I would like some advice on sizing a new boiler and indirect hot water heater. My local HVAC'ers contradict each other and I'm trying to be as intelligent as possible.
House is old Cape Cod, 2200 Sq/Ft baseboard hot water heat, 3 zones. Boiler is natural gas 100K btu 81.4% AFUE, hot water is natural gas 40 Gal 40K btu. Two adults - no kids. The house stays warm but feels chilly when its very cold with a wind.
The house is leaky at sidewall to roof joint and very difficult (expensive) to fix (second opinion validates).
I would like to install a sealed combustion direct vent boiler and indirect hot water heater. All of the boilers that I am considering are 86-87% AFUE and about 105-112K btu.
My local HVAC'ers are telling me that I need to have a larger boiler (130-140K btu) due to the indirect HW and after reading this and other sites I'm not conviced I do. I would also like to know if I need a 40 gal indirect with a 40 gal tank or could I go smaller due to the recovery rate?
I've read comments like it will only take 15-20 minutes to recover hot water and that you will not feel the house change temperature during that recovery. Since recovery is fast wouldn't a smaller sized indirect tank work well?
Thanks for your help.