GB142 for hydro coil?

RianS

I am looking for some opinions on switching a oil fired hot air furnace to a hydro air handler using a GB142 on LP gas. I would also use it for domestic hot water. I know it wouldnt condense much, but how much lower would the efficiency be? Is there any harm to the boiler? Also would like to add some solar. Without the oil tanks I could install some storage tanks for the solar system. So what do you guys think?

Brad White

You may still condense

if you get a four or even six row coil and select it for the capacity you need when supplied with 140 degree or cooler water and return it 30 or even 40 degrees cooler.

You would be looking for an average water temperature of 120-125 degrees F to assure a return water temperature about 100-110 degrees. You would still get condensing at slightly higher conditions but why not see how far you can take a multiple row coil? No reason to assume that all coils need 180 degree water, right?

That said, if you do run warmer water, it still all gets down to the return water temperature. Off-hand and strictly as conjecture, I would expect your efficiency to be in the high 80's running 160 degree water out of it yet returning above dewpoint. Buderus might have curves or tabular data specific to that; I am not sure.