condensing boiler quality?

Mikes47

I have had some problems and want to know what the consensus is about quality. In this one particular case I have had 2 heat exchanger failures. The first boiler was a t80m 5 years old and developed a leak in the heat exchanger. Cause of failure looked like poor quality or design problem. The second boiler was 2 years old and the heat exchanger failed or developed a leak, cause of failure was as follows. The indirect sensor failed cold or read cool all the time causing the boiler to heat the water in the storage tank to 180 degrees and than continue to short cycle the boiler due to return and supply temperatures being almost the same and nowhere to dissipate heat. After speaking to the customer they realized the water had seemed much hotter than normal but not until we started asking questions. Then they realized this problem had started about 3 weeks earlier while the weather was still nice so they would not notice any delay or lack of home heating because no heat was necessary. The boiler was programmed with dhw priority for 30 minutes and than to go back to heating for 30 minutes and so on. This was not relevant due to warm outside temps. So the boiler would come on and heat water to 180 deg and than rapidly run past its set point for dhw heating of 180 and run up to about 190 or so and than cycle off, a minute or so later while dhw circulator was running temp would come down to 178 or so and boiler would fire again and so on. Well this went on constantly for 3 weeks or so. I assume this is what caused this 2 year old boiler to fail although I don't think this should be all that was necessary to cause a heat exchanger failure (should be more durable in my opinion not like it was running 200 plus). Also ridiculous that the software does not lock the boiler out after short cycling a few times in a row but I didn't write the software. Any way I have heard some negative things about Munchkin boilers and now I am not sure what to do. The customer does not want another Munchkin but may not have much of a choice at this point. So I am looking for some help on quality comparison of the Munchkin T80m which has a SS heat exchanger (now discontinued) so if replaced with a Muchkin  it will be with the Munchkin Elite 80.  if we go with something else it may be Weil McLain ultra 3ue model # ug 80 with a cast aluminum heat exchanger and the last contender is a Weil Mclain wm97+ Model # wm97+70 which also has a ss heat exchanger.  If anyone has input of something better int the70k to 80k but range I'm all ears...Thank You.

Zman

Triangle tube

Hands down I would use a triangle tube. The firetube HX is the only way to go.

The munchkin elite has the same gianonni exchanger you have experienced. Aluminum has no place in a condensing boiler. The WM 97+ uses the same HX design as triangle tube.

My opinion,

Carl

Steve Whitbeck

warranty

If there is any warranty credit apply it to the EliteFT 80.

Most heat exchanger failures are due to install.

The fact that you lost two tells me something is wrong.

A boiler cycling at 180* with NO load doesn't cause any temp shock.

a hot boiler being shocked with cold water does.

What took out the heat exchangers on Munchkin boilers was exhaust gas reversion.

when the boiler sucks in it's own exhaust the condensate becomes highly acidic.

Also if the boiler is not cleaned properly ( removing the crud between the tubes I have been told by the factory that that has caused isues.

I have cut apart a few boilers but did not see this.