Condensing cast iron?

RobG

How does the Hydrotherm KN series boiler manage to provide high efficiency coupled with cast iron? Granted, it is a manufacturers claim, but up to 99%efficient? Is it a disposable unit, glean the efficiency while it rots out?



I would love a high efficiency cast iron residential unit. How do they do it?



Rob 

hot_rod

RAY

has been around for 6 years or so. No personal experience

RobG

rAY

I remember the rAY thread from a few years ago, but has anything come from the CI condensing technology? I can't find anything on the web about the rAY since 2011. It's not on Mestek's website.



How have the KN's been holding up?

nicholas bonham-carter

Condensing cast iron

There must be two separate heat exchangers, with the cast iron being the primary, and a smaller secondary stainless one to suck the last heat out of the flue gases.

Probably the return water goes to the secondary exchanger first, and then to the primary..

There is probably a low limit on the primary/secondary loop temperature though.--NBC

Robert O'Brien

Peerless

This a RaY in green



http://www.peerlessboilers.com/Products/ResidentialBoilers/Cast922/tabid/211/Default.aspx

Zman

AFUE

It looks like they are doing it with a secondary heat exchanger.

The KN-2 had an AFUE of 92.7% under the old rules. It looks like 90% under the new rules.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Flibrary.cee1.org%2Fsites%2Fdefault%2Ffiles%2Flibrary%2F9301%2F2014_March_CEE_Boilers_QPL.xls&ei=WlvdU5esJqP_igLY9YDICg&usg=AFQjCNFUuahDD6wSx18GbqY4-M2AU-7BUQ&sig2=PhfzjcZnHm-qNzb4CODT3Q

Drewser

Similar question...

Not trying hijack the thread at all, but I was wondering about a similar question...



We are getting quotes for a new boiler, and one of the recommended units is a Burnham ESC4. It is a cast iron boiler, 85%, and the manual says it can accept return water temps down to 110 degrees. I have always heard that 140 was kind of the standard minimum for cast iron, to prevent condensation from eating the boiler sections.



I know that the unit has electronic controls, and an option for a plug-in outdoor reset sensor. So I was kind of wondering, what am I missing about this? Do they just size the burners so that the flue gas temps stay high enough to prevent condensing at 110 degree return water temps? Or perhaps cycle the circulator so that the water in the boiler can come up to temp faster?



Just curious....if anyone could enlighten a relative noob about this, I'd appreciate it.



Thanks,



Andy

kcopp

I have some....

experience w/ the Ray. I had some control issues but the factory came through and got that fixed. The specific unit was in a gravity conversion system...loads of CI rads. Huge mass.

No secondary HX.

They are relying on on the thickness of the CI and the pins to hold up. This is a smaller version of the KN series they have had out for years.

The control can do a bunch of different things. The venting is only in stainless. plastic is not allowed.

jonny88

esc

I believe the ESC and ES2 have similar heat exchangers and have been designed to accept low temp return water.Problem is condensation in the flue.When installing these units I like to put a bypass between supply and return and use a gate valve to increase return temp.

Zman

Higher return?

Raising the return gets the boiler out of condensing zone and greatly reduces the efficiency.

Why bother spending extra money for the HE model?

Drewser

regarding the ESC

Condensing in the flue...I see. I guess in my situation even that would be minimized since it's a powered direct vent unit and the total flue length will be about 4-6 feet (if that is indeed the boiler I decide to go with).

RobG

I may be wrong

I may be wrong but I seem to remember something about siliconized cast iron being used and that helps with the corrosion issues? Once again, I may be wrong but it seems to ring a bell in my noggin. I don't see anything in the product literature though.



Rob

jonny88

ES2

yes Rob G I rememberr something about siliconized cast iron.I think that was their whole selling point so you could use odr without any problems.I still use odr on the boiler withh great success but am concerned with condensing in flue,ESC i am not familiar with.With bypasss odr will work fine.

Henry

CI condensing

I have seen a few installs of the KN and a few in laboratory conditions. There is NO secondary heat exchanger! The burner is along the top of the boiler casings. In the installs that I have seen, they stood up well. Here is the I & O manual:

http://mesteksa.com/fileuploads/Literature/Hydrotherm%20Boilers/KN%20Series%20Boiler/KN-2%20and%20KN-4%20Boiler%20IOM%20(KN-2_4%20IOM2-0714).pdf

In my old home, I had a Viking Junior condense for 5 years with no problems! BTW, It is till condensing nearly 35 years later! Installed in 1929!

kevin_58

condensing cast iron

nbc was right williamson makes the gwc its a cast iron primary heat exchanger and stainless secondary exchanger

kcopp

not the....

same boiler design. KN series/ Ray has no secondary HX.  Williamson and the Weil 90+ is the same boiler....they have a secondary hx.