Hot water baseboard and forced air AC unit

paulex7920

Hello all. I'm new to this group. So we are purchasing a home that has both an oil fired boiler for cast iron baseboard heating and domestic hot water. (House was built in 1954). And, a separate old 1980's vintage ducted Carrier Air conditioning unit (R-22 Refrigerant). Obviously I want to upgrade at least the AC with a new unit. What can I do to streamline/change. Is there such an animal as a heat pump that will serve both purposes? hot water heat and AC? Please point me in the right direction. Thank You in advance.

HVACNUT

You could go with a high efficiency heat pump. 2 stage or inverter. Then the boiler would become stage 3 heat.
For DHW, a heat pump water heater.
There's also something like the Apollo HVAC system that's both heat, AC, and hot water, but I'm not real familiar with them.

Are you looking to phase out the boiler? Personally I wouldn't rely on a heat pump as my only heat source. 

What make and model is the boiler? How old? Are you familiar with oil boilers?

pecmsg

Keep the boiler.
Get a Proper room by room heat load / loss (Manual "J") to determine the proper size heat pump. Have the air flow tested to determine the CFM's to each room and make the corrections need. A duct design (Manual "D") may be needed. Have a properly sized heat pump installed.

Keep the boiler as a backup and for times the heap pump just isn't cutting it!

Hot_water_fan

Two flavors of heat pumps would work best for you: air-to-air and air-to-water. A2A is the most common. It would heat your home with forced air. A2W would heat it with forced water. Both would cool the same way, and the A2W could heat your domestic hot water. A2Ws are much more niche though, so more expensive and harder to get installed. 

pecmsg

Hot_water_fan said:

Two flavors of heat pumps would work best for you: air-to-air and air-to-water. A2A is the most common. It would heat your home with forced air. A2W would heat it with forced water. Both would cool the same way, and the A2W could heat your domestic hot water. A2Ws are much more niche though, so more expensive and harder to get installed. 

Will the A2W provide the temperature needed? They max at around 120-140°F. Lower as it gets colder.

Hot_water_fan

Will the A2W provide the temperature needed? They max at around 120-140°F. Lower as it gets colder.

No way to know from behind a screen. Maybe yes, maybe no. 

EdTheHeaterMan

paulex7920 said:

Hello all. I'm new to this group. So we are purchasing a home that has both an oil fired boiler for cast iron baseboard heating and domestic hot water. (House was built in 1954). And, a separate old 1980's vintage ducted Carrier Air conditioning unit (R-22 Refrigerant). Obviously I want to upgrade at least the AC with a new unit. What can I do to streamline/change. Is there such an animal as a heat pump that will serve both purposes? hot water heat and AC? Please point me in the right direction. Thank You in advance.

I believe this answers that question


1. You will not like how the heat from a heat pump feels compared to the cast iron baseboard heat. So don't get rid of that type heat.
2. Your air conditioner ductwork may be able to provide some heat with a heat pump in the fringe seasons (Spring/Fall).
3. Getting Domestic Hot Water (DHW) from a tankless coil in a boiler is not the most efficient use of energy. I believe that a indirect tank attached to a high efficiency boiler is the best (some disagree).
4. Second best for DHW would be a stand alone tankless because there are no standby losses for the majority of the day when you are not using hot water

bio_guy

Do you have natural gas available in your location? A condensing gas boiler would work most excellently with CI baseboard RADIATORS. (It is more difficult to get performance out of fin-tube baseboard CONVECTORS that seem to be much more common that CI and it needs higher temperature to get decent output.) You can run CI at condensing water temps and it will work with your existing system if you have upgraded sealing with good windows and upgraded insulation with all the radiators retained. The improved heat loss from the structure makes up for the lower temperature radiators. Do not oversize a new boiler. I like the concept of the combo HTP Versa-Hydro appliances. There is a built-in buffer to prevent short-cycling. The primary heat exchangers are a unique concept. (Westinghouse sells , under HTP license think, a water heater with the same primary heat exchanger design and it would work as a good high efficiency boiler if your heat needs are low. Cost is pretty low. It is not, however a combo boiler. You’d need to add a heat exchanger or buy two of them.)

Low temperature heat pump performance is very much improved. My understanding is that heat pump operation costs less than flammable fuels almost everywhere in the US. If that is true, retaining the CI baseboard is going to be mostly a comfort thing. Cost of buying, running and maintaining two systems can be calculated. Try to find a local energy evaluator/rater (BPI or Resnet) that is independent of any heating, insulation or any other construction operation. Government and utilities often pay for or subsidize the cost of the evaluation. Locals will know what to do in your climate and identify the low-hanging fruit.

Keep in mind that maintaining an oil system is more intensive. You need annual service so find a good service company if you stick to oil. There are also high efficiency oil boilers.

If you maintain a boiler for heat, an indirect tank will serve you well.

hot_rod

A heat and cooling load calculation first
An assessment of the amount of fin tube
How much dhw do you need?
Oil tank in good shape?
Natural gas or propane an option?
Electricity cost?

There are so many choices