About to pull the trigger on hydro air with indirect HW, right decision?

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Old 06-29-11, 07:21 AM
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About to pull the trigger on hydro air with indirect HW, right decision?

I currently have an oil fired hot air furnace and separate oil fired hot water heater. I would like to replace both systems and add central AC. After considering all options (forced hot water baseboard with indirect HW and stand alone AC, replacement oil furnace with AC evaporator coil and new separate HW heater, and AC air handler with hydro heat coil and indirect HW) I知 leaning towards doing the hydro air with indirect HW. My thinking (from what I read) is that the indirect HW heater will be much more efficient then the stand alone oil fired HW, and since I will already need an air handler for AC, it makes sense to just add the hot water coil. One of my concerns is that in summer the hot water heating will be less efficient, since you need to heat up the boiler first. I don稚 know if heating this mass every time we use hot water will actually cost more then the stand alone HWH.

For my boiler selection, I知 considering the Buderus G115WS/3 or Burnham MPO-IQ84.
For the air handler, I知 considering the ADP, B series with variable speed blower.
For the indirect, I'm deciding between the Weil-McLain Gold Plus, or Super Store.

Please share your thoughts on my equipment choices and if I知 choosing the best system. I will be doing most of the work myself, so each type of system is within a few hundred dollars of each other (baseboard, hydro, furnace).

Thanks!
 
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Old 06-29-11, 05:58 PM
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It doesn't take much to heat up the boiler for hot water in the summer. I'm not sure if going to a boiler with a hydro coil makes much sense. You still get the same type of heat: forced hot air. So there is no comfort advantage. I would think adding a boiler to your system would cost more than doing a forced air replacement. I doubt it is worth any efficiency gain on heating hot water if there is one.
 
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Old 06-30-11, 05:49 AM
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Thanks for the response Drooplug. My thought process for switching to a boiler was efficiency gains for HW as well as heating (boiler is 3% to 6% more efficient then oil furnace). The finished basement is currently heated by electric baseboard, so I can also replace that in the future with forced hot water. If I was not going to install AC, I would defiantly go with forced hot water baseboard throughout the house.
 
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Old 06-30-11, 06:52 AM
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How about doing mini-split type AC instead of central? They can be really efficient for the AC side, particularly if you have a good floorplan or don't need full AC everywhere. Then go baseboard, radiators, or panel radiators for the hydronics.
 
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Old 06-30-11, 07:09 AM
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I considered mini splits, however the house layout does not make it particle. I can install baseboard for a few hundred more then the hydro setup, but I知 not sure it is worth all the extra effort. I also have a wood stove and was hoping the air handler running on low speed would help distribute the heat more evenly when burning. So I guess I would ask, is forced hot water that much better then hydro air? Also, any thoughts on equipment brands? Thanks again for the help.
 
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Old 06-30-11, 06:12 PM
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Forced hot water is more comfortable. The heat emitters heat up slowly and also cool down slowly. Forced hot air, you get blasts of hot and the nothing when it is off. You also get the wind chill of the air moving. In another thread, someone also mentioned that forced hot air is less efficient because the more the air circulates in the house, the faster it exchanges heat with the outside.
 
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Old 07-01-11, 08:53 AM
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A properly designed and installed forced air heating system will NOT give out blasts of hot and then nothing but can be almost as comfortable as a hot-water system. That stated, I'll add that few residential systems are properly designed OR installed.

Using the same ductwork for heating and cooling is always a compromise and the cooling is more often than not the compromised element. Be darn sure that you can move enough air to effectively cool your house rather than just guess.

With a hydro-air system you CAN vary the water temperature to the coil to achieve some very good temperature control and comfort PROVIDING the ductwork is up to the challenge.

Quite honestly, I think any "efficiency improvements" from using a boiler and coil will take many years, probably decades, to achieve any kind of economic payback.
 
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