New boiler for mixed system house

[Deleted User]

Yes there are different options and if price is not a factor i would go with a mod con boiler. If your hydro system is not calling for heat the radiant will reap the benefits of the new boiler.
The hydro air is set for a higher temp and your boiler will probably not condense with those temps but you will still be able to modulate the gas usage based on what your demand is.
If you go with a cast iron boiler make sure it piped primary secondary to protect the cast iron.

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Andy_17

Which Direct vent Gas boiler for mixed system house

Finishing a big renovation in the NE. 1st.floor is full radiant floor heat. 2nd fl is hydronic coils in air handlers for heat. I'm getting mixed opinions on what type of boiler I should use.
Would really like to go w/ a high efficency condensing unit, but i've had 2 different contractors offer different opinions. 1 said to say cast iron,but it could be a problem w/ low water return temps. Second said Mod/ condensing unit w/ hot water storage tank, but not to expect the efficency that the company claims because of the higher output temps.
It seems that both have draw backs what is the right way to go?
Thanks for any advice.

Brad White_62

I agree in principle

that a ModCon boiler will reap the most benefit from you. As Mike said, the hydro-air will determine your high water temperature and you can (and should) mix down for radiant floors.

The minor point of difference I take is that you can re-set your hydro-air temperature much of the year to a point where you can still condense and take advantage of the high efficiency benefits. May not be as much as you want but it can be more than most people think.

If you have not yet selected your Hydro-Air coils, see if you can get 3 or 4-row coils or whatever is deemed appropriate to use 140 degree F or lower hot water supply temperatures. Adjust your reset according to the air supply temperature to your warmest desired hydro-air heated space.