Versa Hydro or UFT-80, Which will best cover this heat loss?

D107

I’d greatly appreciate feedback on this. I’ve had a pro heat loss done, have attached a pdf that shows heat loss and gain room by room, zone by zone from OT 0 degrees through 60º, for 68º indoor set temp. Design day is 10ºF. For a mod-con we are hoping we can do an AWT of 130º, meaning SWT of 140º. We’ve insulated about as much as we can with closed cell foam in the attic, dense pack cellulose in the walls, and fiberglass in the basement rim joists. Piping is in series 3/4" copper piping except for the old insulated 1" steel risers. With our current 170Kbtu old oversized boiler, no problem with uneven heating @160º SWT, 150º AWT.

The two options are the HTP Versa Hydro PHE130-55 or the HTP UFT-80 with a Turbomax 23 Reverse Indirect to act as both indirect HWH and Buffer Tank. The plan is for an ECM circ with three low-energy draw zone valves, outdoor reset.

Total heat loss is about 38.6K btu. (Using the virtual heatloss method of actual usage with our old 75% AFUE boiler, loss shows about 26Kbtu.) The cast iron emitter gain to loss ratio is good for the main and second floors. Basement zone design day loss is about 11,000btu, slantfin baseboard gain only 6,760. I am seriously considering replacing slantfin with CI rads but contractor suggests the buffer in either system choice would handle the emitter btu basement deficit and that I should go through a heating season and see how it works before spending the money on CI rads.

Major questions:
1. With either of the above systems, my concern is the ability to work around the low basement emitter gain without short cycling or having to install a valve to mix in a higher SWT for the basement. Can the buffer of the Versa Hydro or Turbomax handle this on design OR shoulder day? Smallest zone loss at 60ºF is 1349btu, with a gain of 3300btu. I’ve read that sometimes you can lower the ∆T SWT/RWT to accommodate this problem.
2. Note that my wife and I have been using a 50 gallon stand-alone gas HWH which fires at 30Kbtu set at 140º mixed down to 120º and we have never run out of hot water even with back to back showers. Our makeup water hardness is 126.67ppm, Chlorides 83.5ppm. Conductivity is 530 mmhos. Ph is 7.28. TDS: 355ppm. If the Turbomax DHW coils corrode over time, then I'm guessing that replacing that unit will be less expensive than replacing the entire Versa if it has the same problem. However the Versa saves more space, and its lowest turndown output would equal the lowest firing rate of 26,000btu/10 = 2,600btu. compared to the UFT-80's 8,000 btu. I think I've just talked myself into the Versa....Thoughts? (Post has been edited/corrected so a few subsequent answers may seem non-sequitur.)

Rich_49

What temp is required in the TurboMax to make appropriate temp DHW ?

You mentioned with the TurboMax the heating system will stay sealed . What do you mean by this ? The Versa has complete isolation of DHW and CH fluids .

D107

Turbomax tables are attached.
What I meant by sealed in my awkward way was that with our questionable water, the dhw system would always be the most vulnerable with either system choice; the dhw side would always need the most maintenance. So with the Versa having both dhw and heating within the same unit it would be the most expensive to replace if there was a problem.

Rich_49

From Versa Hydro Manual



LP-314 Rev. 2.3.17
11
as drinkable water supplied from utility or well water in
compliance with EPA secondary maximum contaminant levels
(40 CFR Part 143.3). If the water contains contaminants higher
than outlined by the EPA, water treatment is recommended
and additional, more frequent maintenance may be required.
If you suspect that your water is contaminated in any way,
discontinue use of the appliance and contact an authorized
technician or licensed professional.
•
Water pH between 6.5 and 8.5
•
pH levels below 6.5 can cause an increase in the rate
of corrosion. pH of 8.5 or higher can potentially cause
lime scale build-up
•
Maintain water pH between 6.5 and 8.5. Check with
litmus paper or have it chemically analyzed by a local
water treatment company.
•
If the pH is not between 6.5 and 8.5, consult a local
water treatment company for solutions.
•
Hardness less than 12 grains (200 mg/L) (Residential
Use - water temperatures below 140
o
F)
•
Hardness less than 7 grains (120 mg/L) (Commercial
Use - water temperatures of 140
o
F and greater)
•
Hardness levels above the required amounts can
lead to lime scale build-up throughout the system.
Water below 5 grains/gallon (85 mg/L) may be over
softened.
•
Consult local water treatment companies for
unusually hard water areas (above the required
amounts) or for other treatment solutions if water
is being over softened (below 5 grains/gallon [85
mg/L]).
•
Chloride concentration less than 100 ppm (mg/L)
•
Do not fill appliance or operate with water containing
chlorides in excess of 100 ppm (mg/L).
•
Using chlorinated fresh water should be acceptable
as levels are typically less than 5 ppm (mg/L).
•
Do not connect the appliance to directly heat
swimming pool or spa water.
•
Total Dissolved Solids (TDS) less than 500 ppm
(mg/L)
•
Total dissolved solids are minerals, salts, metals, and
charged particles that are dissolved in water.
•
The greater the amounts of TDS present, the higher
the corrosion potential due to increased conductivity
in the water.
•
If using softened water to fill the appliance, it is
still possible to have high TDS. This water can be
corrosive. Consult local water treatment companies
for other treatment solutions to reduce this effect.
*NOTE:
To promote appliance service life, it is strongly
recommended to follow the maintenance procedures in
this

D107

@Rich Thanks. Well our PH is fine; hardness is borderline (7.40 grains). Chlorides are borderline (83.5ppm--though some recommend 25ppm or lower.) (The heating system could be filled with RO or distilled water, though there are claims that such water can leach metal ions from the system.) My water test chemist converted the conductivity to a TDS of roughly 355ppm. Our conductivity is 530 mmhos; Alkalinity 110, and sulfates 16ppm.

Henry

Go with the VersaHydro due to the water. Also it is made of SS. We have replaced many Thermo 2000 tanks.