Who Would You Recommend -- Indirect Hot Water Heaters

[robos]

Hello,

I'd like your take on the various models of indirect hot water heaters. I'm going to purchase a 40-50 gal unit shortly. I'm located in the north east and the water is hard.

From my reading there appears to be two main types. Those with internal coils and those with a tank within a tank.

The ones with the internal coils feature Porcelan Enamel Coatings (Dunkirk, Utica, etc.), 304 Stainless Steel Tubing (Burnham), Cupronickel fined tubing (Peerless).

The ones with the tank within the tank feature a stainless steel inner (Currugated for added surface area) with a steel outer (Weil-McLain, Triangle Tube).

Is one design better than the others? Does the Porcelan Enamel coating stay on the internal coils after thousands of cycles? The Weil-McLain tank within a tank states "Lowest pressure drop in the industry", how should that factor into a decision? In the tank within a tank design how does the outer tank hold up as its stated as Carbon Steel? Is it a weak link?

Thank you for your advice and thoughts.
Robo

[chocfull-o-nuts]

I am researching this as well but have yet to come to any conclusions. My water is hard but I have a water softener. The PH of the water is 7. I'm leaning towards stainless steel. My difficulty now is finding one with a bottom inspection port rather than a top inspection port.. I dont want to have to disconnect it to hose it out.

[johnsp]

Stay away from finned tubes. These will cake up with sediment the quickest. Stainless steel smooth coil or tank in tank. By the way, Triangle tube makes the W-M tank. I have a TR-36, great tank. Only issue is no bottom drain. Burnham and Crowm (same tank)only use 3/4 piping. I prefer 1". Check out Superstor or Slantfin. Reverse indirect is also a great option. ErgoMax, Turbomax. Laars also makes the Duraflow. I wanted to get one but there are not many distributors that carry their line.

[smadave]

I think the Weil McLain Gold Series is by far the best on the market right now. It is a tank within a tank design...stainless. The only way to go!

Dave in NJ

[robos]

Thanks for the comments. Please keep them coming.

Any thoughts on the longevity of the porcelan enamel coatings ?

Could you elaborate further on the reverse indirect? How do they compare on energy costs with the indirects? On first blush it looks like they would run everytime there is a need for hot water but they do have some thermal mass which could average out boiler cycles.

How does the 1" versus the 3/4" feed line affect operation? Isn't the internal surface area within the tank more important than feed tube diameter?

Thanks from a very curious Robo

[johnsp]

More flow, more heat transfer. I think an indirect should have it's own pump. 1" on a Taco 007 just sounds quieter to me.

A reverse indirect is no different then a tankless coil put in a thermos bottle rather then in a boiler with greater heat loss thanks to the flue pipe. That mass of boiler water will support short calls for hot water just as a mass of DHW does. No less or greater energy savings. They're better for making large amounts of hot water with a small tank, just throw a big boiler against them. Poor water conditions bother it less since the fresh water does not stagnate in a tank allowing sediment to settle out. If the boiler has no leaks, the boiler water should de-oxygenate and no additional chorines/metals/sediment should enter the system. Great to also use if you need a buffer tank for radiant. But I would only team it up with a low mass boiler since you're putting 20+ gl of boiler water in the indirect.

Any kind of coating I equate to a glass lined HWH. You usually only get 6-10 years out of them and you still need an anode rod. Buderus has a much better coating but still requires an anode. Stainless steel is beter IMO as long as your water is not high in chorides or has an off the scale PH level.

[Edited by johnsp on 11-05-2005 at 09:05 AM]