Smaller indirect water heaters with best recovery rate.

Ron Jr._3

We currently install a few different brands depending on the customers needs. If they want a lifetime warantee we go with one particular brand that seems to have a horrible recovery time in a significant minority of installs. We always check by running 1 shower with blended water like someone's in the shower. With a tank already heated to usually 130 to 140 on a 40 to 50 gal tank. 

Most of them are connected to an oil boiler in the 100,000 btu range. Always installed with the proper circ and piping and mixing valve. 

We used to use one with a tank in tank design. And they recovered faster than any other style. But the longevity on those around here ( Long Island ) are extremely short. 

Wondering what the go to indirects the pros use here. 

Thanks ! 

motoguy128

My only experience is with a Weil McClain. According to the specs, the 40 gallon seems to have a good sized coil. I‘m pulling 100k from the boiler @190F inlet, 8GPM, 140F tank temp, 50F entering water temp. Will get close top 120F with colder 45F incoming water and 195F water.

That’s 2.5GPM @ a 77F temp rise. Enough for a continuous shower. Only time it comes close to falling behind is filling The whirlpool tub. But the 140F storage gives a little more buffer.

So if you filled a tub, did a hot load of laundry and then tried to take two showers at the same time while washing dishes... You might have an issue. Or wait 8-10 minutes and it recovers.

I do wish I had put in a HTP/Westinghouse 50 gallon so the 200k steam boiler shorty cycles a little less and I had a dedicated recirc connection. But it was $300 more.

hot_rod

It's a surface area game if you want performance so look at the square footage of the coils. Dual coils are great for performance, but $$.
I think Heat Flo still uses a lot of large diameter coil, so if you have the boiler HP to drive it. Tank in tank, reverse indirects, coil in tank, external plate HX, they all have pros and cons.

Could be the only way around metal tanks developing leaks is to go to a composite tank, but they can also have thermal expansion issues and temperature limitations.

Water is a big part, in some areas glass lined steel work best, in others the stainless tanks last longer.
Testing the water at each jobsite would give you some indication, but water can change over the seasons and as different sources are used. It could have low TDS, low chlorides one day, mid winter chlorides could skyrocket from deicers entering the aquifer. Stainless and high chlorides is a recipe for problems.

clammy

How about turbomax ,I ve put a couple in and no complaints as of yet . I like the fact that it does not contain much portable water so if you do have to de scale / de lime it flushing the chemical out isn’t as time consuming as trying to flush a standard say 40 gal indirect and get the smell of the cleaner out . . I still like the buderus tanks but being the manhole isn’t available on the newer style smaller tanks sizes and a few failures ( lack of anode replacement )so I have switched to the turbomax . They do require some extra piping and consideration but as of now I haven’t had any issues . I ve also used bock side kicks as a second again anode replacement is important . The bock from cold start 50 to 130 was about the same time as my old buderus st 150 so not to bad plus 1 inch connections but no manhole for cleaning . . I have found that even w a smaller output boiler like 70 mbtu w a model 34 they still work great and I have yet to get a not enough hot water complaint even in house holds w 2 female teenagers now that’s amazing lol . Peace and good luck clammy

TAG

Have often wondered how the "recovery" is determined. How many people install an indirect .. live with it and then replace and live with the replacement for a while?

My original Buderus setups back in the early 90's used an earlier version of the Thermoglase (sp) tanks. They were unbelievably heavy and had a faster recovery vs the ST150 that replaced them in the Buderus line. The ST150 was heavy as well .. but not as.

With the old tanks it seemed the mass of the tank itself added to the tanks ability to recover. I noticed this with the first St150 install .... using the same boiler as the older ones the ST150 would high limit before reaching temp. This was not the case using the old ... so the old must have had more tubing/ transfer area. The boiler would shut off prior to limit.

Both of the original ones have now failed .. and the ST from the early 00's as well. I replaced them with the Buderus SS tank -- it's much smaller and weighs a fraction of the old tank. They do not recover as fast as either tank ....

I was reading of too many failures w/ the glass tanks from Buderus ... so went with SS. Also -- they have the temp sensor well that fits the Buderus sensor

Robert O'Brien

Bock Sidekick or Laars/Bradford White and run them hotter. 150F-160F

Zman

I agree with your assessment of Amtrol and Triangle Tube (+rebadged).
Models with generously sized coils like Heatflo, Lochinvar and HTP seem to have plenty of happy customers.

Ron Jr._3

Thanks for all the input. And sorry to take so long to respond. 

Went back to a severely underperforming indirect and used their method to flush the outer surface of the coil. I was shocked it worked ! Maintained a steady 125 degrees out for almost 30 min then dropped to a low of 116 and maintained that temp and increased a bit over time. Ran the water like someone was in a shower throughout. 

sunlight35

curious what's their method for cleaning the coil.

motoguy128

Most homes find a 50 gallon with a little 30k output Gas burner Adequate unless you do long back to back showers. So a 40 gallon with 60-90k is nearly and endless supply.

Just stumbled into a mod con boiler and indirect today. Was Setup for 140F DHW temp with no mixing valve and 180F Boiler supply set point. Asked if they ever ran out of hot water. Turned it down to 130/160F. Knowing that in summer that setting has kept up just fine on my own system and will be a lot more efficient. Also configured the outdoor reset correctly. They have radiant floor target supply at 180F!!! I doubt it ever got there before the call ended. Nice way to crack concrete and tile.

JohnNY

clammy said:

I have switched to the turbomax

I don't think it gets any better than Turbomax. You just have to make sure you're using a high efficiency boiler or good thermal protection on your standard efficiency boiler. They pull ALL of the heat out of the boiler water.

As @hot_rod said, I look only at the EDR of the heat exchanger used in the tank. The published recovery numbers are often deliberately vague and somewhat contrived. As in, a First Hour delivery chart showing 200° boiler water and a 50° rise. That's not a real-world condition.

In reality, I use a lot of Weil-McLain indirects and since standby losses are minimal in sealed insulated tanks, I tend to rely more on storage capacity rather than recovery.

hot_rod

JohnNY said:

clammy said:

I have switched to the turbomax

I don't think it gets any better than Turbomax. You just have to make sure you're using a high efficiency boiler or good thermal protection on your standard efficiency boiler. They pull ALL of the heat out of the boiler water.

As @hot_rod said, I look only at the EDR of the heat exchanger used in the tank. The published recovery numbers are often deliberately vague and somewhat contrived. As in, a First Hour delivery chart showing 200° boiler water and a 50° rise. That's not a real-world condition.

In reality, I use a lot of Weil-McLain indirects and since standby losses are minimal in sealed insulated tanks, I tend to rely more on storage capacity rather than recovery.

And I have heard they sometimes test and rate tank performance in a hot room, 80• or so. That changes both standby and recovery to some degree. Plenty of ways to tweak tank performance numbers