My parents are getting quotes to replace a 30 YO oil fired boiler that has a small "add-on" hot water tank. He is looking into getting a gas fired unit so that he can replace his very old electric stove with a gas range.
AC is not part of the equation because he already has a separate central air system.
They live in Western Massachusetts in a brick house that is not well insulated.
Another factor to consider is that it's just the two of them, except for a few times a year when the rest of us visit. During these visits there could be up to 14 people in the house for 3 - 4 days. During these visits, both showers are in use at the same time, lots of dishes get done, etc.
I know next to nothing about boilers, so this is the best I can do to describe their current system:
They have a thermostat that controls the boiler for the baseboard hot water radiators and a timer switch that controls the same boiler for the hot water tank. There is a large (1=94?) pipe that runs through the hot water tank, so I assume that the water is heated via heat transfer from this pipe. The tank is not directly fired.
The timer has a "Hold" position so that they never run out of hot water when the house is full of guests. The boiler does not run constantly when the timer is set to hold, so obviously there must be a thermostat associated with hot water tank also.
OK, so here are the options he=92s been given via a few quotes:
1 =96 A combo unit that will include a water heater built into the boiler. 2 =96 A boiler just for heat and a separate 40 gallon water heater.BTW=85no one has suggested an instant water heater in any of the quotes, but my dad and I discussed it and he feels the expense would not be worth it, considering their age. He=92d like to do what=92s best for the house as far as resale value, but the extra cost of the instant water heater doesn=92t seem to make sense.
The other issue is the efficiency of his choices. The quotes he has received so far are for 85% efficiencies, but the rebates from his utility don=92t start until the units hit the 90%+ range.
So my main questions are these:
Which makes more sense in this situation:
1 - A combo unit or a boiler and separate water heater? 2 =96 85% efficiency or a higher efficiency with the rebate offsets? The rebates seem to be in the range of $1000 - $1200 but I don=92t know how much more a 90%+ boiler would cost.Thanks for any thoughts you have on this matter.