Reports on Hydrotherm KN boilers?

Brad White_151

KC.... Ken Cohen. He wanted to use KC for the new line but KC was taken, so the new line is the KN for Ken.

tim smith

? Reports on Hydrotherm KN boilers

Just looking for responses on the KN series boilers from Hydrotherm. Trying to evaluate them and need input from any/all who have used them. Thanks in advance, Tim.

Brad White_9

We specify them among others.

We have these specified at a number of public jobs. None have been placed in service yet. The owners, the vendors and our company understand the risks associated with any new product. So from an actual, personally experienced track record standpoint, the jury is still out.


When we first heard of a cast iron condensing boiler, we said, "Aw, you have to be kidding...".

A co-worker and I, both skeptics and good tire-kickers, agreed to meet with folks from Mestek (parent company of HydroTherm) and the boiler designer, Ken Cohen. They came to near Boston, to the representative distributor, Sweeney-Rogers Co. in Franklin, MA. last February.

We watched one in action, a 600 MBH model firing in a test stand in their warehouse. We were briefed on their rationale of using CI in a condensing mode, forcing down-flow and the flow of condensate and combustion gasses in the same direction so as not to re-evaporate. (Re-evaporation deposits concentrated corrosives and begins the cycle.) The collection system for condensate is 316L stainless steel. The condensate pathways are essentially "brushed" of the droplets during fire and post-purge.


The White Paper KNWP-1, written by Ken Cohen, outlines all of this in more detail. Corrosion of cast iron is acknowledged but the material thickness and mitigation of the initial effects limits the potential significantly. Extrapolated lifespan of 24/7 100% load operation is 32 years and 163 years with 40% load over 6-month operation before the wall thickness is reduced below ASME standards.

We did question the part-load life being longer than a full 24/7 duty given that the downflow effect would be less at lower firing rates and cycling effects of course would be greater. Cycling wear is what it is, with any boiler (these having a 4:1 to 5:1 turndown depending on size). The longevity was expressely given for the heat exchanger, not replaceable/consumable components.

This lifespan range was explained to us by their independent laboratory analysis, examining the amount of iron present in the condensate, versus a non-CI condensing boiler. All boilers had traces of the boiler HEX parent metal regardless of resistance to corrosion. The CI leaching was determined over time, not only the absolute amount but the rates of loss at different firing rates.

The section castings were designed to be small, with stress patterns and limited thermal expansion when fed with near-freezing water at full fire. Not that you would run a boiler this way of course. Sections are joint with graphite port connectors.
The warranty is 21 years on thermal shock and is backed by Mestek, a company with some stability (a broad range of brands across the industry).

What we liked about it (basic functionality aside) is the alumina ceramic burner with limited flame and high radiant output, low gas pressure requirements (Dungs Gas Valve which will work fine on less than the 4 inches available in some parts of our city (Boston). Also ease of service, access to burner and gas valve, condensate tray; modulation range was reasonable. Replacement parts are of common manufacture, Dungs and Honeywell IIRC.

As stated, no personal track record yet, but we are ourselves eager to have this product prove itself. We have a high level of confidence in it, absent the final proof of long term operation.

Hope this helps.

Brad

marc friedman

ken ..
is a smart dude ...
you recognize the name, right ...??

Coen burner, Aerco, etc ....

however ....
my experiences w/ Mestek, Hydrotherm, and Sweeney-Rogers

all leave me pinching my A$$ tight ....

feel free to P.M. for Details ....

[Deleted User]

Installed a KN-6 (600mbh)

this fall. Started up by Hydrotherm Service Manager. Except for the gas valve being trimmed too much @ factory, it was a smooth start. Running @ 3:1 turndown.

Came w/ an integral Tekmar Control w/ 6 operating options. We are operating on O/D Reset - Primary/Secondary. Have not yet bugged the owners for consumption comparisons. So far, so good.

Josh_10

A very smart dude indeed. The Aerco KC-1000 is a heck of a boiler.

I was un-aware that he was of the Coen burner family..

Petewest

Info

How's your Hydrotherm KN-6 boiler running?.... Contemplating installing one.

Petewest

Info

What's your opinion on Hydrotherm KN-6 boilers?