DIYbanter - View Single Post - Heating finished basement: add hydronic zone or use AC/heat pump?

Art Todesco

On 5/14/2015 8:40 PM, wrote:
On Thu, 14 May 2015 19:13:37 -0500, Unquestionably Confused
wrote:

On 5/14/2015 7:01 PM, Ralph Mowery wrote:
wrote in message
...
Hi.

I'm finishing my basement (open floor plan, 800sqft, walk-out, full height,
cinderblock walls, no water issues, in New York). It will have 2" EPS
insulation on interior of cinderblock walls, covered with sheetrock. I
have hydronic radiators in main floor of the house (oil-fired boiler) and I
also have just installed a mini-split A/C & Heat pump system for all rooms
of house with capacity for one more unit of 18,000BTU. I'm going to install
that last one to air condition the basement.

My question is: should I rely on that mini-split to heat the basement, or
should I install a new hydronic zone for the basement and install some
baseboards?

I just don't want to be done and then have to tear open walls to install
pipe and baseboards if it's going to be too cold to watch tv and hang out
down there.

My question is how cold does it get where you are at ?

If many days below about 25 to 30 deg F , that mini-split will probably not
be able to make enough heat, especially at 25 and below. For the southern
half of the US they usually work fine in many areas, but it does not get
below 25 for too many days.

Efficiency wise (and cost wise), you're probably spot on, Ralph. But it
being a split A/C and Heatpump would suggest to me that the unit has a
built-in resistance unit for just those cold snaps you suggest. OTOH,
depending upon just how much of the walkout basement is exposed at
grade, he may not need a helluva lot of heat to raise an average year
round ground temp (below frost line) to the 65 - 70 degree range.

We KNOW the hydronic will do the job. We SUSPECT the mi i-split will
need to run the electric coils at least part time to do the job if it
is capable of doing the job. I'd put in the hydronics. The mini-split
will still be used for AC - correct???. If so, the mini-split can
provide heat when the basement is a bit cool in the summer
/spring/fall and the hydronic boiler is not fired up.

And, the walls are either at ground lever or some of them below. It will
always feel cold by the walls. A lot depends on what the space will be
used for. But a nice perimeter of heat will go a long way to feel good
when it is really cold outside. The mini split units usually have an
air handler on the wall. When heating, it is ideal for the heat to be
low and keep the tootsies warm. Blowing around heat pump air will
usually make you feel cold even though the temp may be 70 or above.
Although I have a heat pump and a zoned furnace and I usually don't feel
the drafts. But I do feel the cool breeze in bed, when the heat pump
de-ices. Plus when it is too cold for the heat pump, my backup is
propane which can supply lots of heat .... probably much more than heat
coils. BTW, I am in western NC where it is certainly not as cold as in
NY.