. Obviously the 97% heat recovery is the best, but is it much better than the 86% system? There's about 2,000 euro price difference between the various systems.

beyondpassive

When comparing efficiencies you also need to know what method is used for testing. Sap appendix Q testing is measured on the supply side where as Passivhaus measures on the exhaust side. Therefore you need to subtract 12% (although I'm now told its 18%) to the sap Q efficiencies when comparing it to passivhaus certified components. Also note that energy recovery and heat recovery are not the same. One recovers entropy or enthalpy (recovered heat from steam condensing) and the other recovers heat from dry air. make sure to sketch out the duct routes, drops and flow rates at each diffuser and at the intake and exhaust. Limit the use of flexi's.

brophis

Insulated ducting also has a role to play in the overall efficiency of the system.