1...New construction, put pex tubing in garage and basement concrete.
Customer wants a water to water that also has forced air. This is a first
for me. I told him its going to be two units. Anybody know if there is such
2... Have to reverse engineer this job since he just put pex all over the
place. He said he did it at his previous home that had a wood burner. Asked
him what his design BTU/ft/sq is, Reynolds number etc. Oh well, thinking
about charging him for design if he doesn't go with it.
3.. Is there a two stage/speed water to water out there? never sold one
Good night, hot, tired, & ticked off. Jr and I were in 130 degree attics,
rain, wind, crawls, rooftops, I'm wore out watching him work so
I did one in Canada, back a good 12 or so years ago. Econar was trying
to make head way in the area and they sold a drafstman of an MEP firm
one cheap. I ended up doing the tin, and later fixing up some
It could dump all its heat to water or to air, one or the other, not
at the same time.They were heating a swimming pool in summer and
forced air heat in house in winter. The heat came from the ground in
both situations, not like they were cooling the house and dumping heat
to the pool.
You could hack or 'reverse engineer' a system to do this, but I think
you would be better off with two systems.
There are a lot of mfgrs that make dual water & air units.
I'm not sold on any of them, the cost for 2 units makes the other option
I'm also not a fan of the desuperheaters for domestic water heating.
Unfortunately, these are required for any sort of rebate/incentive from the
utilities in some areas... (states)
I'm a fan of a water to water unit with water coils for the air side.
Whenever your doing water to water for radiant, make sure you include a
buffer tank, sized appx 1 gallon/1000 btu.
In a 60,000 Btuh home, you'd need a min 60 gal buffer tank.
An Aquastat will operate the geo unit & allow it to run longer & avoid the
short cycling that kills those tied direct to a radiant floor.
In addition, your HP can generate chilled water in the summer & you can
circulate that to fan coils. Make sure your buffer tank is well insulated
w/foam, as a fiberglass wrapped tank will condense water inside the batt &
rot the thing from the outside in.
To cut down on loopfield install costs in cold climates, size the unit for
125-130% of cooling load & add aux electric or ?? heat to cover the coldest
design temps. Pump & dump, size for full heating loads.
Also, rather than a large fan coil unit for the whole house, you can get a
number of smaller ones for zoning & less ductwork...
Multi Aqua makes a number of interesting & inexpensive units. Not the best,
but a decent option for the price.
I've done a couple of these systems over the years & they've been very happy
with the outcome.
Also, tying the GSHP into a primary loop serving & circulating through the
tank w/ secondary circ pumps for the radiant, fan coils, etc... allows a
couple extra capped & valved lines for a emergency boiler attachment, a wood
boiler, etc... This is the system I'm planning for the home I'm building
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