My concern would be not having the HR system freeze while away. Using propylene glycol in the system could mitigate that concern. If, as Dana suggested, an electric boiler is an option, you might want consider using a NextGen boiler which is actually a fully automatic plug & play HR appliance that contains everything necessary to fully operate your HR system (e.g., control system, differential pressure valve, expansion tank, and pump). You could just plumb the NextGen so it could be isolated from your existing manual system. Cost is about $1,200 and you would want their NextGen-12 model (12 kW or 40,956 Btu/h) if your numbers are correct, but perhaps you don’t need that much while away (i.e., perhaps you don’t need DHW and as high an indoor temp setting). http://www.nextgenboiler.com/ |