Indirects

DC123

Wondering which small indirect (<50 gallons) has the largest heat exchanger? Any reason that you would want to pair a specific indirect with the same brand boiler or are they entirely mix-and-match?

hot_rod

No need to match brands.

If you want high performance and lots of HX surface you can buy a dual coil solar tank and supply both coils at once.

Usually around 12 sq. feet of HX in 50 gallon.

Reverse indirects have lots of coil surface for instant transfer.

I prefer smooth coils or corrugated stainless like the new HTP. The finned copper coils can lime up and reduce performance quickly in hard water conditions..

DC123

Great, thanks. Other than HTP (are you referring to the superstor pro?), any others that have the smooth coils or corrugated stainless? Does that describe the lochinvar squire?

hot_rod

One thought would be to sample your water first. Be sure it falls within the parameters of the tanks warranty. Stainless will be more sensitive to chlorides, for example.

I really like the water spec that HTP shows in the Pro manual, see below.

IF you have water outside of those parameters, perhaps a glass lined steel tank would be worth considering. The plumbers and suppliers in your area generally have an idea of which brands last in the local water.

HTP, Lochinvar Squire, HeatFlo are some good suggestions for stainless tanks. Bradford White, Bock or Caleffi for glass lined steel.

DC123

Thanks, Bob. I found the water quality report for my reservoir - looks like hardness avg is 138 (range 90-194) and chloride level is 67. Didn't see total dissolved solids anywhere (though they do report out specific conductance of 450 - which I think translates to ~250 for TDS), but looks like a stainless steel tank should work assuming I keep the temp to 140 or below.

Tinman

I use to be a Triangle Tube guy for indirects but the control is just a thermostat, not a sensor. On the existing TTs I have out there, I've retrofitted a sensor into the existing well. Quick and easy..

hot_rod

DC123 said:

Thanks, Bob. I found the water quality report for my reservoir - looks like hardness avg is 138 (range 90-194) and chloride level is 67. Didn't see total dissolved solids anywhere (though they do report out specific conductance of 450 - which I think translates to ~250 for TDS), but looks like a stainless steel tank should work assuming I keep the temp to 140 or below.

That hardness range must be in ppm or mg/l, same number? I'm use to gpg grains per gallon.

138 ppm is fairly hard water, probably on the high side of what the tank manufacturers like to see.

It is what it is, softening is an option but ion exchange softening brings other baggage.