direct vent boiler choice opitions?

clammy

looking at a job owners are doing a addation to there home adding a garage ,master suite over the garage ,small family room and some bump out to the front bedrooms .The home is steam now and not being against steam i replaced this steamer 8 years ago there is no way to add raditors to the system so in the plan we,ve decided radiant for the slab for the garage and baseboard for the remainder with 1 or 2 toespace heaters all in all 4 zones baseboard and 1 radaint .Now my true question am i better off getting a condensing direct vent pvc intake and exhuast or a non condensing direct vent ?I know that with the base board i won't really see that low of return temp but i may size the basebord for lower temp to give me a supply and return temp more giving to a condensing boiler also this unit will be used for a indirect dhwt .I origanally though about a munchkin or a dunkrick quatium 90 but i do like the modulating gas valves on the munchkin .thanks for any input doing this one for a close buddy and yes i did do a quick heat lose came out to about 74000 but i didn,t add in the basementand i will use a domistics hot water priority on the system don,t know about a reset on it though thanks and peace clammy

hr

6's really

with a conventional cast you will need to mix down for the radiant, and provide return protection, of course. As you noted with a condensing you would have to upsize emitters to meet the load at condensing temperatures. Do the math and see how much more baseboard and fan coil size and cost you would need.

Also how much DHW demand? If the condensor is always kicking into high gear to recover DHW and dropping out the heating zones to do so??? This may be inconvient.

A cast may be a better match.

Is noise an issue? Hard to beat a Munchkin for quiet operation. I've yet to find a quiet sealed comdustion or direct vent cast boiler.

Condensors will need a condensate drain or pump, add that into the mix. I suspect all things considered the condensing will price out a bit higher even with the radiant needed components for the cast boiler.

Venting for a Munchkin is very inexpensive with PVC. Most sealed or direct cast boilers require stainless AL 29 vent material.

Probably come down to what you are most comfortable installing and servicing Either would do the job.

hot rod

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